Rules for the classification of ships, Part 2, 2013 - crs.hr for the... · 11.7 construction and initial tests of watertight decks, ... annex d guidelines for direct calculations

RULESFOR THE CLASSIFFICATION OF

SHIPS

Part 2 - HULL

2013

CROATIAN REGISTER OF SHIPPING

Hrvatska (Croatia) • 21000 Split • Marasovićeva 67 • P.O.B. 187Tel.: (...) 385 (0)21 40 81 11Fax.: (...) 385 (0)21 35 81 59

E-mail: [email protected] site: www.crs.hr

By decision of the General Committee of Croatian Register of Shipping,

RULES FOR THE CLASSIFICATION OF SHIPSPART 2 – HULL

has been adopted on 19th June 2013 and shall enter into force on 1st July 2013

RULES FOR THE CLASSIFICATION OF SHIPSPART 2

2013

REVIEW OF AMENDMENTS IN RELATION TO PREVIOUSEDITION OF THE RULES

RULES FOR THE CLASSIFICATION OF SHIPSPart 2 – HULL

All major changes throughout the text in respect to the Rules for the classiffication of ships, Part 2 – Hull,edition 2012, forming the basis for this edition of the rules are shaded.

Items not being indicated as corrected have not been changed.

The grammatical and print errors, have also been corrected throughout the text of subject Rules but are notindicated as a correction.


2013

The subject Rules include the requirements of the following international Organisations::

International Maritime Organization (IMO)

Conventions: International Convention for the Safety of Life at Sea 1974 (SOLAS 1974) and all subsequentamendments up to and including the 2010 amendments (MSC.291(87))Protocol of 1988 relating to the International Convention for the Safety of Life at Sea 1974, asamended (SOLAS PROT 1988)International Convention for the Prevention of Pollution from Ships 1973, as modified by theProtocol of 1988 thereto (MARPOL 73/78) and all subsequent amendments up to and includingthe 2006 amendments ((MEPC.141(54))

International Association of Classification Societies (IACS)

Unified Requirements (UR): F1 (Rev.1, 2002), F2 (Rev.2, 2012), S1 (Rev.7, 2010), S1A (Rev.6, 2010), S2 (Rev.1, 2010), S3(Rev.1, 2010), S4 (Rev. 3, 2010), S5 (Rev.1, 2010), S6 (Rev.6, 2010), S7 (Rev.4, 2010), S10(Rev.3, 2012), S11 (Rev.7, 2010), S12 (Rev.5, 2010), S13 (Rev.2, 2010), S14 (Rev.4, 2012), S17(Rev.8, 2010), S18 (Rev.8, 2010), (S19 (Rev.5, 2004), S20 (Rev.5, 2010), S22 (Rev.3, 2004),S23 (Rev.4, 2007), S28 (Rev.3, 2010), S31 (Rev.4, 2007), Z8 (Rev.1, 1995), Z9 (Rev.2, 1997),Z10.1 (Rev. 19, 2011), Z10.2 (Rev.29, 2011), Z10.4 (Rev.10, 2011),

Procedural Requirements (PR): PR 34 (Rev.0, Corr.1 2009) - deleted 2012 and replaced by UI SC 223

Unified Interpretations MPC94 (2008), SC93 (Rev.1, 2010), SC122 (Rev.1, Corr.1 2008), SC154 (2000), SC179 (Rev.2,2011), SC180 (Rev.3, 2012), SC182 (Rev.1, 2005), SC207 (Corr.1, 2007), SC208 (Corr.2, 2009),SC209 (2006), SC210 (2006), SC223 (Rev.2, Corr.1,2012), SC258 (2013), SC259 (2013),

Recommendations REC83 (2003), REC94 (2007), REC97 (2007),

Other requirements “Finnish - Swedish ice class rules” (1985), as amended 2010


2013

ContentsPage

1 GENERAL REQUIREMENTS.............................................................................................................................. 11.1 APPLICATION .............................................................................................................................................................................11.2 DEFINITIONS ..............................................................................................................................................................................11.3 SCOPE OF SUPERVISION ..........................................................................................................................................................21.4 MATERIALS ................................................................................................................................................................................21.5 WATER LEVEL DETECTORS ON SINGLE HOLD CARGO SHIP OTHER THAN BULK CARRIERS (SOLAS 1974, Ch.

II-1, Reg. 25) ...............................................................................................................................................................................10

2 DESIGN PRINCIPLES......................................................................................................................................... 112.1 GENERAL...................................................................................................................................................................................112.2 UPPER AND LOWER HULL FLANGE ....................................................................................................................................112.3 UNSUPPORTED SPAN..............................................................................................................................................................122.4 END ATTACHMENTS ..............................................................................................................................................................122.5 EFFECTIVE WIDTH OF PLATING ..........................................................................................................................................132.6 STRUCTURAL DETAILS..........................................................................................................................................................132.7 RIGIDITY OF TRANSVERSES AND GIRDERS .....................................................................................................................152.8 EVALUATION OF NOTCH STRESSES ...................................................................................................................................152.9 CORROSION ADDITIONS........................................................................................................................................................15

3 DESIGN LOADS ................................................................................................................................................... 173.1 GENERAL...................................................................................................................................................................................173.2 EXTERNAL SEA LOADS..........................................................................................................................................................173.3 CARGO LOADS, LOAD ON ACCOMMODATION DECKS..................................................................................................193.4 LOAD ON TANK STRUCTURES .............................................................................................................................................203.5 DESIGN VALUES OF ACCELERATION COMPONENTS.....................................................................................................20

4 LONGITUDINAL STRENGTH .......................................................................................................................... 224.1 GENERAL...................................................................................................................................................................................224.2 VERTICAL LONGITUDINAL BENDING MOMENTS AND SHEAR FORCES....................................................................244.3 BENDING STRENGTH..............................................................................................................................................................274.4 SHEARING STRENGTH ...........................................................................................................................................................284.5 ADDITIONAL BENDING MOMENTS.....................................................................................................................................304.6 BUCKLING STRENGTH...........................................................................................................................................................304.7 HULL GIRDER ULTIMATE STRENGTH................................................................................................................................36

5 SHELL PLATING................................................................................................................................................. 425.1 GENERAL...................................................................................................................................................................................425.2 BOTTOM PLATING ..................................................................................................................................................................425.3 SIDE SHELL PLATING .............................................................................................................................................................435.4 STRENGTHENING OF BOTTOM FORWARD........................................................................................................................445.5 BILGE KEEL ..............................................................................................................................................................................445.6 BULWARK .................................................................................................................................................................................455.7 OPENINGS IN THE SHELL PLATING ....................................................................................................................................45

6 DECKS ................................................................................................................................................................... 476.1 STRENGTH DECK.....................................................................................................................................................................476.2 LOWER DECKS.........................................................................................................................................................................486.3 HELICOPTER DECKS...............................................................................................................................................................49

7 BOTTOM STRUCTURES ................................................................................................................................... 517.1 SINGLE BOTTOM .....................................................................................................................................................................517.2 DOUBLE BOTTOM ...................................................................................................................................................................517.3 BOTTOM STRUCTURE IN WAY OF THE MAIN PROPULSION PLANT............................................................................557.4 DOCKING CALCULATION......................................................................................................................................................56

8 FRAMING SYSTEM ............................................................................................................................................ 578.1 TRANSVERSE FRAMING ........................................................................................................................................................578.2 BOTTOM, SIDE-AND DECK LONGITUDINALS, SIDE TRANSVERSES............................................................................59

9 SUPPORTING DECK STRUCTURES............................................................................................................... 629.1 GENERAL...................................................................................................................................................................................629.2 DECK BEAMS, LONGITUDINALS AND GIRDERS ..............................................................................................................62


2013

9.3 PILLARS .................................................................................................................................................................................... 639.4 CANTILEVERS ......................................................................................................................................................................... 639.5 HATCHWAY GIRDERS AND GIRDERS FORMING PART OF THE LONGITUDINAL HULL STRUCTURE................. 63

10 WATERTIGHT BULKHEADS ...........................................................................................................................6510.1 GENERAL.................................................................................................................................................................................. 6510.2 SCANTLINGS............................................................................................................................................................................ 6610.3 SHAFT TUNNELS..................................................................................................................................................................... 67

11 TANK STRUCTURES ..........................................................................................................................................6811.1 GENERAL.................................................................................................................................................................................. 6811.2 SCANTLINGS............................................................................................................................................................................ 6811.3 TANKS WITH LARGE LENGTHS OR BREADTHS............................................................................................................... 7011.4 DETACHED TANKS................................................................................................................................................................. 7011.5 SWASH BULKHEADS.............................................................................................................................................................. 7011.6 PROCEDURES FOR TESTING TANKS AND TIGHT BOUNDARIES.................................................................................. 7111.7 CONSTRUCTION AND INITIAL TESTS OF WATERTIGHT DECKS, TRUNCKS, ETC.................................................... 73

12 STEM AND STERNFRAME................................................................................................................................7612.1 DEFINITIONS............................................................................................................................................................................ 7612.2 STEM.......................................................................................................................................................................................... 7612.3 STERNFRAME .......................................................................................................................................................................... 7612.4 PROPPELER SHAFT BRACKETS ........................................................................................................................................... 7912.5 BOW AND STERN THRUST UNIT STRUCTURE ................................................................................................................. 80

13 SUPERSTRUCTURES AND DECKHOUSES ...................................................................................................8113.1 GENERAL.................................................................................................................................................................................. 8113.2 SIDE PLATING AND DECKS OF NON-EFFECTIVE SUPERSTRUCTURES ...................................................................... 8113.3 SUPERSTRUCTURE END BULKHEADS AND DECKHOUSE WALLS .............................................................................. 8213.4 DECKS OF SHORT DECKHOUSES ........................................................................................................................................ 83

14 STRENGTHENING FOR NAVIGATION IN ICE............................................................................................8414.1 GENERAL.................................................................................................................................................................................. 8414.2 SCANTLINGS............................................................................................................................................................................ 8514.3 REQUIREMENTS FOR THE ICE CLAS NOTATION 1D....................................................................................................... 9014.4 ICE CLASS DRAUGHT MARKING......................................................................................................................................... 91

15 WELDED JOINTS ................................................................................................................................................9215.1 GENERAL.................................................................................................................................................................................. 9215.2 DESIGN...................................................................................................................................................................................... 92

16 FATIGUE STRENGTH ........................................................................................................................................9816.1 GENERAL.................................................................................................................................................................................. 9816.2 FATIGUE STRENGTH ANALYSIS ....................................................................................................................................... 10016.3 FATIGUE STRENGTH ANALYSIS FOR WELDED JOINTS BASED ON LOCAL STRESSES......................................... 108

17 STRENGTHTENINGS FOR HEAVY CARGO, BULK CARRIERS, ORE CARRIERS ...........................10917.1 STRENGHTENINGS FOR HEAVY CARGO ......................................................................................................................... 10917.2 BULK CARRIERS ................................................................................................................................................................... 10917.3 ORE CARRIERS ...................................................................................................................................................................... 12417.4 LOADING INFORMATION FOR BULK CARRIERS, ORE CARRIERS AND COMBINATION CARRIERS .................. 124

18 OIL TANKERS....................................................................................................................................................12918.1 GENERAL................................................................................................................................................................................ 12918.2 STRENGHT OF GIRDERS AND TRANSVERSES................................................................................................................ 13818.3 OILTIGHT LONGITUDINAL AND TRANSVERSE BULKHEADS .................................................................................... 14018.4 WASH BULKHEADS.............................................................................................................................................................. 14018.5 ACCESS ARRANGEMENTS .................................................................................................................................................. 14018.6 STRUCTURAL DETAILS AT THE SHIP'S END................................................................................................................... 14018.7 SMALL TANKERS.................................................................................................................................................................. 141

19 BARGES AND PONTOONS ..............................................................................................................................14219.1 GENERAL................................................................................................................................................................................ 14219.2 LONGITUDINAL STRENGTH............................................................................................................................................... 14219.3 WATERTIGHT BULKHEADS AND TANK BULKHEADS ................................................................................................. 142


2013

19.4 ENDS.........................................................................................................................................................................................142

20 TUGS .................................................................................................................................................................... 14320.1 GENERAL.................................................................................................................................................................................14320.2 STERNFRAME, BAR KEEL....................................................................................................................................................14320.3 ENGINE ROOM CASINGS......................................................................................................................................................143

21 PASSENGER SHIPS........................................................................................................................................... 14421.1 GENERAL.................................................................................................................................................................................14421.2 WATERTIGHT SUBDIVISION...............................................................................................................................................14421.3 LONGITUDINAL STRENGTH................................................................................................................................................14521.4 DOUBLE BOTTOM .................................................................................................................................................................14521.5 DECK STRUCTURE ................................................................................................................................................................14521.6 BOTTOM AND SIDE SHELL..................................................................................................................................................14521.7 SIDE STRUCTURE ..................................................................................................................................................................145

ANNEX A ADDITIONAL REQUIREMENTS FOR EXISTING BULK CARRIERS...................................... 146A.1 EVALUATION OF SCANTLINGS OF THE TRANSVERSE WATERTIGHT CORRUGATED BULKHEAD BETWEEN

CARGO HOLDS NOS. 1 AND 2, WITH CARGO HOLD NO. 1 FLOODED.........................................................................146A.2 EVALUATION OF ALLOWABLE HOLD LOADING OF CARGO HOLD NO. 1 WITH CARGO HOLD NO. 1

FLOODED.................................................................................................................................................................................155A.3 IMPLEMENTATION OF THE ADDITIONAL REQUIREMENTS A.1 AND A.2.................................................................158A.4 REQUIREMENTS OF THE SOLAS 1974, CH. XII, REG. 12&13 FOR BULK CARRIERS.................................................160A.5 ADDITIONAL REQUIREMENTS FOR LOADING CONDITIONS, LOADING MANUALS AND LOADING

INSTRUMENTS FOR BULK CARRIERS, ORE CARRIERS AND COMBINATION CARRIERS......................................161A.6 PROVISION OF DETAILED INFORMATION ON SPECIFIC CARGO HOLD FLOODING SCENARIOS........................162A.7 RENEWAL CRITERIA FOR SIDE SHELL FRAMES AND BRACKETS IN SINGLE SIDE SKIN BULK CARRIERS

AND SINGLE SIDE SKIN OBO CARRIERS (IACS UR S 31)...............................................................................................163A.8 RESTRICTIONS FROM SAILING WITH ANY HOLD EMPTY FOR BULK CARRIERS (SOLAS 1974, CH. XII, REG.

14)..............................................................................................................................................................................................171

ANNEX B ADDITIONAL REQUIREMENTS FOR OIL TANKERS OF 130 M IN LENGTH ANDUPWARDS AND OF OVER 10 YEARS OF AGE........................................................................................... 172

B.1 CRITERIA FOR LONGITUDINAL STRENGTH OF HULL GIRDER FOR OIL TANKERS ...............................................172B.2 EVALUATION RESULT OF LONGITUDINAL STRENGTH OF THE HULL GIRDER OF OIL TANKERS ....................173

ANNEX C WATER LEVEL DETECTORS ON SINGLE HOLD CARGO SHIPS OTHER THAN BULKCARRIERS (SOLAS 1974, CH. II-1, REG. 25)................................................................................................ 175

ANNEX D GUIDELINES FOR DIRECT CALCULATIONS OF SHIP STRUCTURE ................................... 176D.1 BASIC GUIDELINES FOR DIRECT CALCULATION OF SHIP STRUCTURES ................................................................176D.2 FEM STRUCTURAL MODELS...............................................................................................................................................180D.3 LOADING OF THE STRUCTURE ..........................................................................................................................................189D.4 STRUCTURAL RESPONSE CALCULATION BY FINITE ELEMENTS METHOD............................................................192D.5 CALCULATION OF STRUCTURAL FEASIBILITY ACCORDING TO CRS CRITERIA...................................................193D.6 REFERENCES ..........................................................................................................................................................................196

RULES FOR THE CLASSIFICATION OF SHIPS 1PART 2

2013

1 GENERAL REQUIREMENTS

1.1 APPLICATION

1.1.1 The present Part of the Rules applies to steelships and floating facilities of welded construction, whoseratios of main dimensions are taken within the limits given inTable 1.1.1.

For areas of navigation see Rules for the clas-sification of ships, Part 1 - General requirements, Chapter 1-General information, Section 4.2.

Table 1.1.1

Area of navigationRatio1 2 3 4 5 -8

Length/depthL/D 18 18 19 20 20

Breadth/depth 1)

B/D 2,5 2,5 3 3 41) For vessels of dredging fleet, not more than 3.0. For

floating cranes, not less than 4,5

1.1.2 The scantlings of hull members, essential to thestrength of ships and floating facilities whose constructionand dimensions are not regulated by the present Rules aresubjected to special consideration by the CROATIAN REG-ISTER OF SHIPPING (hereafter referred to as: the Regis-ter).

1.2 DEFINITIONS

Definitions and explanations relating to thegeneral terminology of the Rules are given in the Rules, Part1 - General requirements, Chapter 1- General information.

For the purpose of the present Part of the Rulesthe following definitions have been adopted.

1.2.1 Types of ships

For the types of ships see Rules, Part 1 - Gen-eral requirements, Chapter 1- General information, Section4.2

1.2.2 Basic definitions

1.2.2.1 Summer load waterline - waterline on thelevel of the centre of the freeboard mark, for ship's positionwithout permanent trim and heel

1.2.2.2 Forward perpendicular - is the perpendicularat the intersection of the summer load waterline with the foreside of the stem.

1.2.2.3 After perpendicular - is the perpendicular atthe intersection of the summer load waterline with the afterside of the rudder post. For the ships without a rudder post,the A.P. is the perpendicular at the intersection of the water-line with the centreline of the rudder stock.

1.2.2.4 Midship section - the hull section at the middleof ship's length L.

1.2.2.5 Midship region - the part of ship's length; 0,2L aft and 0,2 L forward of amidship (unless expressly pro-vided otherwise).

1.2.2.6 Ship's ends - portions of the ship's length from0,05L abaft perpendiculars to the ship's ends.

1.2.2.7 Machinery space aft - corresponds to the po-sition of the mid-length of the machinery space beyond 0,3 Laft of amidships.

1.2.3 Main dimensions

1.2.3.1 Length of ship, L - distance, in [m], measuredon the summer load waterline from the fore side of the stemto the after side at the rudder post, or the centre of the rudderstock, if there is no rudder post. L are not to be smaller than96% and are not to be greater than 97% of the ship's lengthon the summer load water line.

In ships with unusual stem or stern arrange-ments the length of ship, L, will be specially considered.

This requirement does not apply to CSR BulkCarriers and Oil Tankers.

1.2.3.2 Breadth of ship, B - greatest distance, in [m],measured amidships to the outside of frames.

1.2.3.3 Depth of ship, D - the vertical distance, in [m],measured amidships from the base line, to the top of the deckbeam at side on the uppermost continuous deck. In shipshaving a rounded gunwale, the depth is measured to the pointof intersection of the moulded lines of upper deck and side,the lines extending as though if the gunwale were of angulardesign.

1.2.3.4 Draught of ship, d - the vertical distance, in[m], measured amidships from the top of the plate keel or barkeel to the summer load waterline.

1.2.4 Decks and platforms

1.2.4.1 Upper deck - the uppermost continuous deckextending the full length of the ship

1.2.4.2 Strength deck - the deck forming the upperflange of the hull girder. The uppermost continuous deck orthe deck of a midship superstructure of an effective lengthmay be considered as the strength deck (see 4.1.3).

1.2.4.3 Bulkhead deck - the deck to which the maintransverse watertight bulkheads are carried.

1.2.4.4 Freeboard deck - the deck from which thefreeboard is calculated as stated in the ICLL (InternationalConvention on Load Lines, 1966, as amended).

1.2.4.5 Lower decks - the decks located below the up-per deck. Where the ship has several lower decks, they arecalled: second deck, third deck etc., counting from the upperdeck.

1.2.4.6 Platform - lower deck which is extending overportions of the ship's length or breadth.

1.2.4.7 Superstructure deck - deck forming the top oftier of superstructure. Where the superstructure has severaltiers, the superstructure decks are called as follows: first tiersuperstructure deck, second tier superstructure deck, count-ing from the upper deck.

2 RULES FOR THE CLASSIFICATION OF SHIPSPART 2

2013

1.2.4.8 Deckhouse top - deck forming the top at a tierof a deckhouse. Where the deckhouse has several tiers, thedeckhouse tops are called as follows: first tier deckhouse top,second tier deckhouse top, etc.

1.2.5 Erections

1.2.5.1 Superstructure - a decked structure on the up-per deck, extending from side to side of the ship or with theside plating not being inboard of the shell plating more than4% of the breadth of the ship B.

1.2.5.2 Deck house - a decked structure on the upperdeck or superstructure deck with its side plating, on one sideat least, being inboard of the shell plating by more than 4%of the breadth of the ship B and provided with doors, win-dows or other similar openings in the external bulkheads.

1.2.5.3 Raised quarter deck - an aft part of upperdeck, raised by deck, break to a height less than the standardheight of superstructure.

1.2.5.4 Trunk - a deck structure on the upper deck, notreaching at least one of the sides by a distance exceeding 4%of the breadth B and having no doors, windows or othersimilar openings in the external bulkheads.

1.2.6 Explanations

1.2.6.1 Block coefficient Cb - coefficient at draught dcorresponding to summer load waterline, based on length Land breadth B, determined from the formula:

[ ][ ]3

3

min,min,draughtatntdisplacemesShip'

dBLd

Cb ⋅⋅=

This requirement does not apply to CSR BulkCarriers and Oil Tankers.

1.2.6.2 Effective flange - is to have following size,unless provided otherwise:thickness: equal to the thickness of the associated plating inthe designed section;width: equal to one sixth of the span of half the distancebetween the nearest framing members located on both sidesof the given member, whichever is less. In separate cases, theeffective flange of a different width may be adopted uponspecial agreement with the Register.

1.2.6.3 Section modulus and moments of inertia - offraming members (about the central axis perpendicular to theplane of bending) apply to rolled and built-up framing mem-bers with on effective flange, in [cm3] and [cm4], respec-tively.

1.2.6.4 The design characteristic of ship's hull material- is considered to be the yield stress ReH, in [N/mm2].

1.2.6.5 Rounding of the scantlings - of structuralmembers (except for plates) is to be made in direction of in-crease. Plate thickness is to be rounded to the full or halfmillimetres up to 0,2 or 0,7; above 0,2 or 0,7 mm they are tobe rounded up. Decreasing of the values for rolling materialsis to be in accordance with the standard approved by Regis-ter.

1.2.6.6 Watertight structure - is structure, which iswatertight for liquids (cargo, ballast, fresh water etc.).

1.2.6.7 Ship's speed, v – max. ship's speed, in [kN], atsummer water line in calm water.

1.2.6.8 Frame spacing, s - is spacing measured formmoulding edge to moulding edge adjacent frames, in [m].

1.2.7 Navigation area limitations

For determining the scantlings of the longitudi-nal and transverse structures of ships intended to operatewithin one of the restricted service areas, the dynamic loadsmay be reduced as specified in Section 3 and 4.

Navigation areas are defined in the Rules, Part1 - General requirements, Chapter 1 - General information,Section 4.2.

1.3 SCOPE OF SUPERVISION

1.3.1 The general provisions for supervision of thehull are set in the Rules, Part 1 - General requirements,Chapter 2 - Supervision during construction.

1.3.2 All structures stated in following Sections shallbe subjected to the supervision of the Register. Shipyards andmanufacturers shall ensure easy access to the tested structure.

1.3.3 Prior to beginning the manufacture of struc-tures stated in 1.3.2 the technical documentation for theship's hull should be submitted for approval according to theRules, Part 1-General requirements, Chapter 2 - Supervisionduring construction and initial survey.

1.3.4 During manufacture the structures mentioned in1.3.2 are subject to inspection for compliance with the re-quirements of Rules, Part 24 - Non-metallic materials, Part25 - Metallic materials, Part 26 - Welding and for compli-ance with the approved technical documentation listed in theRules, Part - 1 - General requirements, Chapter 2 - Supervi-sion during construction and initial survey.

1.3.5 The pressure test of hull structures is to be car-ried out according to the Rules, Part 1 - General require-ments, Chapter 2 - Supervision during construction and initialsurvey.

1.4 MATERIALS

1.4.1 The materials used for hull structures regulatedby this Section are to comply with the Rules, Part 25 - Me-tallic materials and Part 26 - Welding.

Manufacturing of the materials has to be super-vised by the Register.

1.4.2 Hull structural steel

1.4.2.1 The material grade requirements for hullstructural members of each class depending on the thicknessare defined in Table 1.4.2.1. This Section provides for nor-mal strength structural steel of grades CRS-A, CRS-B, CRS-D and CRS-E with yield point ReH = 235 N/mm2, highstrength structural steel of grades CRS-A32, CRS-D32, CRS-E32 with yield point ReH = 315 N/mm2, CRS-A36, CRS-D36,CRS-E36 with yield point ReH = 355 N/mm2, CRS-D40 andCRS-E40 with yield point ReH = 390 N/mm2.

In Table 1.4.2.1 grades of the higher tensilesteels are marked by the letter H.


2013

Table 1.4.2.1 Material grade requirements for classes I, II and III

Class I II III

Thickness, [mm] MS HT MS HT MS HT

t ≤15 CRS - A CRS - AH CRS - A CRS - AH CRS - A CRS - AH15 < t ≤ 20 CRS - A CRS - AH CRS - A CRS - AH CRS - B CRS - AH20 < t ≤ 25 CRS - A CRS - AH CRS - B CRS - AH CRS - D CRS - DH25 < t ≤ 30 CRS - A CRS - AH CRS - D CRS - DH CRS - D CRS - DH30 < t ≤ 35 CRS - B CRS - AH CRS - D CRS - DH CRS - E CRS - EH35 < t ≤ 40 CRS - B CRS - AH CRS - D CRS - DH CRS - E CRS - EH40 < t ≤ 50 CRS - D CRS - DH CRS - E CRS - EH CRS - E CRS - EH

1.4.2.2 The material factor, k, in the formulae of thefollowing Sections is to be taken 1,0 for ordinary hull struc-tural steel.

The material factor, k, for groups of higher tensile hullstructural steel is stated in Table 1.4.2.2 provided that themoment of inertia of the midship section is not less then:

Imin = 3 Wmin L , [cm3]

For Wmin and L, see 4.3.4.

These requirements do not apply to CSR Bulk Carriers andOil Tankers.

For higher tensile hull structural steel withother nominal yield stresses, the material factor k may bedetermined by the following formula:

k = 60

295+eHR

If for special structures the use of steels withyield properties less than 235 N/mm2 has been accepted, thematerial factor k is to be determined by:

k = eHR

235

Table 1.4.2.2

ReH, [N/mm2] k

315 0,78355 0,72390 0,68

1.4.2.3 Materials in the various strength members arenot to be of lower grade than those corresponding to the ma-terial classes and grades specified in Table 1.4.2.1 to Table1.4.2.7. General requirements are given in Table 1.4.2.3,while additional minimum requirements for ships with lengthexceeding 150 m and 250 m, bulk carriers subject to the re-quirements of SOLAS regulation XII/6.5.3, and ships with icestrengthening are given in Table 1.4.2.4 to Table 1.4.2.7.

For strength members not mentioned in Tables1.4.2.3 to 1.4.2.7, grade A/AH may generally be used. Thesteel grade is to correspond to the as-built plate thicknesswhen this is greater than the rule requirement.

These requirements do not apply to CSR Bulk Carriers andOil Tankers.

1.4.2.4 Plating materials for sternframes, rudders, rud-der horns and shaft brackets are in general not to be of lowergrades than corresponding to class II. For rudder and rudderbody plates subjected to stress concentrations (e.g. in way oflower support of semi-spade rudders or at upper part of spaderudders) class III is to be applied.

Mechanical properties of clad steel, if it is used, are not to beless than defined in Table 1.4.2.1.

Base material has to be of shipbuilding steel, inaccordance with the Rules, Part 25 - Metallic material, 3.2.

Claded material thickness are to be determinedon the basis of corrosion speed in the service.

1.4.2.6 In case of high local stresses in the thicknessdirection, use of “Z” grade of steel (steel with examinedproperties in thickness direction) is recommended.


2013

Table 1.4.2.3 Material classes and grades for ships in general

STRUCTURAL MEMBER CATEGORY MATERIAL CLASS/GRADE

SECONDARY:

A1. Longitudinal bulkhead strakes, other than that belonging to the Primary categoryA2. Deck plating exposed to weather, other than that belonging to the Primary or Special categoryA3. Side plating

- Class I within 0.4L amidships- Grade A/AH outside 0.4L amidships

PRIMARY:

B1. Bottom plating, including keel plateB2. Strength deck plating, excluding that belonging to the Special categoryB3. Continuous longitudinal members above strength deck, excluding hatch coamingsB4. Uppermost strake in longitudinal bulkheadB5. Vertical strake (hatch side girder) and uppermost sloped strake in top wing tank

- Class II within 0.4L amidships- Grade A/AH outside 0.4L amidships

SPECIAL:

C1. Sheer strake at strength deck 1)

C2. Stringer plate in strength deck 1)

C3. Deck strake at longitudinal bulkhead, excluding deck plating in way of inner-skin bulkhead of double-hull ships 1)

- Class III within 0.4L amidships- Class II outside 0.4L amidships- Class I outside 0.6L amidships

C4. Strength deck plating at outboard corners of cargo hatch openings in container carriers and other ships with similar hatch opening configurations

- Class III within 0.4L amidships- Class II outside 0.4L amidships- Class I outside 0.6L amidships- Min. Class III within cargo region

C5. Strength deck plating at corners of cargo hatch openings in bulk carriers, ore carriers, combination carriers and other ships with similar hatch opening configurations

- Class III within 0.6L amidships- Class II within rest of cargo region

C6. Bilge strake in ships with double bottom over the full breadth andlength less than 150 m 1)

- Class II within 0.6L amidships- Class I outside 0.6L amidships

C7. Bilge strake in other ships 1) - Class III within 0.4L amidships- Class II outside 0.4L amidships- Class I outside 0.6L amidships

C8. Longitudinal hatch coamings of length greater than 0.15LC9. End brackets and deck house transition of longitudinal cargo hatch coamings

- Class III within 0.4L amidships- Class II outside 0.4L amidships- Class I outside 0.6L amidships- Not to be less than Grade D/DH

Notes:1) Single strakes required to be of Class III within 0.4L amidships are to have breadths not less than 800+5L (mm), need not be

greater than 1800 (mm), unless limited by the geometry of the ship’s design.


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Table 1.4.2.4 Minimum material grades for ships with length exceeding 150 m and single strength deck

STRUCTURAL MEMBER CATEGORY MATERIAL GRADE

Longitudinal strength members of strength deck plating Grade B/AH within 0.4L amidships

Continuous longitudinal strength members above strength deck Grade B/AH within 0.4L amidships

Single side strakes for ships without inner continuous longitudinalbulkhead(s) between bottom and the strength deck

Grade B/AH within cargo region

Table 1.4.2.5 Minimum material grades for ships with length exceeding 250 m


Sheer strake at strength deck 1) Grade E/EH within 0.4L amidships

Stringer plate in strength deck 1) Grade E/EH within 0.4L amidships

Bilge strake 1)Grade D/DH within 0.4L amidships

Notes:1) Single strakes required to be of Grade E/EH and within 0.4L amidships are to have breadths not less than 800+5L (mm), need not

be greater than 1800 (mm), unless limited by the geometry of the ship’s design.

Table 1.4.2.6 Minimum material grades for single-side skin bulk carriers subjected to SOLAS regulation XII/6.5.3


Lower bracket of ordinary side frame 1), 2) Grade D/DH

Side shell strakes included totally or partially between the two pointslocated to 0.125l above and below the intersection of side shell and bilgehopper sloping plate or inner bottom plate 2)

Grade D/DH

Notes:1) The term "lower bracket" means webs of lower brackets and webs of the lower part of side frames up to the point of 0.125l above the intersection of side shell and bilge hopper sloping plate or inner bottom plate.2) The span of the side frame, l, is defined as the distance between the supporting structures.

Table 1.4.2.7 Minimum material grades for ships with ice strengthening


Shell strakes in way of ice strengthening area for plates Grade B/AH


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1.4.3 Material selection for structural mem-bers which are continuously exposed tolow temperatures

1.4.3.1 The material for structural members, which arecontinuously exposed to temperatures below 0oC, e.g. refrig-erated cargo holds, is selected by the design temperature ofthe structural members. The design temperature is deter-mined by means of a temperature distribution taking into ac-count the design environmental temperatures. For unre-stricted service the design environmental temperatures are:

air: +5oCsea water: 0oC

1.4.3.2 For ships intended to operate in areas with lowair temperatures (-20oC and lower) e.g. regular service duringwinter seasons to Arctic or Antarctic waters, the materials inthe exposed structural members shall be selected based onthe design temperature to which is taken as defined in1.4.3.3.

The material grade requirements for hull mem-bers of each class depending on thickness and design tem-perature are defined in Table 1.4.3.2.

For design temperatures to < -55oC, materialsare to be specially considered.

Design temperature, to, shall be taken as the lowest meandaily average temperature in the area of operation:

Mean: Statistical mean value over observation period(at least 20 years).

Average: Average during one day and night.

Lowest: Lowest during year.

1.4.3.4 Materials in the various strength membersabove the lowest ballast water line (BWL) exposed to air arenot to be of lower grades than those corresponding to classesI, II and III, as given in Table 1.4.3.4, depending on the cate-gories of structural members (SECONDARY, PRIMARYand SPECIAL).

For non-exposed structures and structures be-low the lowest ballast water line see 1.4.2.

Single strakes required to be of class III or ofgrade E/EH or FH have breadths not less than 800 + 5·L,[mm], maximum 1800 mm.

Plating materials for stern frames, rudder horns,rudders and shaft brackets are not to be of lower grades thanthose corresponding to the material classes given in 1.4.2.

Table 1.4.3.4

Structural memberWithin 0,4 L

amidshipsOutside 0,4 L

amidships

SECONDARY:Deck plating exposed toweather, in generalSide plating above BWL I ITransverse bulkheads aboveBWLPRIMARY:Strength deck plating 1

Continuous longitudinalmembers above strengthdeck

II I

Longitudinal bulkhead BWLTop wing tank bulkheadBWLSPECIAL:Sheer strake at strengthdeck2

Stringer plate in strengthdeck2

III II

Deck strake at longitudinalbulkhead3

Continuous longitudinalhatch coamings4

Notes:1. Plating at corners of large hatch openings is to be spe-

cially considered. Class III or grade E/EH is to be appliedin positions where high local stresses may occur.

2. Not to be less than grade E/EH within 0,4 L amidships inships with length exceeding 250 m.

3. In ships with breadth exceeding 70m at least three deckstrakes shall to be class III.

4. Not to be less than grade D/DH.


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Table 1.4.3.2Class I

Plate thickness -20 - 25 [oC] -26 -35 [oC] -36 -45 [oC] -46 -55 [oC][mm] MS HT MS HT MS HT

t ≤ 10 A AH B AH D DH D DH10 < t ≤ 15 B AH D DH D DH D DH15 < t ≤ 20 B AH D DH D DH E EH20 < t ≤ 25 D DH D DH D DH E EH25 < t ≤ 30 D DH D DH E EH E EH30 < t ≤ 35 D DH D DH E EH E EH35 < t ≤ 45 D DH E EH E EH ∅ FH45 < t ≤ 50 E EH E EH ∅ FH ∅ FH

∅ = Not applicable

Class II

Plate thickness -20 -25 [oC] -26 -35 [oC] -36 -45 [oC] -46 -55 [oC][mm] MS HT MS HT MS HT

t ≤ 10 B AH D DH D DH E EH10 < t ≤ 20 D DH D DH E EH E EH20 < t ≤ 30 D DH E EH E EH ∅ FH30 < t ≤ 40 E EH E EH ∅ FH ∅ FH40 < t ≤ 45 E EH ∅ FH ∅ FH ∅ ∅45 < t ≤ 50 E EH ∅ FH ∅ FH ∅ ∅


Class III

Plate thickness - 20 - 25 [oC] -26 -35 [oC] -36 -45 [oC] -46 -55 [oC][mm] MS HT MS HT MS HT

t ≤ 10 D DH D DH E EH E EH10 < t ≤ 20 D DH E EH E EH ∅ FH20 < t ≤ 25 E EH E EH E FH ∅ FH25 < t ≤ 30 E EH E EH ∅ FH ∅ FH30 < t ≤ 35 E EH ∅ FH ∅ FH ∅ ∅35 < t ≤ 40 E EH ∅ FH ∅ FH ∅ ∅40 < t ≤ 50 ∅ FH ∅ FH ∅ ∅ ∅ ∅



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1.4.4 Aluminium alloy

1.4.4.1 Use of seawater resisting aluminium alloys ispermitted, by these Rules, as follows:

− ships with length 12 < L ≤ 40 m - for hull,superstructure and deckhouses;

− ships with length L > 40 m - for super-structure and deckhouses.

The conversion of the of the hull structuralelements from steel into aluminium alloy is to be speciallyconsidered taking into account the smaller modulus of elas-ticity, as compared with steel, and the fatigue strength as-pects, specifically those of the welded connections.

1.4.4.2 The conversion from steel to aluminium scant-lings is to be carried out by using the material factor:

kAl = m2,0 RRp

635+

where:Rp0,2 = 0,2% proof stress of the aluminium

alloy, in [N/mm2];Rm = tensile strength of the aluminium alloy, in

[N/mm2].Method of conversion:

− section modulus: WAL = Wst ⋅ kAL

− plate thickness: tAL = tst ⋅ ALkWst, tst = section modulus and plate thickness

of steel, respectively.

1.4.5 Corrosion protection

1.4.5.1 General

For the corrosion protection of seagoing steelships in general, see the Rules, Part 24 - Non-metallic mate-rials, Section 4 and Part 1 - General requirements, Chapter 5.

1.4.5.2 Corrosion prevention for bulk carries, tank-ers and combination carriers

1.4.5.2.1 Corrosion protection coating for salt waterballast spacesAt the time of new construction, all salt water

ballast spaces having boundaries formed by the hull envelopeshall have an efficient protective coating, epoxy or equiva-lent, applied in accordance with the manufacturer's recom-mendations.

The scheme for the selection, application andmaintenance of the coating system should follow the re-quirements of IMO Resolution A.798(19) and contain, as aminimum, the following documentation:

.1 Owner’s, coating manufacturer’s andshipyard’s explicit agreement to thescheme for coating selection, applicationand maintenance.

.2 List of seawater ballast tanks identifyingthe coating system for each tank, includ-ing coating colour and whether coatingsystem is a hard coating.

.3 Details of anodes, if used.

.4 Manufacturer’s technical product datasheet for each product.

.5 Manufacturer’s evidence of productquality and ability to meet Owners re-quirements.

.6 Evidence of shipyard’s and/or its sub-contractor’s experience in coating appli-cation.

.7 Surface preparation procedures and stan-dards, including inspection points andmethods.

.8 Application procedures and standards, in-cluding inspection points and methods.

.9 Format for inspection reports on surfacepreparation and coating application.

.10 Manufacturer’s product safety data sheetsfor each product and owner’s, coatingmanufacturer’s and shipyard’s explicitagreement to take all precautions to re-duce health and other safety risks whichare required by the authorities.

.11 Maintenance requirements for the coatingsystem.

Coating of any colour may be accepted, unlessotherwise instructed by the flag Administration. “Light col-our” coating is preferable, and includes colours which facili-tate inspection or are easily distinguishable from rust.

1.4.5.2.2 Corrosion protection coating for cargo holdsspaces on bulk carriers and combinationcarriers

1.4.5.2.2.1 At the time of new construction, all internaland external surfaces of hatch coamings and hatch covers,and all internal surfaces of the cargo holds, excluding the flattank top areas and the hopper tanks sloping plating approxi-mately 300 mm below the side shell frame and brackets, areto have an efficient protective coating (epoxy coating orequivalent) applied in accordance with the manufacturer’srecommendation. In the selection of coating due considera-tion is to be given by the owner to intended cargo conditionsexpected in service.

1.4.5.2.2.2 A corrosion prevention system is normally con-sidered either:

.1 a full hard coating, or

.2 a full hard coating supplemented by an-odes.

Protective coating should usually be hard (ep-oxy) coating or equivalent. Other coating systems may beconsidered acceptable as alternatives provided that they areapplied and maintained in compliance with the manufacturersspecification.

NOTE: Where Soft Coatings (solvent-free coatingsbased of wool grease, grease, mineral oils and/or wax thatremains soft so that it wears off when touched) have beenapplied, during mandatory surveys of ship in service safe ac-cess is to be provided for the Surveyor to verify the effective-ness of the coating and to carry out an assessment of theconditions of internal structures which may include spot re-moval of the coating. When safe access cannot be provided,the soft coating is to be removed.

1.4.5.2.3 Additional requirements for corrosion pre-vention on tankers and combination carriers

1.4.5.2.3.1 Impressed current systems are not permitted inoil cargo tanks.


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1.4.5.2.3.2 Magnesium or magnesium alloy anodes are notpermitted in oil cargo tanks.

1.4.5.2.3.3 Aluminium anodes are only permitted in cargotanks of tankers in locations where the potential energy doesnot exceed 275 J. The height of the anode is to be measuredfrom the bottom of the tank to the centre of the anode, and itsweight is to be taken as the weight of the anode as fitted, in-cluding the fitting devices and inserts. However, where alu-minium anodes are located on horizontal surfaces such asbulkhead girders and stringers not less than 1 m wide andfitted with an upstanding flange or face flat projecting notless than 75 mm above the horizontal surface, the height ofthe anode may be measured from this surface. Aluminiumanodes are not to be located under tank hatches or “Butter-worth” openings (in order to avoid any metal parts falling onthe fitted anodes), unless protected by adjacent structure.

1.4.5.2.3.4 There is no restriction on the positioning ofzinc anodes.

1.4.5.2.3.5 The anodes should have steel cores and theseshould be sufficiently rigid to avoid resonance in the anodesupport and be designed so that they retain the anode evenwhen it is wasted.

1.4.5.2.3.6 The steel inserts are to be attached to thestructure by means of a continuous weld of adequate section.Alternatively they may be attached to separate supports bybolting, provided a minimum of two bolts with locknuts areused. However, approved mechanical means of clamping willbe accepted.

The supports at each end of an anode shouldnot be attached to separate items which are likely to moveindependently.

When anode inserts or supports are welded tothe structure, they should be arranged so that the welds areclear of stress raisers.

1.4.5.2.3.7 The use of aluminium coatings containinggreater than 10 percent aluminium by weight in the dry filmis prohibited in cargo tanks, cargo tank deck area, pumprooms, cofferdams or any other area where cargo vapour mayaccumulate.

1.4.5.2.3.8 Aluminised pipes may be permitted in ballasttanks, in inerted cargo tanks and, provided the pipes are pro-tected from accidental impact, in hazardous areas on opendeck.

1.4.5.3 Protective coatings of dedicated seawaterballast tanks in all types of ships and double-side skin spaces of bulk carriers

1.4.5.3.1 All dedicated seawater ballast tanks arranged inall type of ships of not less than 500 gross tonnage and dou-ble-side skin spaces arranged in bulk carriers of 150 m inlength and upwards shall be coated during construction in ac-cordance with the Performance standard for protective coat-ings for dedicated seawater ballast tanks in all types of shipsand double-side skin spaces of bulk carriers, adopted by theMaritime Safety Committee by resolution MSC.215(82).

1.4.5.3.2 For application of protective coatings on dedi-cated seawater ballast tanks in all types of ships and double-side skin spaces of bulk carriers see IACS Unified Interpre-tation SC 223. This IACS Unified Interpretation shall beread in conjunction with the IMO Performance Standard forProtective Coatings (PSPC), Resolution MSC.215(82).

1.4.5.3.3 The ability of the coating system to reach itstarget useful life depends on the type of coating system, steelpreparation, application and coating inspection and mainte-nance. All these aspects contribute to the good performanceof the coating system.

1.4.5.3.4 Inspection of surface preparation and coatingprocesses shall be agreed upon between the shipowner, theshipyard and the coating manufacturer and presented to theRegister for review. Clear evidence of these inspections shallbe reported and be included in the Coating Technical File(CTF), see 1.4.5.3.5.

1.4.5.3.5 Specification of the coating system applied tothe seawater ballast tanks and double-side skin spaces, recordof the shipyard’s and shipowner’s coating work, detailedcriteria for coating selection, job specifications, inspection,maintenance and repair shall be documented in the CoatingTechnical File (CTF), and the Coating Technical File shall bereviewed by the Register.

1.4.5.3.6 Maintenance of the protective coating systemshall be included in the overall ship’s maintenance scheme.The effectiveness of the protective coating system shall beverified during the life of a ship by the Register, based on theappropriate guidelines.

1.4.5.4 Corrosion protection of cargo oil tanks ofcrude oil tankers (Resolution MSC.291(87))

1.4.5.4.1 All cargo oil tanks of crude oil tankers shall be:

.1 coated during the construction of the shipin accordance with the Performance stan-dard for protective coatings for cargo oiltanks of crude oil tankers, adopted by theMaritime Safety Committee by resolutionMSC.288(87); or

.2 protected by alternative means of corro-sion protection or utilization of corrosionresistance material to maintain requiredstructural integrity for 25 years in accor-dance with the Performance standard foralternative means of corrosion protectionfor cargo oil tanks of crude oil tankers,adopted by the Maritime Safety Commit-tee by resolution MSC.289(87).

1.4.5.4.2 Requirements in 1.4.5.4.1 shall apply to crudeoil tankers, as defined in regulation 1 of Annex I to the Inter-national Convention for the Prevention of Pollution fromShips, 1973, as modified by the Protocol of 1978 relatingthereto, of 5,000 tonnes deadweight and above:

.1 for which the building contract is placedon or after 1 January 2013; or

.2 in the absence of a building contract, thekeels of which are laid or which are at asimilar stage of construction on or after 1July 2013; or

.3 the delivery of which is on or after 1January 2016.

1.4.5.4.3 The Administration may exempt a crude oiltanker from the requirements in 1.4.5.4.1 to allow the use ofnovel prototype alternatives to the coating system specifiedin 1.4.5.4.1.1, for testing, provided they are subject to suit-able controls, regular assessment and acknowledgement of


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the need for immediate remedial action if the system fails oris shown to be failing. Such exemption shall be recorded onan exemption certificate.

1.4.5.4.4 The Administration may exempt a crude oiltanker from the requirements in 1.4.5.4.1 if the ship is built tobe engaged solely in the carriage of cargoes and cargo han-dling operations not causing corrosion. Such exemption andconditions for which it is granted shall be recorded on an ex-emption certificate.

1.4.5.4.5 For application of Performance standard forprotective coatings for cargo oil tanks of crude oil tankers(PSPC-COT), adopted by Resolution MSC.288(87), see alsoIACS Unified Interpretation SC 259.

1.4.5.4.6 For application of Performance standard foralternative means of corrosion protection for cargo oil tanksof crude oil tankers, adopted by Resolution MSC.289(87), seealso IACS Unified Interpretation SC 258.

1.5 WATER LEVEL DETECTORS ONSINGLE HOLD CARGO SHIP OTHERTHAN BULK CARRIERS (SOLAS 1974,

CH. II-1, REG. 25)

1.5.1 For the purpose of this regulation, freeboarddeck has the meaning defined in the International Conventionon Load Lines in force.

1.5.2 Ships having a length (L) of less than 80 m, anda single cargo hold below the freeboard deck or cargo holdsbelow the freeboard deck which are not separated by at leastone bulkhead made watertight up to that deck, shall be fittedin such space or spaces with water level detectors*.

1.5.3 The water level detectors required by 1.5.2shall:

.1 give an audible and visual alarm at thenavigation bridge when the water levelabove the inner bottom in the cargo holdreaches a height of not less than 0.3 m,and another when such level reaches notmore than 15% of the mean depth of thecargo hold; and

.2 be fitted at the aft end of the hold, orabove its lowest part where the innerbottom is not parallel to the designedwaterline. Where webs or partial water-tight bulkheads are fitted above the innerbottom, Administrations may require thefitting of additional detectors.

1.5.4 The water level detectors required by 1.5.2need not be fitted in ships complying with regulation XII/12,or in ships having watertight side compartments each side ofthe cargo hold length extending vertically at least from innerbottom to freeboard deck.

1.5.5 For application of these requirements see alsoIACS unified interpretation SC 180.

* Refer to the Performance standards for water level detectors onbulk carriers and single hold cargo ships other than bulk carriers,adopted by the Maritime Safety Committee by resolutionMSC.188(79).


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2 DESIGN PRINCIPLES

2.1 GENERAL

2.1.1 This Section contains definitions and principlesfor using formulas and explanations of definitions which arerelated to the structural member details.

2.1.2 Permissible stresses and requiredsectional properties

In the following Sections permissible stresseshave been stated in addition to the formulae for calculatingthe section moduli and cross sectional areas of webs offrames, beams, girders, stiffeners etc. and may be used whendetermining the scantlings of those elements by means of di-rect strength calculations. The permissible stresses may beincreased by up to 10 % where exact stress analyses are car-ried out in accordance with approved calculation methods,e.g. where the finite element method is applied or else proofis presented by full scale measurements.

The required section moduli and web areas arerelated on principle to an axis which is parallel to the con-nected plating.

For profiles usual in the trade and connectedvertically to the plating in general the appertaining sectionalproperties are given in tables.

Where webs of stiffeners and girders are notfitted vertically to the plating (e.g. frames on the shell in theflaring fore body) the sectional properties (moment of inertia,section modulus and shear area) have to be determined for anaxis which is parallel to the plating.

For bulb profiles and flat bars the sectionmodulus of the inclined profile including plating can be cal-culated simply by multiplying the corresponding value forthe vertically arranged profile by sinα where α is the smallerangle between web and attached plating.

Note:For bulb profiles and flat bars α in general needs only betaken into account where α is less than 75°.

2.1.3 Plate panels subjected to lateral pres-sure

The formulae for plate panels subjected to lat-eral pressure as given in the following Sections are based onthe assumption of an un-curved plate panel having an aspectratio b/a ≥ 2,24.

For curved plate panels and/or plate panelshaving aspect ratio smaller than b/a ∼ 2,24, the thicknessmay be reduced as follows:

t C a p k f f t k= ⋅ ⋅ ⋅ ⋅ +1 2 [mm]where:

C = constant (e.g. C = 1,1 for tank plating):

f1 = 1 r

a2

− ;

f1min = 0,75;

f2 =2

5011

−

ba,, ;

f2max = 1,0;r = radius of curvature, in [m];a = smaller breadth of plate panel, in [m];b = larger breadth of plate panel, in [m];p = applicable design load, in [kN/m2],tk =corrosion addition in according to 2.9.

This does not apply to plate panels subjected toice pressure according to Section 14 and to longitudinallyframed side shell plating according to Section 5.

2.1.4 Fatigue strength

Where a fatigue strength analysis is requiredfor structures or structural details this is to be in accordancewith requirements of Section 16

2.2 UPPER AND LOWER HULLFLANGE

2.2.1 All continuos longitudinal structural membersup to Hsg below the strength deck and up to Hsd above baseline are considered to be the upper and lower hull flange re-spectively.

2.2.2 Where the upper and/or lower hull flange aremade from ordinary hull structural steel their vertical extentHsg = Hsd equals 0,1 D.

On ships with continuos longitudinal structuralmembers above the strength deck an assumed depth D1 isconsidered, as follows:

D1 = Zd + Z’g [m]where:

Zd - distance between neutral axis of the midshipsection and base line; in [m]

Z’g - see 4.3.1.2.

2.2.3 The vertical extent Z of the upper and lowerhull flange respectively made from higher tensile steel is notto be less than:

Hs = Z(a) ( 1 - f ⋅ k) [m]Hsmin = 0,1 ⋅ D or 0,1 ⋅ D1[m]

where:Hs = Hsg or Hsd (see Fig. 4.3.5-1)Z(a) = actual distance of deck at side (Zg) or of the

base line (Zd) from the neutral axis of themidship section. For ships with continu-ous longitudinal structural membersabove the upper deck see Section 4.3.1.2.

f = W(a)/WW(a) = actual deck or bottom section modulus,

[cm3]W = Rule deck or bottom section modulus, ac-

cording to Section 4.3, [cm3]k = material factor, according to 1.4.2.2.

Where two different steel grades are used it hasto be observed that at no point the stresses are higher than thepermissible stresses in according to 4.3.2.


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2.3 UNSUPPORTED SPAN

2.3.1 Stiffeners and frames

The unsupported span l is the true length of thestiffeners between two supporting girders or else their lengthincluding end attachments (brackets).

The frame spacings and spans are normally as-sumed to be measured in a vertical plane parallel to the cen-treline of the ship. However, if the ship's side deviates morethan 10° from this plane, the frame distances and spans shallbe measured along the side of the ship.

Instead of the true length of curved frames thelength of the chord between the supporting points can be se-lected.

2.3.2 Corrugated bulkhead elements

The unsupported span l of corrugated bulkheadelements is their length between bottom or deck and theirlength between vertical or horizontal girders. Where corru-gated bulkhead elements are connected to box type elementsof comparatively low rigidity, their depth is to be includedinto the span l unless otherwise proved by calculations.

2.3.3 Transverses and girders

The unsupported span l of transverses and gird-ers is to be determined according to Fig. 2.3.3.1 dependingon the type of end attachment (bracket).

In special cases, the rigidity of the adjoininggirders is to be taken into account when determining the un-supported span of girder l.

Figure 2.3.3.1

2.4 END ATTACHMENTS

2.4.1 Definitions

For determining scantlings of stiffeners andgirders the terms constraint and simple support is to be used.

Constraint will be assumed where for instancethe stiffener are rigidly connected to other members bymeans of brackets or are running throughout over supportinggirders.

Simple support is to be assumed where for in-stance the stiffener ends are sniped or the stiffeners are con-nected to plate only (see 2.4.3).

2.4.2 Brackets

2.4.2.1 For the scantlings of brackets the required sec-tion modulus of the section is decisive. Where sections ofdifferent section moduli are connected to each other, thescantlings of the brackets are generally governed by thesmaller section.

2.4.2.2 The thickness of brackets is not to be less than:

t c W k tk= ⋅ +/3 , [mm]

where:c = 1,2 for non-flanged brackets;

c = 0,95 for flanged brackets;k = material factor, according to 1.4.2.2;tk = corrosion addition according to

2.9.1, [mm];W = section modulus of smaller section,

[cm3];tmin = 5 + tk , mm;tmax = web thickness of smaller section,

[mm].For minimum thicknesses tmin in tanks and in

cargo holds of bulk carriers see Section 11.1.7 or 17.2.5.

2.4.2.3 The arm lengths of brackets, measured fromplating to the brackets toe, are not to be less than:

a ≥ 0,8 l

b ≥ 0,8 l

a + b ≥ 2 l

where:

3

1

26,50ktktW

la ⋅

⋅⋅⋅= , [mm]

lmin = 100 mm;ta = "as built" thickness of bracket, [mm]t = thickness of bracket according to 1.4.2.2,

[mm]W = see 2.4.2.2;


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k2 = material factor k for the bracket according to1.4.2.2.

k1 = material factor k for the section, according to1.4.2.2.

The arm length l is the length of the weldedconnection.

2.4.2.4 The free edge of bracket have to be flanged,when l > 50 t.

The width of flange is to be determined ac-cording to the following formula:

b = 40 + 30W

, [mm],

b is not to be taken less than 50 mm and neednot be taken greater than 90 mm.

W = see 2.4.2.2

2.4.2.5 The throat thickness a of the welded connectionis to be determined according to Section 15.

2.4.3 Sniped ends of stiffeners

Stiffeners may be sniped at the ends, if thethickness of the plating supported by stiffeners is not lessthan:

t cp s l s

ReH=

⋅ − ⋅( , )0 5, [mm],

where:p = design load, [kN/m2];l = unsupported length of stiffener, [m];s = spacing of stiffeners, [m];ReH = minimum nominal upper yield point

of the plating's material, [N/mm2];c = 15,8 for watertight bulkheads and for

tank bulkheads when loaded by p2according to 3.4.1.2;

c = 19,6 otherwise.

2.4.4 Corrugated bulkhead elements

Care is to be taken that the forces acting at thesupports of corrugated bulkheads are properly transmittedinto the adjacent structure by fitting structural elements suchas carlings, girders or floors in line with corrugations.

2.5 EFFECTIVE WIDTH OF PLATING

2.5.1 Frames and stiffeners

Generally, the spacing of frames and stiffenersmay be taken as effective width of plating.

2.5.2 Girders

2.5.2.1 The effective width of plating bm of frames andgirders may be determined according to Table 2.5.2.1 con-sidering the type of loading.

Special calculations may be required for deter-mining the effective width of non-symmetrical flanges.

2.5.2.2 The effective cross sectional area of plates isnot to be less than the cross sectional area of the face plate.

2.5.3 Cantilevers

Where cantilevers are fitted at every frame, theeffective width of plating may be taken as the frame spacing.

Where cantilevers are fitted at a greater spacingthe effective with of planting may approximately be taken asthe distance of the respective cross section from the print onwhich the load is acting, but not greater than the spacing ofthe cantilevers.

Table 2.5.2.1

l/b 0 1 2 3 4 5 6 7 ≥ 8

bm1/b 0 0,36 0,64 0,82 0,91 0,96 0,98 1,00 1,00bm2/b 0 0,20 0,37 0,52 0,65 0,75 0,84 0,89 0,90

Notice:1) bm1 is to be applied where girders are loaded by uniformly distributed loads or else by not less

than 6 equally spaced single loads.2) bm2 is to be applied where girders are loaded by 3 or less single loads.3) Intermediate values may be obtained by direct interpolation.4) l = length between zero-points of bending moment curve, i.e. unsupported span in case of sim-

ply supported girders and 0,6 x unsupported span in case of constraint of both ends of girder.5) b = width of plating supported, measured from centre to centre of the adjacent unsupported

fields.

2.6 STRUCTURAL DETAILS

2.6.1 Longitudinal members

2.6.1.1 All longitudinal members taken into accountfor calculating the midship section modulus are to extend

over the required length amidships and are to be taperedgradually to the required ship's ends thicknesses.

2.6.1.2 Abrupt discontinuities of strength of longitudi-nal members are to be avoided as far as practicable. Wherelongitudinal members having different scantlings are con-nected with each other, smooth transitions are to be provided.


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Special attention in this respect is to be paid tothe construction of continuous longitudinal hatch coamingsforming part of the longitudinal hull structure.

2.6.1.3 At the ends of longitudinal bulkheads or con-tinuous longitudinal walls suitable scarping brackets are to beprovided.

2.6.2 Girders and transverses

2.6.2.1 Where transverses and girders fitted in thesame plane are connected to each other, major discontinuitiesof strength are to be avoided. The web depth of the smallergirder is, in general, not to be less than 0,6 of the web depthof the greater one.

2.6.2.2 The taper between face plates with differentdimensions is to be gradual. In general the taper shall not ex-ceed 1:3. At intersections the forces acting in the face platesare to be properly transmitted.

2.6.2.3 For transmitting the acting forces the faceplates are to be supported at their knuckles. The stiffeners atthe knuckles may be omitted if the following condition iscomplied with:

σ σa pe

f

bb

≤ , [N/mm2],

where:σa = actual stress in the face plate at the

knuckle, in [N/mm2];σp = permissible stress in the face plate, in

[N/mm2];bf = breadth of face plate, in [mm];be = effective breadth of face plate:be = tw + n1 [tf + c (b - tf)], in [mm];tw = web thickness, in [mm]tf = face plate thickness, in [mm];

b = ( )1

1nb tf w− [mm]

c = ( )

12

2

32

b t R t n

n t

Rf f

f

− ⋅

−+

⋅

⋅

/ α;

cmax = 1;2 α = knuckle angle, in [o], (see Fig.

2.6.2.3);αmax = 45o;R = radius of rounded face plates, in

[mm];R = tf for knuckled face plates;n1 = 1 for un-symmetrical face plates (face

plate at one side only);n1 = 2 for symmetrical face plates;n2 = 0 for free face plates.

n2 = 0,9 f

f

tR)tb(

⋅

− 2

≤ 1,0 , for face plates

of multi-web girdersn3 = 3 if no radial stiffener is fittedn3 = 3000 if two or more radial stiffeners

are fitted or if one knuckle stiffener isfitted in according (a) in Fig. 2.6.2.3.

n3 =4

8

−

ftd , if one stiffener is fitted in

according to (b) in Fig. 2.6.2.3.3 ≤ n3 ≤ 3 000d = distance of the stiffener from the

knuckle, [mm].Scantlings of stiffeners are:

thickness: tb = σσ

αa

pft⋅ ⋅ 2sin

height: h = 1,5 ⋅ b

Figure 2.6.2.3

2.6.2.4 For preventing the face plates from trippingadequately spaced stiffeners or tripping brackets are to beprovided. The spacing of these tripping elements is not ex-ceed 12 bf.

2.6.2.5 The webs are to be stiffened to prevent buck-ling.

2.6.2.6 The location of lightening holes is to be suchthat the distance from hole edge to face plate is not less than0,3 x web depth.

2.6.2.7 In way of high shear stresses lightening holesin the webs are to be avoided as far as possible.

2.6.2.8 Knuckles (general)

Flanged structural elements transmitting forcesperpendicular to the knuckle, are to be adequately supportedat their knuckle, (i.e. the knuckles of the inner bottom are tobe located above floors, longitudinal girders or bulkheads).See Fig. 2.6.2.8.

If longitudinal structures, such as longitudinalbulkheads or decks, include a knuckle which is formed bytwo butt-welded plates, the knuckle is to be supported in thevicinity of the joint rather than at the exact location of thejoint. The minimum distance d to the supporting structure isto be at least:


2013

225 ft

d += , but not more than 50 mm, see Fig.

2.6.2.8-2.On bulk carriers at knuckles between inner

bottom and tank side slopes in way of floors the welding cut-outs have to be closed by collar plates or insert plates, seeFig. 2.6.2.8-1. In both cases a full penetration weld is re-quired to inner bottom and bottom girder.

Figure2.6.2.8-

1

Figure2.6.2.8-

2

2.7 RIGIDITY OF TRANSVERSESAND GIRDERS

The moment of inertia of deck transverses andgirders is not to be less than:

I = C ⋅ W ⋅ l, [cm4]

C = 4,0 if both ends are simply supported;C = 2,0 if one end is constrained;C = 1,5 if both ends are constrained;W = section modulus of the structural member

considered, in [cm3];l = unsupported span of the structural member

considered, in [m].

2.8 EVALUATION OF NOTCHSTRESSES

The notch stress σk evaluated for linear-elasticmaterial behaviour at free plate edges, e.g. at hatch cornersopenings in decks, walls, girders etc., should, in general, ful-fill the following criterion:

σk ≤ f ⋅ ReH , [N/mm2]

f = 1,1 for normal strength hull structural steel;f = 0,9 for higher strength hull structural steel

with ReH = 315 N/mm2;f = 0,8 for higher strength hull structural steel

with ReH = 355 N/mm2.f = 0,73 for higher strength hull structural steel

with ReH = 390 N/mm2;If plate edges are free of notches and corners

are rounded-off, a 20% higher notch stress σk may be per-mitted.

A further increase of stresses may be permittedon the basis of a fatigue strength analysis as per Section 16.

2.9 CORROSION ADDITIONS

2.9.1 The scantling requirements of the subsequentSections imply the following general corrosion additions tk:

tk = 1,5 mm, for t ≤ 10 mm;

tk =k

t⋅1,0 + 0,5, [mm], max. 3,0 mm, for

t > 10 mm,

where:t = required rule thickness excluding tk,

in [mm];k = material factor according to Section

1.4.2.2.

For structural elements in specified areas tk is not to be lessthan given in Table 2.9.2.

Table 2.9.2

Area tkmin , [mm]

In ballast tanks where the weatherdeck forms the tanktop, 1,5 m belowtanktop1.

2,5

- In cargo oil tanks where theweather deck forms the tanktop, 1,5m below tanktop.- Horizontal members in cargo oiland fuel oil tanks.

2,0

Deck plating below elasticallymounted deckhouses. 3,0Longitudinal bulkheads of ships as-signed to the notation GRAB and ex-posed to grab operation.

2,5

1) tkmin = 2,5 mm for all structures within topside tanks ofbulk carriers.

2.9.3 For structures in dry spaces such as box girdersof container ships and for similar spaces as well as for hatchcovers of dry cargo holds the corrosion additions is:

tk = k

t, ⋅10, max. 2,5 mm,

but not less than 1,0 mm.


2013

Corrosion additions for hatch covers and hatchcoamings are to be determined in according to the Rules,Part 3 – Hull Equipment, 7.10.


2013

3 DESIGN LOADS

3.1 GENERAL

3.1.1 This Section provides data regarding designloads for determining the scantlings of the hull structuralelements by means of the design formulae given in the fol-lowing Sections or by means of direct calculations.

3.1.2 Definitions

3.1.2.1 Load centre:

a) For plates:− vertical stiffening system:

0,5 x stiffener spacing above the lower supportof plate field, or lower edge of plate when thethickness changes within the plate field;

− horizontal stiffening system:midpoint of plate field.

b) For stiffeners and girders:- centre of span l.

3.1.2.2 Definition of symbols:

v = ship's speed according to Section 1.2.6;ρc = density of cargo as stowed, [t/m3];ρ = density of liquids, [t/m3];ρ = 1,025 t/m3 for fresh and sea water;z = vertical distance of the structure's load

centre above base line, [m];x = distance from aft end of length L, in [m];Cb = block coefficient according to 1.2.6, but is

not to be taken less than 0,60;po = 2,1 (Cb + 0,7) ⋅ Cw ⋅ CL ⋅ f, [kN/m2], basic

external load for ;

Cw =25L

+ 4,1, for L < 90 [m]

Cw = 10,75 - ,100

300 5,1

− L for 90 ≤ L ≤ 300 m

Cw = 10, 75, for 300 < L ≤ 350 m;

Cw = 10,75 - ,150

350 5,1

−L for L > 350 m;

CL =90L

, for L < 90 m;

CL = 1,0, for L ≥ 90 m;f = 1 for shell plating and weather deck;f = 0,75 for frames and deck beams;f = 0,60 for web frames, stringers and grillage

systems.

Note: For restricted service areas these values po may be de-crease, as follows:

25% for service range 330% for service range 4, 540% for service range 6, 7, 8

3.2 EXTERNAL SEA LOADS

3.2.1 Load on weather deck

3.2.1.1 The load on weather decks is to be determinedaccording to the following formula:

( ) aoD CDdz

dpp ⋅⋅−+

⋅=

1020 , [kN/m2]

where:Ca = factor depending of the longitudinal posi-

tion according to Table 3.2.1.1.

Table 3.2.1.1

Range Coefficient Ca

0 ≤ xL

< 0,2 1,2 - xL

0,2 ≤ xL

≤ 0 7, 1,0

0,7 ≤ xL

≤ 1 0, 1,0 + C3

xL

−

0 7,

C = 0,15 ⋅ L - 10100 m ≤ L ≤ 250 m

3.2.1.2 For strength deck which are to be treated asweather decks as well as for forecastle decks the load is notto be less than the greater of the following two values:

pDmin = 16 ⋅ f, [kN/m2];or

pDmin = 0,7 ⋅ po, [kN/m2]

f = according to 3.1.2.2.

3.2.1.3 Where deck cargo is intended to be carried onthe weather deck resulting in a load greater than the valuedetermined according to 3.2.1.1, the greater load governs thescantlings.

Where the stowage height of deck cargo is lessthan 1,0 m, the deck cargo load may require to be increasedby the following value:

pz = 10 (1 - hs), [kN/m2],

where:hs = stowage height of the cargo, [m].

3.2.2 Load on ship's sides and of bow struc-tures

3.2.2.1 Load on ship's sides

The external load on the ship's sides is to bedetermined according to the following formulae:

a) For elements the load centre of which is locatedbelow load waterline:

ps = 10 (d - z ) + po ⋅ CF

+

dz1 , [kN/m2];

b) For elements the load centre of which is locatedabove load waterline:

ps = po ⋅ CF 20

10 + −z d, [kN/m2];


2013

CF = factor depending of the longitudinal positionaccording to Table 3.2.2.1;

Table 3.2.2.1

Range Coefficient CF

0 ≤ xL

< 0,2 1) 1,0 + 5

Cb 0 2, −

xL

0,2 ≤ xL

< 07 1,0

0,7 ≤ xL

≤ 1 0, 2) 1,0 + 20Cb

xL

−

0 72

,

1) xL

need not be taken less than 0,1

2) xL

need not be taken greater than 0,93

3.2.2.2 Load on bow structures

The design load for bow structures from for-ward to 0,1⋅L behind F.P. and above the ballast waterline inaccordance with the draft db in 3.2.4 is to be determined ac-cording to the following formula:

pe = c (0,2⋅ v + 0,6⋅ L )2, [kN/m2]Lmax = 300 mc = 0,8 in general.

αsin09,12,145,0

⋅−=c , for extremely flared sides

where the flare angle α is larger than 40°.The flare angle at the load centre is to be meas-

ured in the plane of frame between a vertical line and thetangent to the side shell plating, see Fig. 3.2.2.2.

For unusual bow shapes pe can be speciallyconsidered.

pe must not be smaller than ps according to3.2.2.1.

Aft of 0,1⋅L from F.P. up to 0,15⋅L from F.P.the pressure between pe and ps is to be graded steadily.

Figure 3.2.2.2

3.2.2.3 Load on stern structureThe design load for stern structures from the aft

end to 0,1 L forward of the aft end of L and above the small-est design ballast draught at A.P. up to d +Cw/2 is to be de-termined according to the following formula:

pe = cA ⋅L, [kN/m2]cA = 0,3⋅c ≥ 0,36c = see 3.2.2.2Lmax = 300 m.

pe must not be smaller than ps according to 3.2.2.1.

3.2.3 Load on the ship's bottom

The external load pB of the ship's bottom is tobe determined according to the following formula:

pB = 10 ⋅ d + po ⋅ CF , [kN/m2],

where:CF = see Table 3.2.2.1

3.2.4 Design slamming pressure

The design slamming pressure may be deter-mined by the following formulae:

pSL = 162 L ⋅C1⋅C2⋅ CSL, [kN/m2], for L ≤ 150 [m];

pSL = 1984 (1,3 - 0,002 L) C1⋅C2⋅ CSL, [kN/m2], for L > 150 [m]

where:

C1 = 3,6 - 6,5 20,

b

Ld

C1max = 1,0db = the smallest design ballast draught at F.P for

normal ballast conditions, in [m];Where the sequential method for ballastwater exchange is intended to be applied,db is to be considered for the sequence ofexchange.

C2 = 10/AA = loaded area between the supports of the

structure considered, in [m2];C2 = 1,0, for plate panels and stiffeners;

0,3 ≤ C2 ≤ 1,0 generally;CSL = distribution factor, see Figure 3.2.4.

Figure 3.2.4

CSL = 0,for xL

≤ 0,5

CSL =3

5.0

CLx

−, for 0,5 ≤

xL

≤ 0,5 + C3

CSL = 1,0, for 0,5 + C3 ≤ xL

≤ 0,65 + C3


2013

33

0,65for ,35,0

115,0 C

Lx

CLx

CSL +>

−

−+⋅=

C3 = 0,33 ⋅ Cb + L

2500C3max = 0,35

Note: For restricted service areas these values pSL may be de-crease, as follows:

5% for service range 212,5% for service range 3, 417% for service range 5, 620% for service range 7, 8

3.2.5 Load on decks of superstructures anddeckhouses

3.2.5.1 The load on exposed decks and parts of super-structure and deckhouse decks, which are not to be treated asstrength deck, is to be determined as follows:

pDA = pD ⋅ n, in [kN/m2]where:

pD = according to 3.2.1.1;

n = 1 - 10

Dz −;

nmin= 0,5;n = 1,0 for the forecastle deck.

For deckhouses the value so determined may bemultiplied by the factor:

0 7 0 3, ,,

,bB

+

b' = breadth of deckhouse;B' = largest breadth of ship at the position con

sidered.Except for the forecastle deck the minimum

load is:pDAmin = 4 kN/m2.

For exposed wheel house tops the load is not tobe taken less than:

p = 2,5 kN/m2.

3.3 CARGO LOADS, LOAD ONACCOMMODATION DECKS

3.3.1 Load on cargo decks

3.3.1.1 The load on cargo decks is to be determinedaccording to the following formula:

pL = pc (1 + av), [kN/m2],

where:pc = static cargo load, in [kN/m2];pc = 7 ⋅ h for 'tween decks but not less than 15

kN/m2, if no cargo load is given;h = mean 'tween deck height, in [m].

In way of hatch casings the increased height ofcargo is to be taken into account.

av = acceleration factor as follows:av = F ⋅ m

F = 0,11 L

v;

m = mo - 5 (mo - 1) xL

, for 0 < xL

≤ 0,2;

m = 1,0, for 0,2 ≤ xL

≤ 0,7;

m = 1 +

−

+ 7,03,0

1Lxmo , for 0,7 <

xL

≤ 1,0;

mo = (1,5 + F);v = see 3.1.2.2, v is not to be taken less than

L , [kn].

3.3.1.2 For timber and coke deck cargo the load ondeck is to be determined by the following formula:

pL = 5 ⋅ hs (1 + av), [kN/m2],hs = stowing height of cargo, in [m].

3.3.1.3 The loads due to single forces PE (e.g. in caseof containers) are to be determined as follows:

P = PE (1 + av), [kN]

3.3.1.4 The cargo pressure of bulk cargoes is to be de-termined by the following formula:

pbc = pc (1 + av), [kN/m2],

where:pc = 9,81 ⋅ ρc ⋅ h ⋅ n, [kN/m2], static bulk cargo

load;n = tan2 (45o - γ/2) sin2α + cos2α;γ = angle of repose of the cargo, in degrees;α = angle, in degrees, between the structural

element considered and a horizontalplane;

h = distance between upper edge of cargo andthe load centre, in [m];

ρc = density of stowed cargo, in [t/m3].

3.3.2 Load on inner bottom

3.3.2.1 The inner bottom cargo load is to be deter-mined as follows:

pDB = 9,81 ⋅ GV

⋅ h (1 + av), [kN/m2],

where:G = mass of cargo in the hold, [t];V = volume of the hold, in [m3], (hatchways ex-

cluded);h = height of the highest point of the cargo above

the inner bottom, in [m], assuming holdto be completely filled;

av = see 3.3.1.1.For calculating av the distance between the

centre of gravity of the hold and the aft end of the length L isto be taken.

3.3.2.2 For inner bottom load in case of ore stowed inconical shape, see Section 17.


2013

3.3.3 Loads on accommodation and machin-ery decks

3.3.3.1 The deck load in accommodation and servicespaces is:

p = 3,5 (1 + av), [kN/m2]

3.3.3.2 The deck load of machinery decks is:

p = 8 (1 + av), [kN/m2]

3.3.3.3 Significant single forces are also to be consid-ered, if necessary.

3.4 LOAD ON TANK STRUCTURES

3.4.1 Design pressure for filled tanks

3.4.1.1 The design pressure for service conditions isthe greater of the following values:

p1 = 9,81⋅h1⋅ρ ⋅(1+av)+100⋅pv , [kN/m2],or

p1 = 9,81⋅ρ ⋅[h1⋅cosϕ +(0,3⋅b+y)⋅sinϕ]+100⋅pv, [kN/m2]

where:h1 = distance of load centre from tank top,

in [m];av = see 3.3.1.1;ϕ = design heeling angle, [°], for tanks;

= arctan

⋅

BDf bk

, in general;

fbk = 0,5 for ships with bilge keel= 0,6 for ships without bilge keel

ϕ ≥ 20° for hatch covers of holds carryingliquids

b = upper breadth of tank, [m];y = distance of load centre from the vertical

longitudinal central plane of tank, [m];pv = set pressure of pressure relief valve, [bar],

(if a pressure relief valve is fitted);pvmin = 0,1 bar (1,0 mSV), during ballast water

exchange for both, the sequential methodas well as the flow-through method;

pvmin = 0,2 [bar] (2,0 mSV) for cargo tanks oftankers;

mSV = metre of head water.

3.4.1.2 The maximum static design pressure is:

p2 = 9,81 ⋅ h2, [kN/m2]

h2 = distance of load centre from top of overflowor from a point 2,5 m above tank top, which-ever is the greater. Tank venting pipes ofcargo tanks of tankers are not to be regardedas overflow pipes.

For tanks equipped with pressure relief valvesand/or for tanks intended to carry liquids of a density greaterthan 1 t/m3, the head h2 is at least to be measured to a level atthe following distance hp above tank top:

hp = 2,5 ⋅ ρ [mSV], head of water, [m], or

hp = 9,81 ⋅ pv [mSV], where pv > 0,25 ⋅ ρ.

Regarding the design pressure of fuel tanks andballast tanks which are connected to an overflow system, thedynamic pressure increase due to the overflowing is to betaken into account in addition to the static pressure height upto the highest point of the overflow system.

3.4.2 Design pressure for partially filled tanks

3.4.2.1 For tanks which may be partially filled between20% and 90% of their height, the design pressure is not to betaken less than given by the following formulae:

a) For structures located within lt/4 from thebulkheads limiting the free liquid surfacein the ship's longitudinal direction:

pd = 4150

−

L lt ⋅ ρ ⋅ nx + 100 ⋅ pv, [kN/m2];

b) For structures located within bt/4 from thebulkheads limiting the free liquid surfacein the ship's transverse direction:

pd = 5 520

, −

B bt ⋅ ρ ⋅ ny + 100 ⋅ pv, [k/Nm2],

where:lt = distance, in [m], between transverse bulk-

heads or effective transverse wash bulk-heads at the height where the structure is located;

bt = distance in, [m], between tank sides or ef-fective longitudinal wash bulkhead at the height where the structure is located;

nx = 1 - tl4 ⋅ x1

ny = 1 - tb

4⋅ y1

x1 = distance of structural element from the tank'sends in the ship's longitudinal direction,in [m];

y1 = distance of structural element from the tank'ssides in the ship's transverse direction, in[m].

3.4.2.2 For tanks with ratios lt/L > 0,1 or bt/B > 0,6 adirect calculation of the pressure pd may be required.

3.5 DESIGN VALUES OFACCELERATION COMPONENTS

3.5.1 Acceleration components

The following formulae may be taken whencalculating the acceleration components owing to ship’s mo-tions:

- Vertical acceleration (vertical to the base line)due to heave and pitch:

a aL

xL Cz o

b= ± + −

−

1 5 3

450 45

0 62 2 1 5

, ,,

,


2013

- Transverse acceleration (vertical to the ship'sside) due to sway, yaw and roll includinggravity component of roll:

22

6014505260

−

⋅++

−+±=

Bdzk,k,

Lx,,aa oy

- Longitudinal acceleration (in longitudinal di-rection) due to surge and pitch includinggravity component of pitch:

ax = ± + −a A Ao 0 06 0 252, ,where:

ax, ay, az = maximum dimensionless accelerations(i.e., relative to the acceleration ofgravity g) in the related directions x, yand z.

A = 0 7 1200 50 6

,,

− +−

L z dL Cb

;

ao = 0 23

,vL

C CL

fw L+⋅ ⋅

⋅ ;

k = 13 GM

B;

MG = metacentric height, in [m];kmin = 1,0;Cw = wave coefficient, see 3.1.2.2;CL = length coefficient, see 3.1.2.2f = factor depending on probability level Q as

outlined in Table 3.5.1;L = not to be taken less than 100 m.

Table 3.5.1

Q f

10-8 1,00010-7 0,87510-6 0,75010-5 0,62510-4 0,500


2013

4 LONGITUDINAL STRENGTH

4.1 GENERAL

4.1.1 These requirements apply only to steel ships oflength 65 m and greater in unrestricted service. For shipshaving one or more of the following characteristics, specialadditional considerations will be given by the Register.

− ships with proportion L/B ≤ 5 and B/D ≥ 2,5;− ships with length L ≥ 500 m;− ships with block coefficient Cb < 0,6;− ships with large deck openings;− ships with large flare;− ships intended for carriage of heated cargoes;− ships of unusual type or design,

− ships with speed greater than: ν = 1,6 L , [kn].For bulk carriers with notation BC-A, BC-B or

BC-C (for definition of bulk carrier notations see Section17.4.6), these requirements are to be complied with by shipscontracted for construction on or after 1 July 2003. For othership types, this revision of these requirements is to be com-plied with by ships contracted for construction on or after 1July 2004.

These requirements do not apply to CSR BulkCarriers and Oil Tankers except requirements in items 4.1.2to 4.1.5 which apply in addition to those of the CommonStructural Rules for Bulk Carriers and Oil Tankers.

4.1.2 Definitions

Ms = still water bending moment, in [kNm];Mw = vertical wave bending moment, in [kNm];Cw = wave coefficient depending on length;Fs = still water shear force, in [kN];Fw = vertical wave shear force, in [kN];Iy = moment of inertia of the transversal sec-tion,

in [cm4], around the horizontal axis;W = section modulus of transversal section around

the horizontal axis, in [cm3];S = first moment of the sectional area of the lon-

gitudinal members, in [cm3], related tothe neutral axis;

Cb = block coefficient;v = maximum speed of ship, in [kn], at defined

shaft revolution and engine power.k = material factor according to 1.4.2.2x = distance, in [m], between aft end of length L

and the position consideredHsg, Hsd= vertical extent of HS steel used in deck or

bottom, [m].

4.1.3 Explanations

− Longitudinal members - parts of hullstructure which participate in longitudinalstrength and which extend continuouslyover 0,4·L amidship.

− Strength deck - is the deck forming theupper flange of the hull girder. That may bedeck of a midship superstructure if it is at0,4 L amidship and extend in length greaterthan:

L = 3 ⋅ (B/2 + h), [m]

where:h = height from uppermost continuous deck

to the deck considered, in [mm].− Longitudinal bulkhead - longitudinal

bulkhead which extend from bottom todeck and which is efectively connectedwith shell plating by transversal bulkheadsat both ends.

− Effective shear area of shell or innershell - area of entire height.

− Effective shear area of longitudinalbulkhead - area of entire height of bulk-head. Where bulkhead is corrugated area ofcross section is to be deducted for relationbetween projected and developed length ofcorrugation

− Loading manual - is a document whichdescribes:− The loading conditions on which the

design of the ship has been based, in-cluding permissible limits of still waterbending moment and shear force.

− The results of the calculations of stillwater bending moments, shear forcesand where applicable, limitations due totorsional and lateral loads.

− The allowable local loading for hatchcovers, decks, double bottom, etc.

− Loading instrument - is an instrument,which is either analog or digital, consistingof loading computer (hardware) loadingprogram (software) and by means of whichit can be easily and quickly ascertainedthat, at specified read-out points, the stillwater bending moments, shear forces, andthe still water torsional moments and lateralloads, where applicable, in any load orballast condition are not exceed the speci-fied permissible values.An operational manual is always to be pro-vided for the loading instrument.Loading instrument must be approved andtype tested, see also 4.1.4.5.Single point loading instrument are not ac-ceptable.The operation manual is also subject to ap-proval.Type approved hardware may be waived, ifredundancy is ensured by a second certifiedloading instrument.Loading programs shall be approved andcertified, see also 4.1.4.5.

4.1.4 Requirements for loading manuals andloading instruments

4.1.4.1 General, application

− A loading guidance information is a meanswhich enables the master to load and bal-last the ship in a safe manner without ex-ceeding the permissible stresses.

− An approved loading manual is to be sup-plied for all ships except those of CategoryII with length less than 90 m which the


2013

deadweight does not exceed 30% of thedisplacement at the summer loadline raft.In addition, an approved loading instrumentis to be supplied for all ships at Category Iwith length of 100 m and above.In special cases, e. g. extreme loading con-ditions or unusual structural configurations,Register may also require an approvedloading instrument for ships of Category Iless than 100 m in length. carriers and combination carriers are givenin Section 17.Ship categories for the purpose of thisparagraph are defined as follows:Category I ships:

− Ships with large deck openings wherecombined stresses due to vertical and hori-zontal hull girder bending and torsional andlateral loads have to be considered.

− Ships liable to carry non-homogeneousloadings, where the cargo and ballast maybe unevenly distributed. Ships less than 120metres in length, when their design takesinto account uneven distribution of cargo orballast, belong to Category II.

− Chemical tankers and gas carriers.Category II ships:

− Ships with arrangement giving small possi-bilities for variation in the distribution ofcargo and ballast (e.g. passenger vessels)and ships on regular and fixed trading pat-tern where the Loading Manual gives suffi-cient guidance, and in addition those ex-ceptions given under Categories I.

4.1.4.2 Annual and renewal survey

At each Annual and Class Renewal Survey, it isto be checked that the approved loading guidance informa-tion is available on board.

The loading instrument is to be checked for ac-curacy at regular intervals by the ship's Master by applyingtest loading conditions.

At each Class Renewal Survey this checking isto be done in the presence of the Surveyor.

4.1.4.3 Conditions of approval of loading manuals

4.1.4.3.1 The approved Loading Manual is to be basedon the final data of the ship. The Manual is to include the de-sign loading and ballast conditions upon which the approvalof the hull scantlings is based.

The Loading Manual must be prepared in alanguage understood by the users. If this language is notEnglish, a translation into English is to be included.

In case of modifications resulting in changes tothe main data of the ship, a new approved Loading Manual isto be issued.

Item 4.1.4.3.2 contains, as guidance only, a listof the loading conditions which normally should be includedin the Loading Manual.

4.1.4.3.2 The Loading Manual should contain the designloading and ballast conditions, subdivided into departure andarrival conditions, and ballast exchange at sea conditions,

where applicable, upon which the approval of the hull scant-lings is based.

In particular the following loading conditionsshould be included:

Cargo ships, container ships, roll-on/roll-offand refrigerated carriers, ore carriers and bulk carriers:

− Homogeneous loading conditions at maxi-mum draught.

− Ballast conditions.− Special loading conditions e.g., container or

light load conditions at less than the maxi-mum draught, heavy cargo, empty holds ornon-homogeneous cargo conditions, deckcargo conditions, etc., where applicable.

− Short voyages or harbour conditions, whereapplicable.

− Docking conditions afloat.− Loading and unloading transitory condi-

tions, where applicable.

Oil tankers:

− Homogeneous loading conditions (exclud-ing dry and clean ballast tanks) and ballastor part loaded conditions for both departureand arrival.

− Any specified non-uniform distribution ofloading.

− Mid-voyage conditions relating to tankcleaning or other operations where thesediffer significantly from the ballast condi-tions.

− Docking conditions afloat.− Loading and unloading transitory condi-

tions.

Chemical tankers:

− Conditions as specified for oil tankers.− Conditions for high density or heated cargo

and segregated cargo where these are in-cluded in the approved cargo list.

Liquefied gas carriers:

− Homogeneous loading conditions for allapproved cargoes for both arrival and de-parture.

− Ballast conditions for both arrival and de-parture.

− Cargo conditions where one or more tanksare empty or partially filled or where morethan one type of cargo having significantlydifferent densities are carried, for both arri-val and departure.

− Harbour condition for which an increasedvapour pressure has been approved.

− Docking condition afloat.

Combination carriers:- Conditions as specified for oil tankers and

cargo ships.

4.1.4.4 Conditions of approval of loading instru-ments

4.1.4.4.1 The approval of the loading instrument is to in-cluded:


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− Verification of type approval, if any,− Verification that the final ship data have

been used,− Acceptance of number and position of read-

out points,− Acceptance of relevant limits for all read-

out points,− Checking of proper installation and opera-

tion of the instrument on board, in accor-dance with agreed test conditions, and thata copy of the approved operation manual isavailable.

4.1.4.4.2 Paragraph 4.1.4.5 contains information on ap-proval procedures for loading instruments.

4.1.4.4.3 In case of modifications implying changes inthe main ship data, the loading instrument is to be modifiedaccordingly and approved.

4.1.4.4.4 The operation manual and the instrument out-put must be prepared in a language understood by the users.If this language is not English, a translation into English is tobe included.

4.1.4.4.5 The operation of the loading instrument is to beverified upon installation. It is to be checked that the agreedtest conditions and the operation manual for the instrument isavailable on board.

4.1.4.5 Approval procedures of loading instruments

4.1.4.5.1 Type test of the loading instrument

The type test requires:

− The instrument has to undergo successfultests in simulated conditions to prove issuitability for shipboard operation,

− The type test may be waived if a loadinginstrument has been tested and certified byan independent and recognised authority,provided the testing program and results areconsidered satisfactory.

4.1.4.5.2 Certification of the loading program

a) After the successful type test of thehardware, if required, see 4.1.3, the pro-ducer of the loading program shall applyat Register for certification.

b) The number and location of read-outpoints are to be to the satisfaction of theRegister.Read-out points are to be usually selectedat the positions of the transverse bulk-heads or other obvious boundaries. Addi-tional read-out points may be requiredbetween bulkheads of long holds/tanks.

c) The Register will specify:- the maximum permissible still water

shear forces, bending moments (lim-its) at the agreed read-out points -when applicable, the shear force cor-rection factors at the transverse bulk-heads,

- when applicable, the maximum per-missible torsional moment,

- also when applicable the maximumlateral load.

d) For approval of the loading program thefollowing documents have to be handedin:- operation manual for the loading pro-

gram,- print-outs of the basic ship data like

distribution of light ship weight, tankand hold data etc.,

- print-outs of at least 4 test cases,

- diskettes with loading program andstored test cases.

The calculated strength results at the fixedread-out points shall not differ from the results of the testcases by more than 5 % related to the approved limits.

4.1.4.5.3 Loading instrument

Final approval of the instrument be grantedwhen the accuracy of the instrument has been checked in thepresence of the Surveyor after installation on board ship us-ing the approved test conditions.

If the performance of the loading instrument isfound satisfactory during the installation test on board, thecertificate issued by Register and handed over on board willbecome valid.

4.2 VERTICAL LONGITUDINALBENDING MOMENTS AND SHEAR

FORCES

4.2.1 Still water bending moment and shear force

4.2.1.1 Still water bending moments, Ms [kNm], andstill water shear forces, Fs [kN], are to be calculated at eachsection along the ship length for design cargo and ballastloading conditions as specified in 4.2.1.2.

For these calculations, downward loads are as-sumed to be taken as positive values, and are to be integratedin the forward direction from the aft end of L. The sign con-ventions of Ms and Fs are as shown in Fig. 4.2.1.1.

Figure 4.2.1.1

4.2.1.2 Design loading conditions

In general, the following design cargo and bal-last loading conditions, based on amount of bunker, freshwater and stores at departure and arrival, are to be consideredfor the Ms and Fs calculations. Where the amount and dispo-sition of consumables at any intermediate stage of the voyage


2013

are considered more severe, calculations for such intermedi-ate conditions are to be submitted in addition to those for de-parture and arrival conditions. Also, where any ballastingand/or deballasting is intended during voyage, calculations ofthe intermediate condition just before and just after ballastingand/or deballasting any ballast tank are to be submitted andwhere approved included in the loading manual for guidance.

General cargo ships, container ships, roll-on/roll-off and refrigerated cargo carriers, bulk carriers,ore carriers:

− Homogeneous loading conditions at maxi-mum draught.

− Ballast conditions.− Special loading conditions e.g., container or

light load conditions at less than the maxi-mum draught, heavy cargo, empty holds ornon-homogeneous cargo conditions, deckcargo conditions, etc., where applicable.

− All loading conditions specified in Section17.4.6.4 for bulk carriers with notation BC-A, BC-B or BC-C, as applicable.

Oil tankers:− Homogeneous loading conditions (exclud-

ing dry and clean ballast tanks) and ballastor part loaded conditions.

− Any specified non-uniform distribution ofloading.

− Mid-voyage conditions relating to tankcleaning or other operations where thesediffer significantly from the ballast condi-tions.

Chemical tankers:− Conditions as specified for oil tankers.− Conditions for high density or segregated

cargo.Liquefied gas carriers:− Homogeneous loading conditions for all

approved cargoes.− Ballast conditions.− Cargo conditions where one or more tanks

are empty or partially filled or where morethan one type of cargo having significantlydifferent densities are carried.

Combination carriers:− Conditions as specified for oil tankers and

cargo ships.

4.2.1.3 Partially filled ballast tanks in ballast load-ing conditions

Ballast loading conditions involving partiallyfilled peaks and/or other ballast tanks at departure, arrival orduring intermediate conditions are not permitted to be usedas design conditions unless:

− design stress limits are satisfied for all fillinglevels between empty and full and

− for bulk carriers, Section 17.2.2.2, as appli-cable, is complied with for all filling levelsbetween empty and full.

To demonstrate compliance with all filling lev-els between empty and full, it will be acceptable if, in eachcondition at departure, arrival and where required by Section4.2.1.2 any intermediate condition, the tanks intended to bepartially filled are assumed to be:

- empty

- full- partially filled at intended level

Where multiple tanks are intended to be par-tially filled, all combinations of empty, full or partially filledat intended level for those tanks are to be investigated. How-ever, for conventional ore carriers with large wing waterballast tanks in cargo area, where empty or full ballast waterfilling levels of one or maximum two pairs of these tankslead to the ship’s trim exceeding one of the following condi-tions, it is sufficient to demonstrate compliance with maxi-mum, minimum and intended partial filling levels of theseone or maximum two pairs of ballast tanks such that theship’s condition does not exceed any of these trim limits.Filling levels of all other wing ballast tanks are to be consid-ered between empty and full. The trim conditions mentionedabove are:

- trim by stern of 3% of the ship’s length, or- trim by bow of 1,5% of ship’s length, or- any trim that cannot maintain propeller im-

mersion (I/D) not less than 25%, where;I = the distance from propeller centerline to the

waterlineD = propeller diameter (see Fig. 4.2.1.3)

Figure 4.2.1.3

The maximum and minimum filling levels ofthe above mentioned pairs of side ballast tanks are to be indi-cated in the loading manual.

It is recommended that IACS Rec. No.97 betaken into account when compiling ballast loading condi-tions.

4.2.1.4 Partially filled ballast tanks in cargo loadingconditions

In cargo loading conditions, the requirement in4.2.1.3 applies to the peak tanks only.

4.2.1.5 Sequential ballast water exchange

Requirements of 4.2.1.3 and 4.2.1.4 are not ap-plicable to ballast water exchange using the sequentialmethod. However, bending moment and shear force calcula-tions for each deballasting or ballasting stage in the ballastwater exchange sequence are to be included in the loadingmanual or ballast water management plan of any vessel thatintends to employ the sequential ballast water exchange met-hod.


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4.2.2 Wave bending moment

The vertical wave bending moments, Mw[kNm], at each section along the ship length are given by thefollowing formulae:Mw = + 190 M Cw L2 B Cb ⋅ 10-3, [kNm], hogging condi-

tion,Mw = -110 M Cw L2 B (Cb + 0,7) ⋅ 10-3, [kNm ], sagging

condition,where:

M = Distribution factor given in Fig. 4.2.2.

Cw = 10,75 - 300

100

1 5−

L ,, for 90 ≤ L ≤ 300

Cw = 10,75, for 300 < L ≤ 350

Cw = 10,75 - L −

350150

1 5,, for 350 < L ≤ 500

Cb − not to be taken less than 0,6

M = 2,5 xL

, for xL

< 0,40

M = 1,0, for 0,4 ≤ xL

≤ 0,65

M = 1

0 35

−xL

,, for

xL

> 0,65

Figure 4.2.2

Wave bending moment for ships in limitedservice conditions may be reduced as follows:

− navigation area 7 and 8 for 40%,− navigation area 5 and 6 for 30%,− navigation area 3 and 4 for 25%− navigation area 2 for 10%.Wave bending moment for harbour conditions

may be multiplied with coefficient 0,1, and for conditions ofthe off-shore terminal with 0,5.

4.2.3 Wave shear force

The wave shear forces Fw, at each section alongthe length of the ship are given by the following formulae:

Fw = + 30 F1 Cw L B (Cb + 0,7) ⋅ 10-2 [kN], forpositive shear force;

Fw = - 30 F2 Cw L B (Cb + 0,7) ⋅ 10-2 [kN], fornegative shear force.

where:F1, F2 = Distribution factors given in Figs. 4.2.3-1

and 4.2.3-2, see also Table 4.2.3;Cb = not to be less than 0,6

Figure 4.2.3-1

Figure 4.2.3-2

Table 4.2.3

Range Positive shear forces Negative shear forces

0 ≤ xL

< 0,2 5 ⋅ m xL

4,6 ⋅xL

0,2 ≤ xL

< 0,3 m 0,92

0,3 ≤ xL

< 0,4 4 ⋅ m - 2,1 + (7 - 10 ⋅ m) ⋅xL

158 2 2, ,− ⋅xL

0,4 ≤ xL

< 0,6 0,7 0,7

0,6 ≤ xL

< 0,7 3 ⋅xL

- 1,1 4,9 - 6 m1 + (10 ⋅ m1 - 7) ⋅xL

0,7 ≤ xL

< 0,85 1,0 m1

where:

m = 0 92 190

110 0 7,

( , )⋅ ⋅

⋅ +C

Cb

b; m1 =

190110 0 7

⋅⋅ +

CC

b

b( , )

The wave shear forces for harbour and offshoreterminal conditions may be reduced as stipulated in 4.2.2.


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4.3 BENDING STRENGTH

4.3.1 Bending strength amidships

4.3.1.1 General

The deck modulus Wd, is related to the mouldeddeck line at side (lower edge of deck stringer)

The bottom modulus Wb, is related to the baseline (upper edge of keel plate)

4.3.1.2 Members included in calculation of midshipsection moduliContinuous trunks and longitudinal hatch

coamings are to be included in the longitudinal sectional areaprovided they are effectively supported by longitudinal bulk-heads or deep girders. The deck modulus is then to be calcu-lated by dividing the moment of inertia by the following dis-tance, provided this is greater than the distance to the deckline at side:

Wd' =IZ

y

g′⋅ 10-2 [cm3]

Zg' = Zg ⋅ 0 9 0 2, ,+

YB

, [m]

where:Zg − distance in from neutral axis to top of conti-

nous strength member (hatch coaming),in [m];

Y − distance from centre line of the ship to top ofcontinous strength member in [m];

(Y and Zg) − are to be measured to the point giving thelargest value of Zg'.

When continuous hatch coamings or other lon-gitudinal continous members are not above longitudinalbulkheads or similar constructions, Register can accept re-duced area of their cross section.

4.3.1.3 Effective sectional area used in calculation

When calculating the midship section moduluswithin 0.4L amidships the sectional area of all continuouslongitudinal strength members is to be taken into account.

Large openings, i.e. openings exceeding 2,5 min length or 1,2 m in breadth and scallops, where scallop-welding is applied, are always to be deducted from the sec-tional areas used in the section modulus calculation.

Smaller openings (manholes, lightening holes,single scallops in way of seams, etc.) need not be deductedprovided that the sum of their bradths or shadow areabreadths in one transverse section does not reduce the sectionmodulus at deck or bottom by more than 3% and providedthat the height of lightening holes, draining holes and singlescallops in longitudinal girders does not exceed 25% of theweb depth, for scallops maximum 75 mm.

A deduction-free sum of smaller openingbreadths in one transverse section in the bottom or deck areaof 0,06 (B - Σb) (Σb = total breadth of large openings) maybe considered equivalent to the above reduction in sectionmodulus.

The shadow area is to be obtained by drawingtwo tangent lines with an opening angle of 30o (see Fig.4.3.1.3).

Figure 4.3.1.3Longitudinal girders between multi-hatchways

will be considered by special calculations.

4.3.2 Section modulus - strength criteria

Hull section modulus, W, calculated in accor-dance with 4.3.1, is not to be less than the values given bythe following formula in way of 0,4 L midships for the Msgiven in 4.2.1 and the Mw given in 4.2.2, respectively:

310⋅+σ

ws MM , [cm3],

where:

σ =18 5, L

k, for L < 90 m and 0,3 ≤

xL

≤ 0,7

σ = permissible bending stress = 175/k [N/mm], for

L ≥ 90 m and 0,3 ≤ xL

≤ 0,7;

σ = 0 553

, + ⋅

⋅xL

σ, for xL

< 0,30

σ =53

1 3, −

⋅xL

σ, for xL

> 0,70

k = 1,0 for ordinary hull structural steel;k < 1 for higher tensile steel according to 1.4.2.2

Hull section modulus at 0,4 L amidship is notto be less than Wmin given in 4.3.4.

4.3.3 Moment of inertia

Moment of inertia of hull section at the midshippoint is not to be less than:

Imin = 3 ⋅ L /k⋅ Wmin, [cm4],where:

Cw,Cb = as specified in 4.2.2.Wmin = section moduli according to 4.3.2 and

4.3.4, which is the greater value.

4.3.4 Minimum midship section modulus

These requirements do not apply to CSR BulkCarriers and Oil Tankers

The minimum midship section modulus at deckand keel for ships 90 m ≤ L ≤ 500 m is:

Wmin = Cw ⋅ L2 ⋅ B (Cb + 0,7) k [cm3]

where:L, B, Cb = according to Section 1.2;Cb ≥ 0,6;k = material factor according to 4.3.2;Cw = as specified in 4.2.2 for new ships;Cw = 0,9 ⋅ Cw for ships in service.


2013

Minimum midship section modulus for ships inlimited service conditions may be reduced as follows:

- 5% for navigation area 2- 15% for navigation area 3- 20% for navigation area 4,5- 25% for navigation area 6,7,8

Scantlings of all continuous longitudinal mem-bers of hull girder based on the section modulus requirementare to be maintained within 0,4 L amidships.

However, in special cases, based on considera-tion of type of ship, hull form and loading conditions, thescantlings may be gradually reduced towards the end of the0,4 L part, bearing in mind the desire not to inhibit the ves-sel's loading flexibility.

In ships where part of the longitudinal strengthmaterial in the deck or bottom area are forming boundaries oftanks for oil cargoes or ballast water and such tanks are pro-vided with an effective corrosion protection system, certainreductions in the scantlings of these boundaries are allowed.These reductions, however, should in no case reduce theminimum hull girder section modulus for a new ship by morethan 5%.

4.3.5 Extent of high strength steel (HS)

The vertical extent of HS steel used in deck orbottom are determined in according Section 2.2.3 and Fig.4.3.5-1.

Longitudinal members which are made of HS,are to be extended outside 0,4 L amidship to a point wherethe scantling is equal to those of an identical ship built ofnormal strength steel over the full length as shown in Fig.4.3.5-2.

Figure 4.3.5-1

Figure 4.3.5-2

4.3.6 Bending strength outside amidships

4.3.6.1 As a minimum, hull girder bending strengthchecks are to be carried out at the following locations:

- In way of the forward end of the engine room.- In way of the forward end of the foremost cargo

hold.- At any locations where there are significant cha-

nges in hull cross-section.- At any locations where there are changes in the

framing system.

4.3.6.2 Buckling strength of members contributing to thelongitudinal strength and subjected to compressive and shearstresses is to be checked, in particular in regions where chan-ges in the framing system or significant changes in the hullcross-section occur. The buckling evaluation criteria used forthis check is given in Section 4.6.

4.3.6.3 Continuity of structure is be maintained throug-hout the length of the ship. Where significant changes instructural arrangement occur adequate transitional structureis to be provided.

4.3.6.4 For ships with large deck openings such as con-tainerships, sections at or near to the aft and forward quarterlength positions are to be checked. For such ships with cargoholds aft of the superstructure, deckhouse or engine room,strength checks of sections in way of the aft end of the aft-most holds, and the aft end of the deckhouse or engine roomare to be performed.

4.4 SHEARING STRENGTH

4.4.1 Correction of still water shear forcecurve

4.4.1.1 In case of alternate loading the conventionalshear force curve may be corrected according to the directload transmission by the longitudinal structure at the trans-verse bulkheads. See also Fig. 4.4.1.


2013

Fs1

Fs1

Fs2

Fs2

Figure 4.4.1

4.4.1.2 The supporting forces of the bottom grillage atthe transverse bulkheads may either be determined by directcalculation or by approximation, according to 4.4.1.3.

4.4.1.3 The sum of the supporting forces of the bottomgrillage at the aft or forward boundary bulkhead of the holdconsidered may be determined by the following formulae:

∆Fs = ∆Fs1 - ∆Fs2 = u ⋅ G - v d1 , [kN]

where:G = mass of cargo or ballast, in [t], in the hold

considered, including any contents ofbottom tanks within the flat part of thedouble bottom;

d1 = mean draught, in [m], coresponding consid-ered load condition;

u, v = correction coefficients for cargo and buoy-ancy as follows:

u = 10 ⋅ ⋅ ⋅ ⋅c l b k

V

v = 10 ⋅ c ⋅ l ⋅ b

c = Bb l2 3, ( )+

l = length of the flat part of the double bottom, in[m];

b = breadth of the flat part of the double bot-tom, in [m];

h = height of the hold, in [m];V = volumen of the hold, in [m3].

4.4.2 Calculation of shear stresses

4.4.2.1 The shear stress distribution may be determinedby means of calculation procedures approved by Register.For ships having more than 2 longitudinal bulkheads and fordouble hull ships, particularly with uneven load distributionover the ship's cross section, the application of such approvedcalculation procedures may be required.

4.4.2.2 For ships without longitudinal bulkheads andwith two longitudinal bulkheads respectively the shear stressdistribution in the side shell and in the longitudinal bulkheadsmay be determined by the following formula:

τ = ( )F F S

I ts w

y

+ ⋅⋅

(0,5 - Φ) ⋅ 102 [N/mm2]

where:

Iy, Fs, Fw = according to 4.1.2S = first moment, in [cm3], about the neutral axis,

of the area of the effective longitudinalmembers between the vertical level atwhich the shear stress is being deter-mined and the vertical extremity of ef-fective longitudinal members, taken at thesection under consideration;

t = thickness of side shell or longitudinal bulk-head plating, in [mm], at the section con-sidered;

Φ = 0 for ships without longitudinal bulkheadWhere two longitudinal bulkhead are fitted:For the side shell:

Φ = 0,34 - 0,08 L

s

AA

For the longitudinal bulkheads:

Φ = 0,16 + 0,08 L

s

AA

As = sectional area of side shell plating, in [cm2],within the depth D;

AL = sectional area of longitudinal bulkhead plating, in [cm2], within the depth D.

For ships with usual design and form the ratioS/Iy determined for the midship section may be used forother sections also.

4.4.2.3 Permissible shear stress

The shear stress in the side shell and in the lon-gitudinal bulkheads due to the shear forces Fs and Fw are notto exceed 110/k, [N/mm2].where:

k = material factor according to 1.4.2.2

4.4.2.4 Where stringers on transverse bulkheads aresupported at longitudinal bulkheads or at the side shell, thesupporting forces of these girders are to be considered whendetermining the shear stresses in longitudinal bulkheads orside shell. The shear stress introduced by the stringer into thelongitudinal bulkhead or side shell may be determined by thefollowing formula.

τst = F

b tst

st ⋅[N/mm2]

Fst = supporting force of stringer, in [kN];bst = breadth of stringer including end bracket (if

any), in [m], at the supporting point.The additional shear stress is to be added to the

shear stress due to longitudinal bending in the following area:− 0,5 m on both sides of stringer in the ship's

longitudinal direction;− 0,25 bst above and below the stringer.

4.4.3 Shearing strength for ships without effectivelongitudinal bulkheads

The thickness of side shell is not to be less thanthe values given by following formula (for the still water


2013

shear forces Fs given in 4.2.1 and the wave shear forces Fwgiven in 4.2.3 respectively):

2105,0

⋅⋅+

=y

ws

ISFF

tτ

[mm],

where:τ = permissible shear stress = 110/k [N/mm2]k = as specified in 4.1.2.

4.4.4 Shearing strenght for ships with two ef-fective longitudinal bulkheads

The thickness of side shell and longitudinalbulkheads are not to be less than the values given by the fol-lowing formulae:for side shell:

210)()5,0(

⋅⋅∆++Φ−

=y

shws

ISFFF

tτ

, [mm]

for longitudinal bulkheads:

210)(

⋅⋅∆++Φ

=y

blws

ISFFF

tτ

, [mm]

where:Φ, As, AL = according to 4.4.2.2

τ =110

k, [N/mm2];

∆Fsh, ∆ Fbl = shear force acting upon the side shell platingand longitudinal bulkhead plating, re-spectively, due to local loads (see 4.4.2.4)

4.5 ADDITIONAL BENDINGMOMENTS

4.5.1 Additional bending moments due toslamming loads in the forebody region

For ships with lengths between 110 m and 180m, the mean bow flare of which amounts to α > 30° withinthe forebody region 0,2 L aft of x/L = 1,0, the following ad-ditional bending moment MSL due to slamming loads in theforebody region is to be considered when determining thetotal bending moment. The additional bending moment maybe determined approximately by the following formula:

MSL = w ⋅ L4 ⋅ B ⋅ n1 ⋅ n2 ⋅ n3 ⋅ M1 ⋅ 10-5 [kNm]

where:w = 1,4 hogging condition;w = -2,2 sagging condition;

n1 = )(2,1 1

21

dDbb−

− - 1, n1 ≥ 0;

b1 = breadth of the uppermost continuous deck, in

[m], at Lx

= 0,8;

b2 = breadth of the waterline, in [m],

at Lx

= 0,8;

d1 = draft of the actual loading or ballast con-dition, in [m];

n2 = 1 - 1225

)L145( 2−, n2 ≥ 0

n3 = 0,33 + 0,67 ⋅ L,61

ν;

M1 = distribution factor;

M1 = 2,5 Lx

, for Lx

< 0,4

M1 = 1,0, for 0,4 ≤ Lx

≤ 0,8

M1 = 5

−

Lx1 , for

Lx

> 0,8

L,B,D = according to Section 1.2.3v =according to Section 1.2.6.7.

4.5.2 Horizontal wave bending moments

The rule horizontal wave bending momentsalong the length of the ship are given by formula:

MWH = 0,32 ⋅ Cw ⋅ M ⋅ L d3 ⋅ ⋅ B , [kNm]

where:Cw = wave coefficient, see 4.2.2;M = distribution factor, see 4.2.2;

L,B,d = according to Section 1.2.3.

4.5.3 Design stresses σL and τL

a) In design hull girder bending stress σL is to becalculated by the following formulae:

σL = M M M

Ws w SL+ ⋅ +0 75,

⋅ 103, [N/mm2]

where:W = Wd(a) or Wb(a) for deck or bottom according to

4.3.1 in [cm3];b) The design shear stress τL is to be calculated as

follows:

τL = τs + 0,75 ⋅ τw , [N/mm2]

where:τs = shear stress due to Fsτw = shear stress due to Fw

4.6 BUCKLING STRENGTH

4.6.1 These requirements apply to plate panels andlongitudinals subject to hull girder bending and shearstresses.

4.6.2 Elastic buckling stresses

4.6.2.1 Elastic buckling of plates

4.6.2.1.1 Compression

The ideal elastic buckling stress is given by:


2013

σE = 0,9 mEt

bb

1000

2

⋅

, [N/mm2],

− For plating with longitudinal stiffeners(parallel to compressive stress):

m = 11

48,

,+ψ

, buckling factor

O ≤ ψ ≤ 1

− For plating with transverse stiffeners (per-pendicular to compressive stress):

m = c 12 1

11

2 2

+

+

ba

,,ψ

,

O ≤ ψ ≤ 1For same load cases of plates the buckling fac-

tor m. given in Tables 4.6.2.1-2 and 4.6.2.1-3.E = modulus of elasticity of material, N/mm2]E = 2.06 x 105 N/mm2, for shipbuilding steel;E = 0,69 ⋅ 105 N/mm2, for alumminium alloys;tb = net thickness, in [mm], of plating, consid-

ering standard deductions equal to theval-ues given in the Table 4.6.2.1-1;

b = shorter side of plate panel, in [m], seeFig. 4.6.2.1;

a = longer side of plate panel, in [m], seeFig. 4.6.2.1;

c = correction factor;c = 1,0 for stiffeners sniped at both ends;c = 1,3 when plating stiffened by floors or

deep girders;c = 1,21 when stiffeners are angles or

T-sections;c = 1,10 when stiffeners are bulb bars;c = 1,05 when stiffeners are flat bars;ψ = ratio between smallest and largest com-

pressive σa stress when linear variationacross panel.

a

bam b m

n·b

Figure 4.6.2.1

Table 4.6.2.1-1

Structure

Stan-dard

deduc-tion

[mm]

Limit valuesmin-max.

[mm]

− Compartments carrying dry bulkcargoes

− One side exposure to ballastand/or liquid cargo 0,05 t 0,5 ÷ 1

− Vertical surfaces and surfacessloped at an angle greater than 25o

to the horizontal line− One side exposure to ballast

and/or liquid cargoHorizontal surfaces and surfacessloped at an angle less than 25o tothe horizontal line 0,1 t 2 ÷ 3

− Two side exposure to ballastand/or liquid cargoVertical surfaces and surfacessloped at an angle greater than 25o

to the horizontal line− Two side exposure to ballast

and/or liquid cargoHorizontal surfaces and surfacessloped at an angle less than 25o tothe horizontal line

0,15 t 2 ÷ 4


2013

Table 4.6.2.1-2

Load case Buckling factor

m = 8 4

11,

,ψ +

m = c ⋅ 12 1

11

2 2

+

+

ba

,( , )ψ

m =

1 333 0 425

0 333

2, ,

,

⋅ +

+

ba

ψ

m = ( )0 425 15 0 52

, , ,+

− ⋅ba

ψ

kt = 5,34 + 4 ⋅ba

2

for (a - da) ≥ (b - db):

kt = 1 5 34 42

−

+

db

ba

b ,

for (a - db) < (b - db)

kt = 1 5 34 42

−

+ ⋅

da

ba

a ,

m = 1,28

m = 6,97

m = 4 + 4

32 74

4

−

⋅

ba

,

m = 6,97 +4

331

4

−

⋅

ba

,


2013

Table 4.6.2.1-3Curved plate field R/t ≤ 2500

Load case Aspect ratio b/R Buckling factor

bR

≤ 1,63Rt

m = ( )b

R t

R t

b⋅+

⋅3

0 175

0 35

,

,

bR

> 1,63Rt m = 0,3

bR

2

2 + 2,25 Rb t

2 2

⋅

bR

≤ 0,5 Rt

bR

> 0,5Rt

m = 1 + 23

2bR t⋅

m = 0,267 bR t

2

⋅3−

bR

tR

≥ 0,4 bR t

2

⋅

bR

≤Rt

bR

>Rt

m = 0 6, ⋅

⋅

bR t

+ R tb

⋅- 0,3

R tb

⋅2

m = 0,3 bR

2

2 + 0,291 Rb t

2 2

⋅

bR

≤ 8,7Rt

bR

> 8,7Rt

m = kt ⋅ 3

kt = 28 30 67 3

1 5 1 5

0 5

,,

, ,

,⋅

⋅

bR t

kt = 0,28 b

R R t

2

⋅

Explanations for boundary conditions: plate edge freeplate edge simply supported

plate edge clamped


2013

4.6.2.1.2 Shear

The ideal elastic buckling stress is given by:

τE = 0,9 kt E t

bb

1000

2

⋅

, [N/mm2],

where:

kt = 5,34 + 4 ba

2;

E, tb, b and a − see 4.6.2.1.1For some load cases of plates the buckling

factor kt is given in Tables 4.6.2.1-2 and 4.6.2.1-3.

4.6.2.2 Elastic buckling of longitudinals

4.6.2.2.1 Stress of longitudinal without rotation oftransversal sections.For the column buckling mode (perpendicular

to plane of plating) the ideal elastic buckling stress is givenby:

σe = 0,001 E I

Ala2 , [N/mm2],

where:A = cross-sectional area, in [cm2], of lon-

gitudinal, including plate flange;Ia = moment of inertia, in [cm4], of lon-

gitudinal, including plate flange andcalculated with thickness as specifiedin 4.6.2.1.1,

l = span, in [m], of longitudinal,A plate flange equal to the frame spacing may

be included.

4.6.2.2.2 Stress of longitudinal with rotation of trans-versal sectionsThe ideal elastic buckling stress for the tor-

sional mode is given by:

σE = p

t

p

w

II

E,mKm

lI

EI3850

10 22

24

2+

+

π, [N/mm2],

where:

K = C l

E I w

⋅

⋅⋅

4

4610

π;

m = number of half waves, given by thefollowing table:

O < K< 4 4 < K < 36 36 < K < 144(m - 1)2 m2 < K≤ m2 (m + 1)2

m 1 2 3 m

It = torsional, moment of inertia, in [cm4],of profile without plate flange:

It =h tw w

34

310⋅ − , for flat bars (slabs)

and:

It = 13

1 0 63 103 3 4h t b ttbw w f f

f

f⋅ + ⋅ −

⋅ −, ,

for flanged profiles:

Ip = polar moment of inertia, in [cm4], ofprofile about connection of stiffenerto plate:

Ip =h tw w

34

310

⋅⋅ − , for flat bars:

Ip =h t

h b tw ww f f

32 4

310

⋅+ ⋅ ⋅

⋅ − ,

for flanged profiles:Iw = sectional moment of inertia, in [cm6], of profile

about connection of stiffener to plate:

Iw =h tw w

3 36

3610

⋅⋅ − for flat bars (slabs):

Iw = 623

1012

−⋅⋅⋅ wff hbt

, for "Tee" profiles

( )[ ]Ib h

b ht b b h h t b hw

f w

f wf f f w w w f w=

++ + + ⋅ −

3 2

22 2 6

122 4 3 10

( )for angles and bulb profiles

where:hw = web height, in [mm], see Fig. 4.6.2.2.2,tw = web thickness, in [mm], considering stan-

dard deductions as specified in 4.6.2.1.1,see Fig. 4.6.2.2.2,

bf = flange width, in [mm], see Fig. 4.6.2.2.2,tf = flange thickness, in [mm], considering

standard deductions as specified in4.6.2.1.1, see Fig. 4.6.2.2.2.

For bulb profiles the means thickness of the bulb maybe used.l = span of profile, in [m],s = spacing of profiles, in [m],

Figure 4.6.2.2.2

C = spring stiffness exerted by supportingplate panel:

C = k E t

sk h t

s t

p p

p w p

w

3

3

3

3

3 11 33

100

10

+

⋅ −

,

where:kp = 1 - ηp, not to be taken less than zero;tp = plate thickness, in [mm], considering

standard deductions as specified in4.6.2.1.1;

ηp =σσ

a

Ep;

σa = calculated compressive stress. For lon-gitudinals, see 4.6.4.1;


2013

σEp = elastic buckling stress of supportingplate as calculated 4.6.2.1, in [N/mm2].

For flanged profiles, kp need not be taken lessthan 0,1.

4.6.2.2.3 Web and flange bucklingFor web plate of longitudinals the ideal elastic

buckling strees is given by:

σE = 3,8 E th

w

w

, [N/mm2]

For flanges on angles and T-sections of longi-tudinals, buckling is taken care of the following requirement:

bt

f

f≤ 15,

where:bf = flange width, in [mm],

for angles, half the flange width forT-sections;

tf = as built flange thickness, in [mm].

4.6.3 Critical buckling stresses

4.6.3.1 CompressionThe critical buckling stress in compression is

determined as follows:

σc = σE, if σE ≤ σ F2

odnosno σc = σF 14

−

σ

σF

E, σE >

σ F2

,

where:σF = yield stress of material, in [N/mm2]σF = 235 [N/mm2] (may be taken for mild

steel,);σE = ideal elastic buckling stress calcu-

lated according to 4.6.2.4.6.3.2 Shear

The critical buckling stress in shear is deter-mined as follows:

τc = τE, if τE < τF2

odnosno τc = τF 14

−

τ

τF

E, if τE >

τ F2

where:

τF = σ F

3;

σF = as given in 4.6.3.1;τE = according to 4.6.2.1.2

4.6.4 Working stress

4.6.4.1 Longitudinal compressive stressesThe compressive stresses are given in the fol-

lowing formula:

σa = M M

Iys w

n

+⋅ 105 , [N/mm2],

but not less than:

σa ≥ 30k

,

whereMs = still water bending moment, [kNm],as

given in 4.2.1;Mw = wave bending moment, [kNm], as

given in 4.2.2;In = moment of inertia, in [cm4],of the

midship section;y = vertical distance, in [ m ], from neu-

tral axis to considered point;k = as specified in 1.4.2.2.Ms and Mw are to be taken as sagging or hog-

ging bending moments, respectively, for members above orbelow the neutral axis.

Where the ship is always in hogging conditionin still water, the sagging bending moment (Ms + Mw) is to bespecially considered.

4.6.4.2 Shear stresses

4.6.4.2.1 Ships without effective longitudinal bulk-headsFor side shell:

τs = 0 5

102, ( )F Ft

SI

s w

y

+⋅ , [N/mm2],

where:Fs, Fw, S and Iy = as specified in 4.1.2;

t = as specified in 4.4.3.

4.6.4.2.2 Ships with two effective longitudinal bulk-heads

For side shell:

τa = [ ]

y

shwsIS

tFFF

⋅∆++Φ− )()5,0(

⋅ 102, [N/mm2]

For longitudinal bulkheads:

τa = [ ]Φ ∆( )F F F

ts w bl+ +

⋅ 102, [N/mm2]

Fs, Fw, ∆Fsh, ∆Fbl, t, S, Iy − as specified in 4.4.4.

4.6.5 Scantling criteria

4.6.5.1 Buckling StressThe design buckling stress, σc, of palte panels

and longitudinals (as calculated in 4.6.3.1) is not to be lessthan:

σc ≥ β σa,

where:β = 1 - for plating and for web plating of

stiffeners (local buckling);β = 1,1 - for stiffeners.The critical buckling stress τc, of plate panels

(as calculated in 4.6.3.2) is not to be less than:τc ≥ τa


2013

4.7 HULL GIRDER ULTIMATESTRENGTH

4.7.1 General

4.7.1.1 Application

The requirements of this section apply to ships with length Lequal to or greater than 90 m.

4.7.1.2 Definitons

The ultimate hull girder vertical bending mo-ment capacity, MU, is defined as the maximum sagging (MUS)or hogging (MUH) hull girder vertical bending moment ca-pacity beyond which the hull will collapse. Hull girder inter-frame collapse is defined as the progressive collapse of thecritical hull girder transverse section. Longitudinal structuralmembers of the critical hull girder transverse section fail dueto buckling and/or yielding under hull girder flexure. Pro-gressive collapse analysis is to be performed according to in-cremental – iterative method, as described in 4.7.3 of thissection.

The ultimate hull girder vertical bending mo-ment capacities in sagging and hogging conditions are de-fined as the maximum values of the M – κ curve, see Figure4.7.1, which represents static non-linear relationship betweenvertical bending moment capacity M and curvature κ of theconsidered hull girder transverse section and describes it'sprogressive collapse behavior.

MUH

KF

Hoggingcondition

KUH

K

M

MUS

KF

Saggingcondition

KUS

Figure 4.7.1 Plot of vertical bending moment capacityversus curvature (M – κ curve).

The curvature κ of the considered inter-framesection is to be taken as positive for hogging condition andnegative for sagging condition. κ is defined by:

lθκ = , in [1/m]

where:

θ = relative angle of rotation of the twoadjacent hull girder cross-sections attransverse frame position;

l = transverse frame spacing, in [m], i.e.span of longitudinals.

4.7.1.3 Assumptions

Only vertical bending is considered. The ef-fects of horizontal bending moment, shear force, torsionalloading and lateral pressure are neglected.

Throughout the hull girder flexure, it’s trans-verse sections remain plane, infinitely stiff (in their ownplane) and perpendicular on elastic line throughout the cur-vature incrementation process.

Hull girder (isotropic) material is idealized bybilinear (elastic – perfectly plastic) material model.

The ultimate strength is calculated at a hullgirder transverse section between two adjacent transverseweb frames.

The hull girder transverse section can be di-vided into a set of decoupled discrete structural elementswhich act independently while responding on the imposedhull girder flexure.

4.7.2 Criteria

It is to be verified that ultimate hull girder ver-tical bending moment capacity at any hull girder transversesection is in compliance with the following criteria:

R

UWWSS

MMMγ

γγ ≤+

where:

MS = vertical still water bending moment, in[kNm], for sagging and hogging condi-tions at the considered hull girdertransverse section;

MW = vertical wave bending moment, in[kNm], for sagging and hogging condi-tions at the considered hull girdertransverse section;

MU = ultimate hull girder vertical bendingmoment capacity, in [kNm], for sag-ging (MU = MUS) and hogging (MU =MUH) conditions at the considered hullgirder transverse section;

γS = partial safety factor for vertical stillwater bending moment, equal to: γS =1.0;

γW = partial safety factor for vertical wavebending moment covering environ-mental and wave load prediction un-certainties, equal to: γW = 1.2;

γR = partial safety factor for ultimate hullgirder vertical bending moment capac-ity covering material, geometric andload carrying capacity prediction

uncertainties, equal to: γW = 1.1.


2013

4.7.3 Incremental – iterative method for hullgirder progressive collapse analysis

The M – κ curve is obtained by means of an in-cremental-iterative procedure given in 4.7.3.1 and illustratedby Fig. 4.7.2. MU represents the peak value of obtained M – κcurve.

4.7.3.1 Procedure

4.7.3.1.1 General overview

The vertical bending moment M which acts onthe hull girder transverse section due to the imposed curva-ture κ is calculated for each step of the incremental proce-dure. This imposed curvature corresponds to an angle of ro-tation of the hull girder transverse section about its effectivehorizontal neutral axis, which induces an average axial strainεxA in each decoupled longitudinal structural element of theconsidered longitudinal inter-frame segment.

Figure 4.7.2 Flowchart of the incremental – iterative pro-gressive collapse analysis method.

The average longitudinal stress σxA induced ineach structural element by the εxA is obtained from the set ofapplicable average stress – average strain (σxA - εxA) curves ofthe element, which consider structural behavior of the ele-ment in the non-linear elasto-plastic domain. In the saggingcondition, elements below the neutral axis are lengthened,

while elements above the neutral axis are shortened, andvice-versa in hogging condition. Elements compressed be-yond their buckling limit have reduced load-carrying capac-ity. All relevant failure modes for individual longitudinalstructural elements (yielding, plate buckling, torsionalstiffener buckling, stiffener web buckling, lateral orglobal stiffener buckling) are considered in order to identifythe critical inter-frame failure mode.

The axial force in each individual element FxAis represented by the product of element’s cross-sectionalarea A (total area of the longitudinal structural element) andσxA. Forces of all individual elements are summated to derivethe total axial force on the hull girder transverse section.Since the position of the effective neutral axis of the trans-verse section is not constant throughout the flexure (due tothe non-linear response), total axial force might not initiallyassume the zero value. Total axial force value should beequal to zero since sectional equilibrium implies equality oftotal compressive and tensile axial forces. This is enforced byiterative repositioning of the effective neutral axis which re-quires recalculation of εxA, σxA, FxA and the total axial forceon the hull girder transverse section for each iterative step.Once the correct position of the neutral axis is determined,the correct σxA distribution becomes available.

M (about the neutral axis of the balanced trans-verse section) corresponding to imposed κ can be obtainedthen by summation of the individual moment contributions(of each element).

4.7.3.1.2 Algorithm

Step1: Divide the hull girder transverse section on dis-crete uncoupled structural elements, as described by 4.7.3.2.

Step2: Derive the σxA - εxA curves (load-end shorteningcurves) for all discrete structural elements, as described by4.7.3.3.

Step3: Determine the expected maximum consideredcurvature κF:

y

YF EI

M003.0±=κ

where:

MY = vertical bending moment given by thelinear elastic bending stress equal toyield strength of deck or keel, which-ever appears first. To be taken as thegreater of MYd and MYk;

MYd = ZdReH1000, in [kNm];

MYk = ZkReH1000, in [kNm];

Zd = section modulus at deck, in [m3];

Zk = section modulus at keel, in [m3];

E = Young’s modulus, in [N/mm2];

ReH = minimum yield stress, in [N/mm2];

Iy = hull girder transverse section momentof inertia, in [m4].

Curvature step size ∆κ is to be taken as κF/300.The curvature for the first step is to be taken as equal to ∆κ.


2013

Step4: For each discrete structural element, calculatethe εxA = κ(z–zNA) corresponding to imposed κ, correspondingσxA (to be taken as the minimum value from all applicable σxA- εxA curves) and resulting FxA = σxAA.

Step5: Determine the current neutral axis position zNAon the basis of longitudinal force equilibrium over the wholetransverse section. Hence, adjust zNA until ΣFxA = 0.1ΣσxAA =0, in [kN].

Note: σxA is positive for elements under compressionand negative for elements under tension. Iteratively repeatprocedure from step4 until the change in neutral axis positionis less than 0.0001m.

Step6: Calculate the M of the balanced hull girdertransverse section corresponding to imposed κ, by summatingthe force contributions of all elements as follows:

∑ −= )(1.0 NAxA zzAM σ , in [kNm]

Step7: Increase the curvature by ∆κ and use the cur-rent neutral axis position as the initial value for the next cur-vature increment. Repeat the procedure from step4 until theκF is reached. Eventually, the MU is determined as the peakvalue of the M – κ curve. If the peak is not reached within theconsidered interval of curvature, then κF is to be increaseduntil the peak is reached.

4.7.3.2 Modelling of the hull girder transverse sec-tion

Hull girder transverse sections are to be consid-ered as being constituted by the three different kinds of dis-crete uncoupled structural elements contributing to the hullgirder longitudinal ultimate strength: stiffener – plate combi-nations (longitudinal stiffeners with effective breadth of at-tached plating; structural behavior described in 4.7.3.3),transversely stiffened plate panels (longitudinally unstiffenedplating; structural behavior described in 4.7.3.3) and hardcorners (structural behavior described in 4.7.3.3).

Hard corners (HCs) are generally constitutedby two or more plates not lying in the same plane. They areconsidered to be stiff enough to collapse only according toelasto-plastic mode of failure (material yielding), both incompression and tension. Structural areas idealized by hardcorner elements are: plating area adjacent to intersectingplates, plating area adjacent to knuckles in the plating withan inclination angle greater than 30 degrees and plating com-prising rounded gunwales. It is to be assumed that the hardcorner element extends up to s/2 from the plate intersectionfor longitudinally stiffened plate, where s is the stiffenerspacing. It is to be assumed that the hard corner extends up to20tp from the plate intersection for transversely stiffenedplates, where tp is the plate thickness.

For stiffener – plate combinations (SPCs), theeffective breadth of attached plate is equal to the mean spac-ing of the ordinary stiffener (when the panels on both sides ofthe stiffener are longitudinally stiffened), or equal to thebreadth of the longitudinally stiffened panel (when the panelon one side of the stiffener is longitudinally stiffened and theother panel is transversely stiffened).

For transversely stiffened plates (TSPs), the ef-fective breadth of plate for the load shortening (compression)portion of the σxA - εxA curve is to be taken as the full platebreadth, i.e. to the intersection of other plates, not from theend of the hard corner if any. The area on which σxA applies

is to be taken as the breadth between the hard corners, i.e.excluding the end of the hard corner if any.

s4 s4 s4 s4 s4

s3

s2

s1 s1-Min(20tw, 0.5s1)-0.5s2

Min(20tw, 0.5s1)

s2

0.5(s2+s3)0.5s3

s4 s4 s4 s4 0.5s4

HCs

SPCs

TSPs

Figure 4.7.3 Illustration of transverse cross section discre-tization rules

Where the plate members are stiffened by non-continuous longitudinal stiffeners, the non-continuous stiff-eners are not modeled as stiffener plate combinations sincethey do not contribute to the hull girder ultimate strength.They are considered only as dividers of the plating into vari-ous elementary plate panels.

4.7.3.3 σxA - εxA Curves (Load – end shorteningcurves)

Discrete structural elements are assumed to failaccording to one of the failure modes specified in Table4.7.3.3. For each element appropriate σxA – εxA curve (Table4.7.3.3) is to be obtained for lengthening and shorteningstraining regime.

Table 4.7.3.3 Applicable failure modes for discrete struc-tural elements

Discrete structuralelement

Applicable mode(s)of failure

σxA - εxAcurve ref-erence

Lengthened (loaded inuniaxial tension) orshortened (loaded inuniaxial compression)HCs, SPCs and TSPs.

Elasto-plastic failure(yielding).

4.7.3.3.1

Shortened (loaded inuniaxial compression)SPCs.

Elasto-plastic failure(yielding);Beam column buck-ling;Torsional buckling;Web local bucklingof flanged profiles;Web local bucklingof flat bars.

4.7.3.3.1

4.7.3.3.2

4.7.3.3.34.7.3.3.4

4.7.3.3.5

Shortened (loaded inuniaxial compression)TSPs.

Elasto-plastic failure(yielding);Plate buckling.

4.7.3.3.1

4.7.3.3.6Notes: HC Hard corner;

SPC Stiffener-plate combination;TSP transversely stiffened plate.

4.7.3.3.1 Elasto – plastic failure (material yielding)

The equation describing the σxA – εxA curve forthe elasto-plastic failure of discrete structural elements com-posing the hull girder transverse section is to be obtained


2013

from the following formula, valid for both positive (shorten-ing) and negative (lengthening) strains:

eHAxA RΦ=σ

where:

Φ = edge function, in [-]:

>

≤≤−

−<−

=Φ

11

11

11

eH

eHeH

eH

R

xA

R

xA

R

xA

R

xA

for

for

for

εε

εε

εε

εε

;

eHRε = yield strain, in [-],of the consid-

ered element:

EReHA

ReH=ε ;

εxA = average axial strain, in [-],of the con-sidered element;

ReHA = equivalent minimum yield stress, in[N/mm2], of the considered element:

sp

seHspeHpeHA AA

ARARR

++

= ;

ReHp = minimum yield stress of the platematerial, in [N/mm2];

ReHs = minimum yield stress of the stiffenermaterial, in [N/mm2];

As = sectional area of the stiffener withoutattached plating, in [cm2]:

fws AAA += ;

Ap = sectional area of the attached plating,in [cm2]:

ppp tbA 01.0= ;

Aw = sectional area of the stiffener web, in[cm2]:

www hbA 01.0= ;

Af = sectional area of the stiffener flange,in [cm2]:

fff tbA 01.0= ;

bp = breadth of attached plating, in [mm];

hw = height of stiffener web, in [mm];

bf = breadth of stiffener flange, in [mm];

tp = thickness of attached plating, inthickness of stiffener web, in [mm];

tw = thickness of stiffener web, in [mm];

tf = thickness of stiffener flange, in [mm];

4.7.3.3.2 Beam column buckling

The equation describing the shortening portionof the σxA – εxA curve for the beam column buckling of stiff-ener – plate combinations is to be obtained from the follow-ing formula:

ps

EsCExA AA

AA++

Φ= σσ

where:

σCE = critical stress, in [N/mm2], correctedfor the effect of plasticity accordingto Johnson – Ostenfeld formula:

>

−

≤

=

eHeH

eH

eH

R

xAeHAE

R

xA

E

eHAeHA

R

xAeHAE

xA

RE

CERforRR

Rfor

εεσ

εε

σ

εεσ

εεσ

σ

241

2 ;

σE = Euler column buckling stress, in[N/mm2]:

2

2

0001.0lAEI

EE

πσ = ;

l = span of the stiffener – plate combina-tion, in [m], equal to the spacing be-tween primary supporting members;

I = moment of inertia of the stiffener –plate combination, in [cm4], with at-tached plating of width be;

be = effective width of attached plating, in[mm]:

≤

>=

1

1

efp

efef

p

e

forb

forb

bβ

ββ ;

βef = effective plate slenderness of the at-tached plating, in [-]:

ER

tb

eHR

eHpxA

p

pef ε

εβ = ;

AE = sectional area of the stiffener – platecombination, in [cm2], with attachedplating of width bE:

)(01.0 pEwwffE tbthtbA ++= ;

bE = effective width of attached plating, in[mm]:

≤

>

−

=

25.1

25.125.125.22

efp

efefef

pE

forb

forbb

β

βββ .

4.7.3.3.3 Torsional buckling

The equation describing the shortening portionof the σxA – εxA curve for the flexural – torsional buckling of


2013

stiffener – plate combinations is to be obtained from the fol-lowing formula:

ps

CPpCTsxA AA

AA+

+Φ=

σσσ

where:

σCT = critical stress, in [N/mm2], correctedfor the effect of plasticity accordingto Johnson – Ostenfeld formula:

>

−

≤

=

eHeH

eH

eH

R

xAeHAET

R

xA

ET

eHAeHA

R

xAeHAET

xA

RET

CTRforRR

Rfor

εεσ

εε

σ

εεσ

εεσ

σ

241

2 ;

σET = Euler torsional buckling stress, in[N/mm2]:

+Θ= T

T

W

PET I

lI

IE 385.02

2πσ ;

Θ = degree of fixation parameter, in [-],defined by following formula:

+

+=Θ

334

4

34

43

001.01

w

w

p

pW t

htb

I

l

π

;

IP = polar moment of inertia of the stiff-ener, in [cm4], about stiffener root(point where stiffener is joined withthe attached plating), defined in Table4.7.3.3.3;

IT = St. Venant’s moment of inertia of thestiffener, in [cm4], defined in Table4.7.3.3.3;

IW = sectorial moment of inertia of thestiffener, in [cm6], about stiffener root(point where stiffener is joined withthe attached plating), defined in Table4.7.3.3.3;

Table 4.7.3.3.3 Moments of inertia.

Stiffenertype IP IT IW

Flat bar 4

3

103⋅wwth

−

⋅ w

www

htth 63.01

103 4

3

6

33

1036 ⋅wwth

Angle /Bulb

++

⋅ wf

wffff

AAAAbeA 6.2

1012 6

22

T-section

422

103

−

+ ff

ww eAhA

−

⋅ w

www

htth 63.01

103 4

3

+

−

⋅ f

fff

bttb

63.01103 4

3

6

23

1012 ⋅fff etb

ef = distance from the stiffener root (pointwhere stiffener is joined with the at-tached plating) to the centre of flange,in [mm]:

2w

wfthe += ;

lT = torsional buckling length, in [m], tobe taken equal to the distance be-tween tripping supports;

σCP = buckling stress of the attached plat-ing, in [N/mm2]:

≤

>

−

=

25.1

25.125.125.22

efeHp

efefef

eHpCP

forR

forR

β

βββσ .

4.7.3.3.4 Web local buckling of flanged stiffeners

The equation describing the shortening portionof the σxA – εxA curve for the web local buckling of flangedstiffener – plate combinations is to be obtained from the fol-lowing formula:

sp

eHsfwweeHppefxA AA

RAthRtb+

++Φ=

)(σ

where:

hwe = effective height of web, in [mm]:

≤

>

−

=

25.1

25.125.125.22

ww

www

wwe

zah

zahh

β

βββ ;

βw = web plate slenderness, in [-]:

ER

th

eHR

eHsxA

w

ww ε

εβ = .

4.7.3.3.5 Web local buckling of flat bar stiffeners

The equation describing the shortening portionof the σxA – εxA curve for the web local buckling of flat barstiffener – plate combinations is to be obtained from the fol-lowing formula:

sp

CLsCPpxA AA

AA++

Φ=σσ

σ

where:

σCL = critical stress, in [N/mm2], correctedfor the effect of plasticity accordingto Johnson – Ostenfeld formula:

>

−

≤

=

eHeH

eH

eH

R

xAeHAEL

R

xA

EL

eHAeHA

R

xAeHAEL

xA

REL

CTRforRR

Rfor

εεσ

εε

σ

εεσ

εεσ

σ

241

2 ;

σEL = local Euler buckling stress, in[N/mm2]:


2013

2

160000

=

w

wEL h

tσ

4.7.3..6 Plate buckling

The equation describing the shortening portionof the σxA – εxA curve for the plate buckling of transverselystiffened plates is to be obtained from the following formula:

+

−+

−Φ

Φ

=2

221111.025.125.2

ef

p

efef

peHp

eHp

xA

lb

lb

R

R

MINβββ

σ


2013

5 SHELL PLATING

5.1 GENERAL

5.1.1 The application of the design formulae given in5.2.1.2 to ships of less than 90 m in length may be acceptedby the Register when a proof of longitudinal strenth has beencarried out.

5.1.2 Definitions

Following definitions are used in this Section:

k = material factor according to 1.4.2.2;pB = load on bottom, in [kN/m2], accord-

ing to 3.2.3;ps = load on sides, in [kN/m2], according

to 3.2.2.1;pe = design pressure for the bow area, in

[kN/m2], according to 3.2.2.2;pSL = design slamming pressure, in

[kN/m2], according to 3.2.4;n1 = 1,0, for transverse framing;n1 = 0,83, for longitudinal framing;σL = maximum hull girder bending stress

in [N/mm2] for calculating stress andfor fatigue analysis at the consideredstation is given by the following for-mula:

σ Ls w SLM M M

W=

+ +0 75,⋅ 103, [N/mm2]

where:W = Wd, ili Wb section modulus at deck or

bottom, in [cm3];τL = maximum design shear stress due to

longitudinal hull girder bending, in[N/mm2], where the wave shear forcemay be taken as 0,75 Fw;

σdop = permissible design stress in [N/mm2];

σdopL

k= +

⋅0 8450

230, , [N/mm2], for L < 90 m;

σdop = 230/k, [N/mm2], for L ≥ 90 m;

tk = corrosion addition according to Sec-tion 2.9.1.

5.2 BOTTOM PLATING

5.2.1 Plating within 0,4 L amidships

5.2.1.1 The thickness of the bottom plating of ships upto 90 m in length is not to be less than:

t1 = 1,9 n1 ⋅ s ⋅ p kB ⋅ + tk, [mm]

5.2.1.2 The thickness of the bottom plating for ships of90 m in length and more is not to be less than the followingtwo values:

t1 = 18,3 ⋅ n1 ⋅ s ⋅PB

aσ+ tk , [mm]

t2 = 1,21 ⋅ s ⋅ p kB ⋅ + tk, [mm];

σa = σ τdop L2 23− ⋅ - 0,89 ⋅ σL , [N/mm2];

As a first approximation σL may be taken asfollows:

σL =12 6, ⋅ L

k, [N/mm2], for L < 90 m;

σL =120

k, [N/mm2], for L ≥ 90 m;

τL = 0;s = stifferner's spacing, [m], according to

1.2.6.

5.2.2 Critical plate thickness

5.2.2.1 For ships, for which proof of longitudinalstrength is carried out, the thickness is not to be less thanthickness according to the following formula:

tkrit = c1 ⋅ 2,32 ⋅ s ⋅ σ L + tk, [mm]where:

c1 = 0,5, for longitudinal framing;

c1 =1

1 2( )+ ⋅α c, for transverse framing;

α = aspect ratio of plate panel considered,sl

;

c = according to 4.6.2.1.1;c = 1,0 for longitudinal framing;σL = according to 5.1.2;s = stiffener's spacing according to 1.2.6;l = larger side of panel, [m].

5.2.2.2 The values obtained from 5.2.2.1 are to be veri-fied according to Section 4.6. For this purpose the stressesdue to hull grider bending and the stresses to local loads ofthe bottom structure are to be considered.

5.2.3 Bottom plating outside 0,4 L amidships

5.2.3.1 The thickness at the ends for 0,1 L from aft endof the length L and for 0,05 L from F.P. respectively is not tobe less than the value t2 obtained according to 5.2.1.2.

5.2.3.2 The thicknesses are to be gradually taperedfrom the midship thicknesses to the thicknesses at the ends.

Gradual taper is also to be effected between thethicknesses required for strengthening of the bottom forwardand the adjacent thicknesses.

5.2.4 Bilge strake

5.2.4.1 The thickness of the bilge strake is to be deter-mined as required for the bottom plating according to 5.2.1.The thickness so determined is to be verified for sufficientbuckling strength according to Section 4.6, see Table4.6.2.1-3, load cases 1a, 1b, 2 and 4.

5.2.4.2 If a higher steel grade than A/AH is requiredfor the bilge strake, the width of the bilge strake is not to beless than:

b = 800 + 5 ⋅ L, [mm]


2013

5.2.5 Flat plate keel and garboard strake

5.2.5.1 The width of the flat plate keel is not to be lessthan:

b = 800 + 5 L, [mm]and need not be greater than:

bmax =1800 mm.The thickness of the flat plate keel within 0,7 L

amidships is not to be less than:

tKB = t + 2,0, [mm]where:

t = thickness of the adjacent bottomplating, in [mm].

5.2.5.2 Where a bar keel is arranged, the adjacent gar-board strake is to have the scantling of a flat plate keel.

5.2.6 Minimum thickness

At no point the thickness of the bottom shellplating is to be less than:

tmin = (1,5 - 0,01 ⋅ L) ⋅ L k⋅ [mm], for L < 50 m

tmin = L k⋅ [mm], for L ≥ 50 mor 16,0 mm, whichever is less.

5.3 SIDE SHELL PLATING

5.3.1 Side shell plating within 0,4 L amidships

5.3.1.1 The thickness of the side shell plating for shipsup of 90 m in length is not to be less than:

ts = 1,9 ⋅ n1 ⋅ s ⋅ p ks ⋅ + tk [mm]

5.3.1.2 The thickness of the side shell plating for shipsof 90 m in length and more is not to be less than the greaterof the two following values:

ts1 = 18,3 ⋅ n1 ⋅ s ⋅ps

aσ+ tk, [mm]

ts2 = 1,21 ⋅ s ⋅ p ks ⋅ + tk, [mm]

σa = σ τdop L2 23− - 0,89 ⋅ σLS, [N/mm2]

As first approximation σLs and τL may be takenas follows:

σLS = 0,76 ⋅ σLσL = according to 5.2.1.2

τL =55k

, [N/mm2].

5.3.1.3 In way of large shear forces, the shear stressesare to be checked in accordance with 4.4.

5.3.2 Plating outside 0,4 L amidships

5.3.2.1 The plate thickness at the ends for 0,1 L fromaft end of the length L and for 0,05 L from forward perpen-dicular is not to be less than ts2 according to 5.3.1.2.:

5.3.2.2 The plate thicknesses may be tapered from 0,4L amidship the ends.


For the minimum thickness of the side shellplating 5.2.6 applies accordingly.

Above a level d + Cw/2 above base line smallerthicknesses than tmin may be accepted if the stress levelpermits such reduction.

Cw = according to 4.2.2.

5.3.4 Sheerstrake

5.3.4.1 The width of the sheerstrake is not to be lessthan:

b = 800 + 5 L , [mm],

and need not be greater than:

bmax = 1800 mm.

5.3.4.2 The thickness of the sheer strake within 0,4 Lamidships, in general, not to be less than the greater of thefollowing values:

t = 0,5 (td + ts), [mm];t = ts [mm];td = required thickness of strength deck;ts = required thickness of side shell.

5.3.4.3 Where the connection of the deck stringer withthe sheerstrake is rounded, the radius is to be at least 15 timesthe plate thickness.

5.3.4.4 In ships exceeding 60 m in length, in principlewelding is not allowed on the upper edge of the sheerstrakewithin 0,5 L amidships.

5.3.5 Buckling strength

For ships for which proof of longitudinalstrength is required or carried out proof of buckling strengthof the side shell is to be provided in accordance with the re-quirements of Section 4.6.

5.3.6 Side plating of superstructures

The side plating of effective superstructures isto be determined according to 5.3.

The side plating of non-effective superstruc-tures is to be determined according to Section 13. For thedefinition of effective and non-effective superstructures seeSection 13.

5.3.7 Strengthenings for harbour and tug manoeuvres

5.3.7.1 In those zones of the side shell which may beexposed to concentrated loads due to harbour manoeuvres theplate thickness is not to be less than required by 5.3.7.2.These zones are mainly the plates in way of the ship's foreand aft shoulder and in addition amidships. The exact loca-tions where the tugs shall push are to be defined in thebuilding specification. They are to be identified in the shellexpansion plan. The length of the strengthened areas shallnot be less than approximately 5 m. The height of thestrengthened areas shall extend from about 0,5 m above bal-last draught to about 4,0 m above scantling draught. Wherethe side shell thickness so determined exceeds the thicknessrequired by 5.3.1 – 5.3.4 it is recommended to specially markthese areas.


2013

5.3.7.2 The plate thickness in the strengthened areas isto be determined by the following formula:

t = 0,65· kPfl ⋅ + tk , [mm]

where:

Pfl = local design impact force, [kN]

= D/100, [kN] with a minimum of 200 kN anda maximum of 1 000 kN

D = displacement of the ship, [t].

Any reductions in thickness for restricted service are notpermissible.

5.3.7.3 In the strengthened areas the section modulusof side longitudinals is not to be less than:

W = 0,35· Pfl · l ·k , [cm3]

l = unsupported span of longitudinal, [m].

5.3.7.4 Tween decks, transverse bulkheads, stringerand transverse walls are to be investigated for sufficientbuckling strength against loads acting in the ship's transversedirection.

5.4 STRENGTHENING OF BOTTOMFORWARD

5.4.1 Arrangement of floors and girders

5.4.1.1 In case of transverse framing, plate floors are tobe fitted at every frame. Where the longitudinal framingsystem or the longitudinal girder system is adopted thespacing of plate floors may be equal to three transverse framespaces.

5.4.1.2 In case of transverse framing, the spacing ofside girders is not to exceed L/250 + 0,9 (m), up to a maxi-mum of 1,4 m.

In case of longitudinal framing, the side girdersare to be fitted every two longitudinal frame spacings apart.

5.4.1.3 Spacing stated in 5.4.1.1 and 5.4.1.2 are:

- forward of xL

= 0,7, for L ≤ 100 m

- forward of xL

= 0,6 + 0,001 L, for 100 <L≤ 150 m

- forward of xL

= 0,75, for L > 150 m

5.4.2 Bottom plating forward of xL

= 0,5

5.4.2.1 The thickness of the bottom plating of the flatpart of the ship's bottom up to a height of 0,05 dmin or 0,3 mabove base line, whichever is the smaller value, is not to beless than:

t = 0,9 ⋅ f2 ⋅ s ⋅ p ksl ⋅ + tk , [mm]

where:f2 = see Section 2.1.3;s = stiffeners spacing, in [m];psl = according to Section 3.2.4;

tk = according to Section 2.9.1.

5.4.2.2 Above 0,05 dmin or 0,3 m above base line theplate thickness may gradualy be tapered to the rule thicknessdetermined according to 5.2.

5.4.3 Stiffeners forward of xL

= 0,5

5.4.3.1 The section modulus of transverse or longitudi-nal stiffeners is not to be less than:

W = 0,155 ⋅ psL ⋅ s ⋅ l2 ⋅ k, [cm3]

5.4.3.2 The shear area and the cross sectional area ofthe welded connection is not to be less than:

A = 0,028 ⋅ psL ⋅ s (l - 0,5 ⋅ s) ⋅ k , [cm2]

l = unsupported span of stiffener, in [m];k = material factor according 1.4.2.2.

5.4.4 Strengthening in way of propellers andpropeller prackets

5.4.4.1 In way of propeller bracket and shaft bossings,the thickness of the shell plating is to be the same as requiredfor 0,4 L amidships. in way of the struts, the shell plating isto have a strengthened plate of 1,5 times the midship thick-ness.

5.4.4.2 Where propeller revolution are exceeding 300rpm (aproxim.) particularly in case of that bottoms intercostalcarlings are to be fitted above or forward of the propeller inorder to reduce the size of the bottom plate panels (see alsoSection 7.1.1.2.3).

5.5 BILGE KEEL

5.5.1.1 Where bilge keels are provided they are to becontinuous over their full length. the bilge keels are to bewelded to continuous flat bars which are welded to the shellplating with their flat side.

5.5.1.2 The ends of the bilge keels are to have softtransition zones according to Fig. 5.5.1.2, and they shall ter-minate above an internal stiffening element.


2013

Figure 5.5.1.2

5.5.1.3 Any scallops or cut-outs in the bilge keels areto be avoided.

5.6 BULWARK

5.6.1 The thickness of bulwark plating is not to beless than:

t = 0 751000

, −

LL , [mm], for L ≤ 100 m

t = 0,65 L , [mm], for L> 100 m

L need not be taken greater than 200 m. Thethickness of bulwark plating forward particularly exposed towash of sea is to be equal to the thickness of the forecastleside plating according to 1.3.2.1.

In way of superstructures above the freeboarddeck abaft 0,25 L from F.P. the thickness of the bulwarkplating may be reduced by 0,5 mm.

The bulwark height or height of guard rails isnot to be less than 1,0 m.

Plate bulwarks are to be stiffened at the upperedge by bulb section or other similar.

5.6.2 The bulwark is to be supported by bulwarkstays fitted at every alternate frame and at every frame onthis with respectively bow flare.

Where the stays are designed as per Fig. 5.6.2,the section modulus of their cross section effectively attachedto the deck is not to be less than:

W = 4 ⋅ ps ⋅ e ⋅ l2, [cm3]

where:ps = load, in [kN/m2], as per Section 3.2.2.1;psmin = 15 kN/m2;e = spacing of stays, in [m];l = length of stay, in [m].

The stays are to be fitted above deck beams, orother transversal members. Where deck is longitudinalyframed, ends of stayes have to finish above longitudinalmembers.

Figure 5.6.2

5.6.3 An adequate number of expansion joints is tobe provided in the bulwark.

The number of expansion joints for ships ex-ceeding 60 m in length should not be less than:

n = L/40,but need not be greater than n= 5.

5.6.4 Openings in the bulwarks shall have sufficientdistance from the end bulkheads of superstructures. Connec-tion of bulwarks to superstructure sides is to be constructedcarefully.

5.7 OPENINGS IN THE SHELLPLATING

5.7.1 General

5.7.1.1 Where openings are cut in the shell plating forwindows or side scuttles, hawses, scuppers, sea valves etc.,they are to have well rounded corners. If they exceed 500mm in width in ships up to L = 70 metres, and 700 mm inships having a length L of more than 70 metres, the openingsare to be surrounded by framing, a thicker plate or a dou-bling.

5.7.1.2 Above openings in the sheer strake within 0,4 Lamidships, generally a strengthened plate or a continuousdoubling is to be provided compensating the omitted platesectional area. For shell doors and similar large openings seeRules, Part 3 – Hull Equipment, 7.4. Special strengthening isrequired in the range of openings at ends of superstructures.


2013

5.7.1.3 The shell plating in way of the hawse pipes isto be reinforced.

5.7.2 Pipe connections at the shell plating

Scupper pipes and valves are to be connected tothe shell by weld flanges. Instead of weld flanges shortflanged sockets of adequate thickness may be used if they arewelded to the shell in an appropriate manner. Reference ismade to Rules, Part 3 – Hull equipment, 7.4 and Part 8 –Piping, 1.5.

Construction drawings are to be submitted forapproval.


2013

6 DECKS

6.1 STRENGTH DECK

6.1.1 General, definitions

6.1.1.1 The strenght deck is:- the uppermost continuous deck which is

forming the upper flange of the hullstructure,

- a superstructure deck which extends into0,4 L amidships and the length of whichexceeds 0,15 L.

- a quarter deck or the deck of a sunk su-perstructure which extends into 0,4 Lamidships.

6.1.1.2 In way of a superstructure deck which is to beconsidered as a strength deck, the deck below the super-structure deck is to have the same scantlings as a 2nd deck,and the deck below this deck the same scantlings as a 3rddeck. The thicknesses of a strength deck plating are to beextended into the superstructure for a distance equal to thewidth of the deck plating abreast the hatchway. For strength-ening of the stringer plate in the breaks, see Section 13.

6.1.1.3 If the strength deck is protected by sheathing asmaller corrosion addition tk than required by Section 2.9may be permitted. Where a sheathing other than wood isused, attention is to be paid that the sheathing does not affectthe steel. The sheathing is to be effectively fitted to the deck..

6.1.1.4 For ships with a speed v = 1,6 L , [kn], addi-tional strengthening of the strength deck and the sheerstrakemay be required.

6.1.1.5 The following definitions apply throughout thisSection:

k = material factor according to 1.4.2.2pD = load according to 3.2.1.1pL = load according to 3.3.1.2tk = corrosion addition according to 2.9.1

6.1.2 Connection between strength deck andsheerstrake

6.1.2.1 The welded connection between strength deckand sheerstrake may be effected by fillet welds according toSection 15.

Where the plate thickness exceeds approximately 25 mm, afully welded connection according to Section 15 shall be car-ried out instead fillet welds.

In special cases a fully welded connections may also be re-quired, where the plate thickness is less than 25 mm.

6.1.2.2 Where the connection of deck stringer to sheer-strake is rounded, the requirements of 5.3.3 are to be ob-served.

6.1.3 Openings in the strength deck

6.1.3.1 All openings in the strength deck are to havewell rounded corners. Circular openings are to be edge-

reinforced. The sectional area of the face bar is not to be lessthan:

A = 0,25 ⋅ do ⋅ t , [cm2]

do = diameter of opening, in [cm],t = deck thickness, in [cm].The distance between the outer edge of opening

and the ship's side is not to be less than the opening diameter.The reinforcing face bar may be dispensed

with, where the diameter is less than 300 mm and the small-est distance from another opening is not less than 5 x diame-ter of the smaller opening.

6.1.3.2 The hatchway corners are to be surrounded bystrengthened plates which are to extend over at least oneframe spacing fore-and-aft and athwartships. Within 0,5 Lamidships, the thickness of the strengthened plate is to beequal to the deck thickness abreast the hatchway plus thedeck thickness between the hatchways. Outside 0,5 L amid-ships the thickness of the strengthened plates need not exceed1,6 times the thickness of the deck plating abreast the hatch-way.

6.1.3.3 The hatchway corner radius is not to be lessthan:

r = n ⋅ b (1 - b/B), [m]

rmin = 0,1 mwhere:

n = l/200, but not lesser than 0,1 and notgreater than 0,25;

l = length of hatchway, in [m];b = breadth in [m], of hatchway or total

breadth of hatchways in case of morethan one hatchway;

b/B = need not be taken smaller than 0,4.

6.1.3.4 Where the hatchway corners are elliptic orparabolic, strengthening according to 6.1.3.2 is not required.The dimensions of the elliptical and parabolical corners shallbe as shown in Fig. 6.1.3.4.

Figure 6.1.3.4

Where smaller values are taken for a and c, re-inforced insert plates are required which will be consideredin each individual case.

6.1.3.5 For ships with large deck openings the designof the hatch corners will be specially considered on the basisof the stresses due to longitudinal hull girder bending, torsionand transverse loads.


2013

6.1.3.6 At the corners of the engine room casings,strengthenings according to 6.1.3.2 may also be required, de-pending on the position and the dimensions of the casing.

6.1.4 Scantlings of strength deck of ships upto 65 m length

The scantlings of the strength deck for ships,for which proof of longitudinal strength is not required, i.e. ingeneral for ships with length L ≤ 65 [m], the sectional area ofthe strength deck within 0,4 L amidships is to be determinedsuch that the requirements for the minimum midship sectionmodulus according to Section 4.3.4 are complied with.

The thickness within 0,4 L amidships is not tobe less than the minimum thickness according to 6.1.7. Forthe ranges 0,1 L from ends the requirements of 6.1.7 apply.

6.1.5 Scantlings of strength deck of ships ofmore than 65 m in length

6.1.5.1 Deck sectional areaThe deck sectional area abreast the hatchways,

if any, is to be so determined that the section moduli of thecross sections are in accordance with the requirements ofSection 4.3.

6.1.5.2 Critical plate thickness, buckling strength

6.1.5.2.1 The critical plate thickness is to be determinedaccording to Section 5.2.2 analogously.

6.1.5.2.2 In regard to buckling strength the requirementsof Section 5.2.2 apply analogously.

6.1.5.3 Deck stringerIf the thickness of the strength deck plating is

less than that of the side shell plating, a stringer plate is to befitted having the width of the sheerstrake and the thickness ofthe side shell plating.


The thickness of deck plating for 0,4 L amid-ships outside line of hatchways is not to be less than thegreater of the two following values:

tmin = (4,5 + 0,05 L) ⋅ k , [mm]or

t0,1L according to 6.1.7.1.

L need not be taken greater than 200 m.

6.1.7 Thickness at ship's ends and betweenhatchways

6.1.7.1 The thickness of strength deck plating for 0,1 Lfrom the ends and between hatchways is not to be less than:

t0,1L = 1,21 ⋅ s ⋅ p kD ⋅ + tk, [mm],

t0,1L2 = 1,1 ⋅ s ⋅ p kL ⋅ + tk , [mm]

t0,1Lmin = (5,5 + 0,02 ⋅ L) k , [mm]

L need not be taken greater than 200 m.

6.1.7.2 Between the midship thickness and the endthickness, the thicknesses are to be tapered gradually.

6.1.7.3 The strength of deck structure between hatchopenings has to withstand compressive transversely actingloads. Proof of buckling strength is to be provided accordingto Section 4.6.

6.2 LOWER DECKS

6.2.1 Thickness of decks for cargo loads

6.2.1.1 The plate thickness of decks loaded with cargois not to be less than:

t = 1,1 ⋅ s ⋅ p kL ⋅ + tk, [mm]

but not less than:tmin = (5,5 + 0,02 L) k , [mm], for the 2nd deck;

tmin = 6,0 mm, for other lower decks.

L need not be taken greater than 200 mm.

6.2.2 Thickness of decks for wheel loading

6.2.2.1 The thickness of deck plating for wheel loadingis to be determined by the following formula:

t = c ⋅ ( ) kaP v ⋅+1 + tk, [mm]

where:P = load, in [kN], of one wheel or group

of wheels on a plate panel u ⋅ v;P = Q/n;Q = axle load, in [kN].For fork lift trucks Q is generally to be taken as

the total weight of the fork lift truck and cargo on it.n = number of wheels (or group of

wheels) per axle;av = according to 3.3.1.1;av = 0 - for harbour conditions;c = factor according to the following

formulae:- for u/v = 1:

c = 1,87 -

−

Aa

Aa 4,44,3 , for 0 <

aA

< 0,3

c = 1,20 - 0,40 aA

, for ≤ 0,3 aA

≤ 1,0

- for u/v ≥ 2,5:

c = 2,00 - aA

aA

5 4 7 2, ,−

, for 0 < aA

< 0,3

c = 1,20 - 0,517 aA

, for 0,3 ≤ aA

≤ 1,0

For intermediate values of u/v the factor c is tobe obtained by direct interpolation.

a = print area of wheel or group ofwheels;

A = area of plate panel u ⋅ v according toFig. 6.2.2.1;

ν = width of smaller side of plate panel;u = width of larger side of plate panel;A need not be taken greater than 2,5 ⋅ v2.In case of narrowly spaced wheels these may

be grouped together to one wheel print area.


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Figure 6.2.2.1

6.2.2.2 Where the wheel print area is not known, itmay approximately be determined as follows:

a = 100 ⋅ P

p, [cm2]

where:p = specific wheel pressure according to

Table 6.2.2.2

Table 6.2.2.2

Specific wheel pressure p [bar]Type of vehicle Pnumatic tyres Solid rubber

tyresprivate cars 2 −trucks 8 −trailer 8 15fork lift trucks 6 15

In deck beams and girders, the stress is not to exceed 165/k,[N/mm2].

The scantlings of machinery decks and other accommodationdecks have to be based on the loads given in Section 3.3.3.

The thickness of the plates is not to be lessthan:

t = 1,1⋅s⋅ kp ⋅ + tk, [mm]

tmin = 5 mm.

6.3 HELICOPTER DECKS

6.3.1 General

The starting/landing zone is to be dimensionedfor the largest helicopter type expected to use the helicopterdeck.

Where the conditions of operation are notknown, the data in 6.3.2 my be used as a basis.

6.3.2 Load assumptions

6.3.2.1 For helicopter lashed on deck (LH1), with thefollowing vertical forces acting simultaneously:

a) Wheel and/or ski force P acting at the points resultingfrom the lashing position and distribution of the wheelsand/or supports according to helicopter construction:

P= 0,5 ⋅ G (1 + av), [kN],

where:G = maximum permissible take-off weight, in

[kN];av = according to 3.3.1.1;P = evenly distributed force over the contact

area a = 30 x 30 cm for single wheel or ac-cording to data supplied by helicoptermanufacturers; for dual wheels or skies tobe determined individually in accordancewith given dimensions.

b) Force due to weight of helicopter deck Mhd as follows:

Mhd (1 + av), kN.

c) Evenly distributed load over the entire landing deck de-termined as follows:

p = 2,0 kN/m2.

6.3.2.2 Helicopter lashed on deck (LH2), with the fol-lowing horizontal and vertical forces acting simultaneously:

a) Forces acting horizontally:

PH = 0,6 (G + Mhd) + W , [kN],

where:W = wind load, taking into account the lashed heli-

copter;wind velocity vw = 50 m/s.

b) Forces acting vertically:

Pv = G + Mhd , [kN].

6.4.3.2.3 Normal landing impact (LH3), with forces act-ing simultaneously:a) Wheel and/or ski load P at two points simultaneously, at

an arbitrary point of the helicopter deck (landing zone +safety zone):

P = 0,75 G, [kN]

b) Evenly distributed load for taking into account snow orother environmental loads:

p = 0,5 kN/m2.

c) Weight of the helicopter deckd) Wind load in accordance with the wind velocity admitted

for helicopter operation(vw). Where no data are available,vw = 25 m/s may be used.

6.3.3 Scantlings of structural members

6.3.3.1 Stresses and forces in the supporting structureare to be evaluated by means of direct calcualtions.

6.3.3.2 Permissible stresses for stiffeners, girders andsubstructure:

σp = 235

k s⋅ νN/mm2;

wherevs = safety factors according to Table

6.3.3.2.


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Table 6.3.3.2

νsStructural elementLH1, LH2 LH3

stiffeners(beams, deck longitudinals)

1,25 1,1

main girders(deck girders)

1,45 1,45

load-bearing structure(pillar system) 1,7 2,0

6.3.3.3 The thickness of the plating is to be determinedaccording to 6.2.2 where the coefficient c may be reduced by5%.

6.3.3.4 Proof of sufficient buckling strength is to becarried out in accordance with Section 4.6 for structuressubjected to compressive stresses.


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7 BOTTOM STRUCTURES

7.1 SINGLE BOTTOM

7.1.1 Floor plates

7.1.1.1 GeneralFloor plates are to be fitted at every frame. The

connection of the frames and floors are to be in accordancewith Section 15.

Deep floors, particulary in the after peak, are tobe provided with buckling stiffeners.

The floor plates are to be provided with limbersto permit the water to reach the pump suctions.

7.1.1.2 Scantlings

7.1.1.2.1 Floor plates in the cargo hold areaOn ships without double bottom or outside any

double bottom the scantilngs of floor plates fitted betweenafterpeak bulkhead and collision bulkhead are to be deter-mined according to the following formulae:

a) The section modulus is not to be lessthan:

W = k2 ⋅ d ⋅ s ⋅ l2 [cm3],

where:s = spacing of plate floors, [m];l = unsupported span, [m], generally

measured on upper edge of floor fromside shell to side shell;

lmin = 0,7 B, if the floors are not supportedat longitudinal bulkheads;

k2 = 7,5 for spaces which may be empty atfull draught, e.g. machinery spaces,storerooms, etc.

k2 = 4,5 elsewhere.

b) The depth of the floor plates is not to beless than:

h = 55 ⋅ B - 45 [mm],but not less than:

hmin = 180 mm.In ships having rise of floor, at 0,1 ⋅ l from the

ends of the length l where possible, the depth of the floorplate webs is not to be less than half the required depth.

In ships having a considerable rise of floor, thedepth of the floor plate webs at the beginning of the turn ofbilge is not to be less than the depth of the frame.

c) The web thickness is not to be less than

t = h

100 + 3 [mm]

The web sectional area is to be determined ac-cording to 7.2.6.2.2. analogously.

7.1.1.2.2 The face plates of the floor plates are to becontinuous over the span l. If they are interrupted at the cen-tre keelson, they are to be connected to the centre keelson bymeans of full penetration welding.

7.1.1.2.3 Floor plates in the peaksThe thickness of the floor plates in the peaks is

not to be less than:

t = 0,035L + 5,0 [mm]

The thickness, however, need not be greaterthan required by 7.2.6.2.1.

The floor plate height in the fore peak is not tobe less than:

h = 0,06 ⋅ D + 0,7 [m]

The floor plates in the afterpeak are to extendover the stern tube.

7.1.2 Longitudinal girders

7.1.2.1 All single bottom ships are to have a centregirder keelson. Where the breadth measured on top of floorsdoes not exceed 9 m one additional side girder is to be fitted,and two side girders where the breadth exceeds 9 m. Sidegirders are not required where the breadth does not exceed 6m.

7.1.2.2 For the spacing of side girders from each otherand from the centre girder in way of bottom strengtheningforward see Section 5.4

7.1.2.3 The centre and side girders are to extend as farforward and aft as practicable. They are to be connected tothe girders of a non-continuous double bottom or are to bescarped into the double bottom by two frame spacings.

7.1.2.4 Centre girderThe web thickness within 0,7 L amidships is

not to be less than:t = 0,07 L + 5,5 [mm]

The sectional area of the face plate within 0,7 Lamidships is not to be less than:

Af = 0,7L + 12 [cm2]

Towards the ends the thickness of the web plateas well as the sectional area of the top plate may be reducedby 10%. Lightening holes are to be avoided.

7.1.2.5 Side girderThe web thickness within 0,7 L amidships is

not to be less than:

t = 0,04 L + 5 [mm]

The sectional area of the face plate within 0,7 Lamidships is not to be less than:

Af = 0,2L + 6 [cm2]

Towards the ends, the thickness of the webplate and the sectional area of the face plate may be reducedby 10%.

7.2 DOUBLE BOTTOM

7.2.1 General

7.2.1.1 On cargo ships a double bottom is to be fittedextending from the collision bulkhead to the afterpeak bulk-head, as far as this is compatible with service of the ship.


2013

For ships of less than 500 tons gross tonnageand fishing vessels double bottom are not required. For oiltankers see Section 18 and for passenger ships see Section21.

7.2.1.2 In single hull ships the inner bottom is to becontinued out to the ship's side as to protect the bottom to theturn of the bilge. In double hull ships the inner bottom is tobe extended to the inner hull.

7.2.1.3 Small wells for hold drainage may be arrangedin the double bottom, their depth, however, shall be as smallas practicable. A well extending to the outer bottom, may,however, be permitted at the after end of the shaft tunnel.

7.2.1.4 Other wells may be permitted if their arrange-ment does not reduce the level of protection equivalent tothat afforded by a double bottom complying with this Sec-tion.

7.2.1.5 In fore-and afterpeak a double bottom need notto be arranged.

7.2.1.6 If the double bottom is not subdivided by wa-tertight side girders, the centre girder should be watertight atleast for 0,5 ⋅ L amidships.

7.2.1.7 For bottom strengthening forward, see Section5.4.

For the double bottom structure of bulk carriers, see Section17.2.4.

7.2.1.9 Double bottoms in passenger ships and cargoships other than tankers

7.2.1.9.1 A double bottom shall be fitted extending fromthe collision bulkhead to the afterpeak bulkhead, as far asthis is practicable and compatible with the design and properworking of the ship.

7.2.1.9.2 Where a double bottom is required to be fittedthe inner bottom shall be continued out to the ship's sides insuch a manner as to protect the bottom to the turn of thebilge.

Such protection will be deemed satisfactory ifthe inner bottom is not lower at any part than a plane parallelwith the keel line and which is located not less than a verticaldistance h measured from the keel line, as calculated by theformula:

h = B/20However, in no case is the value of h to be less

than 760 mm, and need not be taken as more than 2,000 mm.

7.2.1.9.3 Small wells constructed in the double bottom inconnection with drainage arrangements of holds, etc., shallnot extend downward more than necessary. A well extendingto the outer bottom is, however, permitted at the after end ofthe shaft tunnel.

Other wells (e.g., for lubricating oil under mainengines) may be permitted by the Register if satisfied that thearrangements give protection equivalent to that afforded by adouble bottom complying with this regulation. In no caseshall the vertical distance from the bottom of such a well to aplane coinciding with the keel line be less than 500 mm.

7.2.2 Centre girder

7.2.2.1 Center girder are to be extended as far as possi-ble toward the aft and forward and to be connected with thestem.

Lightening holes in the centre girder are gener-ally permitted only outside 0,75 L amidships. Their depth isnot to exceed half the depth of the centre girder and theirlengths are not to exceed half the frame spacing.

7.2.2.2 ScantlingsDepth and thickness of the centre girder are

determined as follows:

a) The depth of the centre girder is not to be lessthan:

hdb = 350 + 45 ⋅ B [mm]

hmin = 600 [mm]:

where longitudinal wing bulkheads are fitted, the distancebetween the bulkheads may be taken instead of B, not lessthan 0,8 ⋅ B.

b) The thickness of the centre girder is not be lessthan:

- within 0,7 L amidships:

t = hhdb

akhdb

+ 0,1100

, [mm], for hdb ≤ 1200 mm

t = hhdb

akhdb

+ 0,3120

, [mm], for hdb > 1200 mm

where:ha = depth of centre girder as built, in

[mm], where ha is larger than hdb:

a

dbhh

≤ 1,0

- 0,15 ⋅ L at the ends:

t1 = 0,9 ⋅ t

t = thickness within 0,7⋅L amidships, [mm].

7.2.3 Side girders

7.2.3.1 ArrangementAt least one side girder shall be fitted in the en-

gine room and in way of 0,25 L aft of F.P. In the other partsof the double bottom, one side girder shall be fitted where thehorizontal distance between ship's side and centre girder ex-ceeds 4,5 m. Two side girders shall be fitted where the dis-tance exceeds 8 m, and three side girders where it exceeds10,5 m. The distance of the side girders from each other andfrom centre girder and ship's side respectively shall not begreater than:

- 1,8 m in the engine room within thebreadth of engine seatings,

- 4,5 m where one side girder is fitted inthe other parts of double bottom,

- 4,0 m where two side girders are fitted inthe other parts of double bottom,

- 3,5 m where three side girders are fittedin the other parts of double bottom.


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7.2.3.2 Scantlings

7.2.3.2.1 The thickness of the side girders is not to beless than:

t = kh

h

a

db

⋅120

2[mm],

hdb = depth of the centre girder, in [mm]according to 7.2.2.2.

ha = depth of side girder as built, in [mm],where ha is larger than hdb.

The scantlings of watertight side girders arealso to be in accordance with the requirements given under7.2.6.3.

Lightening holes in the side girders are to be ofsuch size as to level a remainder of web plate around the holenot less than 0,2 of the height of side girder or of framespacing. Where the holes are fitted with flat bars, the abovevalue may be reduced to 0,15 of the height of side girder.

For strenghtenings under the engine seatings,see 7.3.2.3.

7.2.4 Inner bottom

7.2.4.1 The thickness of the inner bottom plating is notto be less than:

t = 1,1 ⋅ s kp ⋅ + tk [mm],

where:p = design pressure in [kN/m2].p is the greater of the following values:p1 = 10 (d - hdb)p2 = 10 ⋅ h, where the inner bottom forms

a tank boundaryp3 = pDB according to Section 3.3.2.1;h = distance from top of overflow pipe to

inner bottom, in [m];hdb = double bottom height, in [m].

7.2.4.2 If no ceiling is fitted on the inner bottom, thethickness determined in accordance with 7.2.4.1 for p1 or p2is to be increased by 2 mm. This increase is not required forcontainer ships.

7.2.4.3 For strengthening in the range of grabs, seeSection 17.

7.2.4.4 For strengthening of inner bottom in machineryspaces, see Section 7.3.

7.2.5 Double bottom tanks

7.2.5.1 Fuel and lubricating oil tanks

7.2.5.1.1 In double bottom tanks, oil fuel may be carried,the flash point of which exceeds 60oC.

7.2.5.1.2 Where practicable, lubricating oil dischargetanks or circulating tanks shall be separated from the shell.

7.2.5.1.3 For the separation of oil fuel tanks from tanksfor other liquids, see Section 11.1.4.

7.2.5.1.4 Requirements for air, overlow and soundingpipes, are stated in Rules, Part 8 – Piping, Section 5.

7.2.5.1.5 Where tanks are intended to carry heated liq-uids thermal stress calculations may be required.

7.2.5.1.6 Manholes for access to oil fuel double bottomtanks situated under cargo oil tanks are not permitted incargo oil tanks nor in the engine room.

7.2.5.1.7 The thickness of structures is not be less thanthe minimum thickness according to Section 11.

7.2.5.2 See chests

7.2.5.2.1 The plate thickness of sea chests is not to beless than:

t = 12 ⋅ s p k⋅ + tk [mm]

where:s = spacing of stiffeners, in [m];p = blow out pressure at the safety valve,

in [bar], but not to be less than 2 bar.

7.2.5.2.2 The section modulus of sea chest stiffeners isnot to be less than:

W = 56 ⋅ s ⋅ p ⋅ l2 ⋅ k [cm3],

where:l = unsupported span of stiffeners, in

[m],s, p = see 7.2.5.2.1.

7.2.5.2.3 The sea-water inlet openings in the shell are tobe protected by gratings.

7.2.5.2.4 A cathodic corrosion protection with galvanicanodes made of zinc or aluminium is to be provided in seachests. For the suitably coated plates a current density of 30µA/m2 is to be provided and for the cooling area a currentdensity of 180 µA/m2.

7.2.6 Double bottom, transverse framing sys-tem

7.2.6.1 Plate floors

7.2.6.1.1 It is recommended to fit plate floors at everyframe in the double bottom if transverse framing is adopted.

7.2.6.1.2 Plate floors are to be fitted at every frame:- in way of strengthening of the bottom

forward according to Section 5.4;- in the engine room;- under the boiler bearers;

7.2.6.1.3 Plate floors are to be fitted:- under bulkheads;- under corrugated bulkheads.

7.2.6.1.4 For the remaining part of the double bottom,the spacing of plate floors shall not exceed approximately 3m.

7.2.6.2 Scantlings

7.2.6.2.1 The thickness of plate floors is not to be lessthan:

tp = t - 2,0 [mm]

t = thickness of centre girder according to 7.2.2.2tpmax = 16,0 mm


2013

If the floor depth exceeds the height hdb ac-cording to 7.2.2.2., the thickness may be reduced, providedthat the buckling strength is considered according to Section4.6.

7.2.6.2.2 The sectional area of the plate floors is not tobe less than:

Aw = f1 ⋅ d ⋅ l ⋅ s (1 - 2 b1/l) ⋅k [cm2]

where:s = spacing of plate floors, in [m];l = span between longitudinal bulkheads,

if any, in [m];l = B, if longitudinal bulkheads are not

fitted;b1 = distance between supporting point of

the plate floor (ship's side, longitudi-nal bulkhead) and the section consid-ered, in [m]. The distance b1 is not tobe taken greater than 0.4 ⋅ l;

f1 = 0,5 for spaces which may be empty atfull draught, e.g. machinery spaces,storerooms, etc.;

f1 = 0,3 elsewhere;k = material factor according to Section

1.4.2.2.

7.2.6.2.3 Where in small ships side girders are not re-quired, at least one vertical stiffener is to be fitted at everyplate floor; its thickness is to be equal to that of the floorsand its depth of web at least 1/15 of the height of centregirder.

7.2.6.2.4 The thickness of watertight floors is not to beless than that required for tank bulkheads according to11.2.2. In no case their thickness is to be less than requiredfor plate floors according to 7.2.6.2.1.

7.2.6.2.5 The scantlings of stiffeners at watertight floorsare to be determined according to 11.2.3.

7.2.6.2.6 In way of strengthening of bottom forward ac-cording to Section 5.4, the plate floors are to be connected tothe shell plating and inner bottom by continuous fillet weld-ing.

7.2.6.3 Bracket floors

7.2.6.3.1 Where plate floors are not required accordingto 7.2.6.1 bracket floors may be fitted.

7.2.6.3.2 Bracket floors consist of bottom frames at theshell plating and reversed frames at the inner bottom, at-tached to centre girder, side girders and ship's side bilge bymeans of brackets.

7.2.6.3.3 The section modulus of bottom and inner bot-tom frames is not to be less than:

W = e ⋅ f2 ⋅ s ⋅ l2 ⋅ p ⋅ k [cm3],

where:p = design load, in [kN/m2] as follows:

- for bottom framesp = pB (according to 3.2.3)

- for inner bottom frames (the greatervalue is to be used)

p = pDB (according to 3.3.2),p = p1 or p2 (according to 3.4.1),p = 10 ⋅ (d - hdb),hdb = double bottom height in [m],

e = 0,44, if p = p2,e = 0,55, if p = pDB or p1,e = 0,70, if p = pB,f2 = 0,60 where struts according to

7.2.6.4.5 are provided at l/2, other-wise f2 = 1,0

l = unsupported span, in [m], disregard-ing struts, if any.

7.2.6.4 Brackets

7.2.6.4.1 The brackets are, in general, to be of the samethickness as the plate floors, and breadth is to be 0,75 of thedepth of the centre girder. The brackets are to be flanged attheir free edges, where the unsupported span of bottomframes exceeds 1 m or where the depth of floors exceeds 750mm.

7.2.6.4.2 As the side girders, bottom frames and innerbottom frames are to be supported by flat bars having thesame depth as the inner bottom frames.

7.2.6.5 Struts

The cross sectional area of the struts is to bedetermined according to 9.3.2. The design force is to betaken as the following value:

P = 0,5 ⋅ p ⋅ s ⋅ l [kN],

p and l as stated in 7.2.6.3.3.

7.2.7 Double bottom, longitudinal framingsystem

7.2.7.1 GeneralWhere the longitudinal framing system changes

to the transverse framing system, structural continuity is tobe provided for.

7.2.7.2 Bottom and inner bottom longitudinals

7.2.7.2.1 The scatlings are to be calculated according to8.2.

7.2.7.2.2 Where bottom and inner bottom longitudinalsare coupled by struts in the centre of their unsupported spanl, their section moduli may be reduced to 60% of the valuesrequired by 8.2.

The scantlings of the struts are to be deter-mined in accordance with 7.2.6.5.

7.2.7.3 Plate floors

7.2.7.3.1 The floor spacing shall, in general, not exceed5 times the transverse frame spacing.

7.2.7.3.2 Plate floors are to be fitted under transversalbulkheads and corrugated bulkheads. Floors are to be fitted atevery frame in the machinery space under the main engine.In the remaining part of the machinery space, floors are to befitted at every alternate frame.

7.2.7.3.3 Regarding floors in way of the strengthening ofthe bottom forward, 5.4 is to be observed. For ships intendedfor carrying heavy cargo, see Section 17.

7.2.7.3.4 The scantlings of floors are to be determinedaccording to 7.2.6.2.

7.2.7.3.5 The plate floors are to be stiffened at everylongitudinal by a vertical stiffener having the same scantlings


2013

as the inner bottom longitudinals. The depth of the stiffenerneed not exceed 150 mm.

7.2.7.4 Brackets

7.2.7.4.1 Where the ship's sides are framed transversallyframe flanged brackets having a thickness of the floors are tobe fitted between the plate floors at every transverse frame,extending to the outer longitudinals at the bottom and innerbottom.

7.2.7.4.2 One bracket is to be fitted at each side of thecentre girder between the plate floors where the plate floorsare spaced not more than 2,5 m apart. Where the floor spac-ing is greater, two brackets are to be fitted.

7.2.7.5 Longitudinal girder system

7.2.7.5.1 Where longitudinal girders are fitted instead ofbottom longitudinals, the spacing of floors may be greaterthan permitted by 7.3.1, provided that adequate strength ofthe structure is proved.

7.2.7.5.2 The plate thickness of the longitudinal girdersis not to be less than:

t = (5,0 + 0,03 L) k [mm],

but not less than:

tmin = 6,0 k [mm]

7.2.7.5.3 The longitudinals girders are to be examinedfor sufficient safety against buckling according to Section4.6.

7.2.8 Design loads, permissible stresses for di-rect calculations

7.2.8.1 Design Loads

p = pDB - pa [kN/m2], for loaded holds

p = pa [kN/m2], for empty holdswhere:

PDB = load on inner bottom according toSection 3.3.2, in [kN/m2], or Section3.3.1.3, in [kN], (where applicable);

pa = 10 ⋅ d - po ⋅ CF, sagging conditions;pa = 10 ⋅ d + po ⋅ CF, hogging conditions;po, CF = according to 3.2.2.Where single loads are acting (e.g. loads of

containers), such loads are to be used instead of the load PDB.

7.2.8.2 Permissible stresses

7.2.8.2.1 Equivalent permissible stress, σekv

The equivalent stress is not to exceed the fol-lowing value:

σekv = 230k

[N/mm2]

σekv = 222 3 τσσσσ ⋅+⋅−+ yxyx

where:σx = stress in the ship's longitudinal direc-

tion;σx = σL + σl;

σL = design hull girder bending stress, in[N/mm2], according to Section 4;

σl = bending stress, in [N/mm2], due to theload p, in longitudinal direction, inlongitudinal girders;

σx = 0, for webs of transverse girders;σy = stress in the ship's transverse direc-

tion;σy = σtσt = bending stress, in [N/mm2], due to

load p, in transverse direction, intransverse girders;

σy = 0, for webs of longitudinal girders;τ = shear stress in the longitudinal girders

or transverse girders due to load p, in[N/mm2].

For direct calculation of bottom grillage maybe used the following stress definitions:

σx = σL + σl + 0,3 ⋅ σt

σy = σt + 0,3 ⋅ (σL + σl)

7.2.8.3 Maximum permissible values of stressesThe stresses σl, σt and τ are not exceed the

following values:

σl, σt = 150

k[N/mm2]

τ = 100

k[N/mm2]

7.2.8.4 Buckling strengthThe buckling strength of the bottom structures

is to be examined according to Section 4.6. For this purposethe design stresses according to Section 4.5.3 and the stressesdue to local loads are to be considered.

7.3 BOTTOM STRUCTURE IN WAYOF THE MAIN PROPULSION PLANT

7.3.1 Single bottom

7.3.1.1 The scantlings of floors are to be determinedaccording to 7.1.1.2 for the greatest span measured in the en-gine room.

7.3.1.2 The web depth of the plate floors in way of theengine foundation should be as large as possible. The depthof plate floors connected to web frames shall be similar to thedepth of the longitudnal foundation girders. In way of thecrank case, the depth shall not be less than 0,5 . h. The webthickness is not to be less than:

t = h

100 + 4 [mm],

where:h = according to 7.1.1.2.1.

7.3.1.3 The thickness of the longitudinal foundationgirders is to be determined according to 7.2.3.2.

7.3.1.4 No centre girder need be fitted in way of lon-gitudinal foundation girders. Intercostal docking profiles areto be fitted instead. The sectional area of the docking profilesis not to be less than:


2013

Aw = 10 + 0,2L [cm2]

7.3.2 Double bottom

7.3.2.1 Lightening holes in way of the engine founda-tion are to be kept as small as possible with due regard, how-ever, to accessibility. Where necessary, the edges of lighten-ing holes are to be strengthened by means of face bars or theplate panels are to be stiffened.

7.3.2.2 Plate floorsPlate floors are to be fitted at every frame. The

floor thickness according to 7.2.6.2.1 is to be increased forpercentage as follows:

50063 P, + [%]

but not less 5 %, and not greater than 15 %.where:

P = single engine output, [kW].

7.3.2.3 Side girders

7.3.2.3.1 The thickness of side girders under an enginefoundation top plate inserted into the inner bottom is to besimilar to the thickness of side girders above the inner bot-tom according to 7.3.3.2.

7.3.2.3.2 Side girders under foundation girders are to beextended into the adjacent spaces and to be connected to thebottom structure. This extension abaft and forward of the en-gine room bulkheads shall be two to four frame spacings ifpracticable.

7.3.2.3.3 Between the foundation girders, the thicknessof the inner bottom plating required according to 7.2.4.1 is tobe increased by 2 mm. The strengthened plate is to be ex-tended beyond the engine seating by three to five framespacings.

7.3.2.3.4 No centre girder is required in way of the en-gine seating (see 7.3.1.4).

7.3.3 Engine seating

7.3.3.1 GeneralThe following regulations apply to low speed

engines. Seating for medium and high speed engines as wellas for turbines will be specially considered.

7.3.3.2 Longitudinal girders

a) The thickness of the longitudinal girders abovethe inner bottom is not to be less than:

t = P15

+ 6 [mm], for P < 1500 kW

t = P

750+ 14 [mm], for 1500 ≤ P ≤ 7500 kW

t = P

1875+ 20 [mm], for P > 7500 kW

P = see 7.3.2.2

b) Where two longitudinal girders are fitted on ei-ther side of the engine, their thickness may be re-duced by 4 mm.

c) The cross sectional area of the top plate is not tobe less than:

A = P15

+ 30 [cm2], for P ≤ 750 kW

A = P75

+ 70 [cm2], for P > 750 kW

d) The longitudinal girders of the engine seating areto be supported transversely by means of webframes or wing bulkheads. The scantlings of webframes are to be determined according to Section8.1.6.

7.4 DOCKING CALCULATION

7.4.1 General

For ships exceeding 120 m in length, for shipsof special design, particularly in the aft body and for shipswith a docking load of more than 700 kN/m a special calcu-lation of the docking forces is required. The maximum per-missible cargo load to remain onboard during docking andthe load distribution are to be specified. The proof of suffi-cient strength can be performed either by a simplified dock-ing calculation or by a direct docking calculation. The num-ber and arrangement of the keel blocks shall agree with thesubmitted docking plan. Direct calculations are required forships with unusual overhangs at the ends or with nohomoge-neous distribution of cargo.

7.4.2 Direct docking calculation

If the docking block forces are determined bydirect calculation, e.g. by a finite element calculation, con-sidering the stiffness of the ship's body and the weight distri-bution, the ship has to be assumed as elastically bedded at thekeel blocks. The stiffness of the keel blocks has to be deter-mined including the wood layers.

If a floating dock is used, the stiffness of thefloating dock is to be taken into consideration.

Transitory docking conditions need also to beconsidered.

7.4.3 Permissible stresses

The permissible equivalent stress σekv is:

05,1eH

ekvR

=σ


The bottom structures are to be examined ac-cording to Section 4.6.


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8 FRAMING SYSTEM

8.1 TRANSVERSE FRAMING

8.1.1 General

8.1.1.1 Forward of the collision bulkhead and aft of theafterpeak bulkhead, the frame spacing shall in general notexceed 600 mm.

8.1.1.2 DefinitionsS = spacing of web frames, [m];s = spacing of frames, in [m];l = unsupported span, in [m], according

to 2.3.1;lmin = 2,0 [m];lk1,lk2 = length of lower / upper bracket con-

nection at main frames within thelenght l in [m], see Fig. 8.1.2;

ps = load on ship's sides, in [kN/m2], ac-cording to 3.2.2;

pe = load on bow structures, in [kN/m2],according to 3.2.2.2;

pL = 'tween deck load, in [kN/m2], ac-cording to 3.3.1;

p1 = pressure, in [kN/m2], according to-Section 3.4.1;

f = factor for curved frames;f = 1,0 - 2 ⋅ e/l;fmin = 0,75;e = max. height of curve, in [m].

Figure 8.1.2

8.1.2 Main frames

8.1.2.1 Scantlings

8.1.2.1.1 The section modulus of the main frames in-cluding end attachements is not to be less than:

W = n ⋅ c ⋅ s ⋅ l2 ⋅ ps ⋅ f ⋅ k [cm3]

where:

n = 0,9 - 0,0035 ⋅ L , for L < 100 [m]

n = 0,55, for L ≥ 100 [m]

c = 1,0 - (lk1 + 0,45 ⋅lk2)cmin = 0,65Within the lower bracket connection the section

modulus is not to be less than the value obtained for c = 1,0.

8.1.2.1.2 In ships with more than 3 decks the mainframes are to extend at least to the deck above the lowestdeck.

8.1.2.1.3 The scantlings, of the main frames are not to beless than those of the 'tween deck frames above.

8.1.2.1.4 Where the scantlings of the main frames aredetermined by strength calculations, the following permissi-ble stresses are to be observed:

- bending stress:

σ = 150/k [N/mm2]

- shear stress:

τ = 100/k [N/mm2]

- equivalent stress:

σekv = 23τσ + = 180/k [N/mm2]

8.1.2.1.5 For main frames in holds of bulk carriers seealso Section 17.2.5.

8.1.2.2 Frames in tanksThe section modulus of frames in tanks or in

hold spaces for ballstwater is not to be less than the greater ofthe following values:

W1 = n ⋅ c ⋅ s ⋅ l2 ⋅ p1 ⋅ f ⋅ k [cm3]or

W2 = according to 11.2.3..1n, c = see 8.1.2.1.1.

8.1.2.3 End attachment

8.1.2.3.1 The lower bracket attachment to the bottomstructure is to be determined according to 2.4.2 on the basisof the main frame section modulus.

8.1.2.3.2 The upper bracket attachment to the deckstructure and/or to the 'tween deck frames is to be determinedaccording to 2.4.2 on the basis of the section modulus of thedeck beams or 'tween deck frames whichever is the greater.

8.1.2.3.3 Where frames are supported by a longitudinallystiffened deck, the frames fitted between web frames are tobe connected to the adjacent longitudinals by brackets. Thescantlings of the brackets are to be determined in accordancewith 2.4.2 on the basis of the section modulus of the frames.

8.1.3 Tween deck and superstructure frames

8.1.3.1 General

8.1.3.1.1 In ships having a speed exceeding v = 1,6 L[kn], the forecastle frames forward of 0,1 L are to have atleast the same scantlings as the frames located between thefirst and the second deck.

For 'tween deck frames in tanks, the require-ments for the section moduli W1 and W2 according to 8.1.2.2are to be observed.


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8.1.3.2 Scantlings

8.1.3.2.1 The section modulus of the 'tween deck and su-perstructure frames are not to be less than:

W = 0,55⋅s⋅l2⋅p⋅f⋅k, [cm3]

p is not to be taken less than:

pmin = 0,4⋅pL⋅(b/l)2, [kN/m2]

b = unsupported span of the deck beambelow the respective 'tween deck frame,in [m].

For 'tween deck frames connected at theirlower ends to the deck transverses, pmin is to be multiplied bythe factor:

f1 = 0,75 + 0,25⋅S/s ≥ 1,0.

8.1.3.3 End attachment'Tween deck and superstructure frames are to

be connected to the main frames below, or to the deck. Theend attachment may be carried out in accordance with Fig.8.1.3.3.

Figure 8.1.3.3

8.1.4 Peak frames and frames in way of thestern

8.1.4.1 Peak frames

8.1.4.1.1 The section modulus of the peak frames is notto be less than:

W = 0,8 ⋅ s ⋅ l2 ⋅ ps ⋅ f ⋅ k [cm3]

p = ps or pe whichever is applicable.

8.1.4.1.2 Where the length of the forepeak does not ex-ceed 0,06 L the section modulus required at half forepeaklength may be maintained throughout the entire forepeak.

8.1.4.1.3 The peak frames are to be connected to thestringer plates to ensure sufficient transmission of shear fore-ces.

8.1.4.1.4 Where peaks are to be used as tanks, the sec-tion modulus of the peak frames is not to be less than re-quired by 11.2.31 for W2.

An additional stringer may be required in theaft body outside the afterpeak where frames are inclined con-siderable and not fitted vertically to the shell.

8.1.5 Strengthenings in fore-and aft body

8.1.5.1 GeneralAs far as practicable and possible, tiers of

beams or web frames and stringers are to be fitted in the fore-and afterpeak.

8.1.5.2 Tiers of beams

8.1.5.2.1 Forward of the collision bulkhead, tiers ofbeams, at every other frame, generally spaced not more than2,6 [m] apart, measured vertically, are to be arranged belowthe lowest deck within the forepeak. Stringer plates are to befitted on the tiers of beams which are to be connected bycontinuous welding to the shell plating and by a bracket toeach frame. The scantlings of the stringer plates are to bedetermined from the following formulae:

width: b = 75 L [mm]thickness: t = 6,0 + L/40 [mm].

8.1.5.2.2 The cross sectional area of each beam is to bedetermined according to 9.3.2. for a load

P = A ⋅ p [kN]where:

A = load area of a beam, in [m2];p = ps or pe whichever is applicable.

8.1.5.2.3 In the afterpeak, tiers of beams, with stringerplates generally spaced 2,6 m apart, measured vertically, areto be arranged as required under 8.1.5.2.1 as far as practica-ble with regard to the ship's shape.

8.1.5.2.4 Intermittent welding at the stringers in the af-terpeak is to be avoided.

8.1.5.2.5 Where peaks are used as tanks, stringer platesare to be flanged or face bars are to be fitted at their inneredges. Stringers are to be effectively fitted to the collisionbulkhead so that the forces can be properly transmitted.

8.1.5.2.6 Where perforated decks are fitted instead oftiers of beams, their scantlings are to be determined as forwash bulkheads according to 11.5. the requirements regard-ing cross sectional area stipulated in 8.1.5.2.2 are, however,to be complied with.

8.1.5.3 Web frames and stringers

8.1.5.3.1 Where web frames and supporting stringers arefitted instead of tiers of beams, their scantlings are to be de-termined as follows:

- for section modulus:

W = 0,55 ⋅ S ⋅ l2 ⋅ ps ⋅ c ⋅ k [cm2]

- for web sectional area at the supports:

Aw = 0,05 ⋅ S ⋅ l1 ps ⋅ k [cm2]where:

l = unsupported span, in [m], withoutconsideration of cross ties, if any;

l1 = similar to l, however, consideringcross ties, if any;

c = coefficient according to the Table8.1.5.3.1.

Table 8.1.5.3.1

Number of cross ties c0 1,01 0,52 0,3

≥ 3 0,2


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8.1.5.3.2 Vertical transverses are to be interconnected bycross ties the cross sectional area of which is to be deter-mined according to 8.1.5.2.2.

8.1.5.4 Web frames and stringers in 'tween decksand superstructure decksWhere the speed of the ship exceeds v = 1,6

L , [kn], or in ships with a considerable bow flare respec-tively, stringers and transverses according to 8.1.5.3 are to befitted within 0,1 L from forward perpendicular in 'tween deckspaces and superstructures.

The spacing of the stringers and transversesshall be less than 2,8 m. A considerable bow flare exists, ifthe flare angel exceeds 40°, measured in the ship's transversedirection and related to the vertical plane.

8.1.5.5 Tripping brackets

8.1.5.5.1 Between the point of greatest breadth of theship at maximum draft and the collision bulkehad trippingbrackets spaced not more than 2,6 m, measured vertically.The arrangement of tripping brackets is shown at Fig.8.1.5.5.1. Where proof of safety against tripping is providedtripping brackets may partly or compeltely be dispensedwith.

Figure 8.1.5.5.1

8.1.5.5.2 In the same range, in 'tween deck spaces andsuperstructures of 3 m and more in height, tripping bracketsaccording to 8.1.5.5.1 are to be fitted.

8.1.5.5.3 Where peaks or other spaces forward of thecollision bulkhead are intended to be used as tanks, trippingbrackets according to 8.1.5.5.1 are to be fitted between tiersof beams or stringers.

8.1.6 Web frames in machinery spaces

8.1.6.1 Arrangement

8.1.6.1.1 In the engine and boiler room, web frames areto be fitted. Generally, they should extend up to the upper-most continuous deck. They are to be spaced not more than 5times the frame spacing in the engine room.

8.1.6.1.2 For combustion engines, web frames shallgenerally be fitted at the forward and aft ends of the engine.The web frames are to be evenly distributed along the lengthof the engine.

8.1.6.1.3 Where combustion engines are fitted aft,stringers spaced 2,6 m apart are to be fitted in the engineroom, in alignment with the stringers in the after peak, if any.Otherwise the main frames are to be adequately strengthened.The scantlings of the stringers shall be similar to those of the

web frames. At least one stringer is required where the depthup to the lowest deck is less than 4 m.

8.1.6.1.4 For the bottom structure in machinery spaces,see Section 7.3.

8.1.6.2 Scantlings

8.1.6.2.1 The section modulus of web frames is not to beless than:

W = 0,8 ⋅ S ⋅ ⋅l2 ⋅ ps⋅ k [cm3]The moment of inertia of web frames is not to

be less than:

I = D (4,5 D - 3,75) ⋅ c ⋅ 102 [cm4],

for 3 m ≤ D ≤ 10 m

I = D (7,25 D - 31) ⋅ c ⋅ 102 [cm4],

for D > 10 mwhere:

c = 1 + (Hu - 4 ) ⋅ 0,07Hu = depth up to the lowest deck, in [m].The scantlings of the webs are to be calculated

as follows:depth: h = 50 ⋅ D [mm],

hmin = 250 mm.thickness: t = h/(32 + 0,03 h) [mm]

tmin = 8,0 mm

8.1.6.2.2 Ships with a depth of less than 3 m are to haveweb frames with web scantlings not less than 250 x 8 mmand a minimum face sectional area of 12 cm2.

8.2 BOTTOM, SIDE-AND DECKLONGITUDINALS, SIDE

TRANSVERSES

8.2.1 General

8.2.1.1 Longitudinals shall preferable be continuousthrough floor plates and transverses. Attachments of theirwebs to the webs of floor plates and transverses shall be suchthat the reaction forces of support will be transmitted. Thepermissible shear stress of 100/k [N/mm2] is not to be ex-ceeded.

8.2.1.2 Where longitudinals abut at transverse bulk-heads or webs, brackets are to be fitted. These longitudinalsare to be attached to the transverse webs or bulkhead bybrackets with the thickness of the stiffeners web thickness,and with a length of weld at the longitudinals equal to 2 xdepth of the longitudinals.

8.2.1.3 Where longitudinals are sniped at watertightfloors and bulkheads, they are to be attached to the floors bybrackets of the thickness of plate floors, and with a length ofweld at the longitudinals equal to 2 x depth of the bottomlongitudinals.

8.2.1.4 Outside the upper and the lower hull flange, thecross sectional areas stipulated in 8.2.1.2 may be reduced by20 per cent.

8.2.1.5 For buckling strength of longitudinals see Sec-tion 4.6.


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8.2.2 Definitions

p = load, in [kN/m2];= pB according to 3.2.3 for bottom longitu-

dinals.= ps according to 3.2.2 for side longitudi-

nals= p1 according to 3.4.1, for longitudinals at

decks and at ship's sides, at longitudinalbulkheads and inner bottom in way oftanks.

For bottom longitudinals in way of tanks p isnot to be taken less than:

p1 - [10 ⋅ dmin - po ⋅ CF] [kN/m2]

For side longitudinals below dmin p need notto be taken larger than:

[ ]2

minmin1 kN/m 1)(10

+⋅−−⋅−

dzCpzdp Fo

= pd according to 3.4.2 for side and decklongitudinals as well as for horizontalstiffeners of longitudinal bulkheads intanks which may be partially filled;

= pD according to 3.2.1 for deck longitudi-nals of the strength deck;

= pDB according to 3.3.2 for inner bottomlongitudinals, however, not less than theload corresponding to the distance be-tween inner bottom and deepest load wa-terline;

= pL according to 3.3.1 for longitudinals ofcargo decks and for inner bottom longitu-dinals;

σD = maximum normal stress σL due to longi-tudinal hull girder bending, in [N/mm2],in the strength deck level at side;

σB = maximum normal stress σL due to longi-tudinal hull girder bending, in [N/mm2],in the bottom;

σL = according to 4.5.3.

Where σD and σB are not known the followingvalues may be taken:

σD = σLmax

σB = 0,8 ⋅ σLmax

z = distance, in [m], above base line;

m = ( 22

21 mm − )

m1 =

− kk sinll

αΣ 21

lk = according to Fig. 8.2.2, in [m]αk = according to Fig. 8.2.2, in [o]

m2 =

−

2

42040ls

ls,

Figure 8.2.2

8.2.3 Scantlings

8.2.3.1 The section modulus and shear area of longitu-dinals and longitudinal beams of the strength deck is not tobe less than:

Wl = 83,3/σdop⋅ m ⋅ s ⋅ l2 ⋅ p [cm3]

Al = (1 - 0,817 ⋅ m2) ⋅ 0,05 ⋅ s ⋅l ⋅ p ⋅ k [cm2]

The permissible stress σdop is to be determinedaccording to the following formulae.

- below the neutral axis of the respective crosssection:

σdop = σt - σB + z σ σB D

D

+[N/mm2]

- above the neutral axis of the respective crosssection:

σdop = σt + σB - z σ σB D

D

+[N/mm2]

σdop ≤ 150/k [N/mm2]

σt = (0,8 + L/450) ⋅ 230/k [N/mm2]

σtmax =230k

[N/mm2]

For calculation purpose the absolute stress val-ues are to be taken for σB and σD.

8.2.3.2 In tanks, the section modulus is not to be lessthan W2 according to 11.2.3.1.

8.2.3.3 For determining the section modulus of longi-tudinals located adjacent to a bilge strake which is not stiff-ened longitudinally, the width.

23sR

+

for R see Fig. 8.2.3.3

is to be inserted, in lieu of s, into the formula as per 8.2.3.1.For safety against tripping, the spacing of

transverses is to be less than 12 x width of the longitudinalface. Otherwise, an additional bracket is to be fitted at halftransverse's spacing.


2013

Figure 8.2.3.3

8.2.3.4 Where the scantlings of longitudinals are de-termined by strength calculations, the total equivalent stresscomprising local bending and shear stresses and normalstresses due to longitudinal hull girder bending is not to ex-ceed the total stress value σt as defined in 8.2.3.1.

8.2.4 Side transverses

8.2.4.1 The section modulus of side transverses sup-porting side longitudinals is not to be less than:

W = 0,55 ⋅ S ⋅ l2 ⋅ p ⋅ k [cm3]

Minimum cross sectional area of the web:

Aw = 0,05 ⋅ S ⋅ l ⋅ p ⋅ k [cm2]

8.2.4.2 Where the side transverses are designed on thebasis of strength calculations the following stresses are not tobe exceeded:

σb = 150/k [N/mm2]

τ = 100/k [N/mm2]

k/bekv 1803 22 ≤+= τσσ [N/mm2]

8.2.4.3 In tanks, the section modulus and the crosssectional area are to be in accordance with 11.2.3, W2 and AW2

respectively.

8.2.4.4 The webs of side transverses in those areas,where concentrated loads due to ship manoeuvres at termi-nals may be expected, are to be examined for sufficientbuckling strength according to 4.6. The force induced by afender into the web frame may approximately be determinedby the following formula:

Pg = ∆ ⋅⋅vf

2

2[kN]

where:∆ = displacement of the ship, in [t];∆max = 100 000 tf = displacement of fender, in [m], guid-

ance values for f are given in Table8.2.4.4-1

v = manoeuvring speed of the ship, in[m/s], guidance values are given inTable 8.2.4.4.

Table 8.2.4.4

∆ [t] f [m] ν [m/s]

≤ 1000 0,25 0,2> 1000≤ 10000 0,22 + 2,8 ⋅ ∆ ⋅ 10-5 0,21 - 1,1 ∆ ⋅ 10-5

> 10000 0,5 0,10

8.2.4.5 The compressive stress in the web of the trans-verse due to the action of the force Pg may be determined bythe following formula:

σD = P

h tg

w

⋅

⋅

103

[N/mm2]

where:h = vertical length of application of the

force Pg if h is not known, h = 300mm may be used as a guidance value;

tw = web thickness, in [mm].


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9 SUPPORTING DECKSTRUCTURES

9.1 GENERAL

9.1.1 Definitions

k = material factor (according to1.4.2.2.);

l = unsupported span, in [m], (accordingto Section 2.3.);

b = width of deck supported, in [m];p = deck load pD, pDA or pL, in [kN/m2]

(according to 3.2.1, 3.2.5 and 3.3.1.);f = 0,55;f = 0,75 for beams, girder and transverses

which are simply supported on one orboth ends;

Pu = pillar load;Pu = p ⋅ A + Pi, [kN];A = load area for one pillar, in [m2];Pi = load from pillars located above the

pillar considered, in [kN];λu = degree of slenderness of the pillar;λu = lu/iu;lu = length of the pillar, in [cm];iu = radius of gyration of the pillar;

iu = uu A/I [cm];Iu = moment of inertia of the pillar, in

[cm4];Au = sectional area of the pillar, in [cm2];iu = 0,25 ⋅ du for solid pillars of circular

cross section;

iu = 22250 uuuv dd, + for tubular pillars;du = pillar diameter in [cm];duv = outside diameter of pilalr, in [cm];duu = inside diameter of pillar, in [cm];m2 = factor according to Section 8.2.2.


Where the scantlings of girders not formingpart of the longitudinal hull structure, or of transverses, deckbeams, etc. are determined by means of strength calculationsthe following stresses are not to be exceeded:

σb = 150/k [N/mm2]τ = 100/k [N/mm2]

σekv = σ τ2 23+ = 180/k [N/mm2]


The buckling strength of the deck structures isto be examined according to Section 4.6. For this purpose todesign stresses according to Section 4.5.3 and the stressesdue to local loads are to be considered.

9.2 DECK BEAMS, LONGITUDINALSAND GIRDERS

9.2.1 Transverse deck beams and deck longi-tudinals

The section modulus and shear area of trans-verse deck beams and of deck longitudinals between 0,25 Dand 0,75 D above base line are to be determined by the fol-lowing formula:

Wd = f ⋅ s ⋅ p ⋅ l2 ⋅ k [cm3]

Ad = (1 - 0,817 ⋅ m2) ⋅ 0,05 ⋅ s ⋅ l ⋅ p ⋅ k [cm2]

9.2.2 Deck longitudinals in way of the upperand lower hull flange

9.2.2.1 The section modulus of deck longitudinals ofdecks located below 0,25 D and/or above 0,75 D above baseline is to be calculated according to 8.2.3.

9.2.3 Attachment

9.2.3.1 Transverse deck beams are to be connected tothe frames by brackets according to 2.4.2.

9.2.3.2 Deck beams crossing longitudinal walls andgirders may be attached to the stiffeners of longitudinal wallsand the webs of girders respectively by welding withoutbrackets.

9.2.3.3 Where deck beams are to be attached to hatch-way coamings and girders of considerable rigidity bracketsare to be provided.

9.2.3.4 Within 0,6 L amidships, the arm lengths of thebeam brackets in single deck ships are to be increased by20%.

9.2.3.5 For the connection of deck longitudinals totransverses and bulkheads, see also Section 8.2.3.


9.2.4.1 The section modulus W is not to be less than:

W = f ⋅ b ⋅ l2 ⋅ p ⋅ k [cm3]

9.2.4.2 The shear area Aw is not to be less than:

Aw = 0,05 ⋅ p ⋅ b ⋅ l ⋅ k [cm2]

9.2.4.3 The depth of girders is not to be less than 1/25of the unsupported span. The web depth of girders scallopedfor continuous deck beams is to be at least 1,5 times thedepth of the deck beams.

Scantlings of girders of tank decks are to bedetermined according to Section 11.2.3.

9.2.4.4 End attachments of girders at bulkheads are tobe so dimensioned that the bending moments and shearforces can be transferred. Bulkhead stiffeners under girdersare to be sufficiently dimensioned to support the girders.

9.2.4.5 Face plates are to be stiffened by trippingbrackets according to 2.6.2.4. At girders of symmetrical sec-


2013

tion, they are to be arranged alternately on both sides of theweb.

9.2.4.6 Where a girder does not have the same sectionmodulus throughout all girder fields, the greater scantlingsare to be maintained above the supports and are to be reducedgradually to the smaller scantlings.

9.2.4.7 For girders forming part of the longitudinal hullstructure and for hatchway girders see Section 9.5.

9.2.5 Supporting structure of windlasses andchain stoppers

9.2.5.1 For the supporting structure under windlassesand chain stoppers, the following permissible stresses are tobe observed:

σb = 200/k [N/mm2]

τ = 120/k [N/mm2]

σekv = σ τ2 23+ = 220/k [N/mm2]

9.2.5.2 The acting forces are to be calculated for 80%and 45% respectively of the rated breaking load of the chaincable, i.e.:

- for chain stoppers 80%;- for windlasses 80%, where chain stoppers

are not fitted;- for windlasses 45%, where chain stoppers

are fitted.

9.3 PILLARS

9.3.1 General

9.3.1.1 Structural members at heads and heels of pillarsas well as substructures are to be constructed according to theforces they are subjected to. The connection is to be so di-mensioned that at least 1 cm2 cross sectional area is availablefor 10 kN of load.

Where pillars are affected by tension loadsdoublings are not permitted.

9.3.1.2 Pillar in tanks are to be checked for tension.Tubular pillars are not permitted in tanks for flammable liq-uids.

9.3.1.3 For structural elements of the pillars' transversesection, sufficient buckling strength according to Section 4.6.has to be verified. The wall thickness of tubular pillars whichmay be expected to be damaged during loading and unload-ing operations is not to be less than:

tu = 4,5 + 0,015 ⋅ duv [mm], for duv ≤ 300 mmtu = 0,03 duv [mm], for duv > 300 mm

where:duv = outside diameter of tubular pillar, in

[mm].

9.3.1.4 Pillars also loaded by bending moments have tobe specially considered.

9.3.2 Scantlings

The sectional area of pillars is not to be lessthan:

Au = 10 ⋅ Pu /σt [cm2]where:

σt = permissible compressive stress ac-cording to Table 9.3.2, in [N/mm2].

Table 9.3.2.-1

Permissible compressive stress [N/mm2 ]Degree ofslenderness

(λu)Pillars within

accommodation Elsewhere

≤ 100 140 - 0,0067 ⋅ λ2u 117 - 0,0056 ⋅ λ2

u

> 100 7,3 ⋅ 105/λ2u 6,1 ⋅ 105/λ2

u

9.4 CANTILEVERS

9.4.1 General

9.4.1.1 Cantilevers for supporting girders, hatchwaycoamings, engine casings and unsupported parts of decks areto be connected to transverses, web frames, reinforced mainframes, or walls in order to withstand the bending momentarising from the load P.

9.4.1.2 Face plates are to be secured against tilting bytripping brackets fitted to the webs at suitable distances (seealso Section 2.6.2).


9.4.2.1 When determining the cantilever scantlings, thefollowing permissible stresses are to be observed:

a) Where single cantilevers are fitted atgreater distances:σb = 125/k [N/mm2]τ = 80/k [N/mm2]

b) Where several cantilevers are fitted atsmaller distances (e.g. at every frame):

σb = 150/k [N/mm2]

τ = 80/k [N/mm2]

σekv = 22 τσ + = 180/k [N/mm2]

The stresses in web frames are not exceed thevalues specified above.

9.5 HATCHWAY GIRDERS ANDGIRDERS FORMING PART OF THE

LONGITUDINAL HULL STRUCTURE

9.5.1 The scantlings of longitudinal and transversehatchway girders are to be determined on the basis ofstrength calculations. The calculations are to be based uponthe deck loads according to Sec. 3.2 and 3.3.


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9.5.2 The hatchway girders are to be so dimensionedthat the stress values given in Table 9.5.2 will not be ex-ceeded.

Table 9.5.2

Longitudinal coaming and girders ofthe strength deck

All other hatch-way girders

upper and lowerflanges 150/k [N/mm2] 150/k [N/mm2]deck level 70/k [N/mm2]

9.5.2.3 For continuous longitudinal coamings the com-bined stress resulting from longitudinal hull girder bendingand local bending of the longitudinal coaming is not to ex-ceed the following value:

σL + σl ≤ 200/k [N/mm2],

where:σl = local bending stress in the ship's lon-

gitudinal direction (permissible stressvalues are given in Table 9.5.2);

σL = design longitudinal hull girder bend-ing stress according to 4.5.3;

9.5.2.4 The equivalent stress is not to exceed the fol-lowing value:

σekv = 0 8450

, +

L ⋅

230k

[N/mm2], for L < 90 m

σekv = 230/k [N/mm2], for L ≥ 90 m

σekv = σ σ σ σ τx x y y2 2 23− ⋅ + + ,

where:σx = σL + σl;σy = stress in the ship's transverse direc-

tion;τ = shear stress;τmax = 90/k [N/mm2]The individual stresses σl and σy are not to ex-

ceed 150/k [N/mm2].

9.5.2.5 The requirements regarding buckling strengthaccording to Section 9.1.3 are to be observed.


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10 WATERTIGHT BULKHEADS

10.1 GENERAL

10.1.1 Watertight subdivision

10.1.1.1 All ships are to have a collision bulkhead, astern tube bulkhead and one watertight bulkhead at each endof the engine room. In ships with machinery aft, the sterntube bulkhead may substitute the aft engine room bulkhead.

10.1.1.2 Number and location of transverse bulkheadsfitted in addition to those specified in 10.1.1.1 are to be de-termined as to ensure sufficient transverse strength of thehull.

10.1.1.3 For ships without longitudinal bulkheads in thecargo hold the number of watertight transverse bulkheadsshould, in general, not be less than given in Table 10.1.1.3.

Table 10.1.1.3

L Arrangement of machinery space[m] aft elsewhereL ≤ 65 3 4

65 < L ≤ 85 4 485 < L ≤ 105 4 5

105 < L ≤ 125 5 6125 < L ≤ 145 6 7145 < L ≤ 165 7 8165 < L ≤ 185 8 9

L > 185 to be specially considered

10.1.1.4 One or more of the watertight bulkheads maybe dispensed with where the transverse strength of the ship isadequate.

10.1.1.5 The number of watertight bulkheads of shipsfor which the floatability in the damaged condition is re-quired will be determined on the basis of the damage stabilitycalculation.

10.1.1.6 Each watertight subdivision bulkhead, whethertransverse or longitudinal, shall be constructed having scant-lings and arrangements capable of preventing the passage ofwater in any direction under the head of water likely to occurin intact and damaged conditions. In the damaged condition,the head of water is to be considered in the worst situation atequilibrium, including intermediate stages of flooding.

In all cases, watertight subdivision bulkheadsshall be capable of supporting at least the pressure due to ahead of water up to the bulkhead deck.

10.1.1.7 Steps and recesses in watertight bulkheads shallbe as strong as the bulkhead at the place where each occurs.

10.1.1.8 For openings in watertight subdivision bulk-heads and their closing appliances see the Rules, Part 3 -Hull equipment, Section 7.12.

10.1.1.9 For initial testing of watertight bulkheads seeSection 11.6.

10.1.2 Arrangement of watertight bulkheads

10.1.2.1 Collision bulkhead

10.1.2.1.1 Cargo ships with Lc ≤ 200 m are to have thecollision bulkhead situated not less than 0,05 Lc from theforward perpendicular. Cargo ships with Lc > 200 m are tohave the collision bulkhead fitted at least 10 m from the for-ward perpendicular, see Fig. 10.1.2.1.3.

10.1.2.1.2 All cargo ships are to have the collision bulk-head located not more than 0,08 Lc from the forward perpen-dicular. Greater distances may be approved by the Register inspecial cases.

10.1.2.1.3 In the case of ships having any part of the un-derwater body extending forward of the forward perpen-dicular, e.g. a bulbous bow, the required distances specifiedin 10.1.2.1.1 and 10.1.2.1.2 may be measured from a refer-ence point loacted at a distance x, as shown on Fig.10.1.2.1.3, forward of the forward perpendicular which is tobe the lesser of:

x = a2

x = 0,015 Lc

x =3,0 m

Figure 10.1.2.1.3

where:LC = length of ship according to Regulation 3 of

ICLL, 1966;HC = depth of ship according to Regulation 3 of

ICLL, 1966.

For passenger ships see Section 21.

10.1.2.1.4 The collision bulkhead is to extend watertightup to the freeboard deck. Steps or recesses may be permittedprovided they are within the limit prescribed in 10.1.2.1.1,10.1.2.1.2 and 10.1.2.1.3.

10.1.2.1.5 In ships having continuous or long superstruc-tures, the collision bulkhead is to extend to the first deckabove the freeboard deck. The extension need not be fitteddirectly in line with the bulkhead below, provided the re-quirements of 10.1.2.1.1, 10.1.2.1.2 and 10.1.2.1.3 with theexception as per 10.1.2.1.6 are fulfilled and the scantlings of


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the part of the freeboard deck which forms the step or recessare not less than required for a collision bulkhead. Openingswith weatherthight closing appliances may be fitted abovethe freeboard deck in the collision bulkhead and in theaforementioned step and recess.

The number of openings in the extension of thecollision bulkhead above the freeboard deck shall be re-stricted to the minimum compatible with the design and nor-mal operation of the ship. All such openings shall be capableof being closed weathertight.

10.1.2.1.6 Where bow doors are fitted and a slopingloading ramp forms part of the extension of the collisionbulkhead above the bulkhead/freeboard deck the ramp shallbe weathertight over its complete length. In cargo ships thepart of the ramp which is more than 2.3 m above the bulk-head deck may extend forward of the limit specified in10.1.2.1.1, 10.1.2.1.2 and 10.1.2.1.3. Ramps not meeting theabove requirements shall be disregarded as an extension ofthe collision bulkhead.

10.1.2.1.7 No doors, manholes, access openings, or ven-tilation ducts are permitted in the collision bulkhead belowthe freeboard deck and above the double bottom.

Where on cargo ships pipes are piercing thecollision bulkhead below the freeboard deck, screw downvalves are to be fitted directly at the collision bulkhead.

Where such valves are fitted within the fore-peak they are to be operable from above the freeboard deck.

Where a readily accessible space which is not ahold space is located directly adjacent to the forepeak (e.g. abow-thruster space), the screw down valves may be fittedwithin this space directly at the collision bulkhead and neednot be operable from a remote position.

10.1.2.2 Stern tube bulkheadAll ships are to have a stern tube bulkhead

which is, in general, to be so arranged that the stern tube andthe rudder trunk are enclosed in a watertight compartment.The stern tube bulkhead is to extend to the freeboard deck orto a watertight platform situated above the load waterline.

In cargo ships a stern tube enclosed in a water-tight space of moderate volume, such as an aft peak tank,where the inboard end of the stern tube extends through theaft peak/engine room watertight bulkhead into the engineroom is considered to be an acceptable solution satisfying therequirement of Chapter II-1, Regulation 12.10 of SOLAS1974, as amended, provided the inboard end of the stern tubeis effectively sealed at the aft peak/engine room bulkhead bymeans of an approved watertight/oiltight gland system. Seealso IACS unified interpretation SC93.

10.1.2.3 Remaining watertight bulkheads

10.1.2.3.1 The remaining watertight bulkheads are, ingeneral, depending on the ship type, to extend to the free-board deck. Wherever practicable, they are to be situated inone frame plane, otherwise those portions of decks situatedbetween part of transverse bulkheads are to be watertight.

10.1.2.3.2 Bulkheads shall be fitted separating the ma-chinery space from cargo and passenger spaces forward andaft and made watertight up to the freeboard/bulkhead deck.In passenger ships an afterpeak bulkhead shall also be fittedand made watertight up to the bulkhead deck. The afterpeakbulkhead may, however, be stepped below the bulkheaddeck, provided the degree of safety of the ship as regardssubdivision is not thereby diminished.

10.2 SCANTLINGS

10.2.1 General

10.2.1.1 Where holds are intended to be filled with bal-last water, their bulkheads are to comply with the require-ments of Section 11.

10.2.1.2 Bulkheads of holds intended to be used for car-rying dry cargo in bulk with a density ρc > 1,0 are to complywith the requirements of Section 17, as far as their strength isconcerned.

10.2.1.3 Definitionstk = corrosion addition according to 2.9.1;s = spacing of stiffeners in [m];l = unsupported span, in [m], according

to Section 2.3.1;p = 9,81 ⋅ h [kN/m2];h = distance from the load centre of the

structure to a point 1 m above thebulkhead deck, at the ship's side, forthe collision bulkhead to a point 1 mabove the collision bulkhead at theship's side.

Cp, Cs = coeficients according to Table10.2.1.3;

eHRk 235

= ;

ReH = minimum nominal upper yield point,in [N/mm2], according to 1.4.2.2.

Table 10.2.1.3

Coefficient Cp and CsCollisionbulkhead

Otherbulkheads

Plating Cp 1,1 k 0,9 k

Cs: in case of con-straint of bothends

0,33 k 0,265 k

Cs: in case of sim-ple support ofone end andconstraint at theother end

0,45 ⋅ k 0,36 ⋅ k

Stiffeners andcorrugatedbulkheadelements

Cs: both ends sim-ply supported 0,66 ⋅ k 0,53 ⋅ k

10.2.1.4 Special requirements for bulk carriers are givenin Section 17.

10.2.2 Bulkhead plating

10.2.2.1 The thickness of the bulkhead plating is not tobe less than:

t = Cp ⋅ s p + tk [mm],but not less than:

tmin = 6,0 k [mm]

10.2.2.2 In small ships, the thickness of the bulkheadplating need not exceed the thickness of the shell plating fora frame spacing corresponding to the stiffener spacing.


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10.2.2.3 The stern tube bulkhead is to be provided witha strengthened plate in way of the stern tube.

10.2.3 Stiffeners

10.2.3.1 The section modulus of bulkhead stiffeners isnot to be less than:

W = Cs ⋅ s ⋅ l2 ⋅ p [cm3]

10.2.3.2 In horizontal part of bulkheads, the stiffenersare also to comply with the rules for deck beams according to9.2.1.

10.2.3.3 The scantilings of the brackets are to be deter-mined in dependence of the section modulus of the stiffenersaccording to Section 2.4.2. If the length of the stiffener is 3,5m and over, the brackets are to extend to the next beam or thenext floor.

10.2.3.4 Unbracketed bulkhead stiffeners are to be con-nected to the decks by welding. The length of welds is to beat least 0,6 x depth of the section.

10.2.3.5 Bulkhead stiffeners which cut in way of water-tight doors are to be supported by carlings or stiffeners.

10.2.4 Corrugated bulkheads

10.2.4.1 The plate thickness of corrugated bulkheads isnot to be less than required according to 10.2.2.1. For thespacing s, the greater one of the values b or c, in [m], ac-cording to 10.2.4.3 is to be taken.

10.2.4.2 The section modulus of a corrugated bulkheadelement is to be determined according to 10.2.3.1. For thespacing s, the width of an element a, in [m], according to10.2.4.3 is to be taken.

10.2.4.3 The actual section modulus of a corrugatedbulkhead element is to be assessed according to the followingformula:

W = t ⋅ h ⋅

+

3cb [cm3],

where:a = width of element, in [cm];b = breadth of face plate, in [cm];c = breadth of web plate, in [cm];h = distance between face plates, in [cm];t = plate thickness, in [cm];α ≥ 45o

See Fig. 10.2.4.3

Figure 10.2.4.3

10.2.4.4 Special requirements for bulk carriers are givenin Section 17.

10.3 SHAFT TUNNELS

10.3.1 General

10.3.1.1 Where one or more compartments are situatedbetween stern tube bulkhead and engine room, a watertightshaft tunnels is to be arranged. The size of the shaft tunnels isto be adequate for service and maintenance purposes.

10.3.1.2 The access opening between engine room andshaft tunnel is to be closed by a watertight sliding door. Forextremely short shaft tunnels watertight doors between tunneland engine room may be dispensed with, subject to specialapproval by the Register.

10.3.1.3 Tunnel ventilators and the emergency exit areto be constructed watertight up to the freeboard deck.

10.3.2 Scantlings

10.3.2.1 The plating of the shaft tunnel is to be dimen-sioned as for a bulkhead according to 10.2.2.1.

10.3.2.2 The plating of the round part of tunnel topsmay be 10 per cent less in thickness.

10.3.2.3 The section modulus of shaft tunnel stiffenersis to be determined according to 10.2.3.1.

10.3.2.4 Shaft tunnels in tanks are to comply with therequirements of Section 11.

10.3.2.5 Horizontal parts of the tunnel are to be treatedas horizontal parts of bulkheads and as cargo deck respec-tively.

10.3.2.6 The tunnel is to be suitably strengthened underpillars.


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11 TANK STRUCTURES

11.1 GENERAL

11.1.1 Subdivision of tanks

11.1.1.1 In tanks extending over the full breadth of theship intended to be used for partial filling, at least one longi-tudinal bulkhead is to be fitted, which may be a swash bulk-head.

11.1.1.2 Where the forepeak is intended to be used astank, at least one complete or partial longitudinal swashbulkhead is to be fitted, if the tank breadth exceeds 0,5 B or 6m, whichever is the greater.

When the afterpeak is intended to be used astank, at least one complete or partial longitudinal swashbulkhead is to be fitted. The largest breadth of the liquid sur-face should not exceed 0,3 ⋅ B in the aft peak.

11.1.1.3 Peak tanks exceeding 0,06 L or 6 m in length,whichever is greater, shall be provided with a transverseswash bulkhead.

11.1.2 Air, overflow and sounding pipes

Each tank is to be fitted with air pipes, over-flow pipes and sounding pipes. See also Rules, Part 8 - Pip-ing, Section 5.

11.1.3 Forepeak tank

Oil is not to be carried in a forepeak tank or atank forward of the collision bulkhead.

11.1.4 Separation of oil fuel tanks from tanksfor other liquids

11.1.4.1 Oil fuel tanks are to be separated from tanks forlubricating oil, hydraulic oil, vegetable oil, feedwater, con-densate water and potable water by cofferdams.

11.1.4.2 Fuel oil tanks adjacent to lubricating oil circu-lation tanks are not permitted.

11.1.5 Tanks for heated liquids

11.1.5.1 Where heated liquids are intended to be carriedin tanks, a calculation of thermal stresses is required, if thecarriage temperature of the liquid exceeds the following val-ues:

T = 65 oC in case of longitudinal framing,T = 80 oC in case of transverse framing.

11.1.5.2 The calculations are to be carried out for bothtemperatures, the actual carriage temperature and the limittemperature T according to 11.1.5.

The calculations are to give the resultantstresses in the hull structure based on a sea water temperatureof 0 oC and an air temperature of 5 oC.

Constructional measures and/or strengtheningwill be required on the basis of the results of the calculationfor both temperatures.

11.1.6 Cross references

11.1.6.1 Where a tank bulkhead forms part of a water-tight bulkhead, its strength is not to be less than required bySection 10.

11.1.6.2 For oil fuel tanks, see also Rules, Part 8 - Pip-ing, Section 8. For tanks in the double bottom, see Section7.2.

11.1.6.3 For cargo oil tanks, see Section 18.

11.1.6.4 For dry cargo holds which are also intended tobe used as ballast water tanks, see 11.3.2.

11.1.6.5 For testing of tanks, see 11.6.

11.1.6.6 For corrosion protection and catodic protectionsee Rules, Part 1 - General requirements, Chapter 5 and Part24 - Non- metallic materials, Section 4.


11.1.7.1 The thickness of all structures in tanks is not tobe less than the following minimum value:

tmin = 5,5 + 0,02 ⋅ L [mm]

11.1.7.2 For fuel oil, lubrication oil and freshwater tankstmin need not be taken greater than 7,5 mm.

11.1.7.3 For ballast tanks of dry cargo ships tmin neednot be taken greater than 9,0 mm.

11.1.7.4 For oil tanker, see Section 18.1.8.

11.2 SCANTLINGS

11.2.1 Definitions

k = material factor according to 1.4.2.2;s = spacing of stiffeners or load width, in

[m];l = unsupported span, in [m], according

to Section 2.3.1;p = load p1 or pd, in [kN/m2], according to

Section 3.4 (the greater load to betaken);

p2 = load, in [kN/m2], according to 3.4;tk = corrosion addition, in [mm], accord-

ing to 2.9.1;h = filling height of tank, in [m];lt = tank length, in [m];bt = tank breadth, in [m];

σa = 235

32

2k L

− ⋅τ - 0,89 ⋅ σL [N/mm2]

σL,τL = design hull girder bending or shearstress respectively, in [N/mm2],within the plate field considered asdefined in Section 4.5.3;

C = 1,0, for transverse stiffening;C = 0,83, for longitudinal stiffening.

11.2.2 Plating

11.2.2.1 The plate thickness is not to be less than:


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t1 = 1,1 ⋅ s ⋅ p k⋅ + tk [mm],

t2 = 0,9 ⋅ s ⋅ p k2 ⋅ + tk [mm],

11.2.2.2 The thickness of tank boundaries (includingdeck and inner bottom) carrying also normal and shearstresses due to longitudinal hull girder bending is not to beless than:

t = 16,8 ⋅ C ⋅ s p

aσ+ tk [mm]

11.2.2.3 The buckling strength of longitudinal andtransverse bulkheads exposed to compressive stresses is to becarried out according to Section 4.6. for longitudinal bulk-heads the design stresses according to 4.5.3 and the stressesdue to local are to be considered.

11.2.3 Stiffeners and girders

11.2.3.1 Stiffeners and girders, which are not consid-ered as longitudinal strength members

11.2.3.1.1 The section modulus of stiffeners and girdersconstrained at their ends, which are not considered as longi-tudinal strength members, is not to be less than:

W1 = 0,55 ⋅ s ⋅ l2 ⋅ p ⋅ k [cm3]

W2 = 0,44 ⋅ s ⋅ l2 ⋅ p2 ⋅ k [cm3]

Where one or both ends are simply supported,the section moduli are to be increased by 50 per cent.

The cross sectional area of the girder webs isnot to be less than:

Aw1 = 0,05 ⋅ s ⋅ l ⋅ p ⋅ k [cm2]

Aw2 = 0,04 ⋅ s ⋅ l ⋅ p2 ⋅ k [cm2]

Aw2 is to be increased by 50 per cent at the po-sition of constraint for a length of 0,1 ⋅ l.

The buckling strength of the webs is to be ex-amined according to Section 4.6.

11.2.3.1.2 Where the scantlings of stiffeners and girders,which are not considered as longitudinal strength members,the following permissible stress values apply:

- if subjected to load p:σb = 150/k [N/mm2]τ = 100/k [N/mm2]

σekv = σ τb2 23+ = 180/k [N/mm2]

- if subjected to load p2:σb = 180/k [N/mm2]τ = 120/k [N/mm2]

σekv = σ τb2 23+ = 200/k [N/mm2]

11.2.3.2 Stiffeners and girders, which are to be con-sidered as longitudinal strength members

11.2.3.2.1 The section moduli and shear areas of horizon-tal stiffeners and griders, which are to be considered as lon-

gitudinal strength members, are to be determined accordingto 8.2.3 as for longitudinals. In this case for girders support-ing transverse stiffeners the factors m = 1 and m2 = 0 are tobe used.

11.2.3.2.2 The scantlings of beams and girders of tankdecks are also to comply with the requirements of Section 9.

11.2.3.2.3 For frames in tanks, see 8.1.2.2.

11.2.3.2.4 The stiffeners of tank bulkheads are to be at-tached at their ends by brackets according to Section 2.4.2.The scantlings of the brackets are to be determined accordingto the section modulus of the stiffeners. Brackets must befitted where the length of the stiffeners exceeds 2 m.

The brackets of stiffeners are to extend to the next beam, thenext floor, the next frame, or are to be otherwise supported attheir ends.

11.2.3.2.5 Regarding buckling strength of girders the re-quirements of 11.2.2.3 are to be observed.

11.2.3.2.5 Where stringers of transverse bulkheads aresupported at longitudinal bulkheads or at the side shell, thesupporting forces of these stringers are to be consideredwhen determining the shear stress in the longitudinal bulk-heads. Likewise, where vertical girders of transverse bulk-heads are supported at deck or inner bottom, the supportingforces of these vertical girders are to be considered whendetermining the shear stresses in the deck or inner bottom re-spectively.

The shear stress introduced by the stringer intothe longitudinal bulkhed or side shell may be determined bythe following formula:

tbP

St

StSt ⋅⋅

=2

τ [N/mm2]

where:PSt = supporting force of stringer or vertical

girder, in [kN];bSt = breadth of stringer or depth of vertical

girder including end bracket (if any) atthe supporting point, in [m;

t = see 11.2.2.1.The additional shear stress σSt is to be added to

the shear stress τL due to longitudinal bending according toSection 4.5.3 in the following area:

– 0,5 m on both sides of the stringer in theship's longitudinal direction

– 0,25 ⋅ bSt above and below the stringerThereby the following requirement shall be

satisfied:

LSt

StSt tb

Pk

ττ +⋅⋅

=≥2

110

11.2.4 Corrugated bulkheads

11.2.4.1 The plate thicknesses of corrugated bulkheadsas well as the required section moduli of corrugated bulkheadelements are to be determined according to 11.2.2 and 11.2.3,proceeding analogously to Section 10.2.4.

The minimum plate thickness is to be in accor-dance with 11.1.7 or as follows:

- if subjected to load p1:


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tmin = b

D905σ + tk [mm];

- if subjected to load p2:

tmin = b

D960σ + tk [mm];

where:σD = compressive stress, [N/mm2];b = breadth of face plate strip, in [mm],

see Fig. 10.2.4.3.

11.2.4.2 For the end attachment Section 2.4 is to be ob-served.

11.3 TANKS WITH LARGE LENGTHSOR BREADTHS

11.3.1 General

Tanks with lengths lt > 0,1 ⋅ L or breadths bt >0,6 ⋅ B (e.g. hold spaces for ballast water) which are intendedto be partially filled, are to be investigated to avoid reso-nance between the liquid motion and motion of the ship.

If necessary, critical tank filling ratios are to beavoided. The ship's periods of pitch and roll motion as wellas the natural periods of the liquid in the tank may be deter-mined by the following formulae:

- natural period of liquid in tank:

Tl,b = 1,132 eft [s],

where:f = tanh (π ⋅ h/et) hyperbolic function;

- period of pitch motion

Ts = 1,8 Lg

[s];

- period of roll motion

Tr =C B

GMr ⋅

[s],

where:Cr = 0,78 in general;Cr = 0,70 for tankers in ballast;GM ≈ 0,07 ⋅ B in general;GM ≈ 0,12 ⋅ B for tankers and bulk carriers;et = characteristic tank dimension lt or bt,

in [m].

11.3.2 Hold spaces for ballast water

In addition to the requirements specified under11.3.1 for hold spaces of dry cargo ships and bulk carriers,which are intended to be filled with ballast water, the fol-lowing is to be observed:

- Adequate venting of the hold spaces and of thehatchway trunks is to be provided.

- For frames also Section 8.1.2.2 is to be ob-served.

- For hold spaces only permitted to be com-pletely filled, a relevant notice will be enteredinto the Certificate.

11.4 DETACHED TANKS

11.4.1 General

11.4.1.1 Detached tanks are to be adequately securedagainst forces due to the ship's motions.

11.4.1.2 Detached oil fuel tanks are not to be installed incargo holds. Where such an arrangement cannot be avoided,provision is to be made to ensure that the cargo cannot bedamaged by leakage oil.

11.4.1.3 Fittings and pipings on detached tanks are to beprotected by battens, and gutterways are to be fitted on theoutside of tanks for draining any leakage oil.

11.4.2 Scantlings

11.4.2.1 The thickness of plating of detached tanks is tobe determined according to 11.2.2.1 using the formula for t1and the pressure p as defined in 11.4.2.2.

11.4.2.2 The section modulus of stiffeners of detachedtanks is not to be less than:

W = C1 ⋅ s ⋅ l2 ⋅ p ⋅ k [cm3],where:

C1 = 0,36 if stiffeners are constrained atboth ends;

C1 = 0,54 if one or both ends are simplysupported;

p = 9,81 ⋅h [kN/m2];h = head measured from the load centre

of plate panel or stiffener respectivelyto the top of overflow; the height ofoverflow is not to be taken less than2,5 m.

11.4.2.3 For minimum thickness the requirements of11.1.7 apply in general.

11.5 SWASH BULKHEADS

11.5.1 The total area of performation is not to be lessthan 5% and are not to exceed 10% of the total bulkheadarea.

11.5.2 The plate thickness is, in general, to be equal tothe minimum thickness according to 11.1.7. Strengtheningsmay be required for load bearing structural parts.

The free lower edge of a wash bulkhead is to beadequately stiffened.

11.5.3 The section modulus of the stiffeners and gird-ers is not to be less than W1 as per 11.2.3.1, however, theload pd according to 3.4.2 is to be taken in lieu of p.

11.5.4 For swash bulkheads in oil tankers see alsoSection 18.4.


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11.6 PROCEDURES FOR TESTINGTANKS AND TIGHT BOUNDARIES

11.6.1 General

11.6.1.1 These test procedures are to confirm the water-tightness of tanks and watertight boundaries, the structuraladequacy of tanks and weathertightness of struc-tures/shipboard outfitting. The tightness of tanks and tightboundaries of:

- New ships prior to delivery, and

- Structures involved in, or affected by,major conversions or repairs1) is to beconfirmed by these test procedures.

11.6.2 Application

11.6.2.1 All gravity tanks2) and other boundaries re-quired to be watertight or weathertight are to be tested in ac-cordance with this Procedure and proven tight and structur-ally adequate as follows:

- gravity tanks for their tightness andstructural adequacy,

- watertight boundaries other than tankboundaries for their watertightness, and

- weathertight boundaries for their weath-ertightness.

11.6.2.2 The testing of the cargo containment systems ofliquefied gas carriers is to be in accordance with standardsdeemed appropriate by the Register.

11.6.2.3 Testing of structures not listed in Table 11.6.1or 11.6.2 is to be specially considered.

11.6.3 Types of tests and definition of test

11.6.3.1 The following two types of test are specified inthis requirement:

Structural test: A test to verify the structural adequacy ofthe construction of the tanks. This may be ahydrostatic test or, where the situation war-rants, a hydropneumatic test.

Leak test: A test to verify the tightness of the boundary.Unless a specific test is indicated, this maybe a hydrostatic/hydropneumatic test or airtest. Leak test with remark *3 in Table11.6.1 includes hose test as an acceptablemedium of the test.

Definition of each type of test is as follows:

1) Major repair means a repair affecting structural integrity2) Gravity tank means a tank that is subject to vapour pressure

nor greater than 70 kPa

Hydrostatic Test:(Leak and Structural)

A test by filling the space with aliquid to a specified head.

Hydropneumatic Test:(Leak and Structural)

A test wherein the space is par-tially filled with liquid and airpressure applied on top of the liq-uid surface.

Hose Test:(Leak)

A test to verify the tightness ofthe joint by a jet of water.

Air Tests:(Leak)

A test to verify the tightness bymeans of air pressure differentialand leak detection solution. It in-cludes tank air tests and joint airtests, such as a compressed airtest and vacuum box test.

Compressed Air FilletWeld Test:(Leak)

An air test of a fillet welded teejoint with a leak indicating solu-tion applied on the fillet welds.

Vacuum Box Test:(Leak)

A box over a joint with leak indi-cating solution applied on the fil-let or butt welds. A vacuum iscreated inside the box to detectany leaks.

Ultrasonic Test:(Leak)

A test to verify the tightness of asealing by means of ultrasound.

Penetration Test:(Leak)

A test to verify that no continuousleakages exist in the boundariesof a compartment by the applica-tion of low surface tension liq-uids.

11.6.4 Test procedures

11.6.4.1 General

Tests are to be carried out in the presence of theSurveyor at a stage sufficiently close to the completion of thework with all hatches, doors, windows, etc., installed and allpenetrations including pipe connections fitted, and beforeany ceiling and cement work is applied over the joints. Spe-cific test requirements are given in 11.6.4.4 and Table 11.6.1.For the timing of application of coating and the provision ofsafe access to joints, see 11.6.4.5, 11.6.4.6 and Table 11.6.3.

11.6.4.2 Structural test procedures

11.6.4.2.1 Type and time of test

Where a structural test is specified in Table11.6.1 or Table 11.6.2, a hydrostatic test in accordance with11.6.4.4.1 will be acceptable. Where practical limitations(strength of building berth, density of liquid, etc.) prevent theperformance of a hydrostatic test, a hydropneumatic test inaccordance with 11.6.4.4.2 may be accepted as an equivalentmethod.

Provided the results of a leak test are confirmedsatisfactory, a hydrostatic test for confirmation of structuraladequacy may be carried out while the vessel is afloat.

11.6.4.2.2 Number of structural tests

.1 A structural test is to be carried out for at leastone tank of the same construction (i.e. tanksof the same structural design and configura-


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tion and same general workmanship as de-termined by the attending Surveyor) on eachvessel provided all subsequent tanks aretested for leaks by an air test.However, where structural adequacy of atank was verified by structural testing re-quired in Table 11.6.1, the subsequent vesselsin the series (i.e. sister ships built in the sameshipyard) may be exempted from such testingfor other tanks which have the structuralsimilarity to the tested tank, provided that thewater-tightness in all boundaries of exemptedtanks are verified by leak tests and thoroughinspection. For sister ships built several yearsafter the last ship of the series, such exemp-tion may be reconsidered. In any case, struc-tural testing is to be carried out for at leastone tank for each vessel in order to verifystructural fabrication adequacy.

.2 For watertight boundaries of spaces other thantanks (excluding chain lockers), structuraltesting may be exempted, provided that thewatertightness in all boundaries of exemptedspaces are verified by leak tests and thoroughinspection.

.3 These subsequent tanks may require structuraltesting if found necessary after the structuraltesting of the first tank.

.4 Tanks for structural test are to be selected sothat all representative structural members aretested for the expected tension and compres-sion.

11.6.4.3 Leak test procedures

For the leak test specified in Table 11.6.1, atank air test, compressed air fillet weld test, vacuum box testin accordance with 11.6.4.4.3 to 11.6.4.4.6, or their combi-nation will be acceptable. A hydrostatic or hydropneumatictest may also be accepted as the leak test provided 11.6.4.5and 11.6.4.6 are complied with. A hose test will also be ac-ceptable for the locations as specified in Table 11.6.1 withnote 3.

A joint air test may be carried out in the blockstage provided all work on the block that may affect thetightness of the joint is completed before the test. See also11.6.4.5.1 for the application of final coating and 11.6.4.6 forsafe access to the joint and their summary in Table 11.6.3.

11.6.4.4 Details of tests

11.6.4.4.1 Hydrostatic Test

Unless other liquid is approved, the hydrostatictest is to consist of filling the space by fresh water or seawater, whichever is appropriate for testing of the space, tothe level specified in Table 11.6.1 or Table 11.6.2.

In case a tank for cargoes with higher density isto be tested with fresh water or sea water, the testing pressureheight is to be specially considered.

11.6.4.4.2 Hydropneumatic test

A hydropneumatic test where approved is to besuch that the test condition in conjunction with the approvedliquid level and air pressure will simulate the actual loadingas far as practicable. The requirements and recommendations

for tank air tests in 11.6.4.4.4 will also apply to the hydro-pneumatic test.

11.6.4.4.3 Hose test

A hose test is to be carried out with the pres-sure in the hose nozzle maintained at least at 2·105 Pa duringthe test. The nozzle is to have a minimum inside diameter of12 mm and be at a distance to the joint not exceeding 1,5 m.

Where a hose test is not practical because ofpossible damage to machinery, electrical equipment insula-tion or outfitting items, it may be replaced by a careful visualexamination of welded connections, supported where neces-sary by means such as a dye penetrant test or ultrasonic leaktest or an equivalent.

11.6.4.4.4 Tank air test

All boundary welds, erection joints and pene-trations including pipe connections are to be examined in ac-cordance with the approved procedure and under a pressuredifferential above atmospheric pressure not less than 0.15·105

Pa with a leak indication solution applied.

It is recommended that the air pressure in thetank be raised to and maintained at about 0.20·105 Pa for ap-proximately one hour, with a minimum number of personnelaround the tank, before being lowered to the test pressure of0.15·105 Pa.

A U-tube with a height sufficient to hold a headof water corresponding to the required test pressure is to bearranged. The cross sectional area of the U-tube is not to beless than that of the pipe supplying air to the tank. In additionto U-tube, a master gauge or other approved means to verifythe pressure is to be approved.

11.6.4.4.5 Compressed air fillet weld test

In this air test, compressed air is injected fromone end of a fillet welded joint and the pressure verified atthe other end of the joint by a pressure gauge on the oppositeside. Pressure gauges are to be arranged so that an air pres-sure of at least 0.15·105 Pa can be verified at each end of allpassages within the portion being tested.

Note: Where a leak test of partial penetration welding is re-quired and the root face is sufficiently large (i.e.,6-8mm), thecompressed air test is to be applied in the same manneras for a fillet weld.

11.6.4.4.6 Vacuum box test

A box (vacuum tester) with air connections,gauges and inspection window is placed over the joint withleak indicator applied. The air within the box is removed byan ejector to create a vacuum of 0.20·105 – 0.26·105 Pa insidethe box.

11.6.4.4.7 Ultrasonic test

An arrangement of an ultrasonic echoes trans-mitter placed inside of a compartment and a receiver outside.A location where the sound is detectable by the receiver dis-plays a leakage in the sealing of the compartment.

11.6.4.4.8 Penetration test

A test of butt welds by applying a low surfacetension liquid to one side of a compartment boundary. Whenno liquid is detected on the opposite side of the boundary af-


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ter expiration of a definite time, the verification of tightnessof the compartments boundary can be assumed.

11.6.4.4.9 Other test

Other methods of testing may be considered byeach society upon submission of full particulars prior tocommencement of the testing.

11.6.4.5 Application of coating

11.6.4.5.1 Final coating

For butt joints by automatic process, finalcoating may be applied anytime before completion of theleak test of the space bounded by the joint.

For all other joints, final coating is to be ap-plied after the completion of the leak test of the joint. Seealso Table 11.6.3.

The Surveyor reserves the right to require aleak test prior to the application of the final coating overautomatic erection butt welds.

11.6.4.5.2 Temporary coating

Any temporary coating which may conceal de-fects or leaks is to be applied at a time as specified for finalcoating. This requirement does not apply to shop primer.

11.6.4.6 Safe access to joints

For leak tests, a safe access to all joints underexamination is to be provided. See also Table 11.6.3.

11.7 CONSTRUCTION AND INITIALTESTS OF WATERTIGHT DECKS,

TRUNCKS, ETC.

11.7.1 Watertight decks, trunks, tunnels, duct keelsand ventilators shall be of the same strength as watertightbulkheads at corresponding levels. The means used for mak-ing them watertight, and the arrangements adopted for clos-ing openings in them, shall be to the satisfaction of the Reg-ister. Watertight ventilators and trunks shall be carried atleast up to the bulkhead deck in passenger ships and up to thefreeboard deck in cargo ships.

11.7.2 Where a ventilation trunk passing through astructure penetrates the bulkhead deck, the trunk shall be ca-pable of withstanding the water pressure that may be presentwithin the trunk, after having taken into account the maxi-mum heel angle allowable during intermediate stages offlooding, in accordance with requirements of the Rules, Part5 – Subdivision, 2.7.

11.7.3 Where all or part of the penetration of thebulkhead deck is on the main ro-ro deck, the trunk shall becapable of withstanding impact pressure due to internal watermotions (sloshing) of water trapped on the ro-ro deck.

11.7.4 After completion, a hose or flooding test shallbe applied to watertight decks and a hose test to watertighttrunks, tunnels and ventilators.


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Table 11.6.1 Test requirements for tanks and boundaries

Tank or boundary to be tested Test type Test head or pressure Remarks

1 Double bottom tanks*4 Leak &Structural*1

The greater of- top of the overflow,- to 2,4m above top of tank *2, or- to bulkhead deck

2 Double bottom voids*5 Leak See 11.6.4.4.4 through 11.6.4.4.6, asapplicable

3 Double side tanks Leak &Structural*1

The greater of- top of the overflow,- to 2,4m above top of tank *2, or- to bulkhead deck

4 Double side voids Leak See 11.6.4.4.4 through 11.6.4.4.6, asapplicable

5 Deep tanks other than those listedelsewhere in this table

Leak &Structural*1

The greater of- top of the overflow, or- to 2,4m above top of tank *2

6 Cargo oil tanks Leak &Structural*1

The greater of- top of the overflow,- to 2,4m above top of tank *2, or- to top of tank *2 plus setting of anypressure relief valve

7 Ballast hold of bulk carriers Leak &Structural*1

The greater of- top of the overflow, or- top of cargo hatch coaming

8 Peak tanks Leak &Structural*1

The greater of- top of the overflow, or- to 2.4m above top of tank *2

After peak to be testedafter installation of sterntube

a. Fore peak voids Leak See 11.6.4.4.4 through 11.6.4.4.6, asapplicable

9b. Aft peak voids Leak See 11.6.4.4.4 through 11.6.4.4.6, as

applicable

After peak to be testedafter installation of sterntube

10 Cofferdams Leak See 11.6.4.4.4 through 11.6.4.4.6, asapplicable

a. Watertight bulkheads Leak See 11.6.4.4.3 through 11.6.4.4.6, asapplicable*711

b. Superstructure end bulkhead Leak See 11.6.4.4.3 through 11.6.4.4.6, asapplicable

12 Watertight doors below freeboardor bulkhead deck Leak *6, 8 See 11.6.4.4.3 through 11.6.4.4.6, as

applicable

13 Double plate rudder blade Leak See 11.6.4.4.4 through 11.6.4.4.6, asapplicable

14 Shaft tunnel clear of deep tanks Leak *3 See 11.6.4.4.3 through 11.6.4.4.6, asapplicable

15 Shell doors Leak *3 See 11.6.4.4.3 through 11.6.4.4.6, asapplicable

16 Weathertight hatch covers andclosing appliances Leak *3, 8 See 11.6.4.4.3 through 11.6.4.4.6, as

applicable

Hatch covers closed bytarpaulins and battens ex-cluded

17 Dual purpose tank/dry cargohatch cover Leak *3, 8 See 11.6.4.4.3 through 11.6.4.4.6, as

applicableIn addition to structuraltest in item 6 or 7

18 Chain locker Leak &Structural Top of chain pipe

19 Independent tanks Leak &Structural*1

The greater of- top of the overflow, or- to 0.9m above top of tank

20 Ballast ducts Leak &Structural*1

The greater of- ballast pump maximum pressure,or- setting of any pressure relief valve


2013

Notes:

*1 Structural test is to be carried out for at least one tank of the same construction (i.e., same design and same workman-ship) on each vessel provided all subsequent tanks are tested for leaks by an air test. However, where structural adequacy of a tankwas verified by structural testing, the subsequent vessels in the series (i.e., sister ships built in the same shipyard) may be exemptedfrom such testing for other tanks which have the structural similarity to the tested tank, provided that the water-tightness in allboundaries of exempted tanks are verified by leak tests and thorough inspection is carried out. In any case, structural testing is to becarried out for at least one tank for each vessel in order to verify structural fabrication adequacy. (See 11.6.4.2.2(1))

*2 Top of tank is deck forming the top of the tank excluding any hatchways.

*3 Hose Test may also be considered as a medium of the test. See 11.6.3.2.

*4 Including tanks arranged in accordance with the provisions of SOLAS regulation II-1/9.4

*5 Including duct keels and dry compartments arranged in accordance with the provisions of SOLAS regulation II-1/9.4

*6 Where water tightness of watertight door has not been confirmed by prototype test, testing by filling watertight spaces withwater is to be carried out. See SOLAS regulation II-1/16.2 and MSC/Circ.1176.

*7 Where a hose test is not practicable, other testing methods listed in 11.6.4.4.7 through 11.6.4.4.9 may be applicable subject toadequacy of such testing methods being verified. See SOLAS regulation II-1/11.1.

*8 As an alternative to the hose testing, other testing methods listed in 11.6.4.4.7 through 11.6.4.4.9 may be applicable subject tothe adequacy of such testing methods being verified. See SOLAS regulation II-1/11.1.

Table 11.6.2 Additional test requirements for special service ships/tanks

Type ofship/tank Structures to be tested Type of test Test head or pressure Remarks

1 Liquefied gas car-rier

Cargo containment sys-tems (See remarks) See 11.6.4.4.1 See 11.6.4.4.1

See also Table11.6.1 for othertanks and bounda-ries

2 Edible liquidtanks Independent tanks Leak & Struc-

tural

The greater of- top of the overflow, or- to 0.9m above top of tank *1

3 Chemical carrier Integral or independentcargo tanks

Leak & Struc-tural

The greater of- to 2.4m above top of tank *1, or- to top of tank *1 plus setting ofany pressure relief valve

Note:

*1 Top of tank is deck forming the top of the tank excluding any hatchways.

Table 11.6.3 Application of leak test, coating and provision of safe access for type of welded joints

Coating *1 Safe Access *2

Type of welded joints Leak test Before leaktest

After leak test & be-fore structural test Leak test Structural test

Automatic Not required Allowed N/A Not required Not requiredButt Manual or

Semi-automatic Required Not allowed Allowed Required Not required

FilletBoundary in-cluding penetra-tions

Required Not allowed Allowed Required Not required

Notes:

*1 Coating refers to internal (tank/hold coating), where applied, and external (shell/deck) painting. It does not refer to shopprimer.

*2 Temporary means of access for verification of the leak test.


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12 STEM AND STERNFRAME

12.1 DEFINITIONS

12.1.1 Definitions stated in this section are as follows:

pe = design pressure, in [kN/m2], accord-ing to 3.2.2.2;

ReH = minimum nominal upper yield point,in [N/mm2], according to 1.4.2.1;

k = material factor according to 1.4.2.2,for cast steel, see Rules, Part 25 -Metallic materials, 3.12;

CR = rudder force, in [N], according toRules, Part 3 - Hull equipment, 2.3;

B1 = support force, in [N], according toRules, Part 3 - Hull equipment, 2.4;

tk = corrosion addition according to 2.9.1.

12.2 STEM

12.2.1 Bar stem

12.2.1.1 The cross sectional area of a bar stem below theload waterline is not to be less than:

As = 1,25 L [cm2]

12.2.1.2 Starting from the load waterline, the sectionalarea of the bar stem may be reduced towards the upper end to0,75 As.

12.2.2 Plate stem

12.2.2.1 The thickness of welded plate stem is not to beless than:

t = (0,08 L + 6) k [mm]

tmax = 25 k [mm]

12.2.2.2 Starting from 600 mm above the load water-line, the thickness may gradually be reduced to 0,8 t.

12.2.2.3 Plate stems and bulbous bows are to have dia-phragm plates spaced not more than 1 m apart.

12.2.2.4 Where the spacing of the diaphragm plates isreduced to 0,5 m the thickness of the plate stem may be re-duced by 20 per cent.

12.2.2.5 The plate thickness of a bulbous bow shall ingeneral not be less than required according to 12.2.2.1.

12.2.2.6 The scantlings of plates and stiffeners of thestem 0,1 L aft of the forward perpendicular and above thedeepest load waterline are to comply with the following cri-teria:

a) plate thickness:

t = 1,26 ⋅ s ⋅ pe + tk [mm]

b) stiffeners:- bending stress:

σb ≤ 0,7 ⋅ ReH

- shear stress:

τ ≤ 0,4 ⋅ ReH


σekv = σ τ2 23+ ≤ 0,75 ⋅ ReH

12.3 STERNFRAME

12.3.1 General

12.3.1.1 Propeller post and rudder post are to be led intothe hull in their upper parts and connected to it in a suitableand efficient manner. In way of the rudder post the shell is tobe strengthened according to 5.4.3. Due regard is to be paidto the design of the aft body, rudder and propeller well in or-der to minimize the forces excited by the propeller.

12.3.1.2 The following value is recommended for thepropeller clearance from shell (sternframe) related to 0,9 R(see Fig. 12.3.1.2-1):

[ ]d n d

Zx

p

B

F0 9

30 0041 0 75 0 5

, ,( , ) ,

≥ ⋅ ⋅ ⋅

− +

ν γsin

∆ [m],

where:R = propeller radius, in [m];v = ship's speed, in [kn];n = number of propeller revolutions

[min-1];∆ = maximum displacement of ship, in

[t];dp = propeller diameter in [m];γ = skew angle of the propeller, in [o],

see Fig. 12.3.1.2-2;ZB = height of wheelhouse deck above

weather deck, in [m], see Fig.12.3.1.2-1;

XF = distance of deckhouse front bulkheadfrom aft edge of stern, in [m], see Fig.12.3.1.2-1.

Figure 12.3.1.2-1


2013

Figure 12.3.1.2-2

12.3.1.3 For single screw ships, the lower part of thesternframe is to be extended forward by at least 3 times theframe spacing from fore edge of the boss, for all other shipsby 2 times the frame spacing from after edge of the stern-frame (rudder post).

12.3.1.4 The stern tube is to be surrounded by the floorplates and connected with welding.

12.3.1.5 The plate thickness of sterns of welded con-struction for twin screw vessels is not to be less than:

t = (0,07 L + 5,0) ⋅ k [mm]

tmax = 22,0 k [mm]

12.3.2 Propeller post

12.3.2.1 The scantlings of rectangular, solid propellerposts are to be determined according to the following for-mulae:

l = 1,4 L + 90 [mm]

b = 1,6 L + 15 [mm]

Where other sections than rectangular ones areused, their section modulus is not to be less than that result-ing from rectangular section.

12.3.2.2 The scantlings of propeller posts of weldedconstruction are to be determined according to the followingformulae:

l = 50 L [mm]

b = 36 L [mm]

t = 2,4 ⋅ L k⋅ [mm]

for l, b and t see Fig. 12.3.2.2.

Figure 12.3.2.2

12.3.2.3 Where the cross sectional configuration is de-viating from Fig. 12.3.2.2 and for cast steel propeller poststhe section modulus of the cross section related to the longi-tudinal axis is not to be less than:

Wx = 1,2 ⋅ L1,5 ⋅ k [cm3]

12.3.2.4 The wall thickness of the boss in the propellerpost in its finished condition is to be not less:

tsc = 0,1 dv + 56 [mm],

tscmin = 0,6 ⋅ b [mm]

where:dv = diameter of tail propeller shaft (see

Fig. 12.3.2.4);

Figure 12.3.2.4All welded connections between sternframe

and propeller post are to be full penetrated.

12.3.3 Rudder post

12.3.3.1 The section modulus of the rudder post relatedto longitudinal axis of the ship is not to be less than:

W = CR ⋅ l ⋅ k ⋅ 10-3 [cm3],

where:l = unsupported span of the rudder post,

in [m].Strenght calculations for the rudder post, taking

into account the flexibility of the sole piece, may be required,by the Register, due to its low rigidity in y-direction.

The bending stress is not to exceed:

σb = 85 [N/mm2]


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12.3.4 Sole piece

12.3.4.1 The section modulus of the sole piece related tothe z-axis is not to be less than:

WZ = B x k1

80⋅ ⋅

[cm3]

where:B1 = according to 12.1.1.For rudders with two supports the support force

is approximately B1 = CR/2, when the elasticity of the solepiece is ignored.

x = distance of the respective cross sec-tion from the rudder axis, in [m];

xmin = 0,5 ⋅ l50;xmax = l50.For x and l50 see Fig. 12.3.4.1.

Figure 12.3.4.1

12.3.4.2 The section modulus Wz may be reduced by 15per cent where a rudder post according to 12.3.3.1 is fitted.

12.3.4.3 The seciton modulus related to the y-axis is notto be less than:

- where no rudder post or rudder axle isfitted:

Wy = Wz2

[cm3]

- where a rudder post or rudder axle is fit-ted:

Wy = Wz3

[cm3]

12.3.4.4 The sectional area at the location X = l50 is notto be less than:

Ax = B148

⋅ k [mm2]

12.3.4.5 The equivalent stress at any loaction within thelength l50 is not to exceed:

σekv = σ τb2 23+ = 115/k [N/mm2]

σb = B xWz

1 ⋅[N/mm2]

τ = BAx

1 [N/mm2]

12.3.4.6 These requirements do not apply to CSR BulkCarriers.

12.3.5 Rudder horn of semi spade rudders

12.3.5.1 The distribution of the bending moment, shearforce and torsional moment is to be determined according tothe following formulae:

- bending moment:

Mb = B1 ⋅ z [Nm]

Mbmax = B1 ⋅ a [Nm]

- shear force:

F =B1 [N]

- torsional moment:

MT = B1 ⋅ e(z) [Nm]

For determining preliminary scantlings theflexibility of the rudder horn may be ignored and the sup-porting force B1 (force at lower bearing) be calculated ac-cording to the following formula:

B1 = CR bc

For b, c, a, e(z) and z see Fig. 12.3.5.1-1 and 12.3.5.1-2.

Figure 12.3.5.1-1

Figure 12.3.5.1-2

12.3.5.2 The section modulus of the rudder horn intransverse direction related to the horizontal x-axis is at anylocation z not to be less than:

Wx = M kb ⋅

67[cm3]

12.3.5.3 At no cross section of the rudder horn the shearstress due to the shear force F is to exceed the value:


2013

τ = 48k

[N/mm2]

The shear stress is to be determined by the fol-lowing formula:

τ = BAh

1 [N/mm2]

where:Ah = effective shear area of the rudder

horn in y-direction, in [mm2].

12.3.5.4 The equivalent stress at any location (z) of therudder horn is not to exceed following value:

σekv = σ τ τb T2 2 23+ +

= 120/k [N/mm2]

where:

σb = MW

b

x [N/mm2];

τTT

T h

M

A t=

⋅

⋅ ⋅

10

2

3[N/mm2];

AT = area of the horizontal section of therudder horn at the examined location,in [mm2];

th = rudder horn plating thickness, [mm].

12.3.5.5 When determining the thickness of the rudderhorn plating the provisions of 12.3.5.2, 12.3.5.3 and 12.3.5.4are to be complied with. The thickness is, however, not to beless than:

tmin = 2,4 ⋅ L k⋅ [mm]

12.3.5.6 The rudder horn plating is to be effectivelyconnected to the aft ship structure, e.g. by connecting theplating to longitudinal girders, according to Fig. 12.3.5.6, inorder to achieve a proper transmission of forces.

Figure 12.3.5.6

12.3.5.7 Transverse webs of the rudder horn are to beled into the hull up to the next deck in a sufficient numberand shall be of adequate thickness. The shear stress is to bedetermined by the following

Strengthened plate floors are to be fitted in linewith the transverse webs in order to achieve a sufficient con-nection with the hull. The thickness of these plate floors is tobe increased by 50 per cent above the Rule values as requiredby Section 7.

12.3.5.8 The centre line bulkhead (wash-plate) in theafterpeak is to be connected to the rudder horn.

12.3.5.9 Where the transition between rudder horn andshell is curved, about 50% of the required total sectionmodulus of the rudder horn is to be formed by the webs in aSection A-A located in the centre of the transition zone, i.e.0,7 ⋅ r above the beginning of the transition zone accordingto Fig. 12.3.5.9.

Figure 12.3.5.9

12.3.5.10 These requirements do not apply to CSR BulkCarriers.

12.4 PROPPELER SHAFT BRACKETS

12.4.1 The strut axes are to be intersect in the axis ofthe propeller shaft as far as practicable. The struts are to beextended through the shell plating and are to be attached inan efficient manner to the frames and plate floors respecit-vely. The construction in way of the shell is to be carried outwith special care.

In case of welded connection, the struts are tohave a weld flange or a thickened part or are to be connectedwith the shell plating in another suitable manner. For stren-ghthening of the shell in way of struts and shaft bossings, seeSection 5.4.4

The requirements of Section 15.2.4.3 are to beobserved.

12.4.2 The scantilings of solid struts are to be deter-mined as outlined below depending on shaft diameter d:

- thickness 0,44 d- cross-sectional area 0,44 d2

- length of boss see Rules, Part 7 - Machineryinstallation, Section 2.6

- wall thickness of boss 0,25 d.

12.4.3 Propeller brackets of welded construction andshaft bossings are to have the same strength as solid ones ac-cording 12.4.2.


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12.5 BOW AND STERN THRUST UNITSTRUCTURE

12.5.1 Unit wall structure

12.5.1.1 The wall thickness of the unit is, in general, tobe in accordance with the manufacturer's practice, but is tobe not less than either the thickness of the surrounding shellplating plus 10 per cent or 15 mm, whichever is greater.

12.5.2 Framing

12.5.2.1 The unit is to be to the same standard as thesurrounding shell plating.

The unit is to be adequately supported and stiffened.


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13 SUPERSTRUCTURES ANDDECKHOUSES

13.1 GENERAL

13.1.1 Explanation

13.1.1.1 For definitions of superstructure and deckhousesee 1.2.5.

13.1.1.2 A long deckhouse is a deckhouse the length ofwhich within 0,4 L amidships ecxeeds 0,2 L or 12 m. Thestrength of a long deckhouse is to be specially considred.

13.1.1.3 Superstructures extending into the range of 0,4L amidships and the length of which exceeds 0,15 L are de-fined as effective superstructures. Their side plating is to betreated as shell plating and their deck as strength deck.

All superstructures being located beyond 0,4 Lamidships or having a length of less than 0,15 L or less than12 m are, for the purpose of this Section, considered as non-effective superstructurs.

13.1.1.4 For deckhouses of aluminium, see 1.4.4. Forthe use of non-magnetic material in way of the wheel house,the requirements of the national Administration concernedare to be observed.

13.1.2 Definitions

Throughout this Section the following defini-tions apply:

k = material factor according to 1.4.2.2.pD = load according to 3.2.1.1.ps = load according to 3.2.2.1.pe = load according to 3.2.2.2.pDA = load according to 3.2.5.pL = load according to 3.3.1.1.tk = corrosion addition according to 2.9.1.

13.1.3 Strengthenings at the ends of super-structures

13.1.3.1 At the ends of superstructures one or both endbulkheads of which are located within 0,4 L amidships, thethickness of the shear strake, the strength deck in a breadth of0,1 B from the shell, as well as the thickness of the super-structure side plating are to be strengthened as specified inTable 13.1.3.1. The strengthenings are to be extend over aregion from 4 frame spacings abaft the end bulkhead to 4frame spacings forward of the end bulkheads.

Table 13.1.3.1-1

Strengthening, in [%]Type ofsuperstructure Strength deck

and shear strakeSide plating ofsuperstructure

Effective, accordingto 13.1.1.3 30 20

Non-effective 20 10

13.1.3.2 Under strength decks in way of 0,6 L amid-ships, girders are to be fitted in alignment with longitudinal

walls, which are to extend at least over three frame spacingsbeyond the end points of the longitudinal walls. The girdersare to overlap with the longitudinal walls by at least twoframe spacings.

13.1.4 Transverse structure of superstructuresand deckhouses

The transverse structure of superstructures anddeckhouses is to be sufficiently dimensioned by a suitable ar-rangement of end bulkheads, web frames, steel walls of cab-ins and casings, or by other measures.

13.1.5 Openings in closed superstructures anddeckhouses

For openings in closed superstructures anddeckhouses see Rules, Part 3 - Hull equipment, 7.5.

13.2 SIDE PLATING AND DECKS OFNON-EFFECTIVE SUPERSTRUCTURES

13.2.1 Side plating

13.2.1.1 The thickness of the side plating is not to beless than the grater of the following values:

t = 1,21 ⋅ s ⋅ kp ⋅ + tk [mm],

or

t = 0,8 ⋅ tmin [mm],

where:p = ps or pe as the case may betmin = according to Section 5.2.6.

13.2.1.2 The thickness of the side plating of upper tiersuperstructures may be reduced by 0,5 mm.

13.2.2 Deck plating

13.2.2.1 The thickness of deck plating is not to be lessthan the greater of the following values:

t = 1,21 ⋅ s ⋅ kp ⋅ + tk [mm];

t = (5,5 + 0,02 L) ⋅ k [mm],

where:p = pDA or pL, (the greater value is to be

taken)L - need not be taken greater than 200 m.

13.2.2.2 Where additional superstructure are arrangedon non-effective superstructures located on the strength deck,the thickness required by 13.2.2.1 may be reduced by 10%.

13.2.2.3 Where plated decks are protected by sheathing,the thickness of the deck plating according to 13.2.2.1 and13.2.2.2 may be reduced by tk, however, it is not to be lessthan 5 mm.

Attention is to be paid that the sheathing doesnot affect the steel. The sheathing is to be effectively fitted tothe deck.


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13.2.3 Deck beams, supporting deck structureand frames

13.2.3.1 The scantling of the deck beams and the sup-porting deck structure are to be determined in accordancewith Section 9.2.

13.2.3.2 The scantlings of superstructure frames aregiven in Section 8.1.3.

13.3 SUPERSTRUCTURE END BULK-HEADS AND DECKHOUSE WALLS

13.3.1 General

The following requirements apply to bulkheadsforming the only protection for openings as per Regulation18 of LLC 1966 and for accommodations. Theserequirements define minimum scantlings based upon locallateral loads and it may be required that they be increased inindividual cases.

These requirements do not apply to CSR BulkCarriers.

13.3.2 Definitions

The design load for determining the scantlingsis:

pA = n ⋅ c ⋅ (b ⋅ f - z) [kN/m2]

where:

n = 20 + L

12, for the lowest tier of unprotected

fronts. The lowest tier is normally thattier which is directly situated above theuppermost continuous deck to which therule depth D is to be measured;

n = 10 + L

12, for 2rd tier unprotected fronnts;

n = 5 + L

15, for 3rd tier of sides and protected

fronts;

n = 7 + L

100 - 8

xL

, for aft ends abaft amidship;

n = 5 + L

100 - 4

xL

, for aft ends forward of

amidship.L need not be taken greater than 300 m.

b = 1,0 +

xLCb

−

+

0 45

0 2

2,

,, for

xL

< 0,45;

b = 1,0 + 1,5

xLCb

−

+

0 45

0 2

2,

,, for

xL

≥ 0,45;

0,60 ≤ Cb ≤ 0,8, when determining scantlings ofaft ends forward of amidships, Cbneed not be taken less than 0,8.

x = distance, in [m], between the bulkhead con-sidered and aft end of the length L.

When determining sides of a deckhouse,the deckhouse is to be subdivided intoparts of approximately equal length, notexceeding 0,15 L each, and x is to betaken as the distance between aft end ofthe length L and the centre of each partconsidered.

f = 0,1 L ⋅ eL

−300 - 1

150

2−

L, for L < 150 m;

f = 0,1 L ⋅ eL

−300 , for 150 m ≤ L ≤ 300 m;

f = 11,0, for L > 300 m;z = vertical distance, in [m], from the summer load

line to the midpoint of stiffener span, or to themiddle of the plate field.

c = 0,3 + 0,7 ′b

B;

b' = breadth of deckhouse at the position considered,in [m];

B' = actual maximum breadth of ship on the exposedweather deck at the position considered, in [m].

b'/B' is not to be taken less than 0,25.For exposed parts of machinery casings, c is

not to be taken less than 1,0.The design load pA is not to be takn less than

the minimum values given in Table 13.3.2.

Table 13.3.2

pAmin [kN/m2]L [m] Lowest tier of

unprotected fronts Elsewhere

≤ 50 30 15

> 50≤ 250

25 + L

1012,5 + L

20

> 250 50 25

13.3.3 Scantlings

13.3.3.1 StiffenersThe section modulus of the stiffeners is to be

determined according to the following formula:

W = 0,35 ⋅ s ⋅ l2 ⋅ pA ⋅ k [cm3]

where:W = stiffener modulus, in [cm3];l = unsupported span, in [m]; l is to be

taken as the superstructure height ordeckhouse height respectively, how-ever, not less than 2,0 m;

s = spacing of stiffeners, in [m].

These requirements assume the webs of lowertier stiffeners to be efficiently welded to the decks. Scant-lings for other types of end connections may be speciallyconsidered.

The section modulus of house side stiffenersneed not be greater than that of side frames on the deck situ-ated directly below; taking account of spacings and unsup-ported span l.


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13.3.3.2 Plate thicknessThe thickness of the plating is to be determined

according to the following formula:

t = 0,95 ⋅ s ⋅ p kA ⋅ + tk [mm]

but not less than:

tmin = 5 0100

, +

L ⋅ k , for the lowest tier;

tmin = 4 0100

, +

L ⋅ k , for the upper tiers,

however, not less than 5,0 mm.

where:s and pA are as defined above.

When determining pA, z is to be measured tothe middle of the plate field..

13.4 DECKS OF SHORT DECKHOUSES

13.4.1 Plating

The thickness of deck plating exposed toweather but not protected by sheathing is not to be less than:

t = 8 ⋅ s ⋅ k + tk [mm]

For decks exposed to weather protected bysheathing and for decks within deckhouses the thickness maybe reduced by tk.

In no case the thickness is to be less than theminimum thickness of 5,0 mm.

13.4.2 Deck beams

The deck beams and the supporting deckstructure are to be determined according to Section 9.


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14 STRENGTHENING FORNAVIGATION IN ICE

14.1 GENERAL

14.1.1 The requirements of this Section are related toships intended for navigation in first year ice conditions pri-marily in the Northern Baltic irrespective of whether assis-tance from ice breakers is anticipated.

14.1.2 Rules stated in this Section are in accordancewith the "Finnish-Swedish'Ice Class Rules 1985".

The relationship between ice class notation inaccordance with the "Finnish-Swedish Ice Class Rules" andthe rules stated in this Section are shown in Table 14.1.2.

Table 14.1.2

Finnish-Swedish Ice Class CRS Ice Class Notation

IA Super 1 ASIA 1 AIB 1 BIC 1 CII 1 D

14.1.3 Definitions

14.1.3.1 The ice belt is the zone of the shell platingwhich is to be strengthened.

14.1.3.2 For the purpose of this Section ice belt is di-vided into regions as follows (see Fig. 14.1.3.2)

14.1.3.2.1 Bow regionThe region from the stem to a line parallel to

and at the distance c aft of the borderline between the parallelmidbody region and the fore ship:

c = 0.04·L , not exceeding 6 m for the ice classnotations 1A and 1AS, not exceeding 5 m forthe ice class notations 1B and 1C

c = 0.02·L , not exceeding 2 m for the ice classnotation D.

14.1.3.2.2 Midbody regionThe region from the aft boundary of the bow

region, as defined in 14.1.3.2.1 to a line parallel to and at thedistance c aft of the borderline between the parallel midbodyregion and the aft ship.

14.1.3.2.3 Stern region:The region from the aft boundary of the mid-

body region, as defined in 14.1.3.2.2 to the stern.

14.1.3.2.4 Forefoot regionThe region below the ice belt from the stem to

a position five main frame spaces abaft the point where thebow profile departs from the keel line. This region is consid-ered for class 1AS only.

14.1.3.2.5 Upper bow ice belt regionThe region from the upper limit of the ice belt

to 2 m above it and from the stem to a position 0,2 L abaftthe forward perpendicular. This region is considered forclasses 1AS and 1A and ships with speed v ≥ 18 kn only.

14.1.3.3 The vertical extension of the bow, midbody andstern regions is to be determined from Table 14.1.3.3. Seealso Fig. 14.1.3.2.

Table 14.1.3.3

Ice classnotation

Hull region Above UIWL[m]

Below LIWL[m]

BowMidbody

1,201AS

Stern0,6

1,0Bow 0,9

Midbody1AStern

0,50,75

Bow 0,7Midbody1B, 1C, 1D

Stern0,4

0,6

Fig. 14.1.3.2

See 14.1.3.3


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14.1.4 Ice class draught

14.1.4.1 The upper ice waterline (UIWL) shall be theenvelope of highest points of the waterlines at which the shipis intended to operate in ice. The line may be a broken line.The lower ice waterline (LIWL) shall be the envelope of thelowest points of the waterlines at which the ship is intendedto operate in ice. The line may be a broken line.

14.1.4.2 The maximum and minimum ice class draughtsat the forward perpendicular, amidships and at the aft per-pendiculars are to be determined in accordance with the up-per and lower ice waterlines and are to be stated in thedrawings submitted for approval to the Register. The iceclass draughts are to be stated in the Class Certificate.

14.1.4.3 If the summer load line in fresh water is any-where located at a higher level than the UIWL, the ship'ssides are to be provided with a warning triangle and with anice class draught mark at the maximum permissible ice classdraught amidships, see 14.4.

The draught and trim, limited by the UIWL, arenot to be exceeded when the ship is navigating in ice. Thesalinity of the sea water along the intended route is to betaken into account when loading the ship.

The ship is always to be loaded down at least tothe LIWL when navigating in ice. The LIWL is to be agreedupon with the owners. Any ballast tank adjacent to the sideshell and situated above the LIWL, and needed to load theship down to this waterline, is to be equipped with devices toprevent the water from freezing. In determining the LIWL,regard is to be paid to the need for ensuring a reasonable de-gree of ice-going capability in ballast. The propeller is to befully submerged, entirely below the ice, if possible.

14.1.4.4 The minimum draught at the forward perpen-dicular is not to be less than:

dmin = ho (2,0 + 0,00025⋅∆) [m],

but need not exceed:dmin = 4 ⋅ ho [m],

∆ = displacement of the ship, in [t], on themaximum ice class draught, accord-ing to 14.1.4.2;

ho = design ice thickness, according to Table14.2.2.1.

14.2 SCANTLINGS

14.2.1 General

14.2.1.1 For transversely-framed plating, a typical iceload distribution is shown in Fig. 14.2.1.1. Due to differencesin the flexural stiffness of frames and shell plating, maximumpressures (pmax) occur at the frames and minimum pressuresoccur between frames. Due to the finite height of the designice load, h, see Table 14.2.2.2-1, the ice load distributionshown in Fig. 14.2.1.1 is not applicable for longitudinallyframed plating.

The design loads are determined by followingformulaes:

p = 0,5 (pmax + pmin) , [N/mm2], for frames andlongitudinally framed shell plating;

p1 = 0,75 ⋅ p , [N/mm2], for transversly framedshell plating.

where:p = according to 14.2.2.2.

Figure 14.2.1.1

14.2.1.2 The formulae and values given in this Sectionmay be substituted by direct calculation methods if they aredeemed by Register to be invalid or inapplicable for a givenstructural arrangement or detail.

Otherwise, direct analysis is not to be utilisedas an alternative to the analytical procedures prescribed bythe explicit requirements in 14.2.3 (shell plating) and 14.2.4(frames, ice stringers, web frames).

Direct analyses are to be carried out using theload patch defined in 14.2.2 (p, h and la ). The pressure to beused is 1.8 · p, where p is determined according to 14.2.2.The load patch is to be applied at locations where the capac-ity of the structure under the combined effects of bendingand shear are minimized. In particular, the structure is to bechecked with the load centred on the UIWL, 0.5 · h0 belowthe LIWL, and several vertical locations in between. Severalhorizontal locations are also to be checked, especially the lo-cations centred at the mid-span or mid-spacing. Further, ifthe load length la cannot be determined directly from the ar-rangement of the structure, several values of la are to bechecked using corresponding values for ca.

The acceptance criterion for designs is that thecombined stresses from bending and shear, using the vonMises yield criterion, are lower than the yield strength ReH.When the direct calculation is performed using beam theory,the allowable shear stress is not to be greater than 0.9· τy,where τy = ReH / 3 .

14.2.2 Ice loads

14.2.2.1 An ice strengthened ships is assumed to operatein open sea conditions corresponding to a level ice thicknessnot exceeding ho. The design height h of the area actuallyunder ice pressure is, however, assumed to be less than ho.The values for ho and h are given in Table 14.2.2.1.

Table 14.2.2.1

Ice class ho [m] h [m]

1 AS 1,0 0,351 A 0,8 0,31 B 0,6 0,251 C 0,4 0,221 D 0,4 0,22

14.2.2.2 The design ice pressure is to be determined ac-cording to the following formula:

p = Cd ⋅ C1 ⋅ Cα ⋅ po [N/mm2],


2013

where:

Cd = 1000bka +⋅ ;

k = 1000

P⋅∆ , for the ice class notations 1AS,

1A, 1B and 1C;

k = 1000

740⋅∆ , for the ice class notation 1D;

a,b = coefficients in accordance with Table14.2.2.2-1:

∆ = displacement of the ship, in [t], ac-cording to 14.1.4.4;

P = engine output [kW];C1 = coefficient in accordance with Table

14.2.2.2-2;

0=aa

lc l

, max 1,0; min 0,35; l0 = 0,6 m.

la = effective length, [m], according toTable 14.2.2.2-3;

po = 5,6 N/mm2 (nominal ice pressure).

Table 14.2.2.2-1

Region Bow Midbody and Sternk k ≤ 12 k > 12 k ≤ 12 k > 12a 30 6 8 2b 230 518 214 286

Table 14.2.2.2-2

RegionIce classnotation Bow Midbody Stern

1 AS 1,0 1,0 0,751 A 1,0 0,85 0,651 B 1,0 0,7 0,451 C 1,0 0,5 0,251 D 0,3 - -

Table 14.2.2.2-3

Structure Framing system la [m]

transverse frame spacingShell

longitudinal 1,7 x frame spacing

transverse frame spacingFrames

longitudinal span of frameIce stringer span of stringer

Web frame 2 x web frame spacing

14.2.3 Thickness of shell plating in the ice belt

14.2.3.1 The thickness of the shell plating is to be de-termined according to the following formulae:

a) transverse framing:

t = 667 ⋅ s ⋅ f p

ReH

1 1⋅ + tk [mm];

b) lognitudinal framing:

t = 667 ⋅ s eHRf

p⋅2

+ tk [mm],

where:p, p1 = see 14.2.1.

f1 = 1,3 - ( )

4 2

182

,

, /+ h s;

f1max = 1,0

f2 = 0,6 + 0 4,/h s

, for h/s ≤ 1;

f2 = 1,4 – 0,4 (h/s), for 1 < h/s ≤ 1,8;tk = allowance for abrasion and corrosion,

in [mm].Usually tk amounts to 2 mm.If a special coating is applied andmaintained, which by experience isshown to be capable to withstand theabrasion of ice, the allowance may bereduced to 1 mm.

s = frame spacing, longitudinal or trans-verse, in [m], taking into account theintermediate frames, in fitted;

ReH = minimum nominal upper yield printfor hull structural steel according toSection 1.4.2.1;

h = design height of ice pressure area, in[m], according to 14.2.2.1.

14.2.3.2 Where the draught is smaller than 1,5 m, orwhere the distance between the lower edge of the ice belt andthe keel plate is smaller than 1,5 m, the thickness of the bot-tom plating in way of the ice belt forward is not to be lessthan required for the ice belt. In the same area the thicknessof the plate floors is to be increased by 10 per cent.

14.2.3.3 If the weather deck in any part of the ship issituated below the upper limit of the ice belt, the bulwark isto have at least the same strength as is required for the shellin the ice belt. Side scuttles are not to be situated in the icebelt.

14.2.3.4 For ships with the ice class notation 1 AS, theforefoot region according to 14.1.3.2.4 is to have at least thethickness of the midbody region.

14.2.3.5 For ships with the ice class notation 1A or 1AS,and with a speed v0 ≥ 18 kn, the upper bow ice belt regionaccording to 14.1.3.2.5 is to have at least the thickness of themidbody region.

A similar strengthening of the bow region isalso advisable for a ship with a lower service speed when it isevident that the ship will have a high bow wave, e.g. on thebasis of model tests.


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14.2.4 Frames, ice stringers, web frames

14.2.4.1 General

14.2.4.1.1 Within the ice-strengthened area, all frames areto be effectively attached to the supporting structures. Lon-gitudinal frames are generally to be attached to supportingweb frames and bulkheads by brackets. Brackets may beomitted with an appropriate increase in the section modulusof the frame, see 14.2.4.3, and with the addition of heel stiff-eners (heel stiffeners may be omitted on the basis of directcalculations, subject to approval by the Register. Bracketsand heel stiffeners are to have at least the same thickness asthe web plate of the frame and the free edge has to be appro-priately stiffened against buckling. When a transverse frameterminates at a stringer or deck, a bracket or similar con-struction is to be fitted. When a frame is running through thesupporting structure, both sides of the web are to be con-nected to the structure by direct welding, collar plate or lug.

14.2.4.1.2 For the ice class notation 1AS, for the ice classnotation 1A within the bow and midbody regions, and for theice class notations 1B and 1C within the bow region, thefollowing applies:

a) Frames which are unsymmetrical, or havingwebs which are not perpendicular to the shellplating, or having an unsupported span l greaterthan 4,0 m, are to be supported against trippingby brackets, intercostal plates, stringers orsimilar at a distance not exceeding 1300 mm.

b) The frames are to be attached to the shell bydouble continuous welds. No scalloping is al-lowed except when crossing shell plate buttwelds.

c) The web thickness tw of the frames is not to beless than determined by the following formu-lae:tw = max (tw1 ; tw2 ; tw3 ; tw4 )tw1 = hw

eHR / C , [mm]

tw2 = 25·s , [mm], for transverse framestw3 = half the thickness of the shell plating t,

[mm]tw4 = 9 mmhw = web height, [mm]C = factor to take the section type into ac-

count, defined as:C = 805, for profilesC = 282, for flat bars.For the purpose of calculating the web thick-

ness of frames, the yield strength ReH of the plating is not betaken greater than that of the framing. The minimum webthickness of 9 mm is independent of the yield strength ReH.

d) Where there is a deck, tank top (or tank bot-tom), bulkhead, web frame or stringer in lieu ofa frame, its plate thickness is to be in accor-dance with 14.2.4.1.2 c) above, to a depth cor-responding to the height of adjacent frames.

14.2.4.1.3 For transverse framing above UIWL and belowLIWL, as well as longitudinal framing below LIWL, the ver-tical extension of the ice-strengthened framing is to be de-termined according to Table 14.2.4.1.3.

Where the vertical extension would extend be-yond a deck or a tank top (or tank bottom) by not more than

250 mm, it may be terminated at that deck or tank top (ortank bottom).

Table 14.2.4.1.3

Ice classnotation Region Above UIWL

[m]Below LIWL

[m]

BowDown to doublebottom or belowtop of floors

Midbody 2,0

Stern

1,2

1,61 AS

Upper bowice belt 1)

Up to top ofice belt

Bow 1,6

Midbody 1,3

Stern

1,0

1,01 A1 B1 C

Upper bowice belt 1)

Up to top ofice belt

1 D 1,0 1,01) If required according to 14.1.3.2.5

14.2.4.2 Transverse frames

14.2.4.2.1 The section modulus of a main, 'tweendeck orintermediate transverse frame is to be determined accordingto the following formula:

W = p s h lm Rt eH

⋅ ⋅ ⋅⋅

⋅ 106 [cm3],

where:

mt = 7

7 5

⋅

−

m

h lo

/;

mo = coeficient according to Table 14.2.4.2The boundary conditions reffered to in Table

14.2.4.2 are those for the main and intermediate frames. Thepossible differences for main frames and 'tween deck framesare included in the mo values. The load centre of the ice loadis taken at l/2.

14.2.4.2.2 The effective shear area of a main, 'tweendeckor intermediate transverse frame is to be determined accord-ing to the following formula:

A= 43 102

3

eHRhpsf

⋅⋅⋅⋅⋅ [cm2],

f3 = factor which takes into account the maximumshear force versus the load location and shearstress distribution, defined as f3 = 1.2.

Where less than 15 % of the frame span l, issituated within the ice strengthened zone for frames as de-fined in 14.2.4.1.3, ordinary frame scantlings may be used.

14.2.4.2.3 The upper end of the ice-strengthened part ofall frames is to be attached to a deck, tanktop (or tank bot-tom) or an ice stringer according to 14.2.4.4..

Where a frame terminates above a deck orstringer, which is situated at or above the upper limit of theice belt, see 14.1.3.3, the part above the deck or stringer need


2013

not be ice-strengthened. In such cases, the upper part of theintermediate frames may be connected to the adjacent mainor 'tweendeck frames by a horizontal member of the samescantlings as the main and 'tweendeck frames, respectively.

14.2.4.2.4 Where an intermediate frame terminates belowa deck, tanktop (or tank bottom) or ice stringer which is situ-ated at or below the lower limit of the ice belt, see 14.1.3.3,its lower end may be connected to the adjacent main or'tweendeck frames by a horizontal member of the samescantlings as the main and 'tweendeck frames, respectively.

Table 14.2.4.2

Boundary condition mo Example

7 Frames in a bulk carrierwith top wing tanks

6Frames extending fromthe tank top to a singledeck

5,7Continuous frames be-tween several decks orstringers

5 Frames extending be-tween two decks only.

14.2.4.3 Longitudinal frames

14.2.4.3.1 The section modulus and the shear area of thelongitudinal frames are to be determined according to thefollowing formulae.

a) section modulus:

W = eHRmlhpf

⋅⋅⋅⋅ 2

4 ⋅ 106, [cm3];

b) shear area:

A = eHR

lhpff⋅

⋅⋅⋅⋅⋅2

3 54 ⋅ 104, [cm2],

In calculating the actual shear area of theframes, the area of the brackets is not to be taken into ac-count.

where:

f4 = factor which takes account of the loaddistribution to adjacent frames:

f4 = 1-0,2 h/s;f5 = factor which takes into account the

pressure definition and maximumshear force versus load location andalso the shear stress distribution:

f5 = 2,16;m = boundary condition factor;m = 13,3 for a continuous beam with dou-

ble end brackets;m = 11,0 for a continuous beam frames

without double end brackets.Where the boundary conditions deviate signifi-

cantly from those of a continuous beam, e.g. in an end field,a smaller boundary factor m may be required.

s = frame spacing, [m];l = total span of frame, [m];p = ice pressure as given in 14.2.2.2,

[N/mm2];h = height of load area as given in

14.2.2.1, [m].

14.2.4.4 Ice stringers

14.2.4.4.1 Ice stringers within the ice beltThe section modulus and the shear area of a

stringer are to be determined according to the following for-mulae:

a) section modulus:

W = eHRm

lhpff⋅

⋅⋅⋅⋅ 276 ⋅ 106, [cm3];

b) shear area:

A = eHR

lhpfff⋅

⋅⋅⋅⋅⋅⋅2

3 876 ⋅ 104, [cm2],

where:m = boundary condition factor as defined

in 14.2.4.3.1p ⋅ h = is not to be taken as less than 0,15;f6 = factor which takes account of the

distribution of load to the transverseframes; to be taken as 0,9;

f7 = safety factor of stringers; to be takenas 1,8;

f8 = factor that takes into account themaximum shear force versus load lo-cation and the shear stress distribu-tion; f8 = 1,2;

l = unsuported span of stringer, in [m].

14.2.4.4.2 Ice stringers outside the ice beltThe section modulus and the shear area of

stringer situated outside the ice belt but supporting framessubjected to ice pressure are to be calculated according to thefollowing formulae:

a) Section modulus:


2013

W = eHRm

lhpff⋅

⋅⋅⋅⋅ 2109 (1 - hs/ls) ⋅106, [cm3];

b) Effective shear area:

A = eHR

lhpfff⋅

⋅⋅⋅⋅⋅⋅2

3 11109 (1 - hs/ls) ⋅104, [cm2],

where:f9 = factor which takes account of the

distribution of load to the transverseframes; to be taken as 0,80;

f10 = safety factor of stringers; to be takenas 1,8;

f11 = factor that takes into account themaximum shear force versus load lo-cation and the shear stress distribu-tion; to be taken as 1,2;

m = boundary conditions factor as definedin 14.2.4.3.1;

p ⋅ h = is not to be taken as less than 0,15;hs = distance of the stringer to the ice belt,

in [m];ls = distance of the stringer to the adjacent

ice stirnger or deck or similar struc-ture, in [m].

14.2.4.4.3 Deck strips

14.2.4.4.3.1 Narrow deck strips abreast of hatches andserving as ice stringers are to comply with the sectionmodulus and shear area requirements in 14.2.4.4.1 and14.2.4.4.2 respecitvely. In the case of very long hatches theproduct p ⋅ h may be taken as less than 0,15 but in no caseless than 0,10.

14.2.4.4.3.2 Regard is to be paid to the deflection of theship's sides due to ice pressure in way of very long hatchopenings (more than B/2) when designing weatherdeck hatchcovers and their fittings.

14.2.4.5 Web frames

14.2.4.5.1 The ice load transferred to a web frame from astringer or from longitudinal framing is to be calculated ac-cording to the following formula:

P = f12·p ⋅ h ⋅ S ⋅ 103 [kN],

where:p ⋅ h = is not to be taken less than 0,15;f12 = safety factor of stringers; to be taken

as 1,8;S = web frame spacing, in [m].In case the supported stringer is outside the ice

belt, the load P may be multiplied by(1-hs/ls)

where hs and ls shall be taken as defined in 14.2.4.4.2.

14.2.4.5.2 The section modulus and effective shear areaare given by the following formulae:

a) Section modulus:

W = M

R AA

eH

a

1

1

1023

−

⋅

γ

, [cm3];

b) Effective shear area:

A = eHRFf 103 13 ⋅⋅⋅α , [cm2],

where:M = maximum calculated bending mo-

ment under the ice load P; this is tobe taken as M = 0,193·P·l.

F = maximum calculated shear force un-der the ice load P, defined as F=P.

A = required shear area;Aa = actual cross sectional area of the web

frame, Aa = Af + Aw .f13 = factor that takes into account the

shear force distribution, f13 = 1,1.Factors γ and α can be obtained from the Table14.2.4.5.2.

Table 14.2.4.5.2

A

Af

w0,00 0,20 0,40 0,60 0,80 1,00 1,20 1,40 1,60 1,80 2,00

α 1,50 1,23 1,16 1,11 1,09 1,07 1,06 1,05 1,05 1,04 1,04γ 0,00 0,44 0,62 0,71 0,76 0,80 0,83 0,85 0,87 0,88 0,89

Af = cross sectional area of free flangeAw = atual effective cross sectional area of web plate


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14.2.5 Stem

14.2.5.1 The stem may be made of rolled, cast or forgedsteel or of shaped steel plates, see Fig. 14.2.5.1.

Figure 14.2.5.1

14.2.5.2 The plate thickness of a shaped plate stem and,in the case of a blunt bow, any part of the shell where α ≥ 30°and ψ ≥ 75°, see Fig. 14.2.5.2, is to be calculated accordingto the formulae in 14.2.3.1 observing that:

p = design pressure according to14.2.1.1and 14.2.2.2;

p1 = design pressure defined as p1 = p;s = smaller of the two unsupported

widths of plate panel, in [m];ls = spacing of vertical supporting ele-

ments, in [m], see Table 14.2.2.2-3.

Figure 14.2.5.2

LPAR = length, [m], of the parallel midshipbody;

Lpp = length, [m], of the ship between per-pendiculars;

LBOW = length, [m], of the bow;

d = maximum and minimum ice classdraughts, [m], amidship according to14.1.4.1 and 14.1.4.3, respectively;

Awf = area, [m2], of the waterplane of thebow;

φ1 = rake [°] of the stem at the centreline.For a ship with a bulbous bow, φ1 isto be taken as 90°;

φ2 = rake, [°], of the bow at B/4, φ2max =90°;

α = angle [°] of the waterline at B/4.

14.2.5.3 The stem and the part of a blunt bow defined in14.2.5.2 (if applicable) are to be supported by floors orbrackets spaced not more than 0,6 m apart and having athickness of at least half the plate thickness. The reinforce-ment of the stem is to extend from the keel to a point 0,75 mabove UIWL or, in case an upper bow ice belt is required tothe upper limit of the upper bow region (see 14.1.3).

14.2.6 Stern

14.2.6.1 An extremely narrow clearance between thepropeller blade tip and the stern frame is to be avoided as asmall clearance would cause verry high loads on the bladetips.

14.2.6.2 On twin and triple screw ships the ice strength-ening of the shell and framing shall be extended to the doublebottom for 1,5 m forward and aft of the side propellers.

14.2.6.3 Shafting and stern tubes of side propellers arenormally to be enclosed within plated bossings. If detachedstruts are used, their design, strength and attachment to thehull are to be duly considered.

14.2.6.4 A wide transom stern extending below the TVLwill seriously impede the capability of the ship to back in ice,which is most essential. If unavoidable, the part of the tran-som below the TVL is to be kept as narrow as possible. Thepart of a transom stern situated within the ice belt shall bestrengthened as for the midship region.

14.2.7 Bilge keels

To limit damage to the shell when a bilge keelis partly ripped off in ice, it is recommended that bilge keelsare cut up into several shorter independent lengths.

14.3 REQUIREMENTS FOR THE ICECLAS NOTATION 1D

14.3.1 Shell plating within the ice belt

14.3.1.1 Within the ice belt the shell plating is to have astrengthened strake extending over the bow region the thick-ness of which is to be determined according to 14.2.3.

14.3.1.2 The midship thickness of the side shell platingis to be maintained forward of amidships up to the strength-ened plating.

d


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14.3.2 Frames

14.3.2.1 In the bow region the section modulus of theframes is to comply with the requirements given in 14.2.4.

14.3.2.2 Tripping brackets spaces not more than 1,3 mapart are to be fitted within the ice belt. The tripping bracketsare to be extended over the bow region.

14.3.3 Stem

The thickness of welded plate stems up to 600mm above UIWL is to be 1,1 times the thickness requiredaccording to 12.2.2, however,need not exceed 25 mm. Thethickness above a point 600 mm above the UIWL may begradually reduced to the thickness required according to12.2.2.

14.4 ICE CLASS DRAUGHT MARKING

14.4.1 According to 14.1.4.3, ship's sides are to beprovided with a warning triangle and with an ice classdraught mark at the maximum permissible ice class draughtamidships if the summer load line in fresh water is located ata higher level than the UIWL. The purpose of the warningtriangle is to provide information on the draught limitation ofthe vessel when it is sailing in ice for masters of icebreakersand for inspection personnel in ports. See Fig. 14.4.1.

ICE

ICE

540 mm aft

300 mm

230 mm

1000 mm

25 m

m

WNAWST

TFF

Figure 14.4.1

Notes to Fig. 14.4.1:

1. The upper edge of the warning triangle is to be lo-cated vertically above the ice class mark, 1000 mmhigher than the Summer Load Line in fresh waterbut in no case higher than the deck line. The sidesof the triangle are to be 300 mm in length and 25mm in width.

2. The ice class draught mark is to be located 540mm abaft the centre of the load line ring or 540mm abaft the vertical line of the timber load linemark, if applicable. The ice class draught mark isto be 230 mm in length and 25 mm in width.

3. The marks and figures are to be cut out of 5 - 8 mmplate and then welded to the ship's side. The marksand figures are to be painted in a red or yellow re-flecting colour in order to make the marks and fig-ures plainly visible even in ice conditions.

4. The dimensions of all figures are to be the same asthose used in the load line mark.


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15 WELDED JOINTS

15.1 GENERAL

15.1.1 Information contained in manufactur-ing documents

15.1.1.1 The shapes and dimensions of welds and,where proof by calculation is supplied, the requirements ap-plicable to welded joints (the weld quality grade, detail cate-gory, are to be stated in drawings and other manufacturingdocuments (partslists, welding and inspection schedules). Inspecial cases, e.g. where special materials are concerned, thedocuments shall also state the welding method, the weldingconsumables used, heat input and control, the weld build-upand any post-weld treatment which may be required.

15.1.1.2 Symbols and signs used to identify weldedjoints are to be explaned if they depart from the symbols anddefinitions contained in the relevant standards. Where theweld preparation conforms both to normal shipbuilding prac-tice and to these Rules and recognized standards, where ap-plicable, no special description is needed.

15.1.2 Materials, weldability

15.1.2.1 Only base materials of proven weldability maybe used for welded structures (in accordance with Section1.4).

15.1.2.2 For ordinary hull structural steels grades A, B,D and E which have been tested by the Register, weldabilityis considered to have been proven. No measures beyondthose laid down in these welding rules need therefore betaken.

15.1.2.3 Higher tensile hull structural steels grade AH,DH and EH which have been approved by the Register andprovided their handling is in accordance with normal ship-builing practice, may be considered to be proven.

15.1.2.4 High tensile (quenched and tempered) finegrain structural steels, low temperature steels, stainless andother (alloyed) structural steels require special approval bythe Register. Proof of weldability of the respective steel is tobe presented in connection with the welding procedure andwelding consumables.

15.1.2.5 Aluminium alloys require testing by the Regis-ter. Proof of their weldability must be presented in connec-tion with the welding procedure and welding consumables.

15.1.3 Manufacture and testing

15.1.3.1 The manufacture of welded structural compo-nents may only be carried out in workshops or plants thathave been approved. The requirements that have to be ob-served in connection with the fabrication of welded joints arelaid in the Rules, Part 26 - Welding.

15.1.3.2 For details concerning the type, scope andmanner of testing, see Rules, Part 26 - Welding, Section 2.Where proof of fatigue strength is required, in addition therequirements of Section 16 apply.

15.2 DESIGN

15.2.1 General design principles

15.2.1.1 During the design stage welded joints are to beplanned such as to be accessible during fabrication, to be lo-cated in the best possible position for welding and to permitthe proper welding sequence to be followed.

15.2.1.2 Both the welded joints and the sequence ofwelding involved are to be so planned as to enable residualwelding stresses to be kept to a minimum in order that no ex-cessive deformation occurs.

15.2.2 Design details

15.2.2.1 Stress flow, transitions

15.2.2.1.1 All welded joints on primary supporting mem-bers shall be designed to provide as smooth a stress profile aspossible with no major internal or external notches, no dis-continuities in rigidity and no obstructions to strains.

15.2.2.1.2 Butt joints in long or extensive continuousstructures such as bilge keels, fenders, slop coamings, etc.attached to primary structural members are therefore to bewelded over their entire crosssection.

15.2.2.1.3 Wherever possible, joints in girders and sec-tions are not to be located in areas of high bending stress.Joints at the knuckle of flanges are to be avoided.

15.2.2.1.4 The transition between differing componentdimensions are to be smooth and gradual. Where the depth ofweb of girders or sections differs, the flanges or bulbs are tobe bevelled and the web split and expanded or pressed to-gether to equalize the depths of the members. The length ofthe transition are to be at least equal twice the difference indepth.

15.2.2.1.5 Where the plate thickness differs at joints per-pendicularly to the direciton of the main stress, differences inthickness grater than 3 mm must be accommodated by bev-elling the proud edge in the manner shown in Fig. 15.2.2.1.5at a ratio of at least 1:3 or according to the notch category.Differences in thickness of 3 mm or less may be accommo-dated within the weld.

Figure 15.2.2.1.5

15.2.2.1.6 For the welding on of plates or other relativelythin-welled elements, steel castings and forgings should beappropriately tapered or provided with integrally cast orforged welding flanges, (in accordance with Fig. 15.2.2.1.6).


2013

Figure 15.2.2.1.6

15.2.2.1.7 For the connection of shaft brackets to the bossand shell plating, see 15.2.4.3 and Section 12.4. For the con-nection of horizontal coupling flanges to the rudder body, see15.2.4.4. For the thickened rudder stock collar required withbuild-up welds and for the connection of the coupling flange,see 15.2.2.5. The joint between the rudder stock and the cou-pling flange must be welded over the entire cross-section.

15.2.2.2 Minimum spacing between weldsThe local clustering of welds and short dis-

tances between welds are to be avoided. Adjacent butt weldsare to be separated from each other by a distance of at least

50 mm + 4 x plate thickness.Fillet welds are to be separated from each other

and from butt welds by a distance of at least

30 mm + 2 x plate thickness.The width of replaced or inserted plates (strips)

should, however, be at least 300 mm or ten times the platethickness (whichever is the greater).

15.2.2.3 Welding cut-outs

15.2.2.3.1 Welding cut-outs for the execution of butt orfillet welds following the positioning of transverse membersshould be rounded minimum radius 25 mm or twice the platethickness (whichever is the greater) and are to be shaped toprovide a switch transition are the adjoning surface as shownin Fig. 15.2.2.3.1.

Figure 15.2.2.3.1

15.2.2.3.2 Where the welds are completed prior to the po-sitioning of the crossing members, no welding cut-outs areneeded. Any weld reinforcements present are to be machinedoff prior to the location of the crossing members or thesemembers are to have suitable cut-outs.

15.2.2.4 Local reinforcements, doubling plates

15.2.2.4.1 Where platings are subjected locally to in-creased stresses, thicker plates are to be used wherever pos-sible in preference to doubling plates.

15.2.2.4.2 Where doublings are not to be avoided, thethickness of the doubling plates are not exceed twice theplating thickness. Doubling plates whose width is greaterthan approximately 30 times their thickness are to be plugwelded to the underlying plating at intervals not exceeding30 times the thickness of the doubling plate.

15.2.2.4.3 Along their edges, doubling plates are to becontinuously fillet welded with a throat thickness a of 0,3 xthe doubling plate thickness. At the ends of doubling plates,the throat thickness a at the end faces are to be increased to0,5 x the doubling plate thickness but is not exceed the plat-ing thickness (see Fig. 15.2.2.4.3).

Figure 15.2.2.4.3

15.2.2.4.4 Doubling plates are not permitted in tanks forflammable liquids.

15.2.2.4.5 Where proof of fatigue strength is required (seeSection 16), the configuration of the end of the doublingplate must conform to the selected detail category.

15.2.2.5 Build-up welds on rudderstock and pintles

15.2.2.5.1 Wear resistance and/or corrosion resitant build-up welds on the bearing surfaces of rudderstocks, pintles etc.are to be applied to a thickened collar exceeding by at least20 mm the diameter of the adjoining part of the shaft.

15.2.2.5.2 Where a thickened collar is impossible for de-sign reasons, the build-up weld may be applied to the smoothshaft provided that relief-turning in accordance with15.2.2.5.3 is possible.

15.2.2.5.3 After welding, the transition areas between thewelded and non-welded portions of the shaft shall be relief-turned with large radii, as shown in Fig. 15.2.2.5.3-1, to re-move geometrical and metallurgical "notches".

Figure 15.2.2.5.3

15.2.3 Weld shapes and dimensions

15.2.3.1 Butt joints

15.2.3.1.1 Depending on the plate thickness, the weldingmethod and the welding position, butt joints shall be of the


2013

square, V or X shape conforming to the relevant standards.Where other weld shapes are applied, these are to be spe-cially described in the drawings.

15.2.3.1.2 As a matter of principle, the rear sides of buttjoints shall be grooved and welded with at least one cappingpass.

15.2.3.1.3 Where the aforementioned conditions cannot bemet, e.g. where the welds are accessible from one side only,the joints shall be executed as lesser bevelled welds with anopen root and an attached or an integrally machined or cast,permanent weld pool support as shown in Fig. 15.2.3.1.3.

Figure 15.2.3.1.3

15.2.3.2 Corner, T and double-T joints

15.2.3.2.1 Corner, T and double-T joints are to be made assingle or double-bevel welds with a minimum root face(welds with full root penetration)and adequate air gap, asshown in Fig. 15.2.3.2.1, and with grooving of the root andcopping from the opposite sides.

The effective weld thickness are to be assumedas the thickness of the abutting plate.

Figure 15.2.3.2.1

15.2.3.2.2 Corner, T and double-T joints with a definedincomplete root penetration, are to be made as single or dou-ble-bevel welds, as described in 15.2.3.2.1, with a back-upweld but without grooving of the root, as shown in Fig.15.2.3.2.2.

Figure 15.2.3.2.2

The effective weld thickness may be asumed asthe thickness of the abutting plate minus f, where f is to beasigned a value of 0,2 t subject to a maximum of 3 mm.

15.2.3.2.3 Corner, T and double-T joints with both an un-welded root face c and a defined incomplete root penetrationf are to be made in accordance with Fig. 15.2.3.2.3.

Figure 15.2.3.2.3

The effective weld thickness is to be assumedas the thickness of the abutting plate t minus (c + f). For f, seeFig. 15.2.3.2.2.

15.2.3.2.4 Corner, T and dobule-T joints which are acces-sible from one side only may be made in accordance withFig. 15.2.3.2.4 in a manner analogous to the butt joints re-ferred to in 15.2.3.1.3.

Figure 15.2.3.2.4The effective weld thickness shall be deter-

mined by analogy with 15.2.3.1.3 or 15.2.3.2.2, as appropri-ate. Wherever possible, these joints should not be used whereproof of fatigue strength is required (see Section 16).

15.2.3.2.5 Where corner joints are flush, the weld shapesshall be as shown in Fig. 15.2.3.2.5.

Figure 15.2.3.2.5


2013

15.2.3.3 Fillet weld connections

15.2.3.3.1 In principle fillet welds are to be of the doublefillet weld type. Exceptions to this rule as in the case ofclosed box girders and mainly shear stresses parallel to theweld, are subject to the Register for approval in each indi-vidual case. The throat thickness a of the weld (the height ofthe inscribed isoscales triangle) is to be determined in accor-dance with Table 15.2.3.3.1. The leg length of a fillet weld isto be not less than 1,4 times the throat thickness a.

15.2.3.3.2 The throat thickness of fillet welds is not ex-ceed 0,7 times the lesser thickness of the parts to be con-nected (generally the web thickness). The minimum throatthickness is defined by the expression:

amin = t t1 2

3+

[mm],

but not less than 3 mm,where:

t1 = lesser plate thickness, [mm],t2 = greater plate thickness, [mm].

15.2.3.3.3 Intermittent fillet welds may be located oppo-site one another (chain intermittent welds, possibly withscallops) or may be staggered (see Fig. 15.2.3.3.3). In waterand cargo tanks, in the bottom area of fuel oil tanks and ofspaces where condensed or sprayed water may accumulateonly continuous or intermittent fillet welds with scallops areto be used.

Figure 15.2.3.3.3

15.2.3.3.4 The throat thickness ai of intermittent filletwelds is to be determined according to the selected pitch ra-tio b/l by applying the formula:

ai = 1,1 ⋅ a ⋅ bl

[mm],

where:a = required fillet weld throat thickness,

in [mm], for a continuous weld ac-cording to Table 15.2.3.3.1;

b = distance between weld's midpoints, in[mm], = e + l;

e = interval between the welds in [mm];l = length of fillet weld, in [mm].The pitch ratio b/l are not to be exceed 5. The

maximum unwelded length are not to be exceed 25 times thelesser thickness of the parts to be welded. The length ofscallops are, however, not to be exceed 150 mm.

15.2.3.3.5 Lap joints are to be avoided wherever possibleand are not to be used for heavily loaded components. In thecase of components subject to low loads lap joints may beaccepted provided that, wherever possible, they are orientedparallel to the direction of the main stress. The width of thelap is to be 1,5 t + 15 [mm] (t = thickness of the thinnerplate).

The fillet weld must be continuous on bothsides and must meet at the ends.

15.2.3.3.6 In the case of plug welding, the distance be-tween the holes and the length of the holes may be deter-mined by analogy with the pitch b and the fillet weld length lin the intermittent welds covered by 15.2.3.3.3. The filletweld throat thickness ai may be determined in accordancewith 15.2.3.3.4. The with of the holes is to be equal to at leasttwice the thickness of the plate and are not to be less than 15mm. The ends of the holes are to be semi-circular. Whereverpossible only the necessary fillet welds are to be welded,while the remaining void is packed with a suitable filler.

15.2.4 Welded joints of particular components

15.2.4.1 Welds at the ends of girders and stiffeners

15.2.4.1.1 The web at the end of intermittently weldedgirders or stiffeners is to be continuously welded to the plat-ing or the flange plate, as applicable, over a distance at leastequal to the depth h of the girder subject to a maximum of300 [mm], as shown in Fig. 15.2.4.1.1.

Fig 15.2.4.1.1

15.2.4.1.2 The areas of bracket plates should be continu-ously welded over a distance at least equal to the length ofthe bracket plate according to Fig. 15.2.4.1.1. Scallops are tobe located only beyond a line imagined as an extension of thefree edge of the bracket plate, according to Fig. 15.2.4.1.1.

15.2.4.1.3 Wherever possible, the free ends of stiffenersare to be abut agianst the transverse plating or the webs ofsections and girders so as to avoid stress concentrations inthe plating. Failing this, the ends of the stiffeners are to besnipped and continuously welded over a distance of at least1,7 ⋅ h subject to a maximum of 300 mm (see Fig.15.2.4.1.1).

15.2.4.1.4 Where butt joints occur in flange plates, theflange is to be continuously welded to the web on both sidesof the joint over a distance at least equal to the width of theflange, according Fig. 15.2.4.1.1.

15.2.4.2 Joints between section ends and plates

15.2.4.2.1 Welded joints connecting section ends andplates may be made in the same plane or lapped, see Fig.15.2.4.2.1.


2013

Figure 15.2.4.2.1

15.2.4.2.2 Where the joint between the plate and the sec-tion end overlaps, the fillet weld must be continuous on bothsides and must meet at the ends. The fillet weld throat thick-ness is not to be less than the minimum specified in15.2.3.3.2.

15.2.4.3 Welded shaft bracket joints

15.2.4.3.1 Strut barrel and struts are to be connected toeach other and to the shell plating in the manner shown inFig. 15.2.4.3.1.

Figure 15.2.4.3.1Explanations:

t = plating thickness in accordance withSection 5.4.4, in [mm];

t' = plating thickness at connecting place;

t' = a3

+ 5 [mm] for a < 50 [mm];

t' = 3 a [mm] za a ≥ 50 [mm]

15.2.4.4 Rudder coupling flanges

15.2.4.4.1 Unless forged or cast steel flanges with inte-grally forged or cast welding flanges are used, horizontalrudder coupling flanges are to be joined to the rudder bodyby plates of graduated thickness and full penetration single ordouble-bevel welds as shown in Fig. 15.2.4.4.1.

Figure 15.2.4.4.1Explanations:

t = rudder plating thickness, in [mm];tf = actual flange thickness, in [mm].

t’ = t f

3 + 5 [mm], for tf < 50 mm;

t’ = 3 t f [mm], for tf ≥ 50 mm.

15.2.4.4.2 The welded joint between the rudder stock(with thickened collar, see 15.2.2.5) and the flange is to bemade in accordance with Fig. 15.2.4.4.2.

Figure 15.2.4.4.2


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Table 15.2.3.3.1

Structural parts to be connectedBasic thickness

of fillet welds a/to1)

for double continu-ous fillet welds

Intermittent filletwelds permissible2)

Bottom structures:Transverse and longitudinal girders to each otherto shell and inner bottom

0,350,20

yesyes

Centre girder to flat keel and inner bottom 0,40 −Transverse and longitudinal girders and stiffeners in way ofbottom strengthening forward

0,30 −

Transverse and longitudinal girders in machinery space 0,30 −Inner bottom to shell 0,40 −Machinery foundation:Longitudinal and transverse girders to each other andto the shell 0,40 −

- to inner bottom and face plates 0,40 −- to top plates 0,503) −- in way of foundation bolts 0,703) −- to brackets and stiffeners 0,30 −

Longitudinal girders of thrust bearing to inner bottom 0,40 −Decks:to shell (general); 0,40 −Deck stringer to sheer strake (see also Chapter 6.1.2) 0,50 −Frames, stiffeners, beams etc.:general 0,15 yesin peak tanks 0,30 yesbilge keel to shell 0,15 −Transverses, longitudinal and transverse girders:general 0,15 yeswithin 0,15 of span from supports 0,25 −cantilevers 0,40 −pillars to decks 0,40 −Bulkheads, tank boundaries, walls of superstructuresand deckhouses:to decks, shell and walls 0,40 −Hatch coamings:to deck 0,40 −to longitudinal stiffeners 0,30 −Hatch covers:general 0,15 −watertight or oiltight fillet welds 0,30Rudder:plating to webs 0,25 yesStem:plating to webs 0,25 yesNotes:1) to =Thickness of the thinner plate;2) See 15.2.3.3;3) For plates thickness exceeding 15 mm single or double bevel butt joints to be applied, with V or X

edge preparation.


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16 FATIGUE STRENGTH

16.1 GENERAL

16.1.1 Definitions

∆σ = applied stress range (σmax - σmin), in [N/mm2],see also Fig. 16.1.1

σmax = maximum upper stress of a stress cycle in[N/mm2]

σmin = maximum upper stress of a stress cycle in[N/mm2]

∆σmax= applied peak stress range within a stressrange spectrum in [N/mm2]

σm = mean stress (σmax/2 + σmin/2), in [N/mm2]∆σp = permissible stress range in [N/mm2]σn = nominal stress in [N/mm2]σs = structural (or hot-spot) stress in [N/mm2]σk = notch stress in [N/mm2]n = number of applied stress cyclesN = number of endured stress cycles according to

S-N curve (= endured stress cycles underconstant amplitude loading)

∆σR = fatigue strength reference value of S-N curveat 2⋅106 cycles of stress range in [N/mm2](= detail category number according toTable 16.2.1.1)

fm = correction factor for material effectfR = correction factor for mean stress effectfw = correction factor for weld shape effectfi = correction factor for importance of structural

elementfs = additional correction factor for structural

stress analysisfn = factor considering stress spectrum and num-

ber of cycles for calculation of permissi-ble stress range

∆σRc = corrected fatigue strength reference value ofS-N curve at 2 stress cycles, in [N/mm2]

D = cumulative damage ratio.

m, mo= see 16.2.3.1.2

Figure 16.1.1

16.1.2 Scope

16.1.2.1 A fatigue strength analysis is to be performedfor structures which are predominantly subjected to cyclic

loads. The notched details i.e. the welded joints as well asnotches at free plate edges are to be considered individually.The fatigue strength assessment is to be carried out either onthe basis of a permissible peak stress range for standard stressspectra (see 16.2.2.1) or on the basis of a cumulative damageratio (see 16.2.2.2).

16.1.2.2 No fatigue strength analysis is required if thepeak stress range due to dynamic loads in the seaway (stressspectrum A according to 16.1.2.4) and/or due to changingdraught or loading conditions, respectively, fulfils the fol-lowing conditions:

- peak stress range only due to seaway-induced dynamic loads:

∆σmax ≤ 2,5 ∆σR

- sum of the peak stress ranges due to sea-way-induced dynamic loads and due tochanges of draught or loading condition,respectively:

∆σmax ≤ 4,0 ∆σR

Note:For welded structures of detail category 80 or higher afatigue strength analysis is required only in case of ex-traordinary high dynamic stresses.

16.1.2.3 The rules are applicable to constructions madeof ordinary and higher-tensile hull structural steels accordingto Section 1.4. Other materials such as cast steel and alu-minium alloys can be treated in an analogous manner by us-ing appropriate design S-N curves.

16.1.2.4 The stress ranges which are to be expectedduring the service life of the ship or structural component, re-spectively, may be described by a stress range spectrum(long-term distribution of stress range). Fig. 16.1.2.4 showsthree standard stress range spectra A, B and C, which differfrom each other in regard to the distribution of stress range asa function of the number of load cycles.

Figure 16.1.2.4


2013

Table 16.1.2.4

Load Maximum load Minimum loadVertical longitudinal bendingmoments (Section 4.2) MS + 0,75 ⋅ Mw + MSL MS - (0,75 Mw + MSL)

Influence off horizontal wavebending moments (Section 4.5) MS + 0,5 ⋅ Mw + MwH MS - (0,5 ⋅ Mw + MwH)

Loads on weather decks1) (Sec-tion 3.2.1) pD 0

Loads on ship’s sides1)

- below TVL 10 ( d - z) + po ⋅ cF

+

dz1 10 (d - z) - po ⋅ cF,

+

dz1 , but ≥ 0

- aboveTVLpo ⋅ cF

dz −+⋅10

20 0

(Section 3.2.2)Loads on ship’s bottom1)

(Section 3.2.3) 10 d + po ⋅ cF 10 d - po ⋅ cF

Liquid pressure in completeyfilled tanks(Section 3.4.1)

9,81 ⋅ h1 ⋅ ρ (1 + av) + 100 pvor9,81 ⋅ ρ [h1 ⋅ cosϕ + (0,3 ⋅ b + y) sinϕ]++ 100 pv

9,81 ⋅ h1 ⋅ ρ (1 - av) + 100 pvor9,81 ⋅ ρ [h1 ⋅ cosϕ + (0,3 ⋅ b - y) sinϕ]++ 100 pv, but ≥ 100 pv

Loads due to cargo(Section 3.3.11 i 3.5.1)

pc (1 + av)p ⋅ ax ⋅ 0,7p ⋅ ay ⋅ 0,7

pc (1 - av)- p ⋅ ax ⋅ 0,7- p ⋅ ay ⋅ 0,7

1) With f =1,0 in general for all structural components

A: straight-line spectrum (typical stress range spectrumof seaway-induced stress ranges),

B: parabolic spectrum (approximated normal distribu-tion of stress range ∆σ),

C: rectangular spectrum (constant stress range within thewhole spectrum; typical spectrum of engine- or pro-peller-excited stress ranges).

In case of only seaway-induced stresses, nor-mally the stress range spectrum A is to be assumed with anumber of cycles nmax = 5 ⋅ 107.

For design lifetime of 30 years the number ofcycles nmax = 7,5 107 is to be assumed.

The maximum and minimum stresses resultfrom the maximum and minimum relevant seaway-inducedload effects. The different load-effects are, in general, to besuperimposed conservatively. Table 16.1.2.4 shows examplesfor the individual loads which have to be considered in nor-mal cases.

16.1.2.5 Additional stress cycles resulting from chang-ing mean stresses, e.g. due to changing loading conditions ordraught, need generally not be considered as long as the sea-way-included stress ranges are determined for the loadingcondition being most critical with respect to fatigue strengthand the maximum change in mean stress is less than themaximum seaway-induced stress range.

16.1.2.6 The fatigue strength analysis is, depending onthe detail considered, based on one of the following types ofstress:

- For notches of free plate edges the notchstress σk, determined for linear-elasticmaterial behaviour (see Section 2.8) isrelevant, which can normally be calcu-lated from a nominal stress σn and a theo-retical stress concentration factor Kt. Val-

ues for Kt are given in Fig. 16.1.2.6-1 and16.1.2.6-2 for different types of cut-outs.The fatigue strength is determined by thedetail category (or ∆σR) according to Ta-ble 16.2.1.1, type 29 and 30.

- For welded joints the fatigue strengthanalysis is normally based on the nominalstress σn at the structural detail consid-ered and on an appropriate detail classifi-cation as given in Table 16.2.1.1, whichdefines the detail category (or ∆σR).

- For those welded joints, for which thedetail classification is not possible or ad-ditional stresses occur, which are not ornot adequately considered by the detailclassification, the fatigue strength analy-sis may be performed on the basis of thestructural stress σs, in accordance with16.3.


2013

Figure 16.1.2.6-1

Figure 16.1.2.6-2

16.1.3 Quality requirements (fabrication toler-ances)

16.1.3.1 The detail classification of the different weldedjoints as given in Table 16.2.1.1 is based on the assumptionthat the fabrication of the structural detail or welded joint, re-spectively, corresponds in regard to external defects at leastto the Production Standard of the Shipbuilding Industry.Equivalent Standards may be accepted by Register.

16.1.3.2 Relevant information have to be included in themanufacturing document for fabrication. If it is not possibleto comply with the tolerances given in the standards, this hasto be accounted for when designing the structural details orwelded joints, respectively. In special cases an improvedmanufacture as stated in 16.1.3.1 may be required, e.g.stricter tolerances or improved weld shapes, see also16.2.3.2.4.

16.2 FATIGUE STRENGTH ANALYSIS

16.2.1 Definition of nominal stress and detailclassification for welded joints

16.2.1.1 Corresponding to their notch effect, weldedjoints are normally classified into detail categories consider-ing particulars in geometry and fabrication, including subse-quent quality control, and definition of nominal stress. Table16.2.1.1 shows the detail classification based on recommen-dation of the International Institute of Welding (IIW) givingthe detail category number (or ∆σR).

16.2.1.2 Details which are not contained in Table16.2.1.1 may be classified on the basis of local stresses in ac-cordance with 16.3.

16.2.1.3 Regarding the definition of nominal stress, thearrows in Table 16.2.1.1 indicate the location and directionof the stress for which the stress range is to be calculated.The potential crack location is also shown in Table 16.2.1.1.Depending on this crack location, the nominal stress rangehas to be determined by using either the cross sectional areaof the parent metal or the weld throat thickness, respectively.Bending stresses in plate and shell structures have to be in-corporated into the nominal stress, taking the nominal bend-ing stress acting at the location of crack initiation.

Additional stress concentrations which are notcharacteristic of the detail category itself, e.g. due to cut-outsin the neighbourhood of the detail, have also to be incorpo-rated into the nominal stress.

16.2.1.4 In the case of combined normal and shear stressthe relevant stress range may be taken as the range of theprincipal stress at the potential crack location which acts ap-proximately perpendicular to the crack front as shown in Ta-ble 16.2.1.1.

16.2.1.5 Where solely shear stresses are acting the larg-est principal stress σ1 = τ may be used in combination withthe relevant detail category.

16.2.2 Permissible stress range for standardstress range spectra or calculation of thecumulative damage ratio

16.2.2.1 For standard stress range spectra according toFig. 16.1.2.4, the permissible peak stress range can be calcu-lated as follows:

∆σp = fn ⋅ ∆σRc∆σRc = detail category or fatigue strength

reference value, respectively, cor-rected according to 16.2.3.2.

fn = factor as given in Table 16.2.2.1The peak stress range of the spectrum must not

exceed the permissible value, i.e.∆σmax ≤ ∆σp

16.2.2.2 If the fatigue strength analysis is based on thecalculation of the cumulative damage ratio, the stress rangespectrum expected during the envisaged service life is to beestablished (see 16.1.2.4) and the cumulative damage ratio Dis to be calculated as follows:

Di

I

==∑

1

(ni/Ni)

I = total number of blocks of the stressrange spectrum for summation (nor-mally I ≥ 20)

ni = number of stress cycles in block iNi = number of endured stress cycles de-

termined from the corrected design S-N curve (see 16.2.3) taking∆σ = ∆σi

∆σi = stress range of block i.To achieve an acceptable high fatigue life, the

cumulative damage ratio should not exceed D = 1.If the expected stress range spectrum can be

superimposed by two or more standard stress spectra ac-cording to 16.1.2.4 the partial damage ratios Di due to the in-dividual stress range spectra can be derived from Table16.2.2.1. In this case a linear relationship between number ofload cycles and cumulative damage ratio may be assumed.


2013

The numbers of load cycles given in Table 16.2.2.1 apply fora cumulative damage ratio of D = 1.

Table 16.2.1.1Catalogue of Details

TypeNo.

Joint configuration showing mode of fa-tigue cracking and stresses

consideredDescription of joint

Detail cate-gory ∆σR

1 Transverse butt weld ground flush to plate, 100 % NTD(Non-Destructive Testing)

112

2Transverse butt weld made in shop in flat position, max.weld reinforcement 1 mm + 0,1 x weld width, smoothtransitions, NTD

90

3Transverse butt weld not satisfying conditions for jointtype No. 2, NDT 80

4 Transverse butt weld on backing strip or three-plateconnection with unloaded branch

Butt weld, welded on ceramic backing, root crack

71

80

5

Transverse butt welds between plates of different widthsor thickness, NDT- as for joint type No. 2, slope 1:5- as for joint type No.2, slope 1:3- as for joint type No. 2, slope 1:2- as for joint type No.. 3, slope 1:5- as for joint type No. 3, slope 1:3- as for joint type No. 3, slope 1:2For the third sketched case the slope results from the ra-tio of the difference in plate thickensses to the breadthof the welded seam.Additional bending stress due to thickness change to beconsoidered, see also 16.2.1.3.

908071807163

6

Transverse butt welds welded from one side withoutbacking bar full penetration

root controlled by NDTnot NDTFor tubular profiles ∆σR may be lifted to the next higherdetail category

7136

7Partial penetration butt weld, the stress is to be relatedto the weld throat sectional area, weld overfill not to betaken into account

36

8Continous automatic longitudinal fully penetrated K-butt weld without stop/start positions (based on stressrange in flange adjacent to weld)

125

9

Continous automatic longitudinalo fillet weld withoutstop/start positions (based on stress range in flange ad-jacent to weld) 100


2013

Table 16.2.1.1 - continued

TypeNo.




10Continous manual longitudinal fillet or butt weld (basedon stress range in flange adjacent to weld) 90

11

Intermittent longitudinal fillet weld (based on stressrange in flange at weld ends)In presence of shear τ in the web, the detail categoryhas to be reduced by the factor (1 – ∆τ / ∆σ), but notbelow 36.

80

12

Longitudinal butt weld, fillet weld or intermittent filletweld with cut outs (based on stress range in flange atweld ends)If cut out is higher than 40% of web height or in pres-ence of shearIn presence of shear τ in the web, the detail categoryhas to be reduced by the factor (1 – ∆τ / ∆σ), but notbelow 36.Note:For Ω shaped scallops, an assessment based on local stressesin recommended.

71

63

13

Longitudinal gusset welded on beam flange, bulb orplate: l ≤ 50 mm 50 mm < l ≤ 150 mm 150 mm < l ≤ 300 mm l > 300 mmFor t2 ≤ 0,5 t1, ∆σR maybe increased by one category,but not over 80; not valid for bulb profiles.When welding close to edges of plates or profiles (dis-tance less than 10 mm) and/or the structural element issubjected to bending, ∆σR is to be decreased by onecategory.

80716356

14

Gusset with smooth transition (sinped end or radius)welded on beam flange, bulb or plate; c ≤ 2 t2, max. 25mm r ≥ 0,5 h r < 0,5 h or ϕ ≤ 20° ϕ > 20° see joint type 13For t2 ≤ 0,5 t1, ∆σR may be increased by one category;not valid for bulb profiles.When welding close to edges of plates or profiles (dis-tance less than 10 mm), ∆σR is to be decreased by onecategory.

7163


2013


TypeNo.




15

Longitudinal flat side gusset welded on plate or beamflange edge:l ≤ 50 mm50 mm < l ≤ 150 mm150 mm < l ≤ 300 mml > 300 mmFor t2 ≤ 0,7 t1, ∆σR may be increased by one category,but not over 56.If the plate or beam flange is subjected to in-planebending, ∆σR has to be decreased by one category.

56504540

16

Gusset with smooth transition (sniped end or radius)welded on beam flange, bulb or plate; c ≤ 2 t2,max. 25 mmr ≥ 0,5 hr < 0,5 h, or ϕ ≤ 20°ϕ > 20°, see joint type 15

For t2 ≤ 0,7 t1, ∆σR smay be increased by one category.

5045

17 Transverse stiffener with fillet welds (applicable forshort and long stiffeners)

80

18 Non-load-carrying shear connector. 80

19

Full penetration weld at the connection between a hol-low section (e.g. pillar) and a plate,

for tubular sectionfor rectangular hollow section

For t ≤ 8mm, ∆σR has to be decreased by one category.

5650

20

Fillet weld at the connection between a hollow section(e.g. pillar) and a plate,

for tubular sectionfor rectangular hollow section

The stress is to be related to the weld sectional area.For t ≤ 8mm, ∆σR has to be decreased by one category.

4540


2013


TypeNo.




21

Cruciform or tee-joint K-butt welds with full penetrationor with defined incomplete root penetration according toFig. 15.2.3.2.2

cruciform jointtee-joint

7180

22

Cruciform or tee-joint with transverse fillet welds, toefailure (root failure particularly for throat thickness a <0,7 ⋅ t, see joint type. 23)

cruciform jointtee-joint

6371

23

Welded metal in transverse load-carrying fillet welds atcruciform or tee-joint, root failure (based on stress rangein weld throat), see also joint type No. 22

a ≥ t/3 a < t/3NoteCrack initiation at weld root

3640

24

End of long doubling plate on beam, welded ends(based on stress range in flange at weld toe)

tD ≤ 0,8 t0,8 t < tD ≤ 1,5 ttD > 1,5 t

The following features increase ∆σR by one categoryaccordingly:– reinforced ends according to Sect. 15, Fig. 15.2.2.4.3– weld toe angle α ≤ 30 °– length of doubling α ≤ 300 mmFor length of doubling ≤150 mm, ∆σR may be increasedby two categories.

565045

25

Fillet welded non-load-carrying lap joint welded tolongitudinal stressed element.– flat bar– to bulb section or flat bar– for angle sectionFor l > 150 mm, ∆σR has to be decreased by one cate-gory, while for l ≤ 50 mm ∆σR may be increased by onecategory.If the component is subjected to bending, ∆σR has to bereduced by one category.

565650

26

Fillet welded lap joint with smooth transition (snipedend with ϕ ≤ 20° or radius), welded to longitudinallystressed element.– flat bar– for bulb section or flat bar– to angle sectionc ≤ 2 t, max. 25 mm

565650


2013


TypeNo.




27

Continuous butt or fillet weld connecting a pipe pene-trating through a plate

d ≤ 50 mmd > 50 mm

Remark:For large diameters and assessment based on localstress is recommended.

7163

28 Rolled or extruded plates and sections as well as seam-less pipes, no surface or rolling defects

160(mo = 5)

29

Plate edge not sheared or machine-cut by any thermalprocess with surface free of cracks and notches, cornersbroken or rounded. Stress increase due to geometry ofcut-outs to be considered.

140(mo = 4)

30

Plate edge not meeting the requirements of type 29, butfree from cracks and sever notches .

Machine cut or sheared edge:

Manually thermally cut

Stress increase due to geometry of cut-outs to be con-sidered.

125(mo = 3,5)

100(mo = 3,5)

31

Joint at stiffened knuckle of a flange, to be assessed ac-cording to type 21, 22 or 23, depending on the type ofjoint. The stress in the stiffener at the knuckle can nor-mally be calculated as follows:

σ σ= af

b

tt

2 sin α

For Type No. 22:– cruciform joint– cruciform joint

For Type No. 23

637136

32

Unstiffened flange to web joint, to be assessed accord-ing to type 21, 22 or 23, depending on the type of joint.The stress in the web is calculated using the force Fg inthe flange as follows:

σ =⋅

F

r tg

For Type No. 21:– cruciform joint– cruciform joint

7180


2013

Table 16.2.2.1Factor fn for the determination of the permissible stress range for standard stress range spectra

Welded Joints Plating Edges(mo = 3) type 28 (mo = 5) type 29 (mo = 4) type 30 (mo = 3,5)nmax = nmax = nmax = nmax =

Stressrange

spectrum103 105 5 ⋅ 107 103 105 5 ⋅ 107⋅ 103 105 5 ⋅ 107 103 105 5 ⋅ 107

A (17,2) 3,66 (8,1) 3,67 (11,0) 3,76 (13,5) 3,74B (9,2) 1,76 (9,5) 5,0 1,99 (15,0) 6,4 1,93 7,5 1,86C (12,6) 2,71 0,465

0,7371) 4,57 1,82 0,6450,8331) (6,7) 2,11 0,572

0,7951) (8,8) 2,35 0,5250,7701)

1) fn for non-corrosive environment, see also 16.2.3.1.4.The values given in parentheses may be applied for interpolation.For interpolation between any pair of values (nmax1 ; fn1) and (nmax2 ; fn2), for following formula may be applied in the case ofstress spectrum A or B:

log fn = log fn1 + log (nmax/nmax1) log

log

( / )

( / )max max

f f

n nn n2 1

2 1For the stress spectrum C intermediate values may be calculated according to 16.2.3.1.2 by taking N = nmax andfn = ∆σ/∆σR.

16.2.3 Design S-N curves

16.2.3.1 Description of the design S-N curves

16.2.3.1.1 The design S-N curves for the calculation ofthe cumulative damage ratio according to 16.2.2.2 are shownin Fig. 16.2.3.1.1-1 for welded joints and in Fig. 16.2.3.1.1-2for notches at free plate edges. The S-N curves represent thelower limit of the scatter band of 95% of all test results avail-

able (corresponding to 97,5 % survival probability) consid-ering further detrimental effects in large structures.

To account for different influence factors, thedesign S-N curves have to be corrected according to 16.2.3.2.

16.2.3.1.2 The S-N curves represent sectionwise linearrelationships between log (∆σ) and log (N):

Figure 16.2.3.1.1-1


2013

Figure 16.2.3.1.1-2

log (N) = 6,6987 + m ⋅ Q

Q = log (∆σR / ∆σ) - 0,39794 / mom = inverse slope of S-N curvemo = inverse slope in the range N ≤ 5 ⋅ 106

mo = 3 for welded jointsmo = 3,5 ÷ 5 for free plate edges (see Fig.

16.2.3.1.1-2)The S-N curve for detail category 160 forms

the upper limit also for free plate edges with detail categories100 - 140 in the range of low stress cycles, see Fig.16.2.3.1.1-2.

16.2.3.1.3 For structures subjected to variable stressranges, the S-N curves shown by the solid lines in Fig.16.2.3.1.1-1 and Fig. 16.2.3.1.1-2 have to be applied (S-Ncurves of type "M"), i.e.

m = mo, for Q ≤ 0m = 2 ⋅ mo – 1, for Q > 0

16.2.3.1.4 For stress ranges of constant magnitude (stressrange spectrum C) in non-corrosive environment the stressrange given at N = 5 ⋅ 106 cycles may be taken as fatiguelimit (S-N curves of type "O" in Fig. 16.2.3.1.1-1 and16.2.3.1.1-2) thus:

m = mo, for Q ≤ 0m = ∞, for Q > 0

16.2.3.2 Correction of the reference value of the de-sign S-N curve

16.2.3.2.1 A correction of the reference value of the S-Ncurve (or detail category) is required to account for addi-tional influence factors on fatigue strength as follows:

∆σRc = fm ⋅ fR ⋅ fw ⋅ fi ⋅ ∆σR

fm, fR, fw, fi defined in 16.2.3.2.2-16.2.3.2.5.

In order to account for the plate thickness ef-fect, application of an additional reduction factor may be re-quired by Register, for welded connections oriented trans-versely to the direction of applied stress with larger platethicknesses.

For the description of the corrected design S-Ncurve, the formulae given in 16.2.3.1.2 may be used by re-placing ∆σR by ∆σRc.

16.2.3.2.2 Material effect (fm)For welded joints it is generally assumed that

the fatigue strength is independent of steel strength, i.e.:

fm = 1,0

For free plate edges the effect of the material'syield point is accounted for as follows:

fm = 1 +ReH − 235

1200

ReH = minimum nominal upper yield pointof the steel [N/mm2].

16.2.3.2.3 Effect of mean stress (fR)The correction factor is calculated as follows:- fR = 1,0

in the range of tensile pulsating stresses

σm ≥ ∆σmax

2

− fR = 1 + c 12

−⋅

σm∆σmax

in the range of alternating stresses

− ∆σ ∆σmax max

2 2≤ ≤σm

- fR = 1 + 2 ⋅ cin the range of compressive pulsatingstresses


2013

σm ≤ −∆σmax

2

c = 0 for welded joints subjected toconstant stress cycles (stressrange spectrum C)

= 0,15 for welded joints subjected tovariable stress cycles (corre-sponding to stress range spectrumA or B)

= 0,3 for free plate edges.

16.2.3.2.4 Effect of weld shape (fw)In normal cases:

fw = 1,0.For butt welds ground flush either the corre-

sponding detail category has to be chosen, e.g. type 1 in Ta-ble 16.2.1.1 or a weld shape factor

fw = 1,25may be applied.For endings of stiffeners or brackets, e.g. type

14 or 16 in Table 16.2.1.1, which have a full penetrationweld and are completely ground flush to achieve a notch-freetransition, the following factor applies:

fw = 1,4.The assessment of a local post-weld treatment

of the weld surface and the weld toe, e.g. by grinding or ap-plying an improved weld profile, has to be agreed on in eachcase.

16.2.3.2.5 Influence of importance of structural ele-ment (fi)In general the following applies:fi = 1,0.For secondary structural elements failure of

which may cause failure of larger structural areas, the cor-rection factor fi is to be taken as:

fi = 0,9.For notches at plate edges in general the fol-

lowing correction factor is to be taken which takes into ac-count the radius of rounding:

fi = 0,9 + 5/r ≤ 1,0.r = notch radius in [mm]; for elliptical

roundings the mean value of the twomain half axes may be taken.

16.3 FATIGUE STRENGTH ANALYSISFOR WELDED JOINTS BASED ON LO-

CAL STRESSES

16.3.1 Alternatively to the procedure described in thepreceding paragraphs, the fatigue strength analysis forwelded joints may be performed on the basis of localstresses. For common plate and shell structures in ships theassessment based on the so-called structural (or hot-spot)stress σs is normally sufficient.

The structural stress is defined as the stressbeing extrapolated to the weld toe excluding the local stressconcentration in the local vicinity of the weld, see Fig.16.3.1.

Fig 16.3.1

16.3.2 For the fatigue strength analysis based onstructural stress, the S-N curves shown in Fig. 16.2.3.1.1-1apply with the following reference values:

∆σR = 100 for K-butt welds with filletwelded ends, e.g. type 21 in Ta-ble 16.2.1.1, and for fillet weldswhich carry no load or only partof the load of the attached plate,e.g. type 17 in Table 16.2.1.1.

∆σR = 90 for fillet welds, which carry thetotal load of the attached plate,e.g. type 22 in Table 16.2.1.1.

For butt welds the values given for types 1 to 4in Table 16.2.1.1 apply. In special cases, where e.g. thestructural stresses are obtained by non-linear extrapolation tothe weld toe and where they contain a high bending portion,increased reference values of up to 15% can be allowed.

16.3.3 The reference value ∆σRc of the corrected S-Ncurve is to be determined according to 16.2.3.2, taking intoaccount the following additional correction factor which de-scribes further influencing parameters such as e.g. predefor-mations:

fs = 0,71 for cruciform joints (correspondingto types 21 and 22 in Table16.2.1.1)

fs = 0,8 for transverse stiffeners or tee-joints(corresponding to type 17 and 21 -22 in Table 16.2.1.1)

fs = 1,0 in all other cases.The permissible stress range or cumulative

damage ratio, respectively, has to be determined according to16.2.2.

16.3.4 In addition to the assessment of the structuralstress at the weld toe, the fatigue strength with regard to rootfailure has to be considered by analogous application of therespective detail category, e.g. type 23 of Table 16.2.1.1. Inthis case the relevant stress is the stress in the weld throatcaused by the axial stress in the plate perpendicular to theweld.


2013

17 STRENGTHTENINGS FORHEAVY CARGO, BULK CARRI-

ERS, ORE CARRIERS

17.1 STRENGHTENINGS FOR HEAVYCARGO

17.1.1 General

17.1.1.1 For ships, occasionally or regularly carryingheavy cargo, such as iron, ore, phosphate etc., and not in-tended to get the notation "Bulk carrier-ESP" or "Ore carrier"strengthenings according to the following regulations arerecommended.

17.1.1.2 Ships complying with these requirements willget the following notation affixed to their character of classi-fication HCS, see Rules, Part 1 – General requirementsChapter 1, 4.2.

17.1.1.3 It is recommended to provide adequatestrengthening or protection of structural elements within theworking range of grabs.

17.1.2 Double bottom

17.1.2.1 Where longitudinal framing is adopted for thedouble bottom, the spacing of plate floors are, in general, notto be greater than the height of the double bottom. The scan-tilings of the inner bottom longitudinals are to be determinedfor the load of the cargo according to Section 8.2.

For the longitudinal girder system, see Section7.2.7.5.

17.1.2.2 Where transverse framing is adopted for thedouble bottom, plate floors according to Section 7.2.6 are tobe fitted at every frame in way of the cargo holds.

17.1.2.3 For strengthening of inner bottom, deep tanktops etc. in way of grabs, see 17.2.4.3.

17.1.3 Longitudinal strength

The longitudinal strength of the ship mustcomply with the requirements of Section 4 irrespective of theship's length.

17.2 BULK CARRIERS

17.2.1 General

17.2.1.1 Bulk carriers built in accordance with the fol-lowing requirements will get affixed the notation Bulk Car-rier. Entries HME will be made into the certificate as towhether specified cargo holds may be empty in case of alter-nating loading. See the Rules, Part 1 – General require-ments, Chapter 1 – General information, 4.2.

Additional indications of the types of cargo forwhich the ship is strengthened may be entered into the cer-tificate.

For harmonised notations and correspondingdesign loading conditions for culk carriers see 17.4.6.

17.2.1.2 Bulk carrier is considered in this section a Sin-gle Side Skin Bulk Carrier when one or more cargo holds arebound by the side shell only or by two watertight boundaries,one of which is the side shell, which are less than 1000 mmapart. The distance between the watertight boundaries is tobe measured perpendicular to the side shell.

When the distance is 1000 mm or above incargo length area, such a ship is considered a Double SideSkin Bulk Carrier.

See also the Rules, Part 1 – General require-ments, Chapter 1 – General information, 4.2.

17.2.1.3 For bulk carriers carrying also oil in bulk seethe Rules, Part 1 – General requirements, Chapter 1 – Gen-eral information, 4.2.

17.2.1.4 The scantlings of the bottom construction are tobe determined on the basis of direct calculations according toSection 7.2.8.

17.2.1.5 Bulk carriers described in 17.2.1.2 that arecontracted for construction on or after 1 January 2003 are tocomply with requirements for detection of water ingress intocargo holds, ballast tanks and dry spaces forward of the colli-sion bulkhead by the time of delivery. For these requirementsand means of water ingress detection, see Annex A, A.4.

17.2.1.6 Bulk carriers described in 17.2.1.2 that arecontracted for construction on or after 1 January 2003 are tocomply with requirements for draining and pumping ballasttanks and dry spaces forward of the collision bulkhead by thetime of delivery. For these requirements and means of wateringress detection, see Annex A, A.4.

17.2.1.7 The requirements of Sections 1 to 16 apply tobulk carriers unless otherwise mentioned in this Section.Paragraph 17.1.1.3 is also to be observed.

17.2.1.8 For hull structural design of bulk carriers of 90m in length or greater, contracted for construction on or after1. April 2006 and in accordance with the definition in17.2.1.9, the IACS Common Structural Rules for Bulk Carri-ers shall apply.

17.2.1.9 Bulk carrier according to the IACS CommonStructural Rules means a ship which is constructed generallywith single deck, double bottom, top-side tanks and hopperside tanks in cargo spaces, with single or double side skinconstruction in cargo length area and is intended primarily tocarry dry cargo in bulk. Typical midship sections are given inFig. 17.2.1.9.

Figure 17.2.1.9 Single and double side skin bulk carrier


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17.2.1.10 Bulk carriers of 150 m in length and upwardsof single-side skin construction, designed to carry solid bulkcargoes having a density of 1,000 kg/m3 and above, con-structed on or after 1 July 1999, shall have sufficient strengthto withstand flooding of any one cargo hold to the waterlevel outside the ship in that flooded condition in all loadingand ballast conditions, taking also into account dynamic ef-fects resulting from the presence of water in the hold, andtaking into account the recommendations adopted by the Or-ganization.*

17.2.1.11 Bulk carriers of 150 m in length and upwardsof double-side skin construction, in which any part of longi-tudinal bulkhead is located within B/5 or 11.5 m, whicheveris less, inboard from the ship's side at right angle to the cen-treline at the assigned summer load line, designed to carrybulk cargoes having a density of 1,000 kg/m3 and above,constructed on or after 1 July 2006, shall comply with thestructural strength provisions in 17.2.1.10.

17.2.1.12 For application of the requirements in 17.2.1.10and 17.2.1.11 (SOLAS XII/5) see IACS unified interpretationSC 207.

17.2.1.13 For application of SOLAS XII/6.5.1 in terms ofprotection of cargo holds from loading/discharge equipment,see IACS unified interpretation SC 208.

17.2.1.14 For application of SOLAS XII/6.5.3 andSLS.14/Circ.250 in terms of redundancy of stiffening struc-tural members for vessels not designed according to CSR forBulk Carriers, see IACS unified interpretation SC 209.

17.2.1.15 For application of the requirements relating todefinition of double-side skin (regulation XII/1.4) and struc-tural and other requirements for bulk carriers in areas withdouble-side skin construction (regulation XII/6.2, see IACSunified interpretation SC 210.

* Refer to resolution 3, Recommendation on compliance withSOLAS regulation XII/s, adopted by the 1997 SOLAS Confer-ence.

17.2.2 Longitudinal strength

17.2.2.1 Unless otherwise mentioned in this Section therequirements of Section 4 apply.

17.2.2.2 Longitudinal strength of hull girder inflooded condition for bulk carriers

17.2.2.2.1 GeneralThis requirement is to be complied with in re-

spect of the flooding of any cargo hold of bulk carriers withnotation BC-A or BC-B, as defined in Section 17.4.6.

Such ships are to have their hull girder strengthchecked for specified flooded conditions, in each of the cargoand ballast loading conditions defined in 4.2.1.2 to 4.2.1.4and in every other condition considered in the intact longitu-dinal strength calculations, including those according to Sec-tion 17.4, except that harbour conditions, docking conditionafloat, loading and unloading transitory conditions in portand loading conditions encountered during ballast water ex-change need not be considered.

17.2.2.2.2 Flooding conditions

17.2.2.2.2.1 Floodable holds

Each cargo hold is to be considered individu-ally flooded up to the equilibrium waterline.

17.2.2.2.2.2 Loads

The still water loads in flooded conditions areto be calculated for the above cargo and ballast loading con-ditions.

The wave loads in the flooded conditions areassumed to be equal to 80% of those given in Section 4.

17.2.2.2.3 Flooding criteriaTo calculate the weight of ingressed water, the

following assumptions are to be made:a) The permeability of empty cargo spaces and

volume left in loaded cargo spaces above anycargo is to be taken as 0.95.

b) Appropriate permeabilities and bulk densitiesare to be used for any cargo carried. For ironore, a minimum permeability of 0.3 with a cor-responding bulk density of 3.0 t/m3 is to beused. For cement, a minimum permeability of0.3 with a corresponding bulk density of 1.3t/m3 is to be used. In this respect, "permeabil-ity" for solid bulk cargo means the ratio of thefloodable volume between the particles, gran-ules or any larger pieces of the cargo, to thegross volume of the bulk cargo.For packed cargo conditions (such as steel mill

products), the actual density of the cargo should be used witha permeability of zero.

17.2.2.2.4 Strength assessment

The actual hull girder bending stress σfld at anylocation is given by:

σfl = M M

Wsf w

z

+ ⋅0 8,⋅ 103, [N/mm2]

where:Msf = still water bending moment, in [kNm], in

the flooded conditions for the section un-der consideration;

MW = wave bending moment, in [kNm], as given inSection 4.2.2 for the section under con-sideration

WZ = section modulus, in [cm3], for the corre-sponding location in the hull girder.

The shear strength of the side shell and the in-ner hull (longitudinal bulkhead) if any, at any location of theship, is to be checked according to the requirements specifiedin Section 4.4 in which FS and FW are to be replaced respec-tively by FSF and FWF, where:

FSF = still water shear force, in [kN], in theflooded conditions for the section underconsideration

FWF = 0,8 FWFW = wave shear force, in [kN], as given in

Section 4.2.3 for the section under con-sideration.

17.2.2.2.5 Strength criteria

The damaged structure is assumed to remainfully effective in resisting the applied loading.

Permissible stress and axial stress bucklingstrength are to be in accordance with Section 4.


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17.2.3 Definitions

k = material factor according to 1.4.2.2;tk = corrosion addition according to 2.9.1;PLh = bulk cargo pressure as defined in

Section 3.3.1.4.

17.2.4 Scantlings of bottom structure

17.2.4.1 GeneralThe scantlings of double bottom structures in

way of the cargo holds are to be determined by means of di-rect calculations according to Section 7.2.8.

17.2.4.2 Floors under corrugated bulkheadsPlate floors are to be fitted under the face plate

strips of corrugated bulkheads. A sufficient connection of thecorrugated bulkhead elements to the double bottom structureis to be ensured. Under the inner bottom, scallops in theabove mentioned plate floors are to be restricted to those re-quired for crossing welds. The plate floors as well as the faceplate strips are to be welded to the inner bottom according tothe stresses to be transferred. In general, single bevel T-jointsor double bevel T-joints are to be used. In general, full orpartial penetration welding is to be used, see also17.2.9.4.4.1.

17.2.4.3 Inner bottom and tank side slopes

17.2.4.3.1 The thickness of the inner bottom plating is tobe determined according to Section 7.2.4.

When determining the load on inner bottompDB, a cargo density of not less than 1 t/m3 is to be used.

For determining scantlings of tank side slopesthe load pDB is not to be taken less than the load which resultsfrom an angle of heel of 20o.

17.2.4.3.2 Where grabs are intended to be used, it is rec-ommended to increase the plate thickness by 5 mm above thethickness required in Section 7.2.4.1, or to protect the platingby ceiling or armament in an equivalent manner.

17.2.4.3.3 Sufficient continuity of strength is to be pro-vided for between the structure of the bottom wing tanks andthe adjacent longitudinal structure.

17.2.4.4 Allowable hold loading for bulk carriersconsidering hold flooding

17.2.4.4.1 GeneralThis requirement is to be complied with in re-

spect of the flooding of any cargo hold of bulk carriers, asdefined in 17.2.1.1, of 150m in length and above, with singledeck, topside tanks and hopper tanks, and of single side ordouble side skin construction, intending to carry solid bulkcargoes having a density 1,0 t/m3, or above.

The loading in each hold is not to exceed theallowable hold loading in flooded condition, calculated asper 17.2.4.4.5, using the loads given in 17.2.4.4.2 and17.2.4.4.3 and the shear capacity of the double bottom givenin 17.2.4.4.4.

In no case is the allowable hold loading, con-sidering flooding, to be taken greater than the design holdloading in intact condition.


17.2.4.4.2 Loads - generalThe loads to be considered as acting on the

double bottom are those given by the external sea pressuresand the combination of the cargo loads with those induced bythe flooding of the hold which the double bottom belongs to.

The most severe combinations of cargo inducedloads and flooding loads are to be used, depending on theloading conditions included in the loading manual:

- homogeneous loading conditions;- non homogeneous loading conditions;- packed cargo condition (such as steel will

products).For each loading condition, the maximum bulk

cargo density to be carried is to be considered in calculatingthe allowable hold loading limit.

17.2.4.4.3 Inner bottom flooding headThe flooding head hf (see Figure 17.2.4.4.3) is

the distance, in [m], measured vertically with the ship in theupright position, from the inner bottom to a level located at adistance df, in m, from the baseline equal to:

a) in general:- D, for the foremost hold- 0,9 D, for the other holds

b) for ships less than 50,000 tonnes deadweightwith Type B freeboard:- 0,95 D, for the foremost hold- 0,85D, for the other holdsD being the distance, in [m], from the baseline

to the freeboard deck at side amidship (see Figure 17.2.4.4.3)

Figure 17.2.4.4.3

17.2.4.4.4 Shear capacity of the double bottomThe shear capacity C of the double bottom is

defined as the sum of the shear strength at each end of:- all floors adjacent to both hoppers, less one half

of the strength of the two floors adjacent toeach stool, or transverse bulkhead if no stool isfitted (see Figure 17.2.4.4.4).

- all double bottom girders adjacent to bothstools, or transverse bulkheads if no stool isfitted.Where in the end holds, girders or floors run

out and are not directly attached to the boundary stool orhopper girder, their strength is to be evaluated for the oneend only.

The floors and girders to be considered arethose inside the hold boundaries formed by the hoppers andstools (or transverse bulkheads if no stool is fitted). The hop-per side girders and the floors directly below the connection


2013

of the bulkhead stools (or transverse bulkheads if no stool isfitted) to the inner bottom are not to be included.

When the geometry and/or the structural ar-rangement of the double bottom are such to make the aboveassumptions inadequate, the shear capacity C of double bot-tom is to be calculated according to the Register's criteria.

In calculating the shear strength, the net thick-ness of floors and girders is to be used. The net thickness tnet,in [mm], is given by:

tnet = t - 2,5where:

t = thickness, in [mm], of floors and girders.

Figure 17.2.4.4.4

17.2.4.4.5 Allowable hold loadingThe allowable hold loading W, in [t] is given

by:

W = ρc ⋅ V ⋅1F

where:F = 1,1 in general

1,05 for steel mill productsρc = bulk cargo density, in [t/m3] (see

17.2.4.4.2)V = volume, in [m3], occupied by cargo at

a level h1

h1 =X

gcρ ⋅X = the lesser of X1 and X2 given by:

X1 =Z g E h

perm

f

c

+ ⋅ ⋅ −

+ −

ρρρ

( )

( )1 1

X2 = Z + ρ ⋅ g ⋅ (E - hf ⋅ perm)ρ = sea water density, in [t/m3]g = 9,81 m/s2, gravity accelerationE = ship immersion, in [m] for flooded

hold condition = df - 0,1 Ddf,D = as given in 17.2.4.4.3hf = flooding head, in [m], as defined in

17.2.4.4.3perm = cargo permeability, (i.e. the ratio be-

tween the voids within the cargo massand the volume occupied by thecargo); it needs not be taken greaterthan 0.3 and is to be taken equal tozero for steel mill products

Z = the lesser of Z1 and Z2 given by:

Z1 =h,DB

h

AC

Z2 =e,DB

e

AC

Ch = shear capacity of the double bottom,in [kN], as defined in 17.2.4.4.4, con-sidering , for each floor, the lesser ofthe shear strengths Sf1 and Sf2 (see17.2.4.4.6) and, for each girder, thelesser of the shear strengths Sg1 andSg2 (see 17.2.4.4.7)

Ce = shear capacity of the double bottom,in [kN], as defined in 17.2.4.4.4, con-sidering, for each floor, the shearstrength Sf1 (see 17.2.4.4.6) and, foreach girder, the lesser of the shearstrengths Sg1 and Sg2 (see 17.2.4.4.7)

ADB,h = = S Bii

i n

DB i=

=

∑ ⋅1

,

ADB,e = S B si DBi

i n

⋅ −=

=

∑ ( )11

n = number of floors between stools (ortransverse bulkheads, if no stool isfitted)

Si = space of ith-floor, in [m]BDB,i = BDB - s1, for floors whose shear

strength is given by Sf1 (see17.2.4.4.6)

BDB,i = BDB,h for floors whose shear strengthis given by Sf2 (see 17.2.4.4.6)

BDB = breadth of double bottom, in [m],between hoppers (see Figure17.2.4.4.5)

BDB,h = distance, in [m], between the twoconsidered opening (see Figure17.2.4.4.5)

s1 = spacing, in [m], of double bottomlongitudinals adjacent to hoppers

Figure 17.2.4.4.5

17.2.4.4.6 Floor shear strengthThe floor shear strength in way of the floor

panel adjacent to hoppers Sf1, in [kN], and the floor shearstrength in way of the openings in the outmost bay (i.e. thatbay which is closer to hopper) Sf2, in [kN], are given by thefollowing expressions:

Sf1 = 10-3 ⋅ Af ⋅τη

a

1


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Sf2 = 10-3 ⋅ Af,h ⋅τη

a

2where:

Af = sectional area, in [mm2], of the floorpanel adjacent to hoppers

Af,h = net sectional area, in [mm2], of thefloor panels in way of the openings inthe outmost bay (i.e. that bay whichis closer to hopper)

τa = allowable shear stress, in [N/mm2], tobe taken equal to the lesser of

τa = 162 0 6

0 8⋅σ F

nets t

,

,( / ) and

σ F

3

For floors adjacent to the stools or transversebulkheads, as identified in 17.2.4.4.4 τa may be takenσF / 3

σF = minimum upper yield stress, in[N/mm2], of the material

s = spacing of stiffening members, in[mm], of panel under consideration

η1 = 1,10η2 = 1,20η2 may be reduced down to 1.10 where ap-

propriate reinforcements are fitted to theRegister's satisfaction

17.2.4.4.7 Girder shear strengthThe girder shear strength in way of the girder

panel adjacent to stools (or transverse bulkheads, if no stoolis fitted) Sg1, in [kN], and the girder shear strength in way ofthe largest opening in the outmost bay (i.e. that bay which iscloser to stool, or transverse bulkhead, if no stool is fitted)Sg2, in [kN], are given by

Sg1 = 10-3 ⋅ Ag ⋅τη

a

1

Sg2 = 10-3 ⋅ Ag,h ⋅τη

a

2

where:Ag = minimum sectional area, in [mm2], of

the girder panel adjacent to stools (ortransverse bulkheads, if no stool isfitted)

Ag,h = net sectional area, in [mm2], of thegirder panel in way of the largestopening in the outmost bay (i.e. thatbay which is closer to stool, or trans-verse bulkhead, if no stool is fitted)

τa = allowable shear stress, in [N/mm2], asgiven in 17.2.4.4.6

η1 = 1,10η2 = 1,15η2 may be reduced down to 1.10 where ap-

propriate reinforcements are fitted to theRegister's satisfaction

17.2.5 Side structures in single side skin bulkcarriers

17.2.5.1 These requirements apply to side structures ofcargo holds bounded by the side shell only of bulk carriers

constructed with single deck, topside tanks and hopper tanksin cargo spaces intended primarily to carry dry cargo in bulk.

These requirements do not apply to CSR Bulk Carriers.

17.2.5.2 The scantlings of side hold frames immediatelyadjacent to the collision bulkhead are to be increased in orderto prevent excessive imposed deformation on the shell plat-ing. As an alternative, supporting structures are to be fittedwhich maintain the continuity of forepeak stringers withinthe foremost hold.

17.2.5.3 The thickness of frame webs within the cargoarea is not to be less than tw,min, in [mm], given by:

tw,min = C (7,0 + 0,03 L)

C = 1,15 for the frame webs in way of theforemost hold;

C = 1,0 for the frame webs in way ofother holds.

where L need not be taken greater than 200 m.

17.2.5.4 The thickness of the frame lower brackets isnot to be less than the greater of tw and tw,min + 2 mm, wheretw is the fitted thickness of the side frame web. The thicknessof the frame upper bracket is not to be less than the greater oftw and tw,min.

The section modulus SM of the frame andbracket or integral bracket, and associated shell plating, atthe locations shown in Figure 17.2.5.4-1, is not to be lessthan twice the section modulus SMF required for the framemidspan area.

The dimensions of the lower and upper brack-ets are not to be less than those shown in Figure 17.2.5.4-2.

Structural continuity with the upper and lowerend connections of side frames is to be ensured within top-sides and hopper tanks by connecting brackets as shown inFigure 17.2.5.4-3. The brackets are to be stiffened againstbuckling according to the Register's criteria.

The section moduli of the side longitudinalsand sloping bulkhead longitudinals which support the con-necting brackets are to be determined according to the Reg-ister's criteria with the span taken between transverses. Otherarrangements may be adopted at the Register's discretion.


2013

b1b1

Figure 17.2.5.4-1

Figure 17.2.5.4-2

Figure 17.2.5.4-3

17.2.5.5 Frames are to be fabricated symmetrical sec-tions with integral upper and lower brackets and are to be ar-ranged with soft toes (see Fig. 17.2.5.4-3).

The side frame flange is to be curved (notknuckled) at the connection with the end brackets. The radiusof curvature is not to be less than r, in [mm], given by:

r =0 4 2, ⋅b

tf

f

where bf and tf are the flange width and thickness of thebrackets, respectively, in [mm]. The end of the flange is to besniped.

In ships less than 190 m in length, mild steelframes may be asymmetric and fitted with separate brackets.The face plate or flange of the bracket is to be sniped at bothends. Brackets are to be arranged with soft toes.

The web depth to thickness ratio of frames isnot to exceed the following values:

- 60 k0,5 for symmetrically flanged frames- 50 ⋅ k0,5 for asymmetrically flanged

frameswhere k = 1,0 for ordinary hull structural steel and k < 1 forhigher tensile steel according to 1.4.2.2.

The outstanding flange b1 shown in Fig.17.2.5.4-1 is not to exceed 10 ⋅ k0,5 times the flange thick-ness.


2013

Figure 17.2.5.6

17.2.5.6 In way of the foremost hold, side frames ofasymmetrical section are to be fitted with tripping brackets atevery two frames, as shown in Figure 17.2.5.6:

17.2.5.7 Double continuous welding is to be adopted forthe connections of frames and brackets to side shell, hopperand upper wing tank plating and web to face plates.

For this purpose, the weld throat is to be (seeFigure 17.2.5.4-1)

- 0,44 t in zone "a"- 0,4 t in zone "b"

where t is the thinner of the two connected members.Where the hull form is such to prohibit an ef-

fective fillet weld, edge preparation of the web of frame andbracket may be required, in order to ensure the same effi-ciency as the weld connection stated above.

17.2.5.8 The thickness of side shell plating located be-tween hopper and upper wing tanks is not to be less than tp,minin [mm], given by:

tp,min = L [mm]

17.2.6 Topside tanks

17.2.6.1 The plate thickness of the topside tanks is to bedetermined according to Section 11.

17.2.6.2 Where the transverse stiffening system is ap-plied for the longitudinal walls of the topside tanks and forthe shell plating in way of the topside tanks, the stiffeners ofthe longitudinal walls are to be designed according to Section11, the transverse frames at the shell according to Section8.1.3.

17.2.6.3 The buckling strength of top side tank struc-tures is to examined in accordance with Section 4.6.

17.2.6.4 Sufficient continuity of strength is to be pro-vided for between the structure of the topside tanks and theadjacent longitudinal structure.

17.2.7 Transverses in the wing tanks

Transverses in the wing tanks are to be deter-mined according to Section 11.2.3 for the load resulting fromthe head of water or for the cargo load.

The greater load is to be considered. Thescantlings of the transverses in the lower wing tanks are alsoto be examined for the loads according to 17.2.4.3.1.

17.2.8 Hatchway coamings

The scantlings of the hatchway coaming platesare to be determined such as to ensure efficient protectionagainst mechanical damage by grabs. The coaming plates areto have a minimum thickness at 15 mm.

The longitudinal hatchway coamings are to beextended in a suitable manner beyond the hatchway corners.

17.2.9 Cargo hold bulkheads

17.2.9.1 The scantlings of cargo hold bulkheads are tobe determined on the basis of the requirements for tankstructures according to Section 11.2, where the load pLh is tobe used for the load p.

17.2.9.2 The scantlings are not to be less than those re-quired for watertight bulkheads according to Section 10. Theplate thickness is in no case to be taken less than 9,0 mm.

17.2.9.3 The scantlings of the cargo hold bulkheads areto be verified by direct calculations.

17.2.9.4 Evaluation of scantlings of corrugatedtransverse watertight bulkheads in bulk car-riers considering hold flooding.

17.2.9.4.1 General

This requirement is to be complied with in re-spect of the flooding of any cargo hold of bulk carriers of150 m in length and above, with single deck, topside tanksand hopper tanks, and of single side or double side skin con-struction, intending to carry solid bulk cargoes having a den-sity of 1,0 t/m3, or above, with vertically corrugated trans-verse watertight bulkheads.

The net thickness tnet is the thickness obtainedby applying the strength criteria given in 17.2.9.4.4.

The required thickness is obtained by addingthe corrosion addition tk, given in 17.2.9.4.6, to the net thick-ness tnet.

In this requirement, homogeneous loading con-dition means a loading condition in which the ratio betweenthe highest and the lowest filling ratio, evaluated for eachhold, does not exceed 1,20, to be corrected for differentcargo densities.


17.2.9.4.2 Loads

17.2.9.4.2.1 GeneralThe loads to be considered as acting on the

bulkheads are those given by the combination of the cargoloads with those induced by the flooding of one hold adjacentto the bulkhead under examination. In any case, the pressuredue to the flooding water alone is to be considered.

The most severe combinations of cargo inducedloads and flooding loads are to be used for the check of the


2013

scantlings of each bulkhead, depending on the loading con-ditions included in the loading manual:

- homogeneous loading conditions;- non homogeneous loading conditions;

considering the individual flooding of both loaded and emptyholds.

The specified design load limits for the cargoholds are to be represented by loading conditions defined bythe designer in the loading manual.

Non homogeneous part loading conditions as-sociated with multiport loading and unloading operations forhomogeneous loading conditions need not to be consideredaccording to these requirements. Holds carrying packed car-goes are to be considered as empty holds for this application.

Unless the ship is intended to carry, in non ho-mogeneous conditions, only iron ore or cargo having bulkdensity equal or greater than 1,78 t/m3, the maximum mass ofcargo which may be carried in the hold is also to be consid-ered to fill that hold up to the upper deck level at center line.

17.2.9.4.2.2 Bulkhead corrugation flooding headThe flooding head hf (see Fig. 17.2.9.4.2.2) is

the distance, in [m], measured vertically with the ship in theupright position, from the calculation point to a level locatedat a distance df, in [m], from the baseline equal to:

a) in general:- D, for the foremost transverse

corrugated bulkhead(bulkhead between cargoholds Nos. 1 and 2)

- 0,9 ⋅ D, for the other bulkheadsWhere the ship is to carry cargoes having bulk

density less than 1,78 [t/m3] in non homogeneous loadingconditions, the following values can be assumed:

- 0,95 ⋅ D, for the foremost trans-verse corrugated bulkhead

- 0,85 ⋅ D, for the other bulkheadsb) for ships less than 50,000 t deadweight

with Type B freeboard:- 0,95 ⋅ D, for the foremost trans-

verse corrugated bulkhead- 0,85 ⋅ D, for the other bulkheads

Where the ship is to carry cargoes having bulkdensity less than 1,78 t/m3 in non homogeneous loading con-ditions, the following values can be assumed:

- 0,9 ⋅ D, for the foremost transversecorrugated bulkhead

- 0,8 ⋅ D, for the other bulkheadsD being the distance, in [m], from the baseline

to the freeboard deck at side amidship (see Fig. 17.2.9.4.2.2)

Figure 17.2.9.4.2.2

17.2.9.4.2.3 Pressure in the non-flooded bulk cargoloaded holdsAt each point of the bulkhead, the pressure pc,

in [kN/m2], is given by:

pc = ρc ⋅ g ⋅ h1 ⋅ tan2γ

where:ρc = bulk cargo density, in [t/m3]g = 9,81 m/s2, gravity accelerationh1 = vertical distance, in [m], from the

calculation point to horizontal planecorresponding to the volume of thecargo (see Fig. 17.2.9.4.2.2), locatedat a distance d1, in [m], from thebaseline.

y = 45o - (ϕ/2)ϕ = angle of repose of the cargo, in de-

grees, that may generally be taken as35o for iron ore and 25o for cement

The force Fc, in [kN], acting on a corrugation isgiven by:

Fc = ρc ⋅ g ⋅ s1 ⋅( )d h hDB LS1

2

2− −

⋅ tan2γ

where:ρc,g d1,y = as given above

s1 = spacing of corrugations, in [m] (seeFig. 17.2.9.4.2.3)

hLS = mean height of the lower stool, in[m], from the inner bottom,

hDB = height of the double bottom, in [m]

Figure 17.2.9.4.2.3

17.2.9.4.2.4 Pressure in the flooded holds

a) Bulk cargo holdsTwo cases are to be considered, depending on

the values of d1 and df.

S = max. a; c


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1) df ≥ d1

At each point of the bulkhead located at a dis-tance between d1 and df from the baseline, the pressure pc,f, in[kN/m2], is given by:

pcf = ρ ⋅ g ⋅ hfwhere:

ρ = sea water density, in [t/m3];g = as given in 17.2.9.4.2.3;hf = flooding head as defined in

17.2.9.4.2.2.At each point of the bulkhead located at a dis-

tance lower than d1 from the baseline, the pressure pc,f, in[kN/m2], is given by:

pc,f = ρ ⋅ g ⋅ hf + [ρc - ρ ⋅ (1 - perm)] ⋅ g ⋅ h1 ⋅ tan2γ

where:p,hf = as given above;

pc, g, h1, y = as given in 17.2.9.4.2.3;perm = permeability of cargo, to be taken as

0,3 for ore (corresponding bulk cargodensity for iron ore may generally betaken as 3,0 t/m3, coal cargoes and forcement (corresponding bulk cargodensity for cement may generally betaken as 1,3 t/m3.

The force Fc,f, in [kN], acting on a corrugationis given by:

( )

−−⋅

+−⋅+

−⋅⋅= LSDBf

lefcfffc hhd

pddgddgsF

2)()(

2)( ,12

11,

ρρ

where:ρ = as given above;

s1,g,d1,hDB,hLS = as given in 17.2.9.4.2.3;df = as given in 17.2.9.4.2.2;

(pc,f) 1e = pressure, in [kN/m2], at the lower endof the corrugation.

2) df < d1

At each point of the bulkhead located at a dis-tance between df and d1 from the baseline, the pressure pc,f,in [kN/m2], is given by

pc,f = ρc ⋅ g ⋅ h1 ⋅ tan2γ

where:pc, g, h1 = as given in 17.2.9.4.2.3At each point of the bulkhead located at a dis-

tance lower than df from the baseline, the pressure pc,f, in[kN/m2], is given by:

pc,f = ρ ⋅ g ⋅ hf + [ρc ⋅ h1 - ρ ⋅ (1 - perm) ⋅ hf] ⋅ g ⋅ tan2γ

where:ρ, hf, perm = as given in 1) above;ρc, g, h1,y = as given in 17.2.9.4.2.3.The force Fc,f, in [kN], acting on a corrugation

is given by:

( )

−−

+−+

−= LSDBf

lefcfcfcfc hhd

pddgddgsF

2)(tan)(

tan2

)( ,2

122

11,

γργρ

where:s1.ρc, g, d1, y, hDB, hLS = as given in 17.2.9.4.2.3;

df = as given in 17.2.9.4.2.2;(ρc,f) le = pressure, in [kN/m2], at the

lower end of the corrugation.

b) Empty holds and pressure due toflooding water alone

At each point of the bulkhead, the hydrostaticpressure pf induced by the flooding head hf is to be consid-ered.

The force Ff, in [kN], acting on a corrugation isgiven by:

Ff = s1 ⋅ ρ ⋅ g ⋅( )d h hf DB LS− − 2

2

where:s1, g, hDB, hLS = as given in 17.2.9.4.2.3;

ρ = as given in 17.2.9.4.2.4.1;df = as given in 17.2.9.4.2.2.

17.2.9.4.2.5 Resultant pressure and force

a) Homogeneous loading conditionsAt each point of the bulkhead structures,the resultant pressure p, in [kN/m2], to beconsidered for the scantlings of the bulk-head is given by:

p = pc,f - 0,8 ⋅ pc

The resultant force F, in [kN], acting on a cor-rugation is given by:

F = Fc,f ⋅ 0,8 ⋅ Fc

b) Non homogeneous loading conditionsAt each point of the bulkhead structures, the re-

sultant pressure p, in [kN/m2], to be considered for the scant-lings of the bulkhead is given by:

p = pc,f


F = Fc,f

17.2.9.4.3 Bending moment and shear force in thebulkhead corrugationsThe bending moment M and the shear force Q

in the bulkhead corrugations are obtained using the formulaegiven in 17.2.9.4.3.1 and 17.2.9.4.3.2. The M and Q valuesare to be used for the checks in 17.2.9.4.4.5

17.2.9.4.3.1 Bending momentThe design bending moment M, in [kN/m], for

the bulkhead corrugations is given by:

M = F l⋅8

where:F = resultant force, in [kN], as given in

17.2.9.4.2.5;l = span of the corrugation, in [m], to be

taken according to Fig. 17.2.9.4.3.1.

17.2.9.4.3.2 Shear forceThe shear force Q, in [kN], at the lower end of

the bulkhead corrugations is given by:

Q = 0,8 ⋅ Fwhere:

F = as given in 17.2.9.4.2.5.


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Note: For the definition of l, the internal end of the upper stool isnot to be taken more than a distance from the deck at thecentre line equal to:- 3 times the depth of corrugations, in general;- 2 times the depth of corrugations, for rectangular stool

Figure 17.2.9.4.3.1

17.2.9.4.4 Strength criteria

17.2.9.4.4.1 GeneralThe following criteria are applicable to trans-

verse bulkheads with vertical corrugations (see Fig.17.2.9.4.2.3 and 17.2.9.4.3.1). For ships of 190 m of lengthand above, these bulkheads are to be fitted with a bottomstool, and generally with a top stool below deck. For smallerships, corrugations may extend from inner bottom to deck.

The corrugation angle φ shown in Fig.17.2.9.4.2.3 is not to be less than 55o.

Requirements for local net plate thickness aregiven in 17.2.9.4.4.7.

In addition, the criteria as given in 17.2.9.4.4.2and 17.2.9.4.4.5 are to be complied with.

The thicknesses of the lower part of corruga-tions considered in the application of 17.2.9.4.4.2 and17.2.9.4.4.3 are to be maintained for a distance from the in-ner bottom (if no lower stool is fitted) or the top of the lowerstool not less than 0,15 ⋅ 1.

The thicknesses of the middle part of corruga-tions as considered in the application of 17.2.9.4.4.2 and17.2.9.4.4.4 are to be maintained to a distance from the deck(if no upper stool is fitted) or the bottom of the upper stoolnot greater than 0,3 ⋅ l.

The section modulus of the corrugation in theremaining upper part of the bulkhead is not to be less than75% of that required for the middle part, corrected for differ-ent yield stresses.

(a) Lower stoolThe height of the lower stool is generallyto be not less than 3 times the depth ofthe corrugations. The thickness and mate-rial of the stool top plate is not to be lessthan those required for the bulkheadplating above. The thickness and materialof the upper portion of vertical or slopingstool side plating within the depth equalto the corrugation flange width from thestool top is not to be less than the re-quired flange plate thickness and materialto meet the bulkhead stiffness require-ment at lower end of corrugation. Thethickness of the stool side plating and thesection modulus of the stool side stiffen-ers is not to be less than those required bythe Register on the basis of the loadmodel in 17.2.9.4.2. The ends of stoolside vertical stiffeners are to be attachedto brackets at the upper and lower ends ofthe stool.The distance from the edge of the stooltop plate to the surface of the corrugationflange is to be in accordance with Fig.17.2.9.4.4.1. The stool bottom is to be in-stalled in line with double bottom floorsand is to have a width not less than 2,5times the mean depth of the corrugation.The stool is to be fitted with diaphragmsin line with the longitudinal double bot-tom girders for effective support of thecorrugated bulkhead. Scallops in thebrackets and diaphragms in way of theconnections to the stool top plate are tobe avoidedWhere corrugations are cut at the bottomstool, corrugated bulkhead plating is to beconnected to the stool top plate by fullpenetration welds. The stool side platingis to be connected to the stool top plateand the inner bottom plating by either fullpenetration or deep penetration welds(see Figure 17.2.9.4.4.1-1). The support-ing floors are to be connected to the innerbottom by either full penetration or deeppenetration welds (see Figure17.2.9.4.4.1-1).


2013

tf = as-built flange thickness

Figure 17.2.9.4.4.1 Permitted distance, d, from edge of stool top plate to surface of corrugation flange

Root face (f): 3 mm to T/3 mmGroove Angle (α): 40˚ to 60˚

Figure 17.2.9.4.4.1-1

b) Upper stoolThe upper stool, where fitted, is to have aheight generally between 2 and 3 times thedepth of corrugations. Rectangular stoolsare to have a height generally equal to 2times the depth of corrugations, measuredfrom the deck level and at hatch side girder.The upper stool is to be properly supportedby girders or deep brackets between theadjacent hatch-end beams.The width of the stool bottom plate is gen-erally to be the same as that of the lowerstool top plate. The stool top of non rectan-gular stools is to have a width not less then2 times the depth of corrugations. Thethickness and material of the stool bottomplate are to be the same as those of thebulkhead plating below. The thickness ofthe lower portion of stool side plating is notto be less than 80% of that required for theupper part of the bulkhead plating wherethe same material is used. The thickness ofthe stool side plating and the sectionmodulus of the stool side stiffeners is not tobe less than those required by the Register

on the basis of the load model in 17.2.9.4.2.The ends of stool side stiffeners are to beattached to brackets at upper and lower endof the stool. Diaphragms are to be fitted in-side the stool in line with and effectivelyattacked to longitudinal deck girders ex-tending to the hatch end coaming girdersfor effective support of the corrugatedbulkhead. Scallops in the brackets and dia-phragms in way of the connection to thestool bottom plate are to be avoided.

(c) AlignmentAt deck, if no stool is fitted, two transversereinforced beams are to be fitted in linewith the corrugation flanges.At bottom, if no stool is fitted, the corruga-tion flanges are to be in line with the sup-porting floors. Corrugated bulkhead platingis to be connected to the inner bottom plat-ing by full penetration welds. The platingof supporting floors is to be connected tothe inner bottom by either full penetrationor deep penetration welds (see Figure17.2.9.4.4.1-1). The thickness and materialproperties of the supporting floors are to be


2013

at least equal to those provided for the cor-rugation flanges. Moreover, the cut-outs forconnections of the inner bottom longitudi-nals to double bottom floors are to beclosed by collar plates. The supportingfloors are to be connected to each other bysuitably designed shear plates, as deemedappropriate by the Register.Stool side plating is to align with the corru-gation flanges and stool side vertical stiff-eners and their brackets in lower stool areto align with the inner bottom longitudinalsto provide appropriate load transmissionbetween these stiffening members. Stoolside plating is not to be knuckled anywherebetween the inner bottom plating and thestool top.

17.2.9.4.4.2 Bending capacity and shear stress

The bending capacity is to comply with thefollowing relationship:

100 5

3 ⋅⋅ ⋅ + ⋅

MZ Zle a le m a m, , ,σ σ

≤ 0,95

where:M = bending moment, in [kNm], as given

in 17.2.9.4.3.1;Zle = section modulus, in [cm3], at the

lower end of corrugations, to be cal-culated according to 17.2.9.4.4.3;

Zm = section modulus, in [cm3], at the mid-span of corrugations, to be calculatedaccording to 17.2.9.4.4.4;

σa,le = allowable stress, in [N/mm2], as givenin 17.2.9.4.4.5, for the lower end ofcorrugations;

σa,m = allowable stress, in [N/mm2], as givenin 17.2.9.4.4.5, for the mid-span ofcorrugations.

In no case Zm is to be taken greater than thelesser of 1,15 ⋅ Zle and 1,15 ⋅ Z'le for calculation of the bend-ing capacity Z'le being defined below.

In case shedders plates are fitted which:- re not knuckled:- are welded to the corrugations and the top

of the lower stool by one side penetrationwelds or equivalent:

- are fitted with a minimum slope of 45o

and their lower edge is in line with thestool side plating;

- have thicknesses not less than 75% ofthat provided by the corrugation flange;

- and material properties at least equal tothose provided by the flanges.

or gusset plates are fitted which:- are in combination with shedder plates

having thickness, material properties andwelded connection in accordance with theabove requirements;

- have a height not less than half of theflange width;

- are fitted in line with the stool side plat-ing;

- are generally welded to the top of thelower stool by full penetration welds, and

to the corrugations and shedder plates byone side penetration welds or equivalent.

- have thickness and material properties atleast equal to those provided for theflanges.

The section modulus Zle, in [cm3], is to be takennot larger than the value Z'le, in [cm3], given by:

Z’le = Zg + 103 ⋅Q h h s pg g g

a

⋅ − ⋅ ⋅ ⋅0 5 21,

σ

where:Zg = section modulus, in [cm3], of the cor-

rugations calculated, according to17.2.9.4.4.4, in way of the upper endof shedder or gusset plates, as appli-cable

Q = shear force, in [kN], as given in17.2.9.4.3.2

hg = height, in [m], of shedders or gussetplates, as applicable (see Fig.17.2.9.4.4.3-1 and 17.2.9.4.4.3-2)

s1 = as given in 17.2.9.4.2.3pg = resultant pressure, in [kN/m2], as de-

fined in 17.2.9.4.2.5, calculated inway of the middle of the shedders orgusset plates, as applicable

σa = allowable stress, in [N/mm2], as givenin 17.2.9.4.4.5

Stresses τ are obtained by dividing the shearforce Q by the shear area. The shear area is to be reduced inorder to account for possible non-perpendicularity betweenthe corrugation webs and flanges. In general, the reducedshear area may be obtained by multiplying the web sectionalarea by (sin φ), φ being the angle between the web and theflange.

When calculating the section modulus and theshear area, the net plate thicknesses are to be used.

The section modulus of corrugations are to becalculated on the basis of the following requirements given in17.2.9.4.4.3 and 17.2.9.4.4.4

17.2.9.4.4.3 Section modulus at the lower end of corruga-tionsThe section modulus is to be calculated with

the compression flange having an effective flange width bef,not larger than as given in 17.2.9.4.4.6

If the corrugation webs are not supported bylocal brackets below the stool top (or below the inner bot-tom) in the lower part, the section modulus of the corruga-tions is to be calculated considering the corrugation webs30% effective.

a) Provided that effective shedder plates, asdefined in 17.2.9.4.4.2, are fitted (see Fig.17.2.9.4.4.3-1) when calculating the sec-tion modulus of corrugations at the lowerend (cross-section in Fig. 17.2.9.4.4.3-1), the area of flange plates, in [cm2],may be increased by:

( )2 5, ⋅ ⋅a t tf sh

(Not to be taken greater than 2,5 ⋅ a ⋅ tf) where:a = width, in [m], of the corrugation

flange (see Fig. 17.2.9.4.2.3);tsh = net shedder plate thickness, in [mm]


2013

tf = net flange thickness, in [mm];b) Provided that effective gusset plates, as

defined in 17.2.9.4.42, are fitted (see Fig.17.2.9.4.4.3-2) when calculating the sec-tion modulus of corrugations at the lowerend (cross-section in Fig. 17.2.9.4.4.3-2), the area of flange plates, in [cm2],may be increased by (7 ⋅ hg ⋅ tf) where:

hg = height of gusset plate in [m], see Fig.17.2.9.4.4.3-2, not to be taken greaterthan

107

⋅

sgu

sgu = width of the gusset plates, in [m];tf = net flange thickness, in [mm], based

on the as built condition.

c) If the corrugation webs are welded to asloping stool top plate, the sectionmodulus of the corrugations may be cal-culated considering the corrugation websfull effective. In case effective gussetplates are fitted, when calculating thesection modulus of corrugations the areaof flange plates may be increased asspecified in b) above. No credit can begiven to shedder plates only.For angles less than 45o the effectivenessof the web may be obtained by linear in-terpolation between 30% for 0o and 100%for 45o.

Figure 17.2.9.4.4.3-1

Symmetric gusset/shedder plates Asymmetric gusset/shedder plates

shedderplate

lowerstool

shedderplate

lowerstool

Symmetric shedder plates Asimmetric shedder plates


2013

Figure 17.2.9.4.4.3-2

17.2.9.4.4.4 Section modulus of corrugations at cross-sections other than the lower end

The section modulus is to be calculated with thecorrugation webs considered effective and the compressionflange having an effective flange width, bef, not larger than asgiven in 17.2.9.4.4.6.1

17.2.9.4.4.5 Allowable stress check

The normal and shear stresses σ and τ are not to exceed theallowable values σa and τa, in [N/mm2], given by:

σa = σFτa = 0,5 σF

σF = minimum upper yield stress, in[N/mm2], of the material.

17.2.9.4.4.6 Effective compression flange width and shearbuckling check

a) Effective width of the compressionflange of corrugations

The effective width bef, in [m], of the corruga-tion flange is given by:

bef = Ce ⋅ a

Ce =2 25 1 25

2, ,β β

− , for β > 1,25

Ce = 1,0, for β ≤ 1,25

β = 103 ⋅ ⋅a

t Ef

Fσ

where:tf = net flange thickness, in [mm];a = width, in [m], of the corrugation flange

(see Fig. 17.2.9.4.2.3);σF = minimum upper yield stress, in

[N/mm2], of the material;E = modulus of elasticity of the material,

in [N/mm2], to be assumed equal to2,06 ⋅ 105 for steel.

b) ShearThe buckling check is to be performed for the

web plates at the corrugation ends.The shear stress τ is not to exceed the critical

value τc, in [N/mm2], obtained by the following formulae:

τc = τE, when τE ≤ τ F2

τc = τF 14

−

ττF

E, when τE >

τ F2

where:

τF = σ F

3

σF = minimum upper yield stress, in[N/mm2], of the material;

τE = 0,09 kt ⋅ E ⋅t

c1000

2

⋅

[N/mm2]

kt,E,t and c are given by:kt = 6.34;E = modulus of elasticity of material as

given in 17.2.9.4.4.6.1;t = net thickness, in [mm], of corrugation

web;c = width, in [m], of corrugation web (see

Fig. 17.2.9.4.2.3).

17.2.9.4.4.7 Local net plate thicknessThe bulkhead local net plate thickness t, in

[mm], is given by:

t = 14,9 ⋅ sw ⋅ 1 05, ⋅ p

Fσ

where:sw = plate width, in [m], to be taken equal

to the width of the corrugation flange

gussetplate

lowerstool

gussetplate

lowerstool

gussetplate

lowerstool


2013

or web, whichever is the greater (seeFig. 17.2.9.4.2.3);

p = resultant pressure, in [kN/m2], as de-fined in 17.2.9.4.2.5, at the bottom ofeach strake of plating; in all cases, thenet thickness of the lowest strake is tobe determined using the resultant pres-sure at the top of the lower stool, or atthe inner bottom, if no lower stool isfitted or at the top of shedders, ifshedder or gusset/shedder plates arefitted;


For built-up corrugation bulkheads, when thethicknesses of the flange and web are different, the net thick-ness of the narrower plating is to be not less than tn, in [mm],given by:

tn = 14,9 ⋅ sn ⋅1 05, ⋅ p

Fσ

sn being the width, in [m], of the narrower plating.The net thickness of the wider plating, in [mm],

is not to be taken less than the maximum of the following

tw = 14,9 ⋅ sw ⋅1 05, ⋅ p

Fσ

and

tw = 440 1 052

2⋅ ⋅ ⋅−

s ptw

Fnp

,σ

where tnp ≤ actual net thickness of the narrower plating andnot to be greater than

14,9 ⋅ sw ⋅1 05, ⋅ p

Fσ

17.2.9.4.5 Local detailsAs applicable, the design of local details is to

comply with the Register’s requirements for the purpose oftransferring the corrugated bulkhead forces and moments tothe boundary structures, in particular to the double bottom andcross-deck structures.

In particular, the thickness and stiffening of ef-fective gusset and shedder plates, as defined in 17.2.9.4.4.3 isto comply with the Register’s requirements, on the basis of theload model in 17.2.9.4.2.

Unless otherwise stated, weld connections andmaterials are to be dimensioned and selected in accordancewith the Register’s requirements.

17.2.9.4.6 Corrosion addition and steel renewalThe corrosion addition ts is to be taken equal to

3,5 mm.Steel renewal is required where the gauged

thickness is less than tnet + 0,5 [mm]Where the gauged thickness is within the range

tnet + 0,5 [mm] and tnet + 1,0 [mm], coating (applied in accor-dance with the coating manufacturer's requirements) or annualgauging may be adopted as an alternative to steel renewal.

17.2.9.4.7 Above vertically corrugated bulkheads, trans-verse girders with double webs are to be fitted below the deck,

to form the upper edge of the corrugated bulkheads. They areto have the following scantlings:- web thickness = thickness of the upper plate strake of

the bulkhead- depth of web ∼ B/22- face plate = 1,5 times the thickness of the upper(thickness) plate strake of the bulkhead.

17.2.9.4.8 Vertically corrugated transverse cargo holdbulkheads are to have a plane stiffened strip of plating at theship's sides. The width of this strip of plating is to be 0,15 Dwhere the length of the cargo hold is 20 m. Where the lengthof the cargo hold is greater/smaller, the width of the strip ofplating is to be increased/reduced proportionally.

17.2.10 Requirements for the fitting of a forecas-tle for bulk carriers, ore carriers andcombination carriers

17.2.10.1 Application

These requirements apply to all bulk carriers,ore carriers and combination carriers, as defined in the Rules,Part 1 – General requirements, Chapter 1 – General informa-tion, 4.2.

Such ships are to be fitted with a closed forecas-tle on the freeboard deck.

The required dimensions of the forecastle aredefined in Section 17.2.10.2.

The structural arrangements and scantlings ofthe forecastle are to comply with these Rules.


17.2.10.2 Dimension

The forecastle is to be located on the freeboarddeck with its aft bulkhead fitted in way or aft of the forwardbulkhead of the foremost hold, as shown in Figure 17.2.10.2.

However, if this requirement hinders hatchcover operation, the aft bulkhead of the forecastle may be fit-ted forward of the forward bulkhead of the foremost cargohold provided the forecastle length is not less than 7% of shiplength abaft the forward perpendicular where the ship lengthand forward perpendicular are defined in Regulation 3 ofICLL, 1966.

The forecastle height HF above the main deck isto be not less than:

.1 the standard height of a superstructure asspecified in the Regulation 33 of ICLL,1966, or,

.2 HC + 0,5 m, where HC is the height of theforward transverse hatch coaming of cargohold No. 1,

whichever is the greater.All points of the aft edge of the forecastle deck

are to be located at a distance lF:

CFF HHl −≤ 5

from the hatch coaming plate in order to applythe reduced loading to the No. 1 forward transverse hatchcoaming and No. 1 hatch cover in applying Section 7.10.8.4.1and Section 7.10.8.5.2, respectively, of the Rules, Part 3-Hull Equipment.


2013

A breakwater is not to be fitted on the forecastledeck with the purpose of protecting the hatch coaming orhatch covers. If fitted for other purposes, it is to be locatedsuch that its upper edge at centre line is not less thanHB/tan20° forward of the aft edge of the forecastle deck,where HB is the height of the breakwater above the forecastle(see Figure 17.2.10.2).

Figure 17.2.10.2

17.3 ORE CARRIERS

17.3.1 General

17.3.1.1 Ore carriers are generally single-deck vesselswith the machinery aft and two continuous longitudinal bulk-heads with the ore cargo holds fitted between them.

Ships built in accordance with the following re-quirements will get affixed the notation “Ore carrier”. EntriesHME will be made into the Certificate as to whether specifiedcargo holds may be empty in case of alternating loading. Ad-ditional indications of the types of cargo for which the ship isstrengthened may be entered into the Certificate.

17.3.1.2 For ships subject to the provisions of this para-graph the requirements of 17.2.9 are applicable unless other-wise mentioned in this sub-section.

17.3.1.3 For ore carriers carrying also oil in bulk alsoSection 18 applies.

17.3.2 Double bottom

17.3.2.1 For achieving good stability criteria in theloaded condition the double bottom between the longitudinalbulkheads should be as high as possible.

17.3.2.2 The strength of the double bottom structure is tocomply with the requirements given in 17.2.4.

17.3.3 Transverse and longitudinal bulkheads

17.3.3.1 The spacing of transverse bulkheads in the sidetanks which are to be used as ballast tanks is to be determinedaccording to Section 18, as for tankers. The spacing of trans-verse bulkheads in way of the cargo hold is to be determinedaccording to Section 10.

17.3.3.2 The scantlings of cargo hold bulkheads exposedto the load of the ore cargo are to be determined according to17.2.9. The scantlings of the side longitudinal bulkheads are tobe at least equal to those required for tankers.

17.4 LOADING INFORMATION FORBULK CARRIERS, ORE CARRIERS AND

COMBINATION CARRIERS

17.4.1 Application

Bulk Carriers, Ore Carriers and CombinationCarriers of 150 m length and above, are to be provided withan approved Loading Manual and approved computer-basedLoading Instrument, in accordance with 17.4.2, 17.4.3 and17.4. 4.

For loading and unloading sequences, see17.4.5.


17.4.2 Definitions

17.4.2.1 Loading manualLoading Manual is a document which describes:a) the loading conditions on which the design

of the ship has been based, including per-missible limits of still water bending mo-ments and shear forces;

b) the results of the calculations of still waterbending moments, shear forces and whereapplicable, limitations due to torsionalloads;

c) for bulk carriers, envelope results andpermissible limits of still water bendingmoments and shear forces in the holdflooded condition according to Section17.2.2.2 as applicable;

d) the cargo hold(s) or combination of cargoholds that might be empty at full draught.If no cargo hold is allowed to be empty atfull draught, this is to be clearly stated inthe Loading Manual;

e) maximum allowable and minimum re-quired mass of cargo and double bottomcontents of each hold as a function of thedraught at mid-hold position;

f) maximum allowable and minimum re-quired mass of cargo and double bottomcontents of any two adjacent holds as afunction of the mean draught in way ofthese holds. This mean draught may becalculated by averaging the draught of thetwo mid-hold positions;

g) maximum allowable tank top loading to-gether with specification of the nature ofthe cargo for cargoes other than bulk car-goes;

h) maximum allowable load on deck andhatch covers. If the vessel is not approvedto carry load on deck or hatch covers, thisis to be clearly stated in the Loading Man-ual;

i) the maximum rate of ballast change to-gether with the advice that a load plan is tobe agreed with the terminal on the basis ofthe achievable rates of change of ballast.


2013

17.4.2.2 Loading instrumentA loading instrument is an approved digital

system as defined in Section 4.1.3. In addition to the require-ments in Section 4.1.4, it shall ascertain as applicable that:

a) the mass of cargo and double bottom con-tents in way of each hold as a function ofthe draught at mid-hold position;

b) the mass of cargo and double bottom con-tents of any two adjacent holds as a func-tion of the mean draught in way of theseholds;

c) the still water bending moment and shearforces in the hold flooded conditions ac-cording to Section 17.2.2.2;

are within permissible values.

17.4.3 Conditions of approval of loading manu-als

In addition to the requirements given in Section4.1.4.3, the following conditions, subdivided into departureand arrival conditions as appropriate, are to be included in theLoading Manual:

a) alternate light and heavy cargo loadingconditions at maximum draught, whereapplicable;

b) homogeneous light and heavy cargo load-ing conditions at maximum draught;

c) ballast conditions. For vessels having bal-last holds adjacent to topside wing, hopperand double bottom tanks, it shall bestrengthwise acceptable that the ballastholds are filled when the topside wing,hopper and double bottom tanks areempty;

d) short voyage conditions where the vesselis to be loaded to maximum draught butwith limited amount of bunkers;

e) multiple port loading/unloading condi-tions;

f) deck cargo conditions, where applicable;g) typical loading sequences where the vessel

is loaded from commencement of cargoloading to reaching full deadweight ca-pacity, for homogeneous conditions, rele-vant part load conditions and alternateconditions where applicable. Typical un-loading sequences for these conditionsshall also be included. The typical load-ing/unloading sequences shall also be de-veloped to not exceed applicable strengthlimitations. The typical loading sequencesshall also be developed paying due atten-tion to loading rate and the deballastingcapability.

h) typical sequences for change of ballast atsea, where applicable.

17.4.4 Conditions of approval of loading instru-ments

The loading instrument is subject to approval. Inaddition to the requirements given in Section 4.1.4.4, the ap-proval is to include as applicable:

a) acceptance of hull girder bending momentlimits for all read-out points

b) acceptance of hull girder shear force limitsfor all read-out points

c) acceptance of limits for mass of cargo anddouble bottom contents of each hold as afunction of draught

d) acceptance of limits for mass of cargo anddouble bottom contents in any two adja-cent holds as a function of draught.

17.4.5 Guidance for loading/unloading se-quences

17.4.5.1 Item 17.4.1 requires that Bulk Carriers, Ore Car-riers and Combination Carriers of 150 m length and above areto be provided with an approved loading manual with typicalloading sequences where the ship is loaded from commence-ment of cargo loading to reaching full deadweight capacity,for homogeneous conditions, relevant part loaded conditionsand alternate conditions where applicable. The typical un-loading sequences shall be developed paying due attention tothe loading rate, the deballasting capacity and the applicablestrength limitations.

17.4.5.2 The shipbuilder will be required to prepare andsubmit for approval typical loading and unloading sequences.

17.4.5.3 The typical loading sequences as relevant shouldinclude:

- alternate light and heavy cargo load con-dition,

- homogeneous light and heavy cargo loadcondition,

- short voyage condition where the ship isloaded to maximum draught but with lim-ited bunkers

- multiple port loading / unloading condi-tion,

- deck cargo condition,- block loading.

17.4.5.4 The loading / unloading sequences may be portspecific or typical.

17.4.5.5 The sequence is to be built up step by step fromcommencement of cargo loading to reaching full deadweightcapacity. Each time the loading equipment changes position toa new hold defines a step. Each step is to be documented andsubmitted to the Register. In addition to longitudinal strength,the local strength of each hold is to be considered.

17.4.5.6 For each loading condition a summary of allsteps is to be included. This summary is to highlight the es-sential information for each step such as:

- How much cargo is filled in each holdduring the different steps,

- How much ballast is discharged from eachballast tank during the different steps,

- The maximum still water bending momentand shear at the end of each step,

- The ship’s trim and draught at the end ofeach step.

17.4.5.7 It is recommended that IACS Rec. 83 be takeninto account when compiling the typical loading and unload-ing sequences described in Section 17.4.5.


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17.4.6 Harmonised notations and correspond-ing design loading conditions for bulkcarriers

17.4.6.1 Application

17.4.6.1.1 This rerequirement is applicable to "Bulk Car-rier" as defined in the Rules for classification of ships, Chap-ter 1, Section 4.2.5.5, having length L as defined in Section1.2.3.1 of 150 m or above and contracted for new constructionon or after 1 July 2003. The consideration of the following re-quirements is recommended for ships having a length L < 150m.

17.4.6.1.2 The loading conditions listed under Section17.4.6.3 are to be used for the checking of rules criteria re-garding longitudinal strength (see Section 4 and Section17.2.2), local strength, capacity and disposition of ballasttanks and stability. The loading conditions listed under17.4.6.4 are to be used for the checking of rule criteria re-garding local strength.

17.4.6.1.3 For the purpose of applying the conditions givenin this requirement, maximum draught is to be taken asmoulded summer load line draught.

17.4.6.1 Harmonized notations and annotations

Bulk Carriers are to be assigned one of the fol-lowing notations:

BC-A: for bulk carriers designed to carry dry bulk cargoes ofcargo density 1.0 tonne/m3 and above with specified holdsempty at maximum draught in addition to BC-B conditions.

BC-B: for bulk carriers designed to carry dry bulk cargoes ofcargo density of 1.0 tonne/m3 and above with all cargo holdsloaded in addition to BC-C conditions.

BC-C: for bulk carriers designed to carry dry bulk cargoes ofcargo density less than 1.0 tonne/m3.

The following additional notations and annota-tions are to be provided giving further detailed description oflimitations to be observed during operation as a consequenceof the design loading condition applied during the design inthe following cases:

1. additional notations;maximum cargo density (in tonnes/m3)for notations BC-A and BC-B if themaximum cargo density is less than 3.0tonnes/m3;no MP for all notations when the vesselhas not been designed for loading and un-loading in multiple ports in accordancewith the conditions specified in Section17.4.6.4.4.3.

2. annotations;allowed combination of specified emptyholds for notation BC-A.

17.4.6.2 Design loading conditions (general)

17.4.6.3.1 BC-CHomogeneous cargo loaded condition where the

cargo density corresponds to all cargo holds, including hatch-ways, being 100% full at maximum draught with all ballasttanks empty.

17.4.6.3.2 BC-B

As required for BC-C, plus:Homogeneous cargo loaded condition with

cargo density 3.0 tonnes/m3, and the same filling rate (cargomass/hold cubic capacity) in all cargo holds at maximumdraught with all ballast tanks empty.

In cases where the cargo density applied for thisdesign loading condition is less than 3.0 tonnes/m3, the maxi-mum density of the cargo that the vessel is allowed to carry isto be indicated with the additional notation maximum cargodensity x.y tonnes/m3.

17.4.6.3.3 BC-AAs required for BC-B, plus:At least one cargo loaded condition with speci-

fied holds empty, with cargo density 3.0 tonnes/m3, and thesame filling rate (cargo mass/hold cubic capacity) in allloaded cargo holds at maximum draught with all ballast tanksempty.

The combination of specified empty holds shallbe indicated with the annotation holds a, b,….may beempty.

In such cases where the design cargo density ap-plied is less than 3.0 tonnes/m3, the maximum density of hecargo that the vessel is allowed to carry shall be indicatedwithin the annotation, e.g. holds a, b,….may be empty, withmaximum cargo density x.y tonnes/m3.

17.4.6.3.4 Ballast conditions (applicable to all notations)

17.4.6.3.4.1 Ballast tank capacity and disposition

All bulk carriers are to have ballast tanks of suf-ficient capacity and so disposed to at least fulfill the followingrequirements.

17.4.6.3.4.1a) Normal ballast condition

Normal ballast condition for the purpose of thisrequirement is a ballast (no cargo) condition where::

.1 the ballast tanks may be full,partially fullor empty. Where partially full option isexercised, the conditions in the last para-graph of Section 4.2.1.2 are to be com-plied with,

.2 any cargo hold or holds adapted for thecarriage of water ballast at sea are to beempty,

.3 the propeller is to be fully immersed, and

.4 the trim is to be by the stern and is not toexceed 0.015L, where L is the length be-tween perpendiculars of the ship.

In the assessment of the propeller immersion andtrim, the draughts at the forward and after perpendiculars maybe used.

17.4.6.3.4.1b) Heavy ballast condition

Heavy ballast condition for the purpose of thisUnified Requirement is a ballast (no cargo)condition where:

.1 the ballast tanks may be full,partially fullor empty. Where partially full option isexercised, the conditions in the last para-graph of Section 4.2.1.2 are to be com-plied with,


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.2 at least one cargo hold adapted for carriageof water ballast at sea, where required orprovided, is to be full,

.3 the propeller immersion I/D is to be atleast 60% whereI = the distance from propeller center-

line to the waterlineD = propeller diameter,and

.4 the trim is to be by the stern and is not toexceed 0.015L, where L is the length be-tween perpendiculars of the ship,

.5 the moulded forward draught in the heavyballast condition is not to be less than thesmaller of 0.03L or 8 m.

17.4.6.3.4.2 Strength requirements

All bulk carriers are to meet the followingstrength requirements:

17.4.6.3.4.2 a) Normal ballast condition

.1 the structures of bottom forward are to bestrengthened in accordance with the Sec-tion 5.4 against slamming for the conditionof Section 17.4.6.3.4.1a) at the lightestforward draught,

.2 the longitudinal strength requirements areto be met for the condition of Section17.4.6.3.4.1a), and

.3 in addition, the longitudinal strength re-quirements are to be met with all ballasttanks 100% full.

17.4.6.3.4.2 b) Heavy ballast condition

.1 the longitudinal strength requirements areto be met for the condition of Section17.4.6.3.4.1b),

.2 in addition to the conditions in .1, the lon-gitudinal strength requirements are to bemet under a condition with all ballast tanks100% full and one cargo hold adapted anddesignated for the carriage of water ballastat sea,where provided, 100 % full, and

.3 where more than one hold is adapted anddesignated for the carriage of water ballastat sea, it will not be required that two ormore holds be assumed 100% full simulta-neously in the longitudinal strength as-sessment, unless such conditions are ex-pected in the heavy ballast condition. Un-less each hold is individually investigated,the designated heavy ballast hold andany/all restrictions for the use of otherballast hold(s) are to be indicated in theloading manual.

17.4.6.3.5 Departure and arrival conditions

Unless otherwise specified, each of the designloading conditions defined in Section 17.4.6.3.1 to Section17.4.6.3.4 is to be investigated for the arrival and departureconditions as defined below.

Departure condition:with bunker tanks not lessthan 95 % full and other consumables 100 %.

Arrival condition:with 10% of consumables.

17.4.6.4 Design loading conditions (for local strength)

17.4.6.4.1 Definitions

The maximum allowable or minimum requiredcargo mass in a cargo hold, or in two adjacently loaded holds,is related to the net load on the double bottom. The net loadon the double bottom is a function of draft, cargo mass in thecargo hold, as well as the mass of fuel oil and ballast watercontained in double bottom tanks.

The following definitions apply:

MH: the actual cargo mass in a cargo hold correspondingto a homogeneously loaded condition at maximumdraught.

MFull: the cargo mass in a cargo hold corresponding tocargo with virtual density (homogeneous mass/holdcubic capacity, minimum 1.0 tonne/m3) filled to thetop of the hatch coaming. MFull is in no case to beless than MH.

MHD: the maximum cargo mass allowed to be carried in acargo hold according to design loading condition(s),with specified holds empty at maximum draft.

17.4.6.4.2 General conditions applicable for all nota-tions

17.4.6.4.2.1 Any cargo hold is to be capable of carrying MFullwith fuel oil tanks in double bottom in way of the cargohold,if any, being 100% full and ballast water tanks in thedouble bottom in way of the cargo hold being empty, atmaximum draught.

17.4.6.4.2.2 Any cargo hold is to be capable of carryingminimum 50% of MH, with all double bottom tanks in way ofthe cargo hold being empty, at maximum draught.

17.4.6.4.2.3 Any cargo hold is to be capable of being empty,with all double bottom tanks in way of the cargo hold beingempty,at the deepest ballast draught.

17.4.6.4.3 Condition applicable for all notations, exceptwhen notation no MP is assigned

17.4.6.4.3.1 Any cargo hold is to be capable of carrying MFullwith fuel oil tanks in double bottom in way of the cargo hold,if any, being 100%full and ballast water tanks in the doublebottom in way of the cargo hold being empty, at 67% ofmaximum draught.

17.4.6.4.3.2 Any cargo hold is to be capable of being emptywith all double bottom tanks in way of the cargo hold beingempty, at 83% of maximum draught.

17.4.6.4.3.3 Any two adjacent cargo holds are to be capableof carrying MFull with fuel oil tanks in double bottom in wayof the cargo hold, if any, being 100% full and ballast watertanks in the double bottom in way of the cargo hold beingempty, at 67% of the maximum draught. This requirement tothe mass of cargo and fuel oil in double bottom tanks in wayof the cargo hold applies also to the condition where the adja-cent hold is filled with ballast, if applicable.

17.4.6.4.3.4 Any two adjacent cargo holds are to be capableof being empty, with all double bottom tanks in way of thecargo hold being empty, at 75% of maximum draught.


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17.4.6.4.4 Additional conditions applicable for BC-Anotation only

17.4.6.4.4.1 Cargo holds, which are intended to be empty atmaximum draught, are to be capable of being empty with alldouble bottom tanks in way of the cargo hold also beingempty.

17.4.6.4.4.2 Cargo holds, which are intended to be loadedwith high density cargo, are to be capable of carrying MHDplus 10% of MH , with fuel oil tanks in the double bottom inway of the cargo hold, if any, being 100% full and ballastwater tanks in the double bottom being empty in way of thecargo hold, at maximum draught.

In operation the maximum allowable cargo massshall be limited to MHD.

17.4.6.4.4.3 Any two adjacent cargo holds which accordingto a design loading condition may be loaded with the nextholds being empty, are to be capable of carrying 10% of MHin each hold in addition to the maximum cargo load accordingto that design loading condition, with fuel oil tanks in thedouble bottom in way of the cargo hold, if any, being 100%full and ballast water tanks in the double bottom in way of thecargo hold being empty, at maximum draught.

In operation the maximum allowable mass shallbe limited to the maximum cargo load according to the designloading conditions.

17.4.6.4.5 Additional conditions applicable for ballasthold(s) only

17.4.6.4.5.1 Cargo holds,which are designed as ballast waterholds,are to be capable of being 100% full of ballast water in-cluding hatchways, with all double bottom tanks in way of thecargo hold being 100% full, at any heavy ballast draught. Forballast holds adjacent to topside wing, hopper and doublebottom tanks, it shall be strengthwise acceptable that the bal-last holds are filled when the topside wing, hopper and doublebottom tanks are empty.

17.4.6.4.6 Additional conditions applicable duringloading and unloading in harbour only

17.4.6.4.6.1 Any single cargo hold is to be capable of hold-ing the maximum allowable sea-going mass at 67% of maxi-mum draught, in harbour condition.

17.4.6.4.6.2 Any two adjacent cargo holds are to be capableof carrying MFull, with fuel oil tanks in the double bottom inway of the cargo hold,if any, being 100% full and ballast wa-ter anks in he double bottom in way of the cargo hold beingempty, at 67% of maximum draught, in harbour condition.

17.4.6.4.6.3 A reduced draught during loading and unloadingin harbour, the maximum allowable mass in a cargo hold maybe increased by 15% of the maximum mass allowed at themaximum draught in sea-going condition, but shall not exceedthe mass allowed at maximum draught in the sea-going condi-tion. The minimum required mass may be reduced by thesame amount.

17.4.6.4.7 Hold mass curves

Based on the design loading criteria for localstrength, as given in Section 17.4.6.4.2 to Section 17.4.6.4.6(except Section 17.4.6.4.1) above, hold mass curves are to beincluded in the loading manual and the loading instrument,showing maximum allowable and minimum required mass as

a function of draught, in sea-going condition as well as duringloading and unloading in harbour.

At other draughts than those specified in the de-sign loading conditions above, the maximum allowable andminimum required mass is to be adjusted for the change inbuoyancy acting on the bottom. Change in buoyancy is to becalculated using water plane area at each draught.

Hold mass curves for each single hold, as wellas for any two adjacent holds, are to be included.


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18 OIL TANKERS

18.1 GENERAL

18.1.1 Scope, definitions

18.1.1.1 The following regulations apply to oil tankerswhich are intended to carry oil in bulk having a flashpoint notexceeding 60oC and whose Reid vapour pressure is bellowthat of atmosferic pressure and other liquid products having asimilar fire hazard. Unless specially mentioned in this Sectionthe regulations of Sections 1-16 apply.

18.1.1.2 For definitions concerning the application of re-quirements as considered in items 18.1.2, 18.1.3, 18.1.4,18.1.5 and 18.1.6, see Annex I of MARPOL 73/78.

18.1.1.3 For the purpose of this Section "oil" means pe-troleum in any form including crude oil, refined products,sludge or oil refuse.

18.1.1.4 For the purpose of this Section "crude oil"means any liquid hydrocarbon mixture occurring naturally inthe earth whether or not treated to render it suitable for trans-portation and includes:

a) crude oil from which certain distillatefractions may have been removed;

b) crude oil to which certain distillate frac-tions may have been added.

18.1.1.5 Products which are permitted to be carried intankers, are stated in the Rules, Part 17 – Fire protection, An-nex 2.

18.1.1.6 For hull structures of double hull oil tankers of150 m in length or greater, contracted for construction on orafter 1st April 2006, IACS Common Structural Rules for Dou-ble Hull Oil Tankers shall apply.

18.1.2 Segregated ballast tanks

18.1.2.1 Every new crude oil tanker (see 18.1.1.2) of20,000 tons deadweight and above and every new product car-rier (see 18.1.1.2) of 30,000 tons deadweight and above shallbe provided with segregated ballast tanks.

18.1.2.2 The capacity of the segregated ballast tanks shallbe so determined that the ship may operate safely on ballastvoyages without recourse to the use of cargo tanks for waterballast except as provided for in paragraph 18.1.2.3 or18.1.2.4. In all cases, however, the capacity of segregatedballast tanks shall be at least such that, in any ballast conditionat any part of the voyage, including the conditions consistingof lightweight plus segregated ballast only, the ship's draughtsand trim can meet each of the following requirements:

.1 the moulded draught amidships (dm) in metres(without taking into account any ship s defor-mation) shall not be less than:dm = 2.0 + 0.02L;(L-lenght, see 1.2.3.1)

.2 the draughts at the forward and after perpen-diculars shall correspond to those determined by

the draught amidships (dm) as specified in for-mula 18.1.2.2.1, in association with the trim bythe stern of not greater than 0.015L; and

.3 in any case the draught at the after perpendicularshall not be less than that which is necessary toobtain full immersion of the propeller(s).

18.1.2.3 In no case shall ballast water be carried in cargotanks, except:

.1 on those rare voyage when weather conditionsare so severe that, in the opinion of the master, itis necessary to carry additional ballast water incargo tanks for the safety of the ship; and

.2 in exceptional cases where the particular char-acter of the operation of an oil tanker renders itnecessary to carry ballast water in excess of thequantity required under paragraph 18.1.2.2, pro-vided that such operation of the oil tanker fallsunder the category of exceptional cases as es-tablished by the Organization.Such additional ballast water shall be processedand discharged in compliance with Regulation34 of Annex I of MARPOL 73/78 and an entryshall be made in the Oil Record Book, Part II.

18.1.2.4 In the case of new crude oil tankers, the addi-tional ballast permitted in 18.1.2.3 shall be carried in cargotanks only if such tanks have been crude oil washed in accor-dance with Regulation 35 of Annex I of MARPOL 73/78 be-fore departure from an oil unloading port or terminal.

18.1.2.5 Three formulations are set forth as guidanceconcerning minimum draught requirements for segregatedballast tankers below 150 metres in length.

.1 Formulation A.1 mean draught (m) = 0.200 + 0.032 L.2 maximum trim = (0.024 - 6x10-5 L)LThe ballast conditions represent sailing condi-

tion in weather up to and including Beaufort 5..2 Formulation B

.1 minimum draught at bow (m)= 0.700 + 0.0170L

.2 minimum draught at stern (m)= 2.300 + 0.030L

or.3 minimum mean draught (m)

= 1.550 + 0.023L.4 maximum trim = 1.600 + 0.013LThese formulae are based on a Sea 6 (Interna-

tional Sea Scale)..3 Formulation C

.1 minimum draught aft (m) = 2.000 + 0.0275L

.2 minimum draught forward (m) = 0.5000 + 0.0225L

These expressions provide for certain increaseddraughts to aid in the prevention of propeller emergence andslamming in higher length ships.

18.1.2.6 Any oil tanker which is not required to be pro-vided with segregated ballast tanks in accordance with para-


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graphs 18.1.2.1 may, however be qualified as a segregatedballast tanker, provided that it complies with the requirementsof paragraphs 18.1.2.2 and 18.1.2.3 or 18.1.2.5 as appropriate.

18.1.2.7 Oil tankers of 70,000 tonnes deadweight andabove delivered after 31 December 1979, as defined in Regu-lation 1.28.2 of Annex I of MARPOL 73/78, shall be providedwith segregated ballast tanks and shall comply with para-graphs 18.1.2.2, 18.1.2.3 and 18.1.2.4 or paragraph 18.1.2.5as appropriate.

18.1.2.8 For separation of oil fuel tanks from other tanks,see Section 11.1.4.

18.1.3 Protective location of segregated ballastspaces

18.1.3.1 In every new crude oil tanker of 20,000 tonsdeadweight and above and every new product carrier of30,000 tons dedaweight and above, the segregated ballasttanks required to provide the capacity to comply with the re-quirements of 18.1.2.2 which are located within the cargo tanklength, shall be arranged in accordance with the requirementsof 18.1.3.2 to 18.1.3.8 to provide a measure of protectionagainst oil outflow in the event of grounding or collision.

18.1.3.2 Segregated ballast tanks and spaces other thanoil tanks within the cargo tank length (Lt) shall be so arrangedas to comply with the following requirement:

ΣPAc + ΣPAs ≥ J ⋅ Lt ⋅ (B + 2D)

where:PAc = the side shell area in square metres for each

segregated ballast tank or space other thanan oil tank based on procjected moulded di-mensions,

PAs = the bottom shell area in square metres foreach such tank or space based on projectedmoulded dimensions,

Lt = length in metres between the forward andafter extremities of the cargo tanks,

B = maximum breadth of the ship in metres asdefined in 1.2.3.2.

D = moulded depth in metres measured verticallyfrom the top of the keel to the top of thefreeboard deck beam at side amidships. Inships having rounded gunwales, the mouldeddepth shall be measured to the point of inter-section of the moulded lines of the deck andside shell plating, the lines extending asthough the gunwale were of angular design,

J = 0,45 for oil tankers of 20,000 tons dead-weight, 0,30 for oil tankers of 200,000 tonsdeadweight and above, subject to the provi-sions of 18.1.3.3.For intermediate values of deadweight thevalue of J shall be determined by linear in-terpolation.

18.1.3.3 For tankers of 200,000 tons deadweight andabove the value of J may be reduced as follows:

+−α−=

A

screduced O4

OO3,0J or 0.2 whichever is

greater.where:

α = 0.25 for oil tankers of 200,000 tons dead-weight,

α = 0,40 for oil tankers of 300,000 tons dead-weight,

α = 0,50 for oil tankers of 420,000 tons dead-weight and above.

For intermediate values of deadweight the valueof "α" shall be determined by linear interpolation.Oc[m3] = the hypothetical outflow of oil in the case of side

damage (see Regulation 25 of Annex I of MAR-POL 73/78)

Os[m3] = the hypothetical outflow of oil in the case of bot-tom damage (see Regulation 25 of Annex I ofMARPOL 73/78)

OA[m3]= the allowable oil outflow (see Regulation 26 ofAnnex I of MARPOL 73/78)).

18.1.3.4 In the determination of PAc and PAs for segre-gated ballast tanks and spaces other than oil tanks the follow-ing shall apply:

.1 the minimum w (m) width of each wingtank or space either of which extends forthe full depth of the ship's side or from thedeck to the top of the double bottom shallbe not less than 2 metres. The width shallbe measured inboard from the ship's sideat right angles to the centreline. Where alesser width is provided the wing tank orspace shall not be taken into account whencalculating the protecting area PAc, e.i.PAc = O.

.2 the minimum vertical depth h (m) of eachdouble bottom tank or space shall be B/15or 2 metres, whichever is the lesser. Wherea lesser depth is provided the bottom tankor space shall not be taken into accountwhen calculating the protecting area PAs,e.i. PAs = 0.

.3 the minimum with (w) and depth (h) ofwing tanks and double bottom tanks shallbe measured clear of the bilge area and, inthe case of minimum width, shall bemeasured clear of any rounded gunwalearea.

18.1.3.5 The measurement of the 2 metres minimumwidth of wing tanks and the measurement of the minimumvertical depth of double bottom tanks of 2 metres or B/15 inrespect of tanks at the ends of the ship where no identifiablebilge area exists should be interpreted as given hereunder. Nodifficulty exists in the measurement of the tanks in the parallelmiddle body of the ship where the bilge area is clearly identi-fied. The regulation does not explain how the measurementsshould be tanken.

18.1.3.6 The minimum width of wing tanks should bemeasured at a height of D/5 above the base line providing areasonable level above which the 2 metres width of collisionprotection should apply, under the assumption that in all cases


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D/5 is above the upper turn of bilge amidships (see Figure18.1.3.1). The minimum height of double bottom tanks shouldbe measured at a vertical plane measured D/5 inboard fromthe intersection of the shell with a horizontal line D/5 abovethe base line (see figure 18.1.3.2).

18.1.3.7 The PAc value for a wing tank which does nothave a minimum width of 2 metres throughout its lengthwould be zero; no credit should be given for that part of thetank in which the minimum width is in excess of 2 metres. Nocredit should be given in the assessment of PAs to any doublebottom tank, part of which does not meet the minimum depthrequirements anywhere within its length. If, however, theprojected dimensions of the bottom of the cargo tank abovethe double bottom fall entirely within the area of the doublebottom tank or space which meets the minimum height re-quirement and provided the side bulkheads bounding thecargo tank above are vertical or have a slope of not more than45o from the certical, credit may be given to the part of thedouble bottom tank defined by the projection of the cargo tankbottom. For similar cases where the wing tanks above thedouble bottom are segregated ballast tanks or void spaces,such credit may also be given. This would not, however, pre-clude in the above cases credit being given to a PAs value inthe first case and to a PAc value in the second case where therespective vertical or horizontal protection complies with theminimum distances prescribed in 18.1.3.4.

18.1.3.8 Projected dimensions should be used as shownin examples of figures 18.1.3.3 to 18.1.3.8. Figures 18.1.3.7and 18.1.3.8 represent measurement of the height for the cal-culation of PAc for double bottom tanks with sloping tank top.Figures 18.1.3.9 and 18.1.3.10 represent the cases wherecredit is given in calculation of PAs to part or the whole of adouble bottom tank.

Section view

Figure 18.1.3.1

Measurement of minimum width of wing ballasttank at ends of ship without of double bottom tank, w must beat least 2 metres along the entire length of the tank for the tankto be used in the calculation of PAc.

Section view

Figure 18.1.3.2

Measurement of minimum height of doublebottom tank at ends of ship, h must be at least 2 metres or

15B

, whichever is less, along the entire length of the tank for

the tank to be used in the calculation of PAs.

Section view

Figure 18.1.3.3

Calculation of PAc and PAs for double bottomtank amidships

If hdb is at least 2 metres of 15B

, whichever is

less, along entire tank length,PAc = hdb x double bottom tank length x 2 (m2)PAs= B x double bottom tank length (m2)

If hdb is less than 2 metres of15B

, whichever is

less,PAc = hdb x double bottom tank length x 2 (m2)PAs = O


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Section view

Figure 18.1.3.4Calculation of PAc and PAs for double bottom

tank at ends of ship.

If hdb is at least 2 metres or15B

, whichever is less, along entire

tank length,PAc = h x double bottom tank lenth x 2 (m2)PAs = B x double bottom tank length (m2)

If hdb is less than 2 metres of 15B

, whichever is

less,PAc = h x double bottom tank length x 2 (m2)PAs = 0

Plan view

Figure 18.1.3.5Calculation of PAc and PAs for wing tank amid-

ships.If w is 2 metres of more,

PAc = D x tank length x 2 * (m2)

PAs = w x tank length x 2 * (m2)If w is less than 2 metres,

PAc = OPAs = w x tank length x 2 *

*(to include port and starboard)

Plan view at 5D

Figure 18.1.3.6Calculation of PAc and PAs for wing tank end of

ship.

If w is 2 metres or more,PAc = D x tank length x 2 * (m2)PAs = b x tank length x 2 * (m2)

If w is less than 2 metres,PAc = OPAs = b x tank length x 2 * (m2)

* (to include port and starboard)

Section view

Figure 18.1.3.7

Measurement of h for calculation of PAc fordouble bottom tanks with sloping tank tops (1)

PAc = h x double bottom tank length x 2 *

B Moul-


2012


Section view

Figure 18.1.3.8Measurement of h for calculation of PAc for

double bottom tanks with sloping tank tops (2).PAc = h x double bottom tank lenght x 2* (m2)


Section view

Figure 18.1.3.9Calculation of PAs for double bottom tank with-

out clearly defined turn of bilge area - when wing tank iscargo tank.

If h is less than 2 metres or 15B

, whichever is

less, anywhere along the tank length, but hdb is at least 2 me-

tres or 15B

, whichever is less, along the entire tank length

within the width of 2b, then:PAs = 2b x cargo tank length [m2]

Section view

Figure 18.1.3.10Calculation of PAs for double bottom tank with-

out clearly defined turn of bilge area - when wing tank is seg-regated ballast tank or void space.

If h is less than 2 metres of 15B

, whichever is

less, anywhere along the tank length, but hdb is at least 2 me-

tres or 15B

. Whichever is less, along the entire tank length

within the width of 2b, then:PAs = B x cargo tank length (m2)

18.1.3.9 Pump room bottom protection

18.1.3.9.1 This regulation applies to oil tankers of 5,000tonnes deadweight and above constructed on or after 1 Janu-ary 2007.

18.1.3.9.2 The pump-room shall be provided with a doublebottom such that at any cross-section the depth of each doublebottom tank or space shall be such that the distance h betweenthe bottom of the pump-room and the ship’s base line meas-ured at right angles to the ship’s base line is not less thanspecified below:

h = B/15 [m] or

h = 2 m, whichever is the lesser.

The minimum value of h = 1 m.

18.1.3.9.3 In case of pump rooms whose bottom plate is lo-cated above the base line by at least the minimum height re-quired in 18.1.3.2 above (e.g. gondola stern designs), therewill be no need for a double bottom construction in way of thepump-room, see Figure 18.1.3.9.3.

Figure 18.1.3.9.3

18.1.3.9.4 Ballast pumps shall be provided with suitable ar-rangements to ensure efficient suction from double bottomtanks.

18.1.3.9.5 Notwithstanding the provisions of paragraphs18.1.3.9.2 and 18.1.3.9.3 above, where the flooding of thepump-room would not render the ballast or cargo pumpingsystem inoperative, a double bottom need not be fitted.

18.1.3.9.6 The term “pump-room” means a cargo pumproom. Ballast piping is permitted to be located within thepump-room double bottom provided any damage to that pip-ing does not render the ship’s pumps located in the “pumproom” ineffective.

18.1.3.9.7 The double bottom protecting the “pump-room”can be a void tank, a ballast tank or, unless prohibited by otherregulations, a fuel oil tank.

18.1.3.9.8 Bilge wells may be accepted within the doublebottom provided that such wells are as small as practicableand the distance between the well bottom and the ship's baseline measured at right angles to the ship's base line is not lessthan 0.5h.

Requireddoublebottom

No doublebottomrequired

Minim. double bottom height

PumproomPump

room

Baseline


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18.1.3.9.9 Where a portion of the pump-room is locatedbelow the minimum height required in 18.1.3.9.2, then onlythat portion of the pump room is required to be a double bot-tom.

18.1.4 Double hull and double bottom require-ments for oil tankers

18.1.4.1 This regulation shall apply to oil tankers of 600tons deadweight and above delivered on or after 6 July 1996as follows:

.1 for which the building contract is placedon or after 6 July 1993, or

.2 in the absence of a building contract, thekeels of which are laid or which are at asimilar stage of construction on or after 6January 1994, or

.3 the delivery of which is on or after 6 July1996, or

.4 which have undergone a major conversion:.1 for which the contract is placed after 6

July 1 993; or.2 in the absence of a contract, the con-

struction work of which is begun after6 January 1994; or

.3 which is completed after 6 July 1996.

18.1.4.2 Every oil tanker of 5,000 tons deadweight andabove shall:

.1 in lieu of 18.1.3.1 to 18.1.3.4, as applica-ble, comply with the requirements of18.1.4.3 unless it is subject to the provi-sions of 18.1.4.4 and 18.1.4.5; and

.2 comply, if applicable, with the require-ments of 18.1.4.6.

18.1.4.3 The entire cargo tank length shall be protectedby ballast tanks or spaces other than cargo and fuel oil tanksas follows:

.1 Wing tanks or spacesWing tanks or spaces shall extend eitherfor the full depth of the ship's side or fromthe top of the double bottom to the upper-most deck, disregarding a rounded gun-wale where fitted. They shall be arrangedsuch that the cargo tanks are located in-board of the moulded line of the side shallplating, nowhere less than the distance wwhich, as shown in figure 18.1.4.3, ismeasured at any cross-section at right an-gles to the side shell, as specified below:

w = 0.5 + 00020.D

[m] or

w = 2.0 m, whichever is the lesser.The minimum value of w = 1.0 m..2 Double bottom tanks or spaces

At any cross-section the depth of eachdouble bottom tank or space shall be suchthat the distance h between the bottom ofthe cargo tanks and the moulded line ofthe bottom shell plating measured at rightangles to the bottom shell plating as shown

in figure 18.1.4.3 is not less than specifiedbelow:

h = B/15 (m) orh = 2.0 m, whichever is the lesser.The minimum value of h = 1.0 m..3 Turn of the bilge area or at locations with-

out a clearly defined turn of the bilge.When the distances h and w are different,the distance w shall have preference atlevels exceeding 1.5 h above the baselineas shown in figure 18.1.4.3.

.4 The agregate capacity of ballast tanksOn crude oil tankers of 20,000 tons dead-weight and above and product carriers of30,000 tons deadweight and above, theaggregate capacity of wing tanks, doublebottom tanks, forepeak tanks and afterpeaktanks shall not be less than the capacity ofsegregated ballast tanks necessary to meetthe requirements of 18.1.2. Wing tanks orspaces and double bottom tanks used tomeet the requirements of 18.1.2 shall belocated as uniformly as practicable alongthe cargo tank length. Additional segre-gated ballast capacity provided for reduc-ing longitudinal hull girder bending stress,trim, etc., may be located anywhere withinthe ship.

.5 Suction wells in cargo tanksSuction wells in cargo tanks may protrudeinto the double bottom below the bound-ary line defined by the distance h providedthat such wells are as small, as practicableand the distance between the well bottomand bottom shell plating is not less than0.5 h.

.6 Ballast and cargo pipingBallast piping and other piping such assounding and vent piping to ballast tanksshall not pass throught cargo tanks. Cargopiping and similar piping to cargo tanksshall not pass through ballast tanks. Ex-emptions to this requirement may begranted for short lengths of piping, pro-vided that they are completely welded orequivalent.

18.1.4.4.1 Double bottom tanks or spaces as required

by 18.1.4.3.2 may be dispensed with, pro-vided that the design of the oil tanker issuch that the cargo and vapour pressureexerted on the bottom shell plating form-ing a single boundary between the cargoand the sea does not exceed the externalhydrostatic water pressure, as expressd bythe following formula:

f ⋅ hc ⋅ ρc ⋅ g + 100∆ρ ≤ dn ⋅ ρs ⋅ gwhere:

hc = hight of cargo in contact with the bot-tom shall plating in metres;

ρc = maximum cargo density in [t/m3];


2012

dn = minimum operating draught under anyexpected loading condition in metres;

ρs = density of sea water in [t/m];∆p = maximum set pressure of pres-

sure/vacuum valve provided fot thecargo tank in bars;

f = safety factor = 1.1;g = standard acceleration of gravity

[9.81 m/s2]..2 Any horizontal partition necessary to fulfil

the above requirements shall be located ata height of not less than B/6 of 6 metres,whichever is the lesser, but not more thaan0.6D, above the baseline where D is themoulded depth amidships.

.3 The location of wing tanks or spaces shallbe as defined in 18.1..4.3.1 except that,below a level 1.5 h above the baselinewhere h is as defined in 18.1.4.3.2, thecargo tank boundary line may be vertica ldown to the bottom plating, as shown infigure 18.1.4.4.

18.1.4.5 Other methods of design and construction of oiltankers may also be accepted as alternatives to the require-ments prescribed in 18.1.4.3, provided that such methods en-sure at least the same level of protection against oil pollutionin the event of collision or stranding and are approved in prin-ciple by the Marine Environment Protection Committee basedon quidelines developed by the Organization.

18.1.4.6 For oil tankers of 20,000 tons deadweight andabove the damage assumptions prescribed in Rules, Part 5 -Subdivision shall be supplemented by the following assumedbottom raking damage:

.1 longitudinal extent:.1 ships of 75,000 tons deadweight and

above:0.6 L measured from the forward per-pendicular

.2 ships of less than 75,000 tons dead-weight:0.4 L measured form the forward per-pendicular

.2 transverse extent: B/3 anywhere in thebottom

.3 vertical extent: breach of the outer hull.

18.1.4.7 Oil tankers of less than 5,000 tons deadweightshall:

.1 at least be fitted with double bottom tanksor spaces having such a depth that thedistance h specified in 18.1.4.3.2 complieswith the following:h = B/15 (m) with a minimum value of h =0,76 m;in the turn of the bilge area and at loca-tions without a clearly defined turn of thebilge, the cargo tank boundary line shallrun parallel to the line of the mid-ship flatbottom as shown in figure 18.1.4.7; and

.2 be provided with cargo tanks so arrangedthat the capacity of each cargo tank doesnot exceed 700 m3 unless wing tanks orspaces are arranged in accordance with18.1.4.3.1 complying with the following:

w = 0.4 + 00020

42.DW,

[m]

with a minimum value of w = 0.76 m.

18.1.4.8 Oil shall not be carried in any space extendingforward of a collision bulkhead located in accordance withregulation II-1/11 of the International Convention for theSafety of Life at Sea, 1974, as amended. An oil tanker that isnot required to have a collision bulkhead in accordance withthat regulation shall not carry oil in any space extending for-ward of the transverse plane perpendicular to the centrelinethat is located as if it were a collision bulkhead located in ac-cordance with that regulation.

18.1.4.9 In approving the design and construction of oiltankers to be built in accordance with the provisions of thisregulation, Register shall have due regard to the general safetyaspects including the need for the maintenance and inspec-tions of wing and double bottom tanks or spaces.

Figure 18.1.4.3

Cargo tank boundary lines for the purpose of 18.1.4.3


2013

Figure 18.1.4.4


Figure 18.1.4.7


18.1.5 Limitation of size and arrangement ofcargo tanks

18.1.5.1 Cargo tanks of oil tankers shall be of such sizeand arrangements that the hypothetical outflow Oc or Os cal-culated in accordance with the provisions of Regulation 25of Annex I of MARPOL 73/78 anywhere in the length of theship does not exceed 30,000 cubic metres or 3 DWT400 ⋅ ,whichever is the greater, but subject to a miximum of 40,000cubic metres.

18.1.5.2.1 The volume of any one wing cargo oil tank of

an oil tanker shall not exceed 75 per cent of thelimits of the hypothetical oil outflow referred toin 18.1.5.1.

.2 The volume of any one centre cargo oil tankshall not exceed 50,000 cubic metres.

.3 However, in segregated ballast oil tankers asdefined in 18.1.2, the permitted volume of awing cargo oil tank situated between two seg-regated ballast tanks, each exceeding lc inlength, may be increased to the maximum limitof hypotheticl oil outflow provided that thewidth of the wing tanks exceeds tc.

The length of each cargo tank shall not exceed 10 m or oneof the values specified in table 18.1.5.3:

Table 18.1.5.3

Number of longitu-dinal bulkheads in-side the cargo tanks

Permissible length of cargo tanks

− ,1,05.0 LBbi ⋅

+ max. 0,2⋅L

1 ,15,025.0 LBbi ⋅

+ max. 0,2⋅L

Wing cargo tanks: 0,2⋅L

Centre tanks:

1) Bbi ≥ 0,2; 0,2⋅L

2) Bbi < 0,2;

- where no centreline longitudinal bulkhead is provided

LBbi ⋅

+ 1,05.0

2 and more

- where a centreline longitudinal bulkhead is provided

LBbi ⋅

+ 15,025.0

Note:bi = minimum distance from the ship's side to the outer lon-

gitudinal bulkhead of the tank in question measured in-board at right angles to the centreline at the level corre-sponding to the assigned summer freeboard.

18.1.5.4 In order not to exceed the volume limits estab-lished by 18.1.5.1, 18.1.5.2 i 18.1.5.3 and irrespective of theaccepted type of cargo transfer system installed, when suchsystem interconnects two or more cargo tanks, valves orother similar closing devices shall be provided for separatingthe tanks from each other. These valves or devices shall beclosed when the tanker is at sea.

18.1.5.5 Lines of piping which run through cargo tanksin a position less than tc from the ship s side or less than υcfrom the ship's bottom shall be fitted with valves or similarclosing devices at the point at which they open into anycargo tank. These valves shall be kept closed at sea at anytime when the tanks contain cargo oil, except that they maybe opened only for cargo transfer needed for the purpose oftrimming of the ship.

18.1.5.6 This regulation does not apply to oil tankersdelivered on or after 1 January 2010.


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18.1.6 Oil fuel tank protection

18.1.6.1 This regulation shall apply to all ships with anaggregate oil fuel capacity of 600 m3 and above which aredelivered on or after 1 August 2010. Ship delivered on or af-ter 1 August 2010 means a ship:

.1 for which the building contract is placed on orafter 1 August 2007; or

.2 in the absence of a building contract, the keelsof which are laid or which are at a similarstage of construction on or after 1 February2008; or

.3 the delivery of which is on or after 1 August2010; or

.4 which have undergone a major conversion:.1 for which the contract is placed after 1

August 2007; or.2 in the absence of contract, the construc-

tion work of which is begun after 1 Feb-ruary 2008; or

.3 which is completed after 1 August 2010.”

18.1.6.2 For ships, other than self-elevating drillingunits, having an aggregate oil fuel capacity of 600 m3 andabove, oil fuel tanks shall be located above the moulded lineof the bottom shell plating nowhere less than the distance has specified below:

h = B/20 m or,

h = 2.0 m, whichever is the lesser.

The minimum value of h = 0.76 mIn the turn of the bilge area and at locations

without a clearly defined turn of the bilge, the oil fuel tankboundary line shall run parallel to the line of the midship flatbottom as shown in Figure 18.1.4.7.

18.1.6.3 For ships having an aggregate oil fuel capacityof 600 m3 or more but less than 5,000 m3, oil fuel tanks shallbe located inboard of the moulded line of the side shell plat-ing, nowhere less than the distance w which, as shown inFigure 18.1.4.3, is measured at any cross-section at right an-gles to the side shell, as specified below:

w = 0.4 + 2.4 C/20,000 [m]The minimum value of w = 1.0 m, however for

individual tanks with an oil fuel capacity of less than 500 m3

the minimum value is 0.76 m.

18.1.6.4 For ships having an aggregate oil fuel capacityof 5,000 m3 and over, oil fuel tanks shall be located inboardof the moulded line of the side shell plating, nowhere lessthan the distance w which, as shown in Figure 18.1.4.3, ismeasured at any cross-section at right angles to the side shell,as specified below:

w = 0.5 + C/20,000 m or

w = 2.0 m, whichever is the lesser.

The minimum value of w = 1.0 m

18.1.6.5 For the purpose of maintenance and inspection,any oil fuel tanks that do not border the outer shell platingshall be located no closer to the bottom shell plating than theminimum value of h in 18.1.6.2 and no closer to the sideshell plating than the applicable minimum value of w in18.1.6.3 and 18.1.6.4.

18.1.6.6 The distance “h” should be measured from themoulded line of the bottom shell plating at right angle to it,see Figure 18.1.4.7.

18.1.6.6.1 For vessels designed with a skeg, the skegshould not be considered as offering protection for the fueloil tanks. For the area within skeg's width the distance “h”should be measured perpendicular to a line parallel to thebaseline at the intersection of the skeg and the moulded lineof the bottom shell plating as indicated in Figure 18.1.6.6.1.

Figure 18.1.6.6.1

18.1.6.6.2 For vessels designed with a permanent trim, thebaseline should not be used as a reference point. The distance“h” should be measured perpendicular to the moulded line ofthe bottom shell plating at the relevant frames where fueltanks are to be protected.

18.1.6.7 For vessels designed with deadrising bottom,the distance “1.5h” should be measured from the mouldedline of the bottom shell plating but at right angle to the base-line, as indicated in Figure 18.1.6.7.

18.1.6.8 Alternatively to paragraphs 18.1.6.2 and either18.1.6.3 or 18.1.6.4, ships shall comply with the accidentaloil fuel outflow performance standard specified in paragraph11 of Regulation 12A of the revised Annex I to MARPOL73/78 as adopted by resolution MEPC.141 (54).

Figure 18.1.6.7

18.1.7 Tank deck openings

18.1.7.1 Any tank openings, e.g. tank cleaning open-ings, ullage plugs, etc. are not to be arranged in enclosedspaces.

18.1.7.2 The number, dimensions and position of holesin the deck are to be sumitted to the Register for approval.


2013


18.1.8.1 In cargo and ballast tanks within the cargo areathe thickness of primary structural members is not to be lessthan the following minimum value:

tmin = 6,5 + 0,02 ⋅ L [mm],where:

L ≤ 300 m.For secondary structures (e.g. local stiffeners)

tmin need not be taken greater than 9,0 mm.

18.1.8.2 For pumprooms, cofferdams and void spaceswithin the cargo area as well as for fore peak tanks the re-quirements for ballast tanks according to Section 11.1.7 ap-ply, however, with an upper limit of:

tmin = 11,0 mm

For aft peak tanks the requirements of Section11.1.7.3 apply.

18.1.9 Testing of cargo and ballast tanks

18.1.9.1 For testing of cargo and segregated ballasttanks as well as cofferdams including cofferdam/engine roombulkhead see Section 11.6.

18.1.9.2 Where one tank boundary is formed by theship's shell the leak test is to be carried out before launching.For all other tanks leak testing may be carried out afloat.Erection welds as well as welds on assembly openings are tobe coated1) after leak testing is carried out. This applies alsoto manual weld connections of bulkheads with tank bounda-ries and of collaring arrangements at intersections of tankboundaries, and e.g. frames, beams, girders etc. When it isensured that similar liquids will be carried in adjacent tanks,the latter weld connections may be coated1) before leak test-ing is carried out.

All other welds on tank boundaries may becoated before leak testing is carried out provided that it is en-sured by suitable measures (e.g. by visual examination of thewelds) that all welding is completed and the surfaces of thewelds do not exibit any craks or pores.

18.1.9.3 Where leak testing in accordance with 18.1.9.2is not carried out and the tanks are pressure tested with water,the bulkheads are, in general, to be tested from one side. Thetesting should be carried out on the building berth or in dry-dock. Subject to agreement by the Register the pressure test-ing may be carried out afloat. Water testing may be carriedout after application of a coating1) if requirements stated in18.1.9.2 are satisfied.

Where in lieu of a cofferdam a pump room issituated between cargo tank and machinery space the engineroom / pump-room bulkhead need not be watertested.

18.1.9.4 The operational tests may be carried out afloator during the sea trials. In the course of these tests at leasttwo cargo tanks and two segregated ballast tanks are to bepressure tested to the test head given in 18.1.9.5 to 18.1.9.7.

18.1.9.5 For cargo tanks a test head corresponding to ahead of water of 2,4 m or as required in accordance with18.1.9.6 the highest point of the tank is to be applied.

1) Shopprimers are not regarded as coatings within the context of these re-quirements.

18.1.9.6 Cargo tanks fitted with pressure relief valvesand/or intended for the carriage of cargoes with a density ofmore than ρ = 1,025 t/m3 are to be tested with a head of wa-ter of at least:

hp = 2,4 ⋅ ρ [m] or 10 ⋅ pv [m],.(whichevers is greater).

where:ρ = density of liquid in [t/m3];pv = see Section 3.4.1.

18.1.9.7 For segregated ballast tanks a test head corre-sponding to a head of water up to the top of the overflowpipe is to be applied.

18.1.9.8 These requirements do not apply to CSR OilTankers.

18.2 STRENGHT OF GIRDERS ANDTRANSVERSES

18.2.1 General

18.2.1.1 Girders and transverses may be predesignedaccording to Section 11.2.3. Subsequently a stress analysisaccording to 18.2.2 is to be carried out. All structural ele-ments exposed to compressive stresses are to be subjected toa buckiling analysis according to 4.6.

18.2.1.2 Brackets fitted in the corners of transverses andtripping brackets fitted on longitudinals are to have smoothtransitions at their toes.

18.2.1.3 Well rounded drain holes for oil and air holesare to be provided. No such holes and no welding scallopsshall be placed near the constraint points of stiffeners andgirders and near the toes of brackets.

18.2.1.4 Transverses are to be effectively supported toresist loads acting verticaly on their webs.

18.2.2 Stress analysis

18.2.2.1 A three-dimensional stress analysis is to be car-ried out for girders and transverses for the load conditions re-sulting from tank arrangement and drafts.


2013

Figure 18.2.2.2

18.2.2.2 For double hull vessels the following basic loadcases are to be considered, according to Fig. 18.2.2.2.

Considereation of additional load cases may berequired by the Register if deemed necessary.

The dynamic allowances according to 3.2.3,3.2.4, 3.3.1 and 3.4 are to be taken into account.

The internal pressure is to be determined in ac-cordance with the formula for p1 as per 3.4.1.1.

ϕ = design angle of heel according to3.4.1.1;

ϕmax = arctan (0,5 ⋅ D/B).

The basic lead cases are as follows:

- load case 1: cargo tanks filled

d = dmax

- load case 2: cargo tanks filled

d = dmin

- load case 3: cargo tanks filled, heeledcondition;

d = d dmax min+

2

- load case 4: ballast tanks filled

d = dbmaxwhere:

dbmax = maximum ballast draft

18.2.2.3 Where required, double bottom structures are tobe examined for alternately filled cargo tanks .

18.2.2.4 Transverse bulkhead girders are to be examinedfor the following load conditions:

- centre and wing tanks full, adjacent tanksempty;

- centre tank full, wing tanks empty;- centre tank empty, wing tanks full.


18.2.3.1 Under load assumption according to 18.2.2 thefollowing permissible stress values in the transverses and inthe bulkhead girders are:

- bending and axial stresses:

σ = 150 /k [N/mm2];

- shear stress:

τ = 100/k [N/mm2];


σekv = σ τ2 23+ = 180/k [N/mm2],

where:σ = stress in longitudinal direction of the

girder, [N/mm2].The stress values as per 11.2.3.2 are not to be

exceeded when the load p2 as per 3.4.1.2 is applied.

18.2.3.2 In the longitudinal girders at deck and bottom,the combined stress resulting from local bending of the girderand longitudinal hull girder bending of the ship's hull undersea load is not to exceed 230/k [N/mm2].

18.2.3.4 Cross tiesThe cross sectional area of the cross ties due to

compressive loads is not to be less than:

Ak = P

9 5 4 5 10 4 2, ,− ⋅ ⋅− λ [cm2], for λ ≤ 100;

Ak = P ⋅

⋅

λ2

45 10 [cm2], for λ > 100

where:λ = l/i degree of slenderness;l = unsupported span, in [cm];i = radius of gyration = I Ak/ [cm];

I = smallest moment of inertia, in [cm4];p = load p1 or pd [kN/m2], according to

3.4.1 and 3.4.2;P = A ⋅ p [kN] (for the first aproxima-

tion);A = area suppported by one cros tie, in

[m2].


2013

Finally the sectional area Ak is to be checkedfor the load P resulting from the transverse strength calcula-tion.

18.3 OILTIGHT LONGITUDINAL ANDTRANSVERSE BULKHEADS

18.3.1 Scantilings

18.3.1.1 The scantlings of bulkheads are to be deter-mined according to Section 11 however, the thicknesses arenot to be less than the minimum thickness as per 18.1.7.

18.3.1.2 The top and bottom strakes of the longitudinalbulkheads are to have a width of not less than 0,1 D, andtheir thickness is not to be less than:

- top strake of plating:tmin = 0,75 x deck thickness;

- bottom strake of plating:tmin = 0,75 x bottom thickness.

18.3.1.3 The section modulus of horizontal stiffeners oflongitudinal bulkheads is to be determined as for longitudi-nals according to Section 8.2., however, it is not to be lessthan W2 according to Section 11.2.3.

18.3.1.4 The stiffeners are to be continuous in way ofthe girders. They are to be attached to the webs of the girdersin such a way that the support force can be transmitted ob-serving τ = 100/k [N/mm2].

18.3.2 Cofferdam bulkheads

Cofferdam bulkheads forming boundaries ofcargo tanks are to have the same strength as cargo tanksbulkheads. Where they form boundaries of ballast tanks ortanks for consumables the requirements of Section 11 are tobe complied with. For cofferdam bulkheads not serving astank bulkheads, e.g. pump-room bolkheads, the scantlings forwatertight bulkheads are as required by Section 10.

18.4 WASH BULKHEADS

18.4.1 General

18.4.1.1 The total area of perforation in wash bulkheadsis to be approximately 5 ÷ 10 per cent of the bulkhead area.

18.4.1.2 The scantlings of the top and bottom strakes ofplating of a perforated bulkhead are to be as required by18.3.1.2. Large openings are to be avoided in way of thesestrakes.

18.4.2 Scantlings

18.4.2.1 The plate thickness of the transverse washbulkheads is to be determined in such a way as to support theforces induced by the side shell, the longitudinal bulkheadsand the longidutinal girders. The shear stress is not to exceed100/k [N/mm2].

Beyond that, the buckling strength of platepanels is to be examined.

The plate thickness is not to be less than theminimum thickness according to 18.1.7.

18.4.2.2 The stiffeners and girders are to be determinedas required for an oiltight bulkhead. The pressure pd accord-ing to Section 3.4.2 is to be substituted for p.

18.5 ACCESS ARRANGEMENTS

18.5.1 Tank hatches

18.5.1.1 Oiltight tank hatches are to be kept to theminimum number and size necessary for access and venting.

18.5.1.2 Openings in decks are to be elliptical and withtheir major axis in the longitudinal direction, wherever this ispracticable. Deck longitudinals in way of hatches should becontinuous within 0,4 L amidships. Where this is not practi-cable, compensation is to be provided for lost cross sectionalarea.

18.5.1.3 Coaming plates are to have a minimum thick-ness of 10 mm.

18.5.1.4 Hatch covers are to be of steel with a thicknessof not less than 12,5 mm. Where their area exceeds 1,2 m2,the covers are to be stiffened. The covers are to close oiltight.

18.5.1.5 Requirements according to 18.5.1.3 and18.5.1.4 may be adopted provided this is compatible withhatch dimensions or special stiffenings, in small tankers.

18.6 STRUCTURAL DETAILS AT THESHIP'S END

18.6.1 General

18.6.1.1 The strengthening of bottom forward is to bebased on the draught obtained by using segregated ballasttanks only, see 18.1.2 and 18.1.3.

18.6.1.2 The following requirements are based on theassumption that the bottom forward of the forward cofferdamand abaft the aft cofferdam bulkhead is framed transversely.

18.6.1.3 For the forepeak and afterpeak, the require-ments of Section 8.1.5 apply.

18.6.2 Fore body

18.6.2.1 Floor plates are to be fitted at every frame andtheir scantlings are to be determined according to Section7.1.1.2.3.

18.6.2.2 Every alternate bottom longitudinal is to becontinned forward as far as practicable by an intercostal sidegirder of same thickness and at least half the depth of theplate floors. The width of their flange is not to be less than 75mm.

18.6.2.3 The sides may be framed transversely or lon-gitudinally in accordance with Section 8.


2013

18.6.3 Aft body

18.6.3.1 Between the aft cofferdam bulkhead and theafterpeak bulkhead the bottom structure is to comply withSection 7.

18.6.3.2 The sides may be framed transversely or lon-gitudinaly in accordance with Section 8.

18.7 SMALL TANKERS

18.7.1 General

18.7.1.1 The following requirements apply to tankers ofless than 90 [m] in length. Small tankers are coastal tankers,bunkering boats and water tankers. Unless otherwise men-tioned in this Section, the requirements of 18.1 - to 18.6 areapplicable.

18.7.1.2 Small tankers may be framed either longitudi-nally or transversely, or a combined system may be adoptedwith the ship's sides being framed transversely and the bot-tom and strength deck longitudinally. For the strength deck,the longitudinal framing system is recommended.

18.7.1.3 The strength deck may extend from side toside, or may consist of a main deck and a raised trunk deck.

18.6.1.4 Two oiltight longitudinal bulkheads, or else oneoiltight center line bulkhead, may be fitted, extending con-tinuously through all cargo tanks from cofferdam to coffer-dam.


18.7.2.1 Girders and transverses are to be determinedaccording to 11.2.3. If deemed neccessary, the Register mayrequest a stress and buckling analysis.

18.7.3 Transverse framing

18.7.3.1 ScantlingsThe section modulus of the transverse frames in

the cargo tank area is not to be less than:

W1 = k ⋅ 0,55 ⋅ s ⋅ l2 ⋅ p [cm3],

or

W2 = k ⋅ 0,44 ⋅ s ⋅ l2 ⋅ p2 [cm3],

where:k, l, p and p2 according to 11.2.1.

The scantlings of the frame section are to bemaintained through out the whole depth D.

18.7.3.2 End attachment

18.7.3.2.1 At their ends, the transverse frames are to beprovided with flanged brackets according to Section 2.4.2.The bilge bracket is to fill the entire round of the bilge and isto be connected to the adjacent bottom longitudinal.

The bracket at the upper end of the frame is tobe attached to the adjacent deck longitudinal.

18.7.3.2.2 Where the unsupported span is considerable,flats or brackets are to be fitted to support the frame againsttripping. The transverse frames are to be attaached to thestringers by means of flats or brackets extending to the face

plate of the stringer in such a way that the force of supportcan be transmitted.

18.7.4 Deck

18.7.4.1 The scantlings of the strength deck are to bedetermined according to Section 6.

The plate thickness is not to be less than:

- for longitudinal framing:

tmin = s

L⋅

− ⋅10

85 0 15

3

,[mm];

- for transverse framing:

tmin = s

L⋅−10

65 0 2

3

,[mm]

The thickness of deck plating is not to be lessthan the minimum thickness as given under 18.1.7 or thethickness required for tank bulkhead plating.

18.7.5 Shell plating

The thickness of the shell plating is to be de-termined according to Section 5. The thickness of the shellplating is not to be less than the minimum thickness accord-ing to 18.1.7 or the thickness required for tank bulkheadplating.

18.7.6 Separation of oil fuel tanks from tanksfor other liquids

18.7.6.1 Upon special approval on small ships the ar-rangement of cofferdams (according to 11.1.4) between oilfuel and lubricating oil tanks may be dispensed with providedthat the common boundary is continuous, i.e. it does not abutat the adjacent tank boundaries, see Fig. 18.7.6.1.18.7.6.2 Where the common boundary cannot be con-structed continuously according to Fig. 18.7.6.1, the filletwelds on both sides of the common boundary are to bewelded in two layers and the throat thickness is not to be lessthan 0,5 ⋅ t (t = plate thickness);

- stiffeners or pipes do not penetrate thecommon boundary;

- the corrosion addition tk for the commonboundary is not less than 2,5 mm.

Figure 18.7.6.1

commonboundary


2013

19 BARGES AND PONTOONS

19.1 GENERAL

19.1.1 Definitions

19.1.1.1 Barges are unmanned or manned vessels with-out self-propulsion, sailing in pushed or towed units. The ra-tios of the main dimensions of barges are in a range usual forseagoing ships. Their construction complies with the usualconstruction of seagoing ships; their cargo holds are suitablefor the carriage of dry or liquid cargo.

19.1.1.2 Pontoons as defined in this Section are un-manned or manned floating units with or without self propul-sion. The ratios of the main dimensions of pontoons deviatefrom those usual for seagoing ships. Pontoons are designed tousually carry deck load or working equipment and have noholds for the carriage of cargo.

19.1.1.3 The requirements given in Sections 1 - 16 ap-ply to barges and pontoons unless otherwise mentioned inthis Section.

19.2 LONGITUDINAL STRENGTH

19.2.1 The scantlings of longitudinal members ofbargers and pontoons of 90 m and more in length are to bedetermined on the basis of longitudinal strength claculations.For barges of less than 100 m in length, the scantlings of lon-gitudinal members are to be generally determined accordingto Section 6.1.4.

19.2.2 The midship scetionmodulus may be 5% lessthan required according to Section 4.

19.2.3 Longitudinal strength calculations for the con-dition "Barge, fully loaded at crane" are required, wherebarges are intended to be lifted on board ship by means ofcranes. The following permissible stresses are to be ob-served:

- bending stress:

σb = 150/k [N/mm2]

- shear stress:

τ = 100/k [N/mm2]

k = material factor according to Section1.4.2.2.

Special attention is to be paid to the transmis-sion of lifting forces into the barge structure.

19.2.4 For pontoons carrying lifting equipment, ramsetc. or concentrated heavy deck loads, calculation of thestresses in the longitudinal structures under such loads maybe required. In such cases the stresses given under 19.2.3 arenot to be exceed.

19.3 WATERTIGHT BULKHEADS ANDTANK BULKHEADS

19.3.1 For barges and pontoons, the position of thecollision bulkhead is to be determined according to 10.1.2.1.

Where in barges the form and construction oftheir ends is identical so that there is no determined fore oraft ship, a collision bulkhead is to be fitted at each end.

19.3.2 A watertight bulkhead is to be fitted at the aftend of the hold area. In the remaining part of the hull, water-tight bulkheads are to be fitted as required for the purpose ofwatertight subdivision and for transverse strength.

19.3.3 The scantlings of watertight bulkheads and oftank bulkheads are to be determined according to Sections 10and 11 respectively.

19.3.4 On barges intended to operate as linked pushbarges, depending on the aft ship design, a collision bulkheadmay be required to be fitted in the aft ship.

19.3.5 Where tanks are intended to be emptied bycompressed air, the maximum blowing-out pressure accord-ing to Section 3.4.1, is to be inserted in the formulae for de-termining the pressures p1 and p2.

19.4 ENDS

19.4.1 Where barges have typical ship-shape fore andaft ends, the scantilings of structural elements are to be de-termined according to Sections 7.1.1.2 and 8.1.5 respec-tively. The scantlings of fore and aft ends deviating from thenormal ship shape are to be determined by applying the for-mulae analogously such as to obtain equal strength.

19.4.2 Where barges have raked ends with flat bot-toms, at least one centre girder and one side girder on eachside are to be fitted. The girders shall be spaced not morethan 4,5 m apart. The girders shall be scarped into the mid-ship structure. A raked fore-end with a flat bottom is to bestrengthened according to Section 5.4.

19.4.3 In pontoons which are not assigned a notationfor restricted service range or which are assigned the notationfor restricted international service, the construction of thefore peak is to be reinforced against wash of the sea by addi-tional longitudinal girders, stringers and web frames. In caseof raked bottoms forward, the reinforcements are, if neces-sary, to be arranged beyond the collision bulkhead. If neces-sary, both ends are to be reinforced, see also 19.3.1.


2013

20 TUGS

20.1 GENERAL

20.1.1 The requirements given in Sections 1 - 16 ap-ply to tugs unless otherwise mentioned in this Section.

20.2 STERNFRAME, BAR KEEL

20.2.1 The cross sectional area of a solid strernframeis to be 20 per cent greater than required according to12.3.2.1. For fabricated sternframes the thickness of the pro-peller post plating is to be increased by 20 per cent above therequirements of 12.3.2.2. The section modulus Wz of the solepiece in the athwartship direction is to be increased by 20 percent above the modulus determined according to 12.3.4.

20.2.2 Where a bar keel is provided, its scantlings areto be determined by the following formulae:

height: h = 1,1 L + 110 [mm]

thickness: t = 0,6 L + 12 [mm]

20.3 ENGINE ROOM CASINGS

20.3.1 The height of exposed engine room and boilerroom casings is not to be less than 900 mm. Where the heightof the casing is less than 1,8 m, the casing covers are to be ofa specially strong construction.

20.3.2 The plate thickness of these casing walls andcasing tops is not to be less than 5,0 mm. The thickness ofthe coamings is not to be less than 6,0 mm. The coamings areto be extend to the lower edges of the beams.

20.3.3 The stiffeners of the casing are to be connectedto the beams of the casing top and are to extend to the loweredge of the coamings.


2013

21 PASSENGER SHIPS

21.1 GENERAL

21.1.1 The requirements given in Section 1-16 applyto passenger ships unless otherwise mentioned in this Sec-tion.

21.1.2 A passenger ship as defined in this Section is aship carrying more than 12 passenger on board.

21.2 WATERTIGHT SUBDIVISION

21.2.1 The subdivision of the vessel by means oftransverse bulkheads is governed by the requirement of theflooding calculation. The smallest spacing a of the watertighttransverse bulkheads (damage length) is not to be less than0,03 Lc + 3,0 m or 11,0 m, whichever is the smaller (see Fig.21.2.1).

Figure 21.2.1

where Lc = according to Section 10.1.2.1.3

21.2.2 A forepeak or collision bulkhead is to be fittedwhich is to be watertight up to the bulkhead deck. The colli-sion bulkhead is to be situated not less than 0,05 Lc and notmore than 0,05 Lc + 3,0 m from F.P., measured at the deepestload waterline, see Fig. 21.2.3.

21.2.3 In the case of ships having any part of the un-derwater body extending forward of the forward perpen-dicular, e.g. a bulbous bow, the required distance specified in21.2.2 is to be measured from a reference point located at adistance x forward of the forward perpendicular which is tobe the least of (see Fig. 21.2.3):

x =2a

x = 0,015 Lc

x = 3,0 m

Figure 21.2.3

21.2.4 Where a long forward superstructure is fittedthe collision bulkhead shall be extended weathertight to thedeck next above the bulkhead deck. The extension need notbe fitted directly above the bulkhead below provided it is lo-cated within the limits prescribed in Sections 21.2.2 or 21.2.3with the exception permitted by Section 21.2.5 and that thepart of the deck which forms the step is made effectivelyweathertight. The extension shall be so arranged as to pre-clude the possibility of the bow door causing damage to it inthe case of damage to, or detachment of, a bow door.

21.2.5 Where bow doors are fitted and a slopingloading ramp forms part of the extension of the collisionbulkhead above the bulkhead deck the ramp shall be weath-ertight over its complete length. Ramps not meeting theabove requirements shall be disregarded as an extension ofthe collision bulkhead. See also IACS unified interpretationSC93.

21.2.6 Deviating from the requirements of Section10.1.2.2 the stern tube bulkhead or after peak bulkhead is tobe extended to the bulkhead deck.

In all cases stern tubes shall be enclosed inwatertight spaces of moderate volume. The stern gland shallbe situated in a watertight shaft tunnel or other watertightspace separate from the stern tube compartment and of suchvolume that, if flooded by leakage through the stern gland,the bulkhead deck will not be immersed. See also IACS uni-fied interpretation SC93.

21.2.7 No doors, manholes, access openings, ventila-tion ducts or any other openings shall be fitted in the colli-sion bulkhead below the bulkhead deck.

deck

deck

deck

tunneldeck

deck

bulkheaddeck

equi

vale

ntbu

lkhe

ad equi

vale

ntbu

lkhe

ad


2013

21.3 LONGITUDINAL STRENGTH

Longitudinal strength calculations are to bemade in accordance with the requirements given in Section 4.For multi-deck arrangements, the effectiveness of super-structures will be specially considered.

21.4 DOUBLE BOTTOM

21.4.1 A double bottom is to be fitted extending fromthe fore peak bulkhead to the after peak bulkhead, as far aspracticable and compatible with the design and proper op-eration of the ship.

21.4.2 The double bottom has to protect the ship'sbottom up to the turn of the bilge. For this purpose, the inter-secting line of the outer edge of the margin plate with theshell plating is not to be lower at any part than a horizontalplane, passing through the point of intersection with theframe line amidships of a transverse diagonal line inclined 25degrees to the base line and cutting the base line at B/2 fromthe centreline of the ship (see Fig. 21.4.2).

Figure 21.4.2

21.4.3 The bottoms of drain sumps are to be situatedat a distance of at least 460 mm from the base line. Onlyabove the horizontal plane determined from 21.4.2 the bot-toms of drain wells may be led to the shell plating. Exemp-tions for the depth of drain wells may also be granted in shafttunnels and pipe tunnels (see Fig. 21.4.2).

21.5 DECK STRUCTURE

21.5.1 Deck plating

21.5.1.1 For passenger ships, the thickness of deckplating (other than for vehicle decks) will generally be in ac-cordance with Section 6. However, in view of the complexityof some multi-deck arrangements in association with largefreeboards, deck thicknesses may require special considera-tion.

21.5.1.2 Vehicle deck plating is to satisfy the require-ments for plating loaded by wheeled vehicles as specified inSection 6.2.2. Where vehicle decks are also to be used for thecarriage of cargo, the thickness of plating derived from Sec-tion 6.2.1 is to be not less than would be required by Section6.2.2.

21.5.2 Deck stiffening

21.5.2.1 For passenger ships, the deck stiffening is gen-erally to be in accordance with Section 9 (using appropriatedeck load). However, in view of the complexity of somemulti-deck arrangements in association with large freeboards,deck stiffening may require special consideration.

21.6 BOTTOM AND SIDE SHELL

21.6.1 The thickness of side shell plating above, 1,6 d,including superstructures, may require special considerationdepending on the particular structural arrangements, hullvertical bending and shear stresses and position of the shellabove the waterline.

21.6.2 Opening in the side shell and superstructureplating for windows and doors are to be suitably stiffenedand the thickness and grade of plating in way will be spe-cially considered.

21.7 SIDE STRUCTURE

21.7.1 The scantlings of frames, or side longitudinals,web frames or transverses, and stringers below 1,6 d abovebase are to satisfy the requirement of Section 8, but may berequired to be confirmed by direct calculation. the scantlingof these members above 1,6 d from base may require specialconsideration on the basis of the particular structural ar-rangements, design deck loading, hull vertical bendingstresses, and position of the member above the waterline.

21.7.2 Where ramp openings are fitted adjacent to theship's side, adequate support for the side framing is to beprovided.


2013

ANNEX A ADDITIONALREQUIREMENTS FOR EXISTING

BULK CARRIERS

A.1 EVALUATION OF SCANT-LINGS OF THE TRANSVERSE WA-TERTIGHT CORRUGATED BULK-

HEAD BETWEEN CARGO HOLDS NOS.1 AND 2, WITH CARGO HOLD NO. 1

FLOODED

A.1.1 Application and definitions

These requirements apply to all bulk carriers of150 m in length and above, in the foremost hold, intending tocarry solid bulk cargoes having a density of 1,78 t/m3 , orabove, with single deck, topside tanks and hopper tanks, fit-ted with vertically corrugated transverse watertight bulk-heads between cargo holds No. 1 and 2 where.

a) the foremost hold is bounded by the sideshell only for ships which were con-tracted for construction prior to 1 July1998, and have not been constructed incompliance with Section 17,

b) the foremost hold is double side skin con-struction of less than 760 mm breadthmeasured perpendicular to the side shellin ships, the keels of which were laid, orwhich were at a similar stage of con-struction, before 1 July 1999 and have notbeen constructed in compliance withSection 17.

The net scantlings of the transverse bulkheadbetween cargo holds Nos. 1 and 2 are to be calculated usingthe loads given in A.1.2, the bending moment and shear forcegiven in A.1.3 and the strength criteria given in A.1.4.

Where necessary, steel renewal and/or rein-forcements are required as per A1.6.

In these requirements, homogeneous loadingcondition means a loading condition in which the ratio be-tween the highest and the lowest filling ratio, evaluated forthe two foremost cargo holds, does not exceed 1,20, to becorrected for different cargo densities.

A.1.2 Load model

A.1.2.1 General

The loads to be considered as acting on thebulkhead are those given by the combination of the cargoloads with those induced by the flooding of cargo hold No.1.

The most severe combinations of cargo inducedloads and flooding loads are to be used for the check of thescantlings of the bulkhead, depending on the loading condi-tions included in the loading manual:

- homogeneous loading conditions;- non homogeneous loading conditions.Non homogeneous part loading conditions as-

sociated with multiport loading and unloading operations for

homogeneous loading conditions need not to be consideredaccording to these requirements.

A.1.2.2 Bulkhead corrugation flooding head

The flooding head hf (see Figure A.1.1) is the distance, in[m], measured vertically with the ship in the upright position,from the calculation point to a level located at a distance df ,in [m], from the baseline equal to:

a) in general:- D

b) for ships less than 50,000 tonnes dead-weight with Type B freeboard:- 0,95 ⋅ D

D being the distance, in [m], from the baselineto the freeboard deck at side amidship (see Figure A.1.1).

c) for ships to be operated at an assignedload line draught dr less than the permis-sible load line draught d, the floodinghead defined in a) and b) above may bereduced by d - dr.

V = volume cargoP = calculation point

Figure A.1.1

A.1.2.3 Pressure in the flooded hold

A.1.2.3.1 Bulk cargo loaded hold

Two cases are to be considered, depending onthe values of d1 and df, d1 (see Figure A.1.1) being a distancefrom the baseline given, in [m], by:

( ) DBHT

DBHTc

LS

cc

c hB

bhh

BIV

BIM

d +⋅−+⋅

+⋅⋅

=ρ1

where:Mc = mass of cargo, in tonnes, in hold

No. 1ρc = bulk cargo density, in [t/m3];lc = length of hold No. 1, in [m];B = ship’s breadth amidship, in [m];VLS = volume, in [m3], of the bottom stool

above the inner bottom;hHT = height of the hopper tanks amidship,

in [m], from the baseline;hDB = height of the double bottom, in [m];bHT = breadth of the hopper tanks amidship,

in [m].

a) df ≥ d1

At each point of the bulkhead located at a dis-tance between d1 and df from the baseline, the pressure pc,f ,in [kN/m2], is given by:

ff,c hgp ⋅⋅= ρ


2013

where:ρ = sea water density, in [t/m3];g = 9,81 [m/s2], gravity accelerationhf = flooding head as defined in A.1.2.2.At each point of the bulkhead located at a dis-

tance lower than d1 from the baseline, the pressure pc,f , in[kN/m2], is given by:

( )[ ] γρρρ 21, tan1 ⋅⋅⋅−⋅−+⋅⋅= hgpermhgp cffc

where:ρ, g, hf = as given above;

ρc = bulk cargo density, in [t/m3];perm = permeability of cargo, to be taken as

0,3 for ore (corresponding bulk cargodensity for iron ore may generally betaken as 3,0 t/m3;

h1 = vertical distance, in [m], from thecalculation point to a level located ata distance d1, as defined above, fromthe base line (see Figure A.1.1)

γ = 45° -(φ/2)φ = angle of repose of the cargo, in de-

grees, and may generally be taken as35° for iron ore.

The force Fc,f, in [kN], acting on a corrugationis given by:

+

−⋅⋅⋅=

2)( 2

11,

ddgsF f

fc ρ

( )

−−⋅

−⋅⋅+

+LSDB

pfhhd

ddglefc

1)()1

2

(,

ρ

where:s1 = spacing of corrugations, in [m], (see

Figure A.1.2a);ρ, g, d1, hDB = as given above;

df = as given in A.1.2.2;(pc,f )le = pressure, in [kN/m2], at the lower end

of the corrugation;hLS = height of the lower stool, in [m], from

the inner bottom.

Figure A.1.2 a

b) df < d1

At each point of the bulkhead located at a dis-tance between df and d1 from the baseline, the pressure pc,f ,in [kN/m2], is given by:

γρ 21, tan⋅⋅⋅= hgp cfc

where:ρc, g, h1, γ = as given in a) above.At each point of the bulkhead located at a dis-

tance lower than df from the baseline, the pressure pc,f , in[kN/m2], is given by:

( )[ ] γρρρ 21, tan1 ⋅⋅⋅−⋅−⋅+⋅⋅= ghpermhhgp fcffc

where:ρ, g, hf, ρc, h1, perm, γ = as given in a) above

The force Fc,f , in [kN], acting on a corrugationis given by:

+⋅

−⋅⋅⋅= y

ddgsF f

cfc2

21

1, tan2

)(ρ

−−⋅

+⋅−⋅⋅+ )(

2)(tan)( ,

21

LSDBflefcfc hhd

pyddgρ

where:s1, ρc, g, γ, (pc,f )le, hLS = as given in a) above;

d1, hDB = as given in A.1.2.3.1;df = as given in A.1.2.2.

A.1.2.3.2 Empty holdAt each point of the bulkhead, the hydrostatic

pressure pf induced by the flooding head hf is to be consid-ered.

The force Ff, in [kN], acting on a corrugation isgiven by:

( )2

2

1LSDBf

fhhd

gsF−−

⋅⋅⋅= ρ

where:s1, ρ, g, hLS = as given in A.1.2.3.1 a);

hDB = as given in A.1.2.3.1;df = as given in A.1.2.2.

A.1.2.4 Pressure in the non-flooded bulk cargoloaded hold

At each point of the bulkhead, the pressure pc ,in [kN/m2], is given by:

γρ 21 tan⋅⋅⋅= hgp cc

where:ρc, g, h1, γ = as given in A.1.2.3.1 a)The force Fc , in [kN], acting on a corrugation

is given by:( )

γρ 22

11 tan

2⋅

−−⋅⋅⋅= LSDB

cchhdsgF

where:ρc, g, s1, hLS, γ = as given in A.1.2.3.1 a);

d1, hDB = as given in A.1.2.3.1.


2013

A.1.2.5 Resultant pressure

A.1.2.5.1 Homogeneous loading conditions

At each point of the bulkhead structures, the re-sultant pressure p, in [kN/m2], to be considered for the scant-lings of the bulkhead is given by:

p = pc,f - 0,8 ⋅ pc


F = Fc,f - 0,8 ⋅ Fc

A.1.2.5.2 Non homogeneous loading conditionsAt each point of the bulkhead structures, the re-

sultant pressure p, in [kN/m2], to be considered for the scant-lings of the bulkhead is given by:

p = pc,f


F = Fc,f

In case hold No.1, in non homogeneous loadingconditions, is not allowed to be loaded, the resultant pressurep, in [kN/m2], to be considered for the scantlings of the bulk-head is given by:

p = pf

and the resultant force F, in [kN], acting on acorrugation is given by:

F = Ff

A.1.3 Bending moment and shear force in thebulkhead corrugations

The bending moment M and the shear force Q in the bulk-head corrugations are obtained using the formlae given inA.1.3.1 and A.1.3.2. The M and Q values are to be used forthe checks in A.1.4.

A.1.3.1 Bending moment

The design bending moment M, in [kN·m], forthe bulkhead corrugations is given by:

8lFM ⋅

=

where:F = resultant force, in [kN], as given in

A.1.2.5l = span of the corrugation, in [m], to be

taken according to Figures A.1.2.aand A.1.2.b.

Figure A.1.2.b

Note: For the definition of l, the internal end of the upperstool is not to be taken more than a distance from thedeck at the centre line equal to:- 3 times the depth of corrugations, in general- 2 times the depth of corrugations, for rectangular

stol

A.1.3.2 Shear force

The shear force Q, in [kN], at the lower end ofthe bulkhead corrugations is given by:

F,Q ⋅= 80where:

F = as given in A.1.2.5

A.1.4 Strength criteria

A.1.4.1 GeneralThe following criteria are applicable to trans-

verse bulkheads with vertical corrugations (see FigureA.1.2a).

Requirements for local net plate thickness aregiven in A.1.4.7.

In addition, the criteria given in A.1.4.2 andA.1.4.5 are to be complied with.

Where the corrugation angle φ shown in FigureA.1.2a if less than 50°, an horizontal row of staggered shed-der plates is to be fitted at approximately mid depth of thecorrugations (see Figure A.1.2a) to help preserve dimen-sional stability of the bulkhead under flooding loads. Theshedder plates are to be welded to the corrugations by doublecontinuous welding, but they are not to be welded to the sideshell.

The thicknesses of the lower part of corruga-tions considered in the application of A.1.4.2 and A.1.4.3 areto be maintained for a distance from the inner bottom (if nolower stool is fitted) or the top of the lower stool not less than0,15⋅l.

The thicknesses of the middle part of corruga-tions considered in the application of A.1.4.2 and A.1.4.4 areto be maintained to a distance from the deck (if no upperstool is fitted) or the bottom of the upper stool not greaterthan 0,3⋅l.

A.1.4.2 Bending capacity and shear stress τ

The bending capacity is to comply with thefollowing relationship:

0150

103 ,ZZ,

M

m,amle,ale≤

⋅+⋅⋅⋅

σσwhere:

M = bending moment, in [kN·m], as givenin A.1.3.1.

Zle = section modulus of one half pitch cor-rugation, in [cm3], at the lower end ofcorrugations, to be calculated ac-cording to A.1.4.3.

Zm = section modulus of one half pitch cor-rugation, in [cm3], at the mid-span ofcorrugations, to be calculated ac-cording to A.1.4.4.

σa,le = allowable stress, in [N/mm2], as givenin A.1.4.5, for the lower end of cor-rugations


2013

σa,m = allowable stress, in [N/mm2], as givenin A.1.4.5, for the mid-span of corru-gations.

In no case Zm is to be taken greater than thelesser of 1,15·Zle .and 1,15·Z’le for calculation of the bendingcapacity. Z’le being defined below.

In case effective shedders plates are fittedwhich:

- are not knuckled;- are welded to the corrugations and the top

of the lower stool by one side penetrationwelds or equivalent;

- are fitted with a minimum slope of 45°and their lower edge is in line with thestool side plating;

or effective gusset plates are fitted which:- are fitted in line with the stool side plat-

ing;- have material properties at least equal to

those provided for the flanges,the section modulus Zle , in [cm3], is to be taken

not larger than the value Z’le , in [cm3], given by:

a

ggggle

psh,hQZ'Z

σ

⋅⋅⋅−⋅⋅+= 1

23 50

10

where:Zg = section modulus of one half pitch cor-

rugation, in [cm3], according toA.1.4.4, in way of the upper end ofshedder or gusset plates, as applica-ble;

Q = shear force, in [kN], as given inA.1.3.2;

hg = height, in [m], of shedders or gussetplates, as applicable (see FiguresA.1.3a, A.1.3b, A.1.4a and A.1.4b)

s1 = as given in A.1.2.3.1 a);pg = resultant pressure, in [kN/m2], as de-

fined in A.1.2.5, calculated in way ofthe middle of the shedders or gussetplates, as applicable;

σa = allowable stress, in [N/mm2], as givenin A.1.4.5.

Stresses τ are obtained by dividing the shearforce Q by the shear area. The shear area is to be reduced inorder to account for possible non-perpendicularity betweenthe corrugation webs and flanges. In general, the reducedshear area may be obtained by multiplying the web sectionalarea by (sin φ), φ being the angle between the web and theflange.

When calculating the section moduli and theshear area, the net plate thicknesses are to be used.

The section moduli of corrugations are to becalculated on the basis of the requirements given in A.1.4.3and A.1.4.4.

A.1.4.3 Section modulus at the lower end of corruga-tions

The section modulus is to be calculated withthe compression flange having an effective flange width, bef,not larger than as given in A.1.4.6.1.

If the corrugation webs are not supported bylocal brackets below the stool top (or below the inner bot-

tom) in the lower part, the section modulus of the corruga-tions is to be calculated considering the corrugation webs30% effective.

a) Provided that effective shedder plates, asdefined in A.1.4.2, are fitted (see FiguresA.1.3a and A.1.3b), when calculating thesection modulus of corrugations at thelower end (cross-section in FiguresA.13a and A.1.3b), the area of flangeplates, in [cm2], may be increased by

⋅⋅⋅⋅

Ffl

Fshshf tta

σσ5,2 (not to be

taken greater than 2,5·a·tf)where:

a = width, in [m], of the corrugationflange (see Figure A.1.2a);

tsh = net shedder plate thickness, in [mm];tf = net flange thickness, in mm];σFsh = minimum upper yield stress, in

[N/mm2], of the material used for theshedder plates;

σFfl = minimum upper yield stress, in[N/mm2], of the material used for thecorrugation flanges.

b) Provided that effective gusset plates, asdefined in A.1.4.2, are fitted (see FiguresA.1.4a and A.1.4b), when calculating thesection modulus of corrugations at thelower end (cross-section in FiguresA.1.4a and A.1.4b), the area of flangeplates, in [cm2], may be increased by (7 ⋅hg ⋅ tgu)

where:hg = height of gusset plate, in [m], see

Figures A.1.4a and A.1.4b, not to betaken greater than :

⋅ gus7

10

sgu = width of the gusset plates, in [m];tgu = net gusset plate thickness, in [mm],

not to be taken greater than tf;tf = net flange thickness, in [mm], based

on the as built condition.c) If the corrugation webs are welded to a

sloping stool top plate, which is at an an-gle not less than 45º with the horizontalplane, the section modulus of the corru-gations may be calculated considering thecorrugation webs fully effective. In caseeffective gusset plates are fitted, whencalculating the section modulus of corru-gations the area of flange plates may beincreased as specified in b) above. Nocredit can be given to shedder platesonly.

For angles less than 45º, the effectiveness ofthe web may be obtained by linear interpolation between30% for 0º and 100% for 45º.

A.1.4.4 Section modulus of corrugations at cross-sections other than the lower end

The section modulus is to be calculated withthe corrugation webs considered effective and the compres-


2013

sion flange having an effective flange width, bef, not largerthan as given in A.1.4.6.1.

A.1.4.5 Allowable stress check

The normal and shear stresses σ and τ are notto exceed the allowable values σa and τa, in [N/mm2], givenby:

σa = σFτa = 0,5 ⋅ σFσF = minimum upper yield stress, in

[N/mm2], of the material.

A.1.4.6 Effective compression flange width andshear buckling check

A.1.4.6.1 Effective width of the compression flange ofcorrugations

The effective width bef, in [m], of the corruga-tion flange is given by:

bef = Ce ⋅ awhere:

2251252

ββ,,Ce −= for β > 1,25

01,Ce = for β < 1,25

Eta F

f

σβ ⋅⋅= 310

tf = net flange thickness, in [mm];a = width, in [m], of the corrugation

flange (see Figure A.1.2a);σF = minimum upper yield stress, in

[N/mm2], of the material;E = modulus of elasticity, in [N/mm2], to

be assumed equal to 2,06⋅105 N/mm2

for steel.

A.1.4.6.2 ShearThe buckling check is to be performed for the

web plates at the corrugation ends.The shear stress τ is not to exceed the critical

value τc, in [N/mm2], obtained by the following:

Ec ττ = ,when 2F

Eτ

τ ≤

−=

E

FF τ

ττ

41 , when

2F

Eτ

τ >

3F

Fσ

τ =

where:σF = minimum upper yield stress, in

[N/mm2], of the material;2

tE c1000tEk9.0

=τ [N/mm2]

kt, E, t and c are given by:kt = 6.34;E = modulus of elasticity of material as

given in A.1.4.6.1;t = net thickness, in [mm], of corrugation

web;c = width, in [m], of corrugation web

(See Figure A.1.2a).

A.1.4.7 Local net plate thickness

The bulkhead local net plate thickness t, in [mm], is givenby:

Fw

ps,tσ

⋅⋅= 914

where:sw = plate width, in [m], to be taken equal

to the width of the corrugation flangeor web, whichever is the greater (seeFigure A.1.2a)

p = resultant pressure, in [kN/m2], as de-fined in A.1.2.5, at the bottom of eachstrake of plating; in all cases, the netthickness of the lowest strake is to bedetermined using the resultant pres-sure at the top of the lower stool, or atthe inner bottom, if no lower stool isfitted or at the top of shedders, ifshedder or gusset/shedder plates arefitted.


For built-up corrugation bulkheads, when thethicknesses of the flange and web are different, the net thick-ness of the narrower plating is to be not less than tn, in [mm],given by:

Fnn

ps,tσ

⋅⋅= 914

sn being the width, in [m], of the narrower plating.The net thickness of the wider plating, in [mm],

is not to be taken less than the maximum of the followingvalues:

Fww

ps,tσ

⋅⋅= 914

22440

npF

ww t

pst −

⋅⋅=

σwhere tnp < actual net thickness of the narrower plating andnot to be greater than:

Fw

ps,σ

⋅⋅914

A.1.5 Local details

1.5.1 As applicable, the design of local details is tocomply with the Register’s requirements for the purpose oftransferring the corrugated bulkhead forces and moments tothe boundary structures, in particular to the double bottomand cross-deck structures.

1.5.2 In particular, the thickness and stiffening ofgusset and shedder plates, installed for strengthening pur-poses, is to comply with the Register’s requirements, on thebasis of the load model in A.1.2.

1.5.3 Unless otherwise stated, weld connections andmaterials are to be dimensioned and selected in accordancewith the Register’s requirements.


2013

A.1.6 Corrosion addition and steel renewal

Renewal/reinforcement shall be done in accor-dance with the following requirements and the guidelinescontained in the A.1.7.

a) Steel renewal is required where the

gauged thickness (ti) is less than tnet + 0,5[mm], tnet being the thickness used for thecalculation of bending capacity and shearstresses as given in A.1.4.2 or the localnet plate thickness as given in A.1.4.7.Alternatively, reinforcing doubling stripsmay be used providing the net thicknessis not dictated by shear strength require-ments for web plates (see A.1.4.5 andA.1.4.6.2) or by local pressure require-ments for web and flange plates (seeA.1.4.7).Where the gauged thickness (ti) is withinthe range tnet + 0,5 [mm] and tnet + 1,0[mm], coating (applied in accordancewith the coating manufacturer’s require-ments) or annual gauging may be adoptedas an alternative to steel renewal.

b) Where steel renewal or reinforcement isrequired, a minimum thickness of tnet +2,5 [mm] is to be replenished for the re-newed or reinforced parts.

c) When:( ) stFSflFfl tt, ⋅≥⋅⋅ σσ80

where:σFfl = minimum upper yield stress, in

[N/mm2], of the material used for thecorrugation flanges;

σFs = minimum upper yield stress, in[N/mm2], of the material used for the

lower stool side plating or floors (ifno stool is fitted);

tfl = flange thickness, in [mm], which isfound to be acceptable on the basis ofthe criteria specified in a) above or,when steel renewal is required, thereplenished thickness according to thecriteria specified in b) above. Theabove flange thickness dictated by lo-cal pressure requirements (seeA.1.4.7) need not be considered forthis purpose;

tst = as built thickness, in [mm], of thelower stool side plating or floors (ifno stool is fitted).

gussets with shedder plates, extending from thelower end of corrugations up to 0,1·l, or reinforcing doublingstrips (on bulkhead corrugations and stool side plating) are tobe fitted.

If gusset plates are fitted, the material of suchgusset plates is to be the same as that of the corrugationflanges. The gusset plates are to be connected to the lowerstool shelf plate or inner bottom (if no lower stool is fitted)by deep penetration welds (see Figure A.1.5).

d) Where steel renewal is required, thebulkhead connections to the lower stoolshelf plate or inner bottom (if no stool isfitted) are to be at least made by deeppenetration welds (see Figure A.1.5).

e) Where gusset plates are to be fitted or re-newed, their connections with the corru-gations and the lower stool shelf plate orinner bottom (if no stool is fitted) are tobe at least made by deep penetrationwelds (see Figure A.1.5).

Figure A.1.3 a Figure A.1.3 b

shedderplate

lowerstool

shedderplate

lowerstool


2013

Figure A.1.4 a Figure A.1.4 b

Root face (f): 3 [mm] to T/3 [mm]Groove angle (α): 40˚ to 60˚

Figure A.1.5

A.1.7 Guidance on renewal/reinforcement ofvertically corrugated transverse water-tight bulkhead between cargo holdsNos. 1 and 2

A.1.7.1 The need for renewal or reinforcement of thevertically corrugated transverse watertight bulkhead betweencargo holds Nos. 1 and 2 will be determined by the classifi-cation society by the Register on a case by case basis usingthe criteria given in this Section in association with the mostrecent gaugings and findings from survey.

A.1.7.2 In addition to class requirements, the assess-ment of this Section of the transverse corrugated bulkheadwill take into account the following:

a) Scantlings of individual vertical corruga-tions will be assessed for reinforce-ment/renewal based on thickness meas-urements obtained in accordance withRegister’s guidance for thickness meas-urements at their lower end, at mid-depthand in way of plate thickness changes inthe lower 70%.

These considerations will take into ac-count the provision of gussets and shed-der plates and the benefits they offer,provided that they comply with A.1.4.2and A.1.6.

(b) Taking into account the scantlings and ar-rangements for each case, permissiblelevels of diminution will be determinedand appropriate measures taken in accor-dance with A.1.6.

A.1.7.3 Where renewal is required, the extent of re-newal is to be shown clearly in plans. The vertical distance ofeach renewal zone is to be determined by considering the re-quirements of this Section, and in general is to be not lessthan 15% of the vertical distance between the upper andlower end of the corrugation -measured at the ship’s centre-line.

A.1.7.4 Where the reinforcement is accepted by addingstrips, the length of the reinforcing strips is to be sufficient toallow it to extend over the whole depth of the diminishedplating. In general, the width and thickness of strips shouldbe sufficient to comply with the requirements of this Section.The material of the strips is to be the same as that of the cor-rugation plating. The strips are to be attached to the existing


2013

bulkhead plating by continuous fillet welds. The strips are tobe suitably tapered or connected at ends in accordance withRegister’s practice.

A.1.7.5 Where reinforcing strips are connected to theinner bottom or lower stool shelf plates, one side full pene-tration welding is to be used. When reinforcing strips are fit-ted to the corrugation flange and are connected to the lowerstool shelf plate, they are normally to be aligned with stripsof the same scantlings welded to the stool side plating andhaving a minimum length equal to the breadth of the corru-gation flange.

A.1.7.6 Figure A.1.7 gives a general arrangement ofstructural reinforcement.

Reinforcement strips with shedder and gusset plates

Figure A.1.7

Notes to Figure A.1.7 on reinforcement:

1. Square or trapezoidal corrugations are to be rein-forced with plate strips fitted to each corrugationflange sufficient to meet the requirements of thisSection.

2. The number of strips fitted to each corrugationflange is to be sufficient to meet the requirementsof this Section.

3. The shedder plate may be fitted in one piece or pre-fabricated with a welded knuckle (gusset plate).

4. Gusset plates, where fitted, are to be welded to theshelf plate in line with the flange of the corruga-tion, to reduce the stress concentrations at the cor-rugation corners. Ensure good alignment betweengusset plate, corrugation flange and lower stoolsloping plate. Use deep penetration welding at allconnections. Ensure start and stop of welding is asfar away as practically possible from corners ofcorrugation.

5. Shedder plates are to be attached by one side fullpenetration welds onto backing bars.

6. Shedder and gusset plates are to have a thicknessequal to or greater than the original bulkheadthickness. Gusset plate is to have a minimumheight (on the vertical part) equal to half of thewidth of the corrugation flange. Shedders and gus-sets are to be same material as flange material.

A.1.8 Guidance to assess capabiltiy of car-riage of high density cargoes on existingbulk carrers according to the strengthof transverse bulkhead between cargoholds Nos. 1 and 2

Figure A.1.8 contains, for guidance only, aflow chart for assessment of capability of high density car-goes carrage according to the strngth of transverse bulkheadbetween cargo holds Nos. 1 and 2.

Upper end tobe suitably ta-pered

Lower end tobe welded tolower shelf byfull penetrati-on weld

Flange reinfo-rcement stripsto be alignedwith strips ofsame scantli-ngs belowshelf plate

CorrugationflangeOne side full

penetrationweld

Lower stoolshelf plate

Lower stoolside plating

Reinforcement strips with shedder plate Weld of reinforcement strip to shelfl t

Upper end to besuitable tapered

Lower end to betapered above shelfplate within line ofgusset

Gussetplate

Lower shelfplate

Reinforcementstrip

Shedderplate

Gussetplate

Lower stoolside plating

Reinforcementstrip

Reinforcementstrip


2013

Guidance to Assess Capability of Carriage of High Density Cargoes on Existing Bulk Carriersaccording to the Strength of Transverse Bulkhead between Cargo Holds No. 1 and 2

Figure A.1.8

Carriage of cargoeshaving ρc ≥ 1.78 /m3?

No need forfurtherasseassment

Check forρc = 1.78 t/m3

Checksatisfactory

Reinforce(2)

Calculateallowable

densityρc1

ρc1 > 1.78 t/m3?Only cargoes

havingρc ≤ 1.78 t/m3

can be carried

Check forρc > 1.78 t/m3

(1)

Cargoes havingρc ≤ ρc1

can be carried

Checksatifactory

All cargoes canbe carried

Reinforcementsfor ρc

(2)

Calculate allowabledensity ρc2

Cargoes havingρc ≤ ρc2

can be carried

Notes:

(1) ρc typical of cargoes to be carried; in any cace a value of3.0 t/m3, corresponding to ore cargo, is to be considered.

(2) In deciding the reinforcement needed, consideration willbe given to the effects of restricting the cargo distribution(homogeneus loading condition or reduction in the shipdeadweight)

No

Yes

No No

YesYes

Yes

No

Yes

No


2013

A.2 EVALUATION OF ALLOWABLEHOLD LOADING OF CARGO HOLD

NO. 1 WITH CARGO HOLD NO. 1FLOODED


These requirements apply to all bulk carriers of150 m in length and above, in the foremost hold, intending tocarry solid bulk cargoes having a density of 1,78 t/m3, orabove, with single deck, topside tanks and hopper tanks,where.

a) the foremost hold is bounded by the sideshell only for ships which were con-tracted for construction prior to 1 July1998, and have not been constructed incompliance with Section 17,

b) the foremost hold is double side skin con-struction less than 760 mm breadth meas-ured perpendicular to the side shell inships, the keels of which were laid, orwhich were at a similar stage of con-struction, before 1 July 1999 and have notbeen constructed in compliance withSection 17.

Early completion of a special survey comingdue after 1 July 1998 to postpone compliance is not allowed.

The loading in cargo hold No. 1 is not to ex-ceed the allowable hold loading in the flooded condition, cal-culated as per A.2.4, using the loads given in A.2.2 and theshear capacity of the double bottom given in A.2.3.

In no case, the allowable hold loading inflooding condition is to be taken greater than the design holdloading in intact condition.

A.2.2 Load model

A.2.2.1 General

The loads to be considered as acting on thedouble bottom of hold No. 1 are those given by the externalsea pressures and the combination of the cargo loads withthose induced by the flooding of hold No. 1.

The most severe combinations of cargo inducedloads and flooding loads are to be used, depending on theloading conditions included in the loading manual:

- homogeneous loading conditions;- non homogeneous loading conditions;- packed cargo conditions (such as steel

mill products).For each loading condition, the maximum bulk

cargo density to be carried is to be considered in calculatingthe allowable hold limit.

Figure A.2.1

A.2.2.2 Inner bottom flooding head

The flooding head hf (see Figure A.2.1) is thedistance, in [m], measured vertically with the ship in the up-right position, from the inner bottom to a level located at adistance df , in [m], from the baseline equal to:

- D in general;- 0,95 · D for ships less than 50,000 tonnes

deadweight with Type B freeboard.D being the distance, in [m], from the baseline

to the freeboard deck at side amidship (see Figure A.2.1).

A.2.3 Shear capacity of the double bottom ofhold No. 1

The shear capacity C of the double bottom ofhold No. 1 is defined as the sum of the shear strength at eachend of:

- all floors adjacent to both hoppers, lessone half of the strength of the two floorsadjacent to each stool, or transverse bulk-head if no stool is fitted (see FigureA.2.2),

- all double bottom girders adjacent to bothstools, or transverse bulkheads if no stoolis fitted.

Figure A.2.2

The strength of girders or floors which run outand are not directly attached to the boundary stool or hoppergirder is to be evaluated for the one end only.

lowerstool

transversebulkhead

Giders

Floors


2013

Note that the floors and girders to be consid-ered are those inside the hold boundaries formed by the hop-pers and stools (or transverse bulkheads if no stool is fitted).The hopper side girders and the floors directly below theconnection of the bulkhead stools (or transverse bulkheads ifno stool is fitted) to the inner bottom are not to be included.

When the geometry and/or the structural ar-rangement of the double bottom are such to make the aboveassumptions inadequate, to the Register’s discretion, theshear capacity C of the double bottom is to be calculated ac-cording to the Register’s criteria.

In calculating the shear strength, the net thick-nesses of floors and girders are to be used. The net thicknesstnet, in [mm], is given by:

tnet = t - tcwhere:

t = as built thickness, in [mm], of floorsand girders;

tc = corrosion diminution, equal to 2 mm,in general; a lower value of tc may beadopted, provided that measures aretaken, to the Register’s satisfaction,to justify the assumption made.

A.2.3.1 Floor shear strength

The floor shear strength in way of the floorpanel adjacent to hoppers Sf1 , in [kN], and the floor shearstrength in way of the openings in the “outermost” bay (i.e.that bay which is closest to hopper) Sf2 , in [kN], are given bythe following expressions:

1

31 10

ητ a

ff AS ⋅⋅= −

Sf2 = 10-3 . Af,h .

2ητ a

where:Af = sectional area, in [mm2], of the floor

panel adjacent to hoppers;Af,h = net sectional area, in [mm2], of the

floor panels in way of the openings inthe “outermost” bay (i.e. that baywhich is closest to hopper);

σF = minimum upper yield stress, in[N/mm2], of the material;

τa = allowable shear stress, in [N/mm2], to

be taken equal to : 3/Fση1 = 1,10η2 = 1,20

η2 may be reduced down to 1,10 where appropriate rein-forcements are fitted to the Register’s satisfaction

A.2.3.2 Girder shear strength

The girder shear strength in way of the girderpanel adjacent to stools (or transverse bulkheads, if no stoolis fitted) Sg1 , in [kN], and the girder shear strength in way ofthe largest opening in the “outermost” bay (i.e. that baywhich is closest to stool, or transverse bulkhead, if no stool isfitted) Sg2 , in [kN], are given by the following expressions:

1

31 10

ητ a

gg AS ⋅= −

2

32 10

ητ a

h,gg AS ⋅⋅= −

where:Ag = minimum sectional area, in [mm2], of

the girder panel adjacent to stools (ortransverse bulkheads, if no stool isfitted);

Ag,h = net sectional area, in [mm2], of thegirder panel in way of the largestopening in the “outermost” bay (i.e.that bay which is closest to stool, ortransverse bulkhead, if no stool isfitted);

τa = allowable shear stress, in [N/mm2], asgiven in A.2.3.1;

η1 = 1,10η2 = 1,15

η2 may be reduced down to 1,10 where appropriate rein-forcements are fitted to the Register’s satisfaction

A.2.4 Allowable hold loading

The allowable hold loading W, in [t], is givenby:

FVW c

1⋅⋅= ρ

where:F = 1,05 in general;

1,00 for steel mill products;ρc = cargo density, in [t/m3] (see A.2.2.1);V = volume, in [m3], occupied by cargo at

a level h1

gXhc ⋅

=ρ1

X = for bulk cargoes, the lesser of X1 andX2 given by:

( ))perm(

hEgZX

c

f

111

−+

−⋅⋅+=

ρρρ

( )permhEgZX f ⋅−⋅⋅+= ρ2

X = for steel products, X may be taken asX1, using perm = 0;

ρ = sea water density, in [t/m3];g = 9,81 m/s2 , gravity acceleration;E = df - 0,1 ⋅ D;df, D = as given in A.2.2.2;hf = flooding head, in [m], as defined in

A.2.2.2;perm = permeability of cargo, to be taken as

0,3 for ore (corresponding bulk cargodensity for iron ore may generally betaken as 3,0 t/m3 ).

Z = the lesser of Z1 and Z2 given by:

h,DB

h

AC

Z =1

e,DB

e

AC

Z =2

Ch = shear capacity of the double bottom,in [kN], as defined in A.2.3, consid-ering, for each floor, the lesser of the


2013

shear strengths Sf1 and Sf2 (seeA.2.3.1) and, for each girder, thelesser of the shear strengths Sg1 andSg2 (see A.2.3.2);

Ce = shear capacity of the double bottom,in [kN], as defined in A.2.3, consid-ering, for each floor, the shearstrength Sf1 (see A.2.3.1) and, foreach girder, the lesser of the shearstrengths Sg1 and Sg2 (see A.2.3.2);

∑=

=

⋅=ni

ii,DBih,DB BSA

1

( )∑=

=

−⋅=ni

iDBih,DB sBSA

1n = number of floors between stools (or

transverse bulkheads, if no stool isfitted);

Si = space of ith-floor, in [m];BDB,i = BDB – s, for floors whose shear

strength is given by Sf1 (see A.2.3.1);BDB,i = BDB,h ,for floors whose shear strength

is given by Sf2 (see A.2.3.1);BDB = breadth of double bottom, in [m],

between hoppers (see Figure A.2.3);BDB,h = distance, in [m], between the two

considered openings (see FigureA.2.3):

s = spacing, in [m], of double bottomlongitudinals adjacent to hoppers.

Figure A.2.3


2013

A.3 IMPLEMENTATION OF THEADDITIONAL REQUIREMENTS A.1

AND A.2

A.3.1 Application and implementation time-table1)

A.3.1.1 The requirements A.1 and A.2 are to be appliedin conjunction with the damage stability requirements setforth in A.3.2. Compliance is required:

.1 for ships which were 20 years of age or moreon 1 July 1998, by the due date of the first in-termediate, or the due date of the first specialsurvey to be held after 1 July 1998, whichevercomes first;

.2 for ships which were 15 years of age or morebut less than 20 years of age on 1 July 1998, bythe due date of the first special survey to beheld after 1 July 1998, but not later than 1 July2002;

.3 for ships which were 10 years of age or morebut less than 15 years of age on 1 July 1998, bythe due date of the first intermediate, or the duedate of the first special survey to be held afterthe date on which the ship reaches 15 years ofage but not later than the date on which the shipreaches 17 years of age;

.4 for ships which were 5 years of age or more butless than 10 years of age on 1 July 1998, bythe due date, after 1 July 2003, of the first in-termediate or the first special survey after thedate on which the ship reaches 10 years of age,whichever occurs first;

.5 for ships which were less than 5 years of age on1 July 1998, by the date on which the shipreaches 10 years of age.

A.3.1.2 Completion prior to 1 July 2003 of an interme-diate or special survey with a due date after 1 July 2003 can-not be used to postpone compliance. However, completionprior to 1 July 2003 of an intermediate survey the windowfor which straddles 1 July 2003 can be accepted.

A.3.2 Damage stability

A.3.2.1 Bulk carriers which are subject to compliancewith the requirements A.1 and A.2 shall, when loaded to thesummer loadline, be able to withstand flooding of the fore-most cargo hold in all loading conditions and remain afloat ina satisfactory condition of equilibrium, as specified in SOLASregulation XII/4.3 to 4.7.

A.3.2.2 A ship having been built with an insufficientnumber of transverse watertight bulkheads to satisfy this re-quirement may be exempted from the application of the re-quirements A.1, A.2 and this requirement provided the shipfulfills the requirement in SOLAS regulation XII/9.

A.3.2.3 For application of the requirements in SOLASregulation XII/9 see IACS unified interpretation SC 182.

A.3.3 Details

A.3.3.1 Surveys to be held

The term "survey to be held" is interpreted tomean that the survey is "being held" until it is "completed".

Note:1) See A.3.3 for details.

A.3.3.2 Due dates and completion allowance

A.3.3.2.1 Intermediate survey :

A.3.3.2.1.1 Intermediate survey carried out either at thesecond or third annual survey: 3 months after the due date(i.e. 2nd or 3rd anniversary ) can be used to carry out andcomplete the survey;

A.3.3.2.1.2 Intermediate survey carried out between thesecond and third annual survey: 3 months after the due dateof the 3rd Annual Survey can be used to carry out and com-plete the survey;

A.3.3.2.2 Special survey : 3 months extension after thedue date may be allowed subject to the terms/conditions ofPR4;

A.3.3.2.3 Ships controlled by “1 July 2002”: same as forspecial survey;

A.3.3.2.4 Ships controlled by ”age 15 years” or “age 17years”: same as for special survey.

A.3.3.3 Intermediate survey interpretations / Appli-cations

A.3.3.3.1 If the 2nd anniversary is prior to or on 1 July1998 and the intermediate survey is completed prior to or on1 July 1998, the ship need not comply until the next specialsurvey.

A.3.3.3.2 If the 2nd anniversary is prior to or on 1 July1998 and the intermediate survey is completed within thewindow of the 2nd annual survey but after 1 July 1998, theship need not comply until the next special survey.

A.3.3.3.3 If the 2nd anniversary is prior to or on 1 July1998 and the intermediate survey is completed outside thewindow of the 2nd annual survey and after 1 July 1998, it istaken that the intermediate survey is held after 1 July 1998and between the second and third annual surveys. Therefore,the ship shall comply no later than 3 months after the 3rd an-niversary.

A.3.3.3.4 If the 2nd anniversary is after 1 July 1998 andthe intermediate survey is completed within the window ofthe 2nd annual survey but prior to or on 1 July 1998, the shipneed not comply until the next special survey

A.3.3.3.5 If the 3rd anniversary is prior to or on 1 July1998 and the intermediate survey is completed prior to or on1 July 1998, the ship need not comply until the next specialsurvey.

A.3.3.3.6 If the 3rd anniversary is prior to or on 1 July1998 and the intermediate survey is completed within thewindow of the 3rd annual survey but after 1 July 1998, theship need not comply until the next special survey.

A.3.3.3.7 If the 3rd anniversary is after 1 July 1998 andthe intermediate survey is completed within the window priorto or on 1 July 1998, the ship need not comply until the nextspecial survey.

A.3.3.4 Special survey interpretations / Applications

A.3.3.4.1 If the due date of a special survey is after 1 July1998 and the special survey is completed within the 3 monthwindow prior to the due date and prior to or on 1 July 1998,


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the ship need not comply until the next relevant survey (i.e.special survey for ships under 20 years of age on 1 July1998, intermediate survey for ships 20 years of age or moreon 1 July 1998).

A.3.3.5 Early completion of an intermediate survey(coming due after 1st July 1998) to postponecompliance is not allowed:

A.3.3.5.1 Early completion of an intermediate surveymeans completion of the survey prior to the opening of thewindow (i.e. completion more than 3 months prior to the 2ndanniversary since the last special survey).

A.3.3.5.2 The intermediate survey may be completedearly and credited from the completion date but in such acase the ship will still be required to comply not later thanthe 3 months after the 3rd anniversary.

A.3.3.6 Early completion of a special survey (comingdue after 1st July 1998) to postpone compli-ance is not allowed:

A.3.3.6.1 Early completion of a special survey meanscompletion of the survey more than 3 months prior to the duedate of the special survey.

A.3.3.6.2 The special survey may be completed early andcredited from the completion date, but in such a case the shipwill still be required to comply by the due date of the specialsurvey.


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A.4 REQUIREMENTS OF THESOLAS 1974, CH. XII, REG. 12&13 FOR

BULK CARRIERS

A.4.1 Requirements for hold, ballast and dryspace water ingress alarms

A.4.1.1 This requirement is applicable to bulk carriersof single side skin construction as defined in the Rules for theclassification of ships, Part 1 – General requirements,Chapter 1 – General information, Section 4.2.

A.4.1.2 Bulk carriers the keels of which are laid orwhich are at a similar stage of construction before 1 July2004 shall comply with the requirements of this regulationnot later than the date of the annual, intermediate or renewalsurvey of the ship to be carried out after 1 July 2004, which-ever comes first.

A.4.1.3 Bulk carriers shall be fitted with water leveldetectors in each cargo hold, giving audible and visualalarms as follows:

a) one when the water level above the inner bottomin any hold reaches a height of 0,5 m and

b) another at a height not less than 15% of the depthof the cargo hold but not more than 2 m.

On bulk carriers to which regulation A.3.2.2applies, detectors with only the latter alarm need be installed.

The water level detectors shall be fitted in theaft end of the cargo holds.

For cargo holds which are used for water bal-last, an alarm overriding device may be installed.

The visual alarms shall clearly discriminatebetween the two different water levels detected in eachhold.

A.4.1.4 In any ballast tank forward of the collisionbulkhead, giving an audible and visual alarm when the liquidin the tank reaches a level not exceeding 10% of the tank ca-pacity. An alarm overriding device may be installed to beactivated when the tank is in use.

A.4.1.5 In any dry or void space other than a chain ca-ble locker, any part of which extends forward of the foremostcargo hold, giving an audible and visual alarm at a waterlevel of 0,1 m above the deck.

Such alarms need not be provided in enclosedspaces the volume of which does not exceed 0,1% of theship.s maximum displacement volume.

A.4.1.6 The audible and visual alarms specified initems A.4.1.3 to A.4.1.5 shall be located on the navigationbridge.

A.4.1.7 The visual and audible alarms are to be in ac-cordance with the relevant requirements for bilge alarms inthe Rules, Part 12 – Electrical Equipment, 19.8.

A.4.1.8 For application of these requirements see alsoIACS unified interpretation SC 180.

A.4.2 Requirements for availability of pump-ing systems

A.4.2.1 This requirement is applicable to bulk carriersof single side skin construction as defined in the Rules for theclassification of ships, Part 1 – General requirements,Chapter 1 – General information, Section 4.2.

A.4.2.2 Bulk carriers the keels of which are laid orwhich are at a similar stage of construction before 1 July2004 shall comply with the requirements of this regulationnot later than the date of the first intermediate or renewalsurvey of the ship to be carried out after 1 July 2004, but, inno case, later than 1 July 2007.

A.4.2.3 On bulk carriers, the means for draining andpumping ballast tanks forward of the collision bulkhead andbilges of dry spaces any part of which extends forward of theforemost cargo hold shall be capable of being brought intooperation from a readily accessible enclosed space, the loca-tion of which is accessible from the navigation bridge or pro-pulsion machinery control position without traversing ex-posed freeboard or superstructure decks.

Where pipes serving such tanks or bilgespierce the collision bulkhead, valve operation by means ofremotely operated actuators may be accepted, as an alterna-tive to the valve control specified in the Rules, Part 8 – Pip-ing, 1.6 (see SOLAS 1974, Reg. II-1/12), provided that thelocation of such valve controls complies with this regulation.

For application of these requirements see alsoIACS unified interpretation SC 179.

A.4.3 Installation, testing and survey

The system is to be installed and tested in ac-cordance with the approved documentation and the manu-facturer's specifications. At the initial installation and at eachsubsequent Intermediate and Special Survey, the Surveyor isto verify the proper operation of the water detection system.


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A.5 ADDITIONAL REQUIRE-MENTS FOR LOADING CONDITIONS,LOADING MANUALS AND LOADING

INSTRUMENTS FOR BULK CARRIERS,ORE CARRIERS AND COMBINATION

CARRIERS

A.5.1 Application

Bulk Carriers, Ore Carriers and CombinationCarriers of 150 m length and above, which are contracted forconstruction before 1st July 1998 are to be provided with anapproved loading instrument of a type to the satisfaction ofthe Register not later than their entry into service or 1st Janu-ary 1999, whichever occurs later.

In addition, Bulk Carriers of 150 m length andabove where one or more cargo holds are bounded by theside shell only, which were contracted for construction be-fore 1st July 1998 are to be provided with an approved load-ing manual with typical loading sequences where the vesselis loaded from commencement of cargo loading to reachingfull deadweight capacity, for homogeneous conditions, rele-vant part load conditions and alternate conditions where ap-plicable.

Typical unloading sequences for these condi-tions shall also be included. Section A.5.5 contains guidancefor loading and unloading sequences for existing bulk carri-ers.

A.5.2 Definitions, see 17.4.2.

A.5.3 Conditions of approval of loadingmanuals, see 17.4.3.

A.5.4 Condition of approval of loading in-struments, see 17.4.4.

A.5.5 Guidance for loading / unloading se-quences for existing bulk carriers

A.5.5.1 Section A.5.1 requires that single side skin bulkcarriers of 150m length and above, which are contracted forconstruction before 1st July 1998, are to be provided, before1st July 1999 or their entry into service, whichever occurslater, with an approved loading manual with typical loadingsequences where the ship is loaded from commencement ofcargo loading to reaching full deadweight capacity, for ho-mogeneous conditions, relevant part loaded conditions andalternate conditions where applicable. Typical unloading se-quences shall be included.

A.5.5.2 This requirement will necessitate shipownersand operators to prepare and submit for approval typicalloading and unloading sequences.

A.5.5.3 The minimum acceptable number of typical se-quences is:

- one homogeneous full load condition,- one part load condition where relevant,

such as block loading or two port un-loading,

- one full load alternate hold condition, ifthe ship is approved for alternate holdloading.

A.5.5.4 The shipowner/operator should select actualloading/unloading sequences, where possible, which may beport specific or typical.

A.5.5.5 Section A.5.1 requires that bulk carriers of150m length and above, where one or more cargo holds arebounded by the side shell only, which were contracted forconstruction before 1st July 1998, are to be provided with anapproved loading manual with typical loading sequenceswhere the ship is loaded from commencement of cargoloading to reaching full deadweight capacity, for homogene-ous conditions, relevant part loaded conditions and alternateconditions where applicable. Typical unloading sequencesshall be included.

A.5.5.6 For each loading condition a summary of allsteps is to be included. This summary is to highlight the es-sential information for each step such as:

- How much cargo is filled in each holdduring the different steps,

- How much ballast is discharged fromeach ballast tank during the differentsteps,

- The maximum still water bending mo-ment and shear at the end of each step,

- The ship’s trim and draught at the end ofeach step.

A.5.5.7 The approved typical loading/unloading se-quences, may be included in the approved loading manual ortake the form of an addendum prepared for purposes of com-plying with Register’s requirements. A copy of the approvedtypical loading/unloading sequences is to be placed onboardthe ship.

A.5.5.7 It is recommended that IACS Rec. 83 be takeninto account when compiling the typical loading and un-loading sequences described in Section A.5.5.


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A.6 PROVISION OF DETAILED IN-FORMATION ON SPECIFIC CARGO

HOLD FLOODING SCENARIOS

A.6.1 Application

A.6.1.1 This requirement is applicable only to bulk car-rier specified in A.1.1 but not capable of complying A.3.2.1(SOLAS regulation XII/4.2).

A.6.1.2 Where bulk carriers are shown to be not capa-ble of complying with the requirement specified in A.6.1.1(SOLAS reg. XII/4.2) due to the design configuration of theircargo holds, SOLAS reg. XII/9 permits relaxation from theapplication of regulations 4.2 and 6 on the basis of compli-ance with certain other requirements, including provision ofdetailed information on specific cargo hold flooding scenar-ios.

A.6.1.3 The information should comprise at least thefollowing:

− Specific cargo hold flooding scenarios;− Instructions for evacuation preparedness;− Details of the ship's means for leakage de-

tection.

A.6.2 Specific cargo hold flooding scenarios

A.6.2.1 Flooding assumption

A.6.2.1.1 The flooding of the foremost cargo hold is to beused as the starting point for any respective flooding sce-nario. Subsequent flooding of other spaces can only occurdue to progressive flooding.

A.6.2.1.2 The permeability of a loaded hold shall be as-sumed as 0.9 and the permeability of an empty hold shall beassumed as 0.95, unless a permeability relevant to a particu-lar cargo is assumed for the volume of a flooded hold occu-pied by cargo and a permeability of 0.95 is assumed for theremaining empty volume of the hold. The permeability of ahold loaded with packaged cargo shall be assumed as 0.7.

A.6.2.2 Loading conditions to be considered:

A.6.2.2.1 Flooding scenarios should be developed forloading conditions loaded down to the summer load line evenif not in compliance with the requirement A.3.2.1 (SOLASregulation XII/4.2). The scope to be covered should includeat least the following:

− A homogenous and, if applicable, an alter-nate hold loading condition are to be con-sidered;

− In case one or more loading conditionsmeet the requirement A.3.2.1 (SOLASregulation XII/4.2) this should be noted;

− A packaged cargo condition, if applicable.

A.6.2.2.2 In case the vessel is able to withstand floodingof the foremost hold at a lower draught, guidance in the formof limiting KG/GM curves, based on the flooding assump-tions in A.6.2.1, should be provided. Curves should indicatethe assumed trim and whether the foremost hold is homoge-neously loaded, loaded with high density cargo (alternatehold loading), loaded with packaged cargo or empty.

A.6.2.3 Presentation of results

The results should clearly indicate the reasonsfor non-compliance with the survival criteria given in reg.XII/4.3 of the SOLAS and explain the implication regardingthe need to abandon ship e.g. immersion of a weathertightclosing appliance if the stability characteristics are otherwisesatisfactory may indicate that there is no immediate dangerof foundering, provided the bulkhead strength is adequate,particularly if the weather conditions are favourable andbilge pumping can cope with any progressive flooding.

A.6.3 Guidance for evacuation

A.6.3.1 The following guidance with regard to prepa-ration for evacuation is in the most general terms. Responsi-bility for the preparation of detailed information rests withthe operator of the ship.

A.6.3.2 In any case of detection of severe flooding(made in accordance with A.4), preparations for abandoningthe vessel shall be envisaged in accordance with the applica-ble rules and procedures, such as SOLAS III, STCW and theISM Code.

A.6.3.3 In the context of severe weather conditions theweather itself may have substantial influence on the devel-opment of the flooding and consequently the time remainingto execute the abandoning of the ship could be much shorterthan estimated in any pre-assessed flooding scenario.


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A.7 RENEWAL CRITERIA FORSIDE SHELL FRAMES AND BRACKETS

IN SINGLE SIDE SKIN BULKCARRIERS AND SINGLE SIDE SKIN

OBO CARRIERS (IACS UR S 31)


A.7.1.1 These requirements apply to the side shellframes and brackets of cargo holds bounded by the singleside shell of bulk carriers constructed with single deck, top-side tanks and hopper tanks in cargo spaces intended primar-ily to carry dry cargo in bulk, which were not built in accor-dance with requirements in Section 17.2.5.

In addition, these requirements also apply tothe side shell frames and brackets of cargo holds bounded bythe single side shell of Oil/Bulk/Ore(OBO) carriers of singleside skin construction.

In the case a vessel as defined above does notsatisfy above definition in one or more holds, these require-ments do not apply to these individual holds.

For the purpose of this Section, “ships” meansboth “bulk carriers” and “OBO carriers” as defined above,unless otherwise specified.

A.7.1.2 Bulk carriers of single side skin construction,as defined in A.7.1.1, are to be assessed for compliance withthese requirements and steel renewal, reinforcement or coat-ing, where required, is to be carried out in accordance withthe following schedule and at subsequent intermediate andspecial surveys.

.1 For bulk carriers which will be 15 yearsof age or more on 1 January 2004 by thedue date of the first intermediate or spe-cial survey after that date;

.2 For bulk carriers which will be 10 yearsof age or more on 1 January 2004 by thedue date of the first special survey afterthat date;

.3 For bulk carriers which will be less than10 years of age on 1 January 2004 by thedate on which the ship reaches 10 yearsof age.

Completion prior to 1 January 2004 of an in-termediate or special survey with a due date after 1 January2004 cannot be used to postpone compliance. However,completion prior to 1 January 2004 of an intermediate surveythe window for which straddles 1 January 2004 can be ac-cepted.

A.7.1.3 OBO carriers of single side skin construction,as defined in A.7.1.1, are to be assessed for compliance withthese requirements and steel renewal, reinforcement or coat-ing, where required, is to be carried out in accordance withthe following schedule and at subsequent intermediate andspecial surveys.

.1 For OBO carriers which will be 15 yearsof age or more on 1 July 2005 by the duedate of the first intermediate or specialsurvey after that date;

.2 For OBO carriers which will be 10 yearsof age or more on 1 July 2005 by the duedate of the first special survey after thatdate;

.3 For OBO carriers which will be less than10 years of age on 1 July 2005 by thedate on which the ship reaches 10 yearsof age.

Completion prior to 1 July 2005 of an interme-diate or special survey with a due date after 1 July 2005 can-not be used to postpone compliance. However, completionprior to 1 July 2005 of an intermediate survey the windowfor which straddles 1 July 2005 can be accepted.

A.7.1.4 These requirements define steel renewal criteriaor other measures to be taken for the webs and flanges ofside shell frames and brackets as per A.7.3.

A.7.1.5 Reinforcing measures of side frames are alsodefined as per A.7.3.3.

A.7.1.6 Finite element or other numerical analysis ordirect calculation procedures cannot be used as an alternativeto compliance with the requirements of this Section, exceptin cases off unusual side structure arrangements or framing towhich the requirements of this Section can not be directlyapplied. In such cases, the analysis criteria and the strengthcheck criteria are to be in accordance with these Rules.

A.7.1.7 It is recommended that IACS Rec. No.94 betaken into account as the guideline for application of theserequirements.

A.7.2 Ice strengthened ships

A.7.2.1 Where ships are reinforced to comply with anice class notation, the intermediate frames are not to be in-cluded when considering compliance with these requiremets.

A.7.2.2 The renewal thicknesses for the additionalstructure required to meet the ice strengthening notation areto be based on Register’s requirements.

A.7.2.3 If the ice class notation is requested to be with-drawn, the additional ice strengthening structure, with theexception of tripping brackets (see A.7.3.1.2.1.b andA.7.3.1.3), is not to be considered to contribute to compli-ance with S31.

A.7.3 Renewal or other measures

A.7.3.1 Criteria for renewal or other measures

A.7.3.1.1 SymbolstM = thickness as measured, in [mm]

tREN = thickness at which renewal is required, seeA.7.3.1.2

tREN,d/t = thickness criteria based on d/t ratio, seeA.7.3.1.2.1.

tREN,S = thickness criteria based on strength, seeA.7.3.1.2.2.

tCOAT = 0,75 tS12

tS12 = thickness, in [mm], as required in 17.2.5.3 forframe webs and in 17.2.5.4 for upper and lowerbracket webs

tAB = thickness as built, in [mm]

tC = see Table A.7.3.1.1.


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Table A.7.3.1.1 Values tC, in mm

Holds other thanNo. 1

Hold No. 1Ship'slength

L, in [m] Span andupper

brackets

Lowerbrackets

Span andupper

brackets

Lowerbrackets

100 2,0 2,5 2,0 3,0

150 2,0 3,0 3,0 3,5

≥ 200 2,0 3,0 3,0 4,0

Note: For intermediate ship lengths, tC is obtained by lin-ear interpolation between the above values.

A.7.3.1.2 Criteria for webs (Shear and other checks)

The webs of side shell frames and brackets areto be renewed when the measured thickness (tM) is equal toor less than the thickness (tREN) as defined below:

tREN is the greatest of:

(a) tCOAT - tC

(b) 0,75 tAB

(c) tREN,d/t (applicable to Zone A and B only)

(d) tREN,S (where required by A.7.3.1.2.2)

A.7.3.1.2.1 Thickness criteria based on d/t ratio

Subject to b) and c) below, tREN,d/t is given bythe following equation:

tREN,d/t = (web depth, in mm)/R

where:R = for frames

65 k0,5 for symmetrically flanged frames

55 k0,5 for asymmetrically flanged frames

for lower brackets, see a) below:

87 k0,5 for symmetrically flanged frames

73 k0,5 for asymmetrically flanged frames

k = 1,0 for ordinary hull structural steel and ac-cording to 1.4.2.2 for higher tensile steel.

In no instance is tREN,d/t for lower integralbrackets to be taken as less than tREN,d/t for the frames theysupport.

a) Lower brackets

Lower brackets are to be flanged or face plateis to be fitted.

In calculating the web depth of the lowerbrackets, the following will apply:

- The web depth of lower bracket may bemeasured from the intersection of the slopedbulkhead of the hopper tank and the side shell

plate, perpendicularly to the face plate of thelower bracket (see Fig. A.7.3).

- Where stiffeners are fitted on the lowerbracket plate, the web depth may be taken asthe distance between the side shell and thestiffener, between the stiffeners or between theoutermost stiffener and the face plate of thebrackets, whichever is the greatest.

b) Tripping bracket alternative

When tM is less than tREN,d/t at section b), of theside frames, see Fig. A.7.2, tripping brackets in accordancewith A.7.3.3 may be fitted as an alternative to the require-ments for the web depth to thickness ratio of side frames, inwhich case tREN,d/t may be disregarded in the determination oftREN in accordance with A.7.3.1.2. The value of tM is to bebased on zone B according to Fig. A.7.4.

c) Immediately abaft collision bulkhead

For the side frames, including the lowerbracket, located immediately abaft the collision bulkheads,whose scantlings are increased in order that their moment ofinertia is such to avoid undesirable flexibility of the sideshell, when their web as built thickness tAB is greater than1,65·tREN,S, the thickness tREN,d/t may be taken as the valuet’REN,d/t obtained from the following equation:

t’REN,d/t = 3SREN,

2d/tREN, tt

where tREN,S is obtained from A.7.4.3.

A.7.3.1.2.2 Thickness criteria based on shear strengthcheck

Where tM ≤ tCOAT in the lower part of sideframes, as defined in Fig. A.7 1, tREN,S is to be determined inaccordance with A.7.4.3.

A.7.3.1.2.3 Thickness of renewed webs of frames andlower brackets

Where steel renewal is required, the renewedwebs are to be of a thickness not less than tAB, 1,2 tCOAT or 1,2tREN, whichever is the greatest.

A.7.3.1.2.4 Criteria for other measures

When tREN < tM ≤ tCOAT, measures are to betaken, consisting of all the following:

.1 Sand blasting, or equivalent, and coating(see A.7.3.2).

.2 Fitting tripping brackets (see A.7.3.3),when the above condition occurs for anyof the side frame zones A, B, C and D,shown in Fig. A.7.1. Tripping bracketsnot connected to flanges are to have softtoe, and the distance between the brackettoe and the frame flange is not to begreater than about 50 mm, see Fig. A.7.4.

.3 Maintaining the coating in "as-new" con-dition (i.e. without breakdown or rusting)at Special and Intermediate Surveys.

The above measures may be waived if thestructural members show no thickness diminution with re-spect to the as built thicknesses and coating is in "as-new"condition (i.e. without breakdown or rusting).


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When the measured frame webs thickness tM issuch that tREN < tM ≤ tCOAT and the coating is in GOOD con-dition, sand blasting and coating as required in a) above maybe waived even if not found in “as-new” condition, as de-fined above, provided that tripping brackets are fitted and thecoating damaged in way of the tripping bracket welding isrepaired.

A.7.3.1.3 Criteria for frames and brackets (Bendingcheck)

When lower end brackets were not fitted withflanges at the design stage, flanges are to be fitted so as tomeet the bending strength requirements in A.7.4.4. The fullwidth of the bracket flange is to extend up beyond the pointat which the frame flange reaches full width. Adequate back-up structure in the hopper is to be ensured, and the bracket isto be aligned with the back-up structure.

Where the length or depth of the lower bracketdoes not meet the requirements in Section 17.2.5, a bendingstrength check in accordance with A.7.4.4 is to be carried outand renewals or reinforcements of frames and/or brackets ef-fected as required therein.

The bending check needs not to be carried outin the case the bracket geometry is modified so as to complywith requirements in Section 17.2.5.

A.7.3.2 Thickness measurements, steel renewal, sandblasting and coating

For the purpose of steel renewal, sand blastingand coating, four zones A, B, C and D are defined, as shownin Figure A.7.1. When renewal is to be carried out, surfacepreparation and coating are required for the renewed struc-tures as given in Section 1.4.5 for cargo holds of new build-ings.

Representative thickness measurements are tobe taken for each zone and are to be assessed against the cri-teria in A.7.3.1.

When zone B is made up of different platethicknesses, the lesser thickness is to be used for the applica-tion of the requirements in this Section.

In case of integral brackets, when the criteria inA.7.3.1 are not satisfied for zone A or B, steel renewal, sandblasting and coating, as applicable, are to be done for bothzones A and B.

In case of separate brackets, when the criteriain A.7.3.1 are not satisfied for zone A or B, steel renewal,sand blasting and coating is to be done for each one of thesezones, as applicable.

When steel renewal is required for zone C ac-cording to A.7.3.1, it is to be done for both zones B and C.When sand blasting and coating is required for zone C ac-cording to A.7.3.1, it is to be done for zones B, C and D.

When steel renewal is required for zone D ac-cording to A.7.3.1, it needs only to be done for this zone.When sand blasting and coating is required for zone D ac-cording to A.7.3.1, it is to be done for both zones C and D.

Special consideration may be given by theRegister to zones previously renewed or re-coated, if foundin “as-new” condition (i.e., without breakdown or rusting).

When adopted, on the basis of the renewalthickness criteria in A.7.3.1, in general coating is to be ap-plied in compliance with the requirements of Section 1.4.5.2,as applicable.

Where, according to the requirements inA.7.3.1, a limited number of side frames and brackets areshown to require coating over part of their length, the fol-lowing criteria apply:

a) The part to be coated includes:- the web and the face plate of the side

frames and brackets,- the hold surface of side shell, hopper

tank and topside tank plating, as ap-plicable, over a width not less than100 mm from the web of the sideframe.

b) Epoxy coating or equivalent is to be ap-plied.

In all cases, all the surfaces to be coated are tobe sand blasted prior to coating application.

When flanges of frames or brackets are to berenewed according to this Section, the outstanding breadth tothickness ratio is to comply with the requirements in17.2.5.5.

A.7.3.3 Reinforcing measures

Reinforcing measures are constituted by trip-ping brackets, located at the lower part and at midspan ofside frames (see A.7.4). Tripping brackets may be located atevery two frames, but lower and midspan brackets are to befitted in line between alternate pairs of frames.

The thickness of the tripping brackets is to benot less than the as-built thickness of the side frame webs towhich they are connected.

Double continuous welding is to be adopted forthe connections of tripping brackets to the side shell framesand shell plating.

Where side frames and side shell are made ofhigher strength steel (HSS), normal strength steel (NSS) trip-ping brackets may be accepted, provided the electrodes usedfor welding are those required for the particular (HSS) grade,and the thickness of the tripping brackets is equal to theframe web thickness, regardless of the frame web material.

A.7.3.4 Weld throat thickness

In case of steel renewal the welded connectionsare to comply with requirements in 17.2.5.7.

A.7.3.5 Pitting and grooving

If pitting intensity is higher than 15% in area(see Fig. A.7.5), thickness measurement is to be taken tocheck pitting corrosion.

The minimum acceptable remaining thicknessin pits or grooves is equal to:

- 75% of the as built thickness, for pittingor grooving in the frame and bracketswebs and flanges;

- 70% of the as built thickness, for pittingor grooving in the side shell, hopper tankand topside tank plating attached to theside frame, over a width up to 30 mmfrom each side of it.

A.7.3.6 Renewal of all frames in one or more cargoholds and renewal of damaged frames

A.7.3.6.1 When all frames in one or more holds are re-quired to be renewed according to this Section, the compli-


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ance with the requirements in 17.2.5 may be accepted in lieuof the compliance with the requirements in this Section, pro-vided that:

- It is applied at least to all the frames ofthe hold(s)

- The coating requirements for side framesof “new ships” are complied with

- The section modulus of side frames iscalculated according to the Register'sRules.

A.7.3.6.2 In case of renewal of a damaged frame alreadycomplying with requirements of this Section, the followingrequirements apply:

- The conditions accepted in compliancewith requirements of this Section are tobe restored as a minimum.

- For localised damages, the extension ofthe renewal is to be carried out accordingto the standard Register's practice.

A.7.4 Strength check criteria

In general, loads are to be calculated andstrength checks are to be carried out for the aft, middle andforward frames of each hold. The scantlings required forframes in intermediate positions are to be obtained by linearinterpolation between the results obtained for the aboveframes.

When scantlings of side frames vary within ahold, the required scantlings are also to be calculated for themid frame of each group of frames having the same scant-lings.

The scantlings required for frames in interme-diate positions are to be obtained by linear interpolation be-tween the results obtained for the calculated frames.

A.7.4.1 Load model

The following loading conditions are to be con-sidered:

- Homogeneous heavy cargo (densitygreater than 1,78 t/m3).

- Homogeneous light cargo (density lessthan 1,78 t/m3).

- Non homogeneous heavy cargo, if al-lowed.

- Multi port loading/unloading conditionsneed not be considered.

A.7.4.1.1 Forces

The forces Pfr,a and Pfr,b, in [kN], to be consid-ered for the strength checks at sections a) and b) of sideframes (specified in Fig. A.7.2; in the case of separate lowerbrackets, section b) is at the top of the lower bracket), aregiven by:

Pfr,a = PS + max (P1, P2),

Pfr,b = Pfr,ah

hh B2− ,

where:

Ps = still water force, u [kN],

=

+

2,, LSUS pp

hs , when the upper end of the

side frame span h (see Fig. A.7.1) is below the loadwater line,

=

2' ,LSp

hs , when the upper end of the side

frame span h (see Fig. A.7.1) is at or abovethe load water line,

P1 = wave force, in [kN], in head sea,

=

+

2,1,1 LU pp

hs ,

P2 = wave force, in [kN], in beam sea,

=

+

2,2,2 LU pp

hs ,

h, hB = side frame span and lower bracket length, in[m], defined in Fig. A.7.1 and A.7.2, respec-tively

h’ = distance, in [m], between the lower end of sideframe span and the load water line

s = frame spacing, in [m],pS,U, pS,L = still water pressure, in [kN/m2], at the upper

and lower end of the side frame span h (see Fig.A.7.1), respectively

p1,U, p1,L = wave pressure, in [kN/m2], as defined inA.7.4.1.2.1 below for the upper and lower endof the side frame span h, respectively

p2,U, p2,L = wave pressure, in [kN/m2], as defined inA.7.4.1.2.2 below for the upper and lower endof the side frame span h, respectively.

A.7.4.1.2 Wave pressure

1) Wave pressure p1

− The wave pressure p1, in [kN/m2], at and below thewaterline is given by:

( ) ( )

−−

++= zd,

BBp,p 21

752135501 111 ,

fS kCkp += 311 ,

− The wave pressure p1, in [kN/m2], above the water-line is given by:

( )dzpp wl −−= 50,711

2) Wave pressure p2

− The wave pressure p2, in [kN/m2], at and below thewaterline is given by:

+

++

+=

dz,

kB,C

)B(C

B,,p fB

r 27014

50752

50500132

− The wave pressure p2, in [kN/m2], above the water-line is given by:

( )dz,pp wl −−= 0522


2013

where:

p1wl = p1 wave sea pressure at the waterline

p2wl = p2 wave sea pressure at the waterline

L = Rule length, in [m], see 1.2.3.1

B = greatest moulded breadth , in [m], see 1.2.3.2

CB = block coefficient, see 1.2.6.1, but not to betaken less than 0,6

d = maximum design draught, in [m], see 1.2.3.4

C = coefficient, see 4.2.2

=5,1

10030075,10

−

−L

, for 90 ≤ L ≤ 300 m

= 10,75, for 300 m < L

Cr = (1,25 - 0,025 GMkr2

) k,

k = 1,2, for ships without bilge keel

= 1,0, for ships with bilge keel

kr = roll radius of gyration. If the actual value ofkr is not avaliable

= 0,39·B, for ships with even distribution ofmass in transverse section (e.g. alternateheavy cargo loading or homogeneous lightcargo loading)

= 0,25·B, for ships with uneven distribution ofmass in transverse section (e.g. homogeneousheavy cargo distribution)

GM = 0,12·B, if the actual value of GM is not avail-able

z = vertical distance, in [m], from the baseline tothe load point

ks =B

BC

C 83,0+ , at aft end of L,

= CB, between 0,2L and 0,6L, from aft end of L

=B

B CC 33,1

+ at forward end of L .

Between the above specified points, ks is to beinterpolated linearly.

kf = 0,8·C.

A.7.4.2 Allowable stresses

The allowable normal and shear stresses σa andτa, in [N/mm2], in the side shell frames and brackets aregiven by:

σa = 0,9·σF

τa = 0,4·σF

where σF is the minimum upper yield stress, in [N/mm2], ofthe material.

A.7.4.3 Shear strength check

Where tM in the lower part of side frames, asdefined in Fig. A.7.1, is equal to or less than tCOAT, shearstrength check is to be carried out in accordance with thefollowing.

The thickness tREN,S, in [mm], is the greater ofthe thicknesses tREN,Sa and tREN,Sb obtained from the shearstrength check at sections a) and b) (see Fig. A.7.2 andA.7.4.1) given by the following, but need not be taken in ex-cess of 0,75·tS12.

- at section a):aa

afrs

d

Pk

τφsin

1000t

,SaREN, =

- at section b):ab

bfrs

d

Pk

τφsin

1000t

,SbREN, =

where:

ks = shear force distribution factor, to be takenequal to 0,6

Pfr,a, Pfr,b = pressure forces defined in A.7.4.1

da, db = bracket and frame web depth, in [mm], atsections a) and b), respectively (see Fig.A.7.2); in case of separate (non integral)brackets, db is to be taken as the minimumweb depth deducing possible scallops

φ = angle between frame web and shell plate

τa = allowable shear stress, in [N/mm2], definedin A.7.4.2.

A.7.4.4 Bending strength check

Where the lower bracket length or depth doesnot meet the requirements in 17.2.5.4, the actual sectionmodulus, in [cm3], of the brackets and side frames at sectionsa) and b) is to be not less than:

- at section a):aa

afr

m

hP

σ,

a

1000Z =

- at section b):ab

afr

m

hP

σ,

b

1000Z =

where:

Pfr,a = pressure forces defined in A.7.4.1

h = side frame span, in [m], see Fig. A.7.1

σa = allowable normal stress, in [N/mm2], de-fined in A.7.4.2

ma, mb = bending moment coefficients defined inTable A.7.2.


2013

Table A.7.2 Bending moment coefficients ma and mb

mbma

hb = 0,08·h hb = 0,1·h hb = 0,125·hEmpty holdsof ships ap-proved to op-erate in nonhomogeneousloading con-ditions

10 17 19 22

Other cases 12 20 22 26Note 1: Non homogeneous loading condition means a loadingcondition in which the ratio between the highest and the lowestfilling ratio, evaluated for each hold, exceeds 1,20 corrected fordifferent cargo densities. Note 2: For intermediate values of the bracket length hB, thecoefficient mb is obtained by linear interpolation between thetable values.

The actual section modulus of the brackets andside frames is to be calculated about an axis parallel to theattached plate, based on the measured thicknesses. For pre-calculations, alternative thickness values may be used, pro-vided they are not less:

- tREN, for the web thickness- the minimum thicknesses allowed by the

Register's renewal criteria for flange andattached plating.

The attached plate breadth is equal to the framespacing, measured along the shell at midspan of h.

If the actual section moduli at sections a) and b)are less than the values Za and Zb, the frames and brackets are

to be renewed or reinforced in order to obtain actual sectionmoduli not less than 1,2 Za and 1,2 Zb, respectively.

In such a case, renewal or reinforcements of theflange are to be extended over the lower part of side frames,as defined in Fig. A.7.1.


2013

Lower part of side frame

Figure A.7.1

Figure A.7.2

Lower bracket web depth for determining tren,d/t

Soft toe

Figure A.7.3

Section

Section

lower bracket web depth fordetermining tREN,s

frame web depth

lower bracket web depth


2013

Figure A.7.4

Figure A.7.5

tripping bracket

distance from knuckle notgreater than 200 mm

5% SCATTERED 20% SCATTERED

10% SCATTERED 25% SCATTERED

15% SCATTERED

tripping bracket not weldedto frame flange

-50 mm


2013

A.8 RESTRICTIONS FROM SAIL-ING WITH ANY HOLD EMPTY FORBULK CARRIERS (SOLAS 1974, CH.

XII, REG. 14)

A.8.1 Bulk carriers of 150 m in length and upwardsof single-side skin construction, if not meeting:

- the requirements in regulation 5.1 of the SOLAS1974, Ch. XII, and Section 17.2.4.4 of these Rules,respectively (for withstanding flooding of any onecargo hold); and

- criteria for side structures of bulk carriers of single-side skin construction as defined in Section 17.2.5(IACS UR S12, Rev. 2.1 or subsequent revisions)or Annex A.7 (UR S31),

where carry cargoes having a density of 1,78 t/m3 and aboveshall not sail with any hold loaded to less than 10% of thehold's maximum allowable cargo weight when in the fullload condition.

A.8.2 The applicable full load condition for thisregulation is a load equal to or greater than 90% of the ship'sdeadweight at the relevant assigned freeboard.

A.8.3 This requirement is applicable to bulk carriersfrom 1st July 2006 or the date on which the ship reaches 10years of age, whichever is later.

Note: Bulk carriers constructed before 1st July 1999 notmeeting the requirements in regulation 5.1 of the SOLAS1974, Ch. XII.

A.8.4 Restrictions imposed by Regulation 14 of theSOLAS 1974, Ch. XII, shall be identified and recorded in theship's booklet (Loading Manual).

A.8.5 In accordance with Reg. 8.3 of the SOLAS1974, Ch. XII, a bulk carrier to which requirement A.8.4 ap-plies shall be permanently marked on the side shell at mid-ships, port and starboard, with a solid equilateral triangle.

Triangle having sides of 500 mm and its apex300 mm below the deck line, and painted a contrasting colourto that of the hull.


2013

ANNEX B ADDITIONAL RE-QUIREMENTS FOR OIL TANK-ERS OF 130 M IN LENGTH AND

UPWARDS AND OF OVER 10YEARS OF AGE

B.1 CRITERIA FOR LONGITUDINALSTRENGTH OF HULL GIRDER FOR

OIL TANKERS

B.1.1 General

B.1.1.1 These criteria is to be used for the evaluation oflongitudinal strength of the hull girder of oil tankers of 130 min length and upwards and of over 10 years of age.

B.1.1.2 In order that ship’s longitudinal strength to beevaluated can be recognized as valid, fillet welding betweenlongitudinal internal members and hull envelopes is to be insound condition so as to keep integrity of longitudinal inter-nal members with hull envelopes.

B.1.2 Evaluation of longitudinal strength

On oil tankers of 130 m in length and upwardsand of over 10 years of age, the longitudinal strength of theship's hull girder is to be evaluated in compliance with therequirements of this Section on the basis of the thicknessmeasured, renewed or reinforced, as appropriate, during thespecial survey.

B.1.2.1 Calculation of transverse sectional areas ofdeck and bottom flanges of hull girder

B.1.2.1.1 The transverse sectional areas of deck flange(deck plating and deck longitudinals) and bottom flange(bottom shell plating and bottom longitudinals) of the ship’shull girder is to be calculated by using the thickness meas-ured, renewed or reinforced, as appropriate, during the spe-cial survey.

B.1.2.1.2 If the diminution of sectional areas of eitherdeck or bottom flange exceeds 10 % of their respective as-built area (i.e. original sectional area when the ship wasbuilt), either one of the following measures is to be taken:

.1 to renew or reinforce the deck or bottomflanges so that the actual sectional area isnot less than 90% of the as-built area; or

.2 to calculate the actual section moduli(Wact) of transverse section of the ship’shull girder by applying the calculationmethod specified by paragraph B.1.3, byusing the thickness measured, renewed orreinforced, as appropriate, during thespecial survey.

B.1.2.2 Requirements for transverse sectionmodulus of hull girder

B.1.2.2.1 The actual section moduli of transverse sectionof the ship’s hull girder calculated in accordance with the

foregoing paragraph B.1.2.1.2.2 is to satisfy either of thefollowing provisions, as applicable:

.1 for ships constructed on or after 1 July2002, the actual section moduli (Wact) ofthe transverse section of the ship's hullgirder calculated in accordance with therequirements of the foregoing paragraphB.1.2.1.2.2 should is not to be less thanthe diminution limits determined by theRegister * ; or

.2 for ships constructed before 1 July 2002,the actual section moduli (Wact) of thetransverse section of the ship's hull girdercalculated in accordance with the re-quirements of the foregoing paragraphB.1.2.1.2.2 is to meet the criteria forminimum section modulus for ships inservice required by the Register, providedthat in no case Wact is to be less than thediminution limit of the minimum sectionmodulus (Wmc) as specified by paragraphB.1.4.

B.1.3 Calculation criteria of section moduli ofmidship section of hull girder

B.1.3.1 When calculating the transverse sectionmodulus of the ship's hull girder, the sectional area of allcontinuous longitudinal strength members is to be taken intoaccount.

B.1.3.2 Large openings, i.e. openings exceeding 2,5 min length or 1,2 m in breadth and scallops, where scallopwelding is applied, are always to be deducted from the sec-tional areas used in the section modulus calculation.

B.1.3.3 Smaller openings (manholes, lightening holes,single scallops in way of seams, etc.) need not be deductedprovided that the sum of their breadths or shadow areabreadths in one transverse section does not reduce the sectionmodulus at deck or bottom by more than 3% and providedthat the height of lightening holes, draining holes and singlescallops in longitudinals or longitudinal girders does not ex-ceed 25% of the web depth, for scallops maximum 75 mm.

B.1.3.4 A deduction-free sum of smaller openingbreadths in one transverse section in the bottom or deck areaof 0,06(B - Σb) (where B = breadth of ship, Σb = total breadthof large openings) may be considered equivalent to the abovereduction in sectional modulus.

B.1.3.5 The shadow area will be obtained by drawingtwo tangent lines with an opening angle of 30°.

B.1.3.6 The deck modulus is related to the mouldeddeck line at side.

B.1.3.7 The bottom modulus is related to the base line.

* The actual transverse section modulus of the hullgirder of oil tankers calculated under paragraphB.1.2.2.1.1 of this Section is not to be less than 90%of the required section modulus for new buildingsspecified in IACS Unified Requirements S7** or S11(see also paragraphs 4.3.2 and 4.3.4 of these Rules),whichever is the greater.

** C = 1,0 · Cw is to be used for the purpose of this calculation


2013

B.1.3.8 Continuous trunks and longitudinal hatchcoamings are to be included in the longitudinal sectional areaprovided they are effectively supported by longitudinal bulk-heads or deep girders. The deck modulus is then to be calcu-lated by dividing the moment of inertia by the following dis-tance, provided this is greater than the distance to the deckline at side:

Χ

+=Bt 2,09,0γγ

where:y = distance from neutral axis to top of continuous

strength member,x = distance from top of continuous strength mem-

ber to centreline of the ship.x and y to be measured to the point giving the larg-

est value of yt.

B.1.3.9 Longitudinal girders between multi-hatchwayswill be considered by special calculations.

B.1.4 Diminution limit of minimum longitudi-nal strength of ships in service

B.1.4.1 The diminution limit of the minimum sectionmodulus (Wmc) of oil tankers in service is given by the fol-lowing formula:

( ) kCBCLW bmc ⋅+= 7,02 [cm3]

whereL = Length of ships. L is the distance, in meters,

on the summer load waterline from the foreside of stem to the after side of the rudderpost, or the centre of the rudder stock if thereis no rudder post. L is not to be less than96%, and need not be greater than 97%, ofthe extreme length on the summer load wa-terline. In ships with unusual stern and bowarrangement the length L may be speciallyconsidered.

B = Greatest moulded breadth in metres.Cb = Moulded block coefficient at draught d corre-

sponding to summer load waterline, based onL and B. Cb is not to be taken less than 0,60.

( )dBL

ddraughtatmntdisplacememouldedCb ⋅⋅

=3

C = 0,9⋅Cw

Cw = 10,75 - 5,1

100300

− L for 130 m ≤ L ≤ 300 m

Cw = 10, 75 for 300 m < L < 350 m;

Cw = 10,75 - 5,1

150350

−L for 350 m ≤ L ≤ 500 m;

k = material factor, e.g.k = 1,0, for mild steel with yield stress of 235

N/mm2 and over;k = 0,78, for high tensile steel with yield stress of

315 N/mm2 and over,k = 0,72, for high tensile steel with yield stress of

355 N/mm2 and over.

B.1.4.2 Scantlings of all continuous longitudinal mem-bers of the ship's hull girder based on the section modulus re-quirement of paragraph B.1.4.1 above are to be maintainedwithin 0,4⋅L amidships. However, in special cases, based onconsideration of type of ship, hull form and loading condi-tions, the scantlings may be gradually reduced towards theend of 0,4⋅L part, bearing in mind the desire not to inhibit theship’s loading flexibility.

B.1.4.3 However, the above standard may not be appli-cable to ships of unusual type or design, e.g. for ships of un-usual main proportions and/or weight distributions.

B.2 EVALUATION RESULT OF LON-GITUDINAL STRENGTH OF THEHULL GIRDER OF OIL TANKERS

B.2.1 This section applies to ships regardless of thedate of construction:

Transverse sectional areas of deck flange (deckplating and deck longitudinals) and bottom flange (bottomshell plating and bottom longitudinals) of the ship’s hullgirder have been calculated by using the thickness measured,renewed or reinforced, as appropriate, during the special sur-vey most recently conducted after the ship reached 10 yearsof age, and found that the diminution of the transverse sec-tional area does not exceed 10% of the as-built area, asshown in the table 1:

Table 1

Transverse sectional area of hull girder flange

Measured(cm2)

As-built(cm2)

Diminution(cm2) or (%)

DeckflangeTransverse

Section 1 BottomflangeDeckflangeTransverse

Section 2 BottomflangeDeckflangeTransverse

Section 3 Bottomflange

B.2.2 This section applies to ships constructed on orafter 1 July 2002:

Section moduli of transverse section of theship’s hull girder have been calculated by using the thicknessof structural members measured, renewed or reinforced, asappropriate, during the special survey most recently con-ducted after the ship reached 10 years of age in accordancewith the provisions of paragraph B.1.2.2.1.1 of this Section,and are found to be within their diminution limits determinedby the Register *, as shown in the Table 2:


2013

Table 2

Transverse sectional area of hull girder

Wact(cm3)*1 Wreq (cm3)*2 RemarksUpperdeckTransverse

Section 1 BottomUperdeckTransverse


Section 3 Bottom

* The actual transverse section modulus of the hull girderof oil tankers calculated under paragraph B.1.2.2.1.1 ofthis Section is not to be less than 90% of the requiredsection modulus for new buildings specified in IACSUnified Requirements S7* or S11 (see also paragraphs4.3.2 and 4.3.4 of these Rules), whichever is the greater.

* C = 1,0 · Cw is to be used for the purpose of this calculation.

Notes:*1 Wact means the actual section moduli of

the transverse section of the ship's hullgirder calculated by using the thicknessof structural members measured, renewedor reinforced, as appropriate, during thespecial survey, in accordance with theprovisions of paragraph B.1.2.2.1.1.

*2 Wreq means diminution limit of the lon-gitudinal bending strength of ships, ascalculated in accordance with the provi-sions of paragraph B.1.2.2.1.1 of thisSection.

The calculation sheets for Wact are to be at-tached to this report.

B.2.3 This section applies to ships constructed before1 July 2002:

Section moduli of transverse section of theship’s hull girder have been calculated by using the thicknessof structural members measured, renewed or reinforced, asappropriate, during the special survey most recently con-ducted after the ship reached 10 years of age in accordancewith the provisions of paragraph B.1.2.2.1.2 of this Section,and found to meet the criteria required by the Register andthat Wact is not less than Wmc (defined in *2 below) as speci-fied in paragraph B.1.4.1, as shown in the Table 3:

Table 3

Transverse sectional area of hull girder

Wac t(cm3)*1 Wmc (cm3)*2 RemarksUpperdeckTransverse



Section 3 Bottom

Notes:*1 As defined in note *1 of Table 2.*2 Wmc means the diminution limit of mini-

mum section modulus calculated in ac-cordance with provisions of paragraphB.1.2.2.1.2 of this Section.

Describe the criteria for acceptance of theminimum section moduli of the ship's hull girder for ships inservice required by the Register.


2013

ANNEX C WATER LEVELDETECTORS ON SINGLE HOLD

CARGO SHIPS OTHER THANBULK CARRIERS (SOLAS 1974,

CH. II-1, REG. 25)

C.1.1 Single hold cargo ships other than bulk carriersconstructed before 1 January 2007 shall comply with the re-quirements of this regulation not later than the date of thefirst intermediate or renewal survey of the ship to be carriedout after 1 January 2007, whichever comes first.

C.1.2 For the purpose of this regulation, freeboarddeck has the meaning defined in the International Conven-tion on Load Lines, 1996, as amended.

C.1.3 Ships having a length (L) of less than 100 m ifconstructed before 1 July 1998, and a single cargo hold be-low the freeboard deck or cargo holds below the freeboarddeck which are not separated by at least one bulkhead madewatertight up to that deck, shall be fitted in such space orspaces with water level detectors*.

C.1.4 The water level detectors required by paragraphC.1.3 shall:

.1 give an audible and visual alarm at thenavigation bridge when the water levelabove the inner bottom in the cargo holdreaches a height of not less than 0.3 m,and another when such level reaches notmore than 15% of the mean depth of thecargo hold; and

.2 be fitted at the aft end of the hold, orabove its lowest part where the innerbottom is not parallel to the designedwaterline. Where webs or partial water-tight bulkheads are fitted above the innerbottom, Administrations may require thefitting of additional detectors.

C.1.5 The water level detectors required by paragraphC.1.3 need not be fitted in ships complying with regulationXII/12, or in ships having watertight side compartments eachside of the cargo hold length extending vertically at leastfrom inner bottom to freeboard deck.

C.1.6 For application of these requirements see alsoIACS unified interpretation SC 180.

* Refer to the Performance standards for water level detectors onbulk carriers and single hold cargo ships other than bulk carriers,adopted by the Maritime Safety Committee by resolutionMSC.188(79).


2013

ANNEX D GUIDELINES FORDIRECT CALCULATIONS OF

SHIP STRUCTURE

D.1 BASIC GUIDELINES FORDIRECT CALCULATION OF SHIP

STRUCTURES

D.1.1 General

The objective of this Appendix to the Rules1) isto provide basic guidelines and instructions for application ofdirect calculations to ship structural response and feasibility(measured by adequacy criteria/parameters).

Direct calculation consists of the followingsteps, see also Figure D.1.1:

(1) detailed determination of calculation objective:preliminary or final control of adequacy,modelling of part or total structure, type ofanalysis (linear or non-linear response analy-sis) and approach for determination of loads,

(2) selection of static, quasi-static and dynamicloads on structure resulting from the Rules ordirect calculation (sea-keeping program),

(3) modelling of the structure by the finite elementmethod (FEM) for response calculation,

(4) determination of force and displacementboundary conditions,

(5) response calculation (displacements andstresses) and definition of demand (designloads or critical response to design loads),

(6) capability calculation,(7) control of adequacy criteria (plasticity, buck-

ling, fatigue) by relating obtained response todesign loads and requested structural capa-bility in accordance with the Rules, evalua-tion of adequacy measures and proposals forstructural modifications.

D.1.2 Types and extent of response analysisby the finite element method

D.1.2.1 Requested types of analysis for approval ofthe ship's structure by direct calculation

D.1.2.1.1 Response analysis by linear fem analysis

This type of analysis implies small displace-ments and linear elastic behaviour of material. For moststructural elements this analysis provides correct response todesign loads.

1) Refers to the Rules for the Classification of Ships, Part 2 – Hull

D.1.2.1.2 Response analysis by non-linear FEM and’linear’ buckling

.1 Geometrically non-linear FEM analysis is ap-plied for relatively flexible structures withlarge displacements and buckling of struc-tural parts, that cannot be comprised by theanalytical calculations or formulae for buck-ling, respectively.

.2 Materially non-linear FEM analysis assumesstructural calculations in plastic domain.

.3 Hull girder ultimate strength analysis (accord-ing to incremental-iterative method pre-scribed by the Rules) in order to determinehull girder longitudinal ultimate load-capacity in terms of the ultimate verticalbending moment that could be sustained atthe position of the critical transverse section.

Most non-linear FEM buckling analyses occurwithin elastic-plastic domains and consequently both types ofnon-linearities shall be included into FEM models.

The present guideline deals with direct calcula-tion within linear FEM response analysis and with non-linearcalculation of feasibility (adequacy) criteria by analyticalmethods e.g. ultimate strength on element level (plate, stiff-ened plate, beam, etc).

Non-linear FEM analysis shall be specially re-quired in case of non-compliance with the requirements inD.1.2.1.1.

D.1.2.2 Extent of analysis

Depending on the objective of the analysis andin order to avoid too excessive FEM models, direct calcula-tion may be performed by combining different FEM modelshaving appropriate mesh density (coarse mesh/finemesh/very fine mesh), see Table D.1.2.2.

Table D.1.2.2 Types of FEM models

Model Type of model Type of mesh Item

A2-D FEM trans-

verse section mod-els (eg. midship s.)

coarse or finemesh 2.1.3

B2-D FEM grillage

model and other 2Dsub-structures


C 3-D FEM modele.g. 3-hold model


D 3-D FEM full shipmodel coarse mesh 2.1.6

E2-D/3-D FEM

structural compo-nents model

fine and veryfine mesh 2.1.7

Force and/or displacement boundary conditionsfor model (E) may be obtained from model (A) – (D).

Definition for density of fine and coarse meshis given in D.2.1.5.2 and definition for very fine mesh isgiven in D.2.1.7.3.

Levels of calculation, based on extent of theanalysis, are given in Figure D.1.2.2-1.


2013

Figure D.1.1 Direct calculation procedure

DETERMINATION OF THE OBJECTIVEAND EXTENT OF CALCULATION (1)

STRUCTURAL MODELLING FEM (3)

DETERMINATION OF DISPLACEMENTBOUNDARY CONDITIONS (4a)

DETERMINATION OF DESIGNLOADING CASES (2)

DETERMINATION OF FORCEBOUNDARY CONDITIONS (4b)

SELECTION OF DESIGNLOADING CONDITIONS (2)

CALCULATION OF RESPONSE AND DEFINITION OF D(Characteristic Response - Demand) (5)

• Displacements• Stresses

Control of adequacy criteria by comparing (7)• Demand (D)• Capability (C)

NO

Technical report

Control of adequacyafter local structuralmodification

REDIMENSIONINGModification of structu-ral model FEM

CAPABILTY CALCULATION C (Capability) (6)• Yielding• Buckling

IS RE-DEMENSIONINGNECESSARY? (8)

YES


2013

STRUCTURE (coarse and fine mesh models) DETAILS (very fine mesh)

Figure D.1.2.2-1 Levels of direct calculation execution

Figure D.1.2.2-2 shows the following LEVEL 2local tanker models:

- 3-D FEM 3-hold models –fine/ coarse mesh

- corrugated bulkhead structure details – veryfine mesh

Global model – fine /coarse mesh

Very fine mesh models

Figure D.1.2.2-2 Various FEM models for the calculation of tanker structure

b) 2-D FEM grillage model

FEM RESPONSE

e) 2-D FEM structuralcomponent models

FEM response calculation

d) 3-D FEM full ship model


START

LEVEL 1

LEVEL 2

LEVEL 3

e) 2D/3D FEM models ofstructural details


c) 3-D FEM partial (hold) model


e) 2D/3D FEM models ofstructural details


a) 2-D FEM section/frame model



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D.1.3 Theoretical assumptions andsuperposition of responses

D.1.3.1 Primary response - D1 (hull girder bending andtorsion) may be calculated by:

.1 extended beam theory

.2 full ship 3-D FEM model.

Distribution of bending moments and shearforces in transverse sections due to the hull girder bending isto be obtained from the standard calculation of longitudinalstrength.

Distribution of primary shear and normalstresses obtained from beam model is to be applied as im-posed force (stress) boundary conditions for partial 3-D FEMmodels.

D.1.3.2 Secondary response - D2 (combined plate andgirder bending) may be calculated by:

.1 eccentric beam element combined withadjoin plate elements,

.2 2-D (grillage, frame) or 3-D FEM beammodel. Hybrid beam element (beammacro-element) is used with effectiveplate widths, as specified in the Rules.

.3 3-D FEM model (stiffened or standardmembranes, plates, shells).

Shear correction is to be applied with beamelement.

D.1.3.3 Tertiary response - D3 (local stresses due tobending of longitudinals or plating between longitudinals)are to be calculated by:

.1 analytical methods (e.g. beam and/orplate bending theory),

.2 FEM methods (fine or very fine mesh offinite elements).

D.1.3.4 In the case of response calculations in lineardomain, superposition of all three response levels may be ap-plied. Superposition may be carried out:

.1 directly – by using special macro-elements

.2 by superimposing the results of separatecalculations (D.1.3.1-D.1.3.3).

D.1.4 As built and net scantlings of structuralelements

D.1.4.1 All calculations are performed on the basis of‘net’element thickness without corrosion addition.

D.1.4.2 If modelling of the structure is performed bymeans of ‘as built’ dimensions, the applied computing pro-gram is to include option for automatic deduction of corro-sion additions, as specified in the Rules, 2.9.

D.1.5 Requested documentation and form ofreport

D.1.5.1 Documentation to be submitted to the Registerfor approval is to include as follows:

.1 list of documentation used for structural modeldevelopment and determination of loads,

.2 main ship's particulars,

.3 detailed description of FEM model, including:- element types,- explanation of imposed assumptions and

simplifications,- explanation of differences related to draw-

ings of structures,.4 characteristics of used materials,.5 definitions of the displacement and force

(stress) boundary conditions,.6 visual verification of FEM model (sufficient

number of model views),.7 description of selected loading conditions in-

cluding relevant Q and M diagrams,.8 design load cases and load components, in-

cluding:- distribution of cargo and structure mass,- external hydrostatic and hydrodynamic

loads,- loads due to cargo in tanks or on decks,- loads due to ship's motion,- loads due to wave bending moments and

wave shear forces,- other loads,

.9 presentation of load components implementedinto the FEM model and verification of accu-racy of applied loads (values of reaction forces,etc.),

.10 graphical plot of deformed structure, verifica-tion of physical acceptability of model dis-placements, table of significant displacements,

.11 graphical plot of normal, shear and equivalentstresses of all structural elements for control ofelement adequacy with respect to the allowablestresses as specified in the Rules,

.12 graphical plot or table of the results of bucklingcontrol of structural elements in accordancewith the Rules (realised safety factor),

.13 table or plot of locations, load cases (demands),capability values and adequacy factors (foryielding, buckling, etc) where the Rules re-quirements are not satisfied,

.14 additional comments of results and proposalsfor revision,

.15 description and licence of applied software.Consultation with the Register (considering the

given requirements) is recommended prior to commencementof works to ensure quality and efficiency of direct calculationprocedure.

D.1.5.2 Application of alternative methods, not com-plying with principles of the subject Guidelines, shall beseparately considered.


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D.2 FEM STRUCTURAL MODELS

D.2.1 FEM models (A-E) and determinationof the displacement boundaryconditions

D.2.1.1 Structural model

Model is to enable physically acceptable distri-bution of displacements and stresses in the structure by ap-plying appropriate mesh density and element types.

Finite element stress distribution (dependent onthe applied shape functions) is the basis for determination ofthe number of elements necessary to approximate physicallyacceptable distribution of response.

Example: Three rows of elements along thedepth of the girder web (with constant stresses along theelement edges) may approximate linearly varying distribu-tion of stresses for bending of girder web. The same may bealso obtained by one beam element, but only outside the in-fluence of brackets.

Macro-elements (e.g. finite elements incorpo-rating discrete stiffeners on the plate field) can also be usedas structural units in coarse mesh models, combining numeri-cal and analytical approaches to the logical substructuressuch as stiffened panels, bracketed and locally reinforcedgirders, cells, etc. Most of the local safety (or failure) crite-ria, e.g. different buckling failure modes of stiffened panels,require specified force and displacement boundary condi-tions. They are available only if such logical structural partsas the complete stiffened panels between girders and framesare modeled (CRS CREST).

The macro-element formulation is based uponthe following principles:

(a) enhancing of the number of standard finiteelement descriptors (geometry, scantlings,material) with additional structural details(brackets, stiffeners, etc.) whose energy ab-sorption is dependent on the basic elementshape functions.

(b) combining of FEM-calculated displacementand stress fields with superimposed analyti-cally calculated local fields (e.g. tertiarystresses in the plate field between stiffeners).

(c) assuring that response fields ad (a) and (b) aresufficient for the evaluation of the subset oflocal adequacy criteria. If we define the fail-ure element as the minimal structural modelcapable of supporting certain failure func-tions, then the macro-element provides suchsupport for most of the yield, buckling, localvibration or fatigue criteria.

(d) If they are formulated as iso-parametric ele-ments they can easily follow the ship hullshape, or be stable elements in different geo-metrical changes.

Available macro-elements in CRS CRESTsoftware are:

1. bracketed beam macro-element permit-ting modeling of brackets on beams. It isobtained by combining the axial super-element and the beam with rigid length(replaces brackets).

2. siffened panel macro-element is obtainedby placing discrete stiffeners on a dis-placement field of a membrane and of aplate.

Depending on the objective of the analysis, di-rect calculation may be performed by combination of differ-ent FEM models mentioned in D.1.2.2 and Table D.1.2.2.Basic aspects of modelling, for all defined models, are de-scribed in this section.

D.2.1.2 Definition of coordinate system

For all models specified in the present Guide-lines the global right-hand Cartesian coordinate system is de-fined as follows:

X-axis is a base line in the ship's longitudinalplane of symmetry, positive forward.

Y-axis is lying in the ship's longitudinal planeof symmetry, positive upwards from the baseline.

Z-axis is perpendicular to the ship's longitudi-nal plane of symmetry, positive to starboard.

Displacements in X direction are denoted as u.Rotations about X axis are denoted as θx..

Displacements in Y direction are denoted as v.Rotations about Y axis are denoted as θy..

Displacements in Z direction are denoted as w.Rotations about X axis are denoted as θz..

D.2.1.3 2-D FEM transverse sections models–modelA

The models are to provide:

- calculation of primary stress distributionfor bending and torsion of the hull girder,

- calculation of secondary structural re-sponse of the transverse girders with at-tached plating for the web frame con-sidered,

- analysis of secondary response for theracking cases.

In principle, full transverse section of hull ismodelled. However, for symmetrical sections, only a halfsection, taking account of relevant boundary conditions, maybe modeled. Examples of coarse mesh models are given inFigure D.2.1.3.


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Figure D.2.1.3 2-D FEM Midship section models of tankersand bulk carriers

D.2.1.3.1 Application: calculation of the primary re-sponse distribution for the hull cross-section

The calculation is to be applied for:

- determination of warping and primarystresses (normal, shear) in the hull girdercross-section for control of permissiblelevels of stresses/displacements, seeRules, 4.5.3,

- determination of the force boundary con-ditions (distribution of stresses) in cross-sections of the partial 3D-FEM hull mod-els.

In calculation of the ship's hull primary re-sponse, appropriate type (A-D) of FEM model is to be se-lected together with the appropriate calculation method:

- where hull girder beam idealisation is ap-plicable, the combination of 1D hullglobal beam model (analytical or FEM)and 2D FEM model of the characteristichull cross sections (model A) may beused. Note: this model is used in CRESTCRS computing system [2].

- where decks are partially effective in thelongitudinal strength calculations (e.g.multi-deck passenger ships) or wheremajor yielding of upper decks is likely tooccur, the calculations are to be speciallyconsidered. In such a case CRS may re-quire 3-D FEM model with adequate hulllength (model C) or full ship model(model D).

Check of stresses and warping are to be carriedout at the following sections:

- position of maximum bending moment –midship section (1/2 L),

- position of maximum shear force - (1/4Land 3/4L),

- any other specific position.For the stress calculation due to bending and

torsion including torsion/shear centre calculation for simplertransverse sections, analytical method of shear stresses flowsmay be applied, but numerical approach based on FEM isrecommended (see computing system CREST CRS, ref.[2]).

Finite elements mesh to be used for the calcu-lation of shear flow is to enable determination of parabolicdistribution of shear stresses over the section by means of:

- sufficiently dense mesh of simple ele-ments (constant shear by element),

- correction of shear flow by element forgreater elements (parabolic shear distri-bution by element).

Standard finite (line) elements have one degreeof freedom by node (section warping) and accordingly assureconstant shear stresses by element (see computing systemCREST CRS providing parabolic distribution, ref. [2]).

Only longitudinally effective hull material is tobe taken into the calculation. In this case, “shadow area rule”may be applied, see Rules, 4.3.1.3, relating to determinationof material efficiency abaft the hatches, shell plating open-ings or partially longitudinal elements (e.g. partial longitudi-nal bulkheads, hatch coamings).

Within the area of major bending momentand/or transverse force locations normal stresses are to becorrected to the influence of shear stresses for reachingmaximum stresses within critical areas of sheer strake anddeck stringer.

As to the matter of hull “open” section torsionwith restrained warping the twist angles and appropriatederivations may be calculated by analytical approach [3] orby finite beam element method [4].

D.2.1.3.2 Application in the calculations of secondarystresses (Transverse strength)

Direct calculation of web frame for control oftransverse strength is to be performed with the followingsections:

- minimum stiffness sections – hatchwaysection,

- maximum local load sections,- midship section.Assumption for the calculation is so called

“cylindrical bending” of the hull segment represented bygiven web frame. With 2D idealisation other 3D effects ofthe remaining ship's structure to bending of web frame are tobe considered and consequently relevant boundary conditionsare to be generated.

FEM model is to include all relevant transversestructural components (floors, beams, frames, pillars, solidweb frames) within a concerned section. Modelling of actualstiffness of frames is to be performed with sufficient accu-racy and used finite elements are to properly present distri-bution of stresses within structural components (e.g. linearvarying stress distribution over the girder depth).


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Macroelements of stiffened membrane platemay be used for modelling floors with local stiffeners or highweb girders.

Membrane elements with linear (or higher or-der) distribution of normal stresses along the edge may repre-sent solid girder web, while face plates may be modelled byrod elements of equivalent section area.

Frames and beams are mostly modelled bybeam finite (macro) elements, for which validity of the beamtheory may be assumed. Pillars are modelled by rod ele-ments.

Beam joint brackets (e.g. bracketed joint ofbeam and frame) are to be modelled by means of beammacro-elements with rigid ends. Shear correction of beamelements is to be included.

Type of beam FE element to be used is to bespecified (hybrid, eccentric).

As a segment supporting modelled web usuallyweb frame spacing is to be taken, from which follows thedefinition of load width and effective breadth of longitudinalstrength elements, included in the transverse bending, seeRules 2.5.

The effect of longitudinal structure supportingconsidered frame within the hold and/or space is to be accu-rately determined, as follows:

- bending and shear stiffness of longitudinalelements (double bottom girders, longitudi-nal bulkheads etc.) supporting transversegirder at the relevant node, is modelledwith spring or rod elements of equivalentstiffness,

- stiffness of structural components taken asclosed boxes (e.g. hopper side tanks andtopside tanks) is modelled by spring systemof equivalent bending and torsion stiffness(see computing system CREST CRS).

D.2.1.4 Application in the calculations of grillageresponse and other 2D sub-structures –model B

These models are used in cases when it is pos-sible to describe correctly the boundary conditions at theiredges and/or sections to the remaining structural part (simplysupported, clamped, partially clamped, symmetry condi-tions).

Typical usage of these models is applied withsecondary response calculation of ship's girder system at-tached to the plating, e.g. for calculations of ship's grillage(bottom, decks, double side, bulkheads, etc.).

Where concept of effective breadth is appliedfor the plating, models are to be built with beam elementsand nodes in system neutral axis. Shear effect to the girderdeflection is to be included and effective breadth is to be cal-culated in accordance with Rules, 2.5.

When beam flange/plating is modelled withmembrane/plate elements, beam elements are to have correc-tion for eccentricity of beam-only centre of gravity in rela-tion to the beam toe (with plating connection) where FEMidealisation 2D structure nodes are located.

D.2.1.5 3-D FEM partial hull models- model C

The present models are intended for performingthe calculation of primary and secondary response by FEMwith:

- ship's hull girder bending,- ship's torsion,- response analysis in case of ship's rackingTertiary response may be calculated analyti-

cally and then superimpose to primary and secondary re-sponse.

Structural model is to enable correct applica-tion of design load cases (e.g. alternative loading).

These models can generate the displacementboundary conditions for direct calculations of structural de-tails through very fine FEM meshes using top-down ap-proach, see D.2.1.7.

D.2.1.5.1 Hull structural part to be modeled, is deter-mined as follows:

- for tankers: three holds within cargospace inside the parallel midbody, seeFigure D.2.1.5.1-1

- for bulk carriers: three holds within cargospace midbody, see Figure D.2.1.5.1-2

- for other types of ships on agreementwith the Register.

The model is also to include additional ring ofweb frame spacing fore and aft the end transverse bulkheads.

Smaller partial models (1/2+1+1/2 hold) will bespecially considered in the terms of the model boundary con-ditions effect to the stress field of the considered structuralpart.

Calculation results are considered relevant onlyfor the central hold and/or space.

In case the structure in fore or aft part essen-tially differs from the modelled space, necessity of additionalmodels or extension of existing model is to be consideredwith the Register.

In case of transversely symmetric structure(symmetric with respect to C.L.) only one side of the struc-ture is to be modelled or half model, respectively. For suchmodels, the following is to be applied:

- In case the asymmetric load is consideredcomputing program is to be designed fordistribution of load to the symmetriccomponent ((port side load + starboardside load)/2) and antisymmetric compo-nent ((port side load – starboard sideload)/2).

- If the computing program is not designedfor such option, both structural sides areto be modelled, although the ship isstructurally symmetric.


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Figure D.2.1.5.1-1 3-D FEM partial tanker hull model

Figure D.2.1.5.1-2 3-D FEM partial bulk carrier hull model


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D.2.1.5.2 3-D FEM model mesh density

(a) macroelement based coarse mesh:

- longitudinally: max two (2) macroelementof framed shell between web frames wheresecondary framing (longitudinals) is in-cluded into model,

- transversely: sufficient density of macro-elements (membranes, beams) for ensuringcorrect stress response field by the ele-ments, see D.2.1.3.2,

vertically: one (1) macroelement over the floordepth, see D.2.1.3.2.

(b) finite elements based fine mesh:

- transversely: one element between stiffen-ers,

- longitudinally: two (2) elements betweenweb frames,

- vertically: three (3) elements over the floordepth,

- stiffeners may be modelled by applying 1Delement type (rod, beam).

In places where stress concentration is expectedto occur, meshes specified in (a) are to provide more precisefineness additionally to the level of meshes specified in (b),in order to ensure more accurate boundary conditions forFEM models with very fine mesh, see D.2.1.7.

D.2.1.5.3 Displacement boundary conditions

D.2.1.5.3.1 Displacement boundary conditions are pre-scribed values of degrees of freedom in the nodes within themodel section with the remaining structure or within specificgiven nodes or physical supports, respectively.

Force boundary conditions are given in thosesection nodes (ring free edge) for which the displacementboundary conditions are not imposed.

Displacement boundary conditions are to sup-press model displacements as rigid body (translations androtations).

Displacement boundary conditions may be pre-scribed as suppressed degrees of freedom (displacement=0)or as prescribed displacement values in the model nodes.

Displacement boundary conditions may be pre-scribed in actual sections with remaining structure – addi-tional rings, see D.2.1.5.1 or at the points of heavy transversesub-structures (transverse bulkheads).

Boundary conditions of symmetry and anti-symmetry for half model are prescribed in all nodes withinlongitudinal symmetric plane in accordance with TableD.2.1.5.3.1.

Table D.2.1.5.3.1

DISPLACEMENTBOUNDARYCONDITIONS

TRANSLATIONS ROTATIONS

u v w θx θy θz

SIMMETRY 0 0 1 1 1 0

ASYMMETRY 1 1 0 0 0 1

1= restrained; 0= freeNote: for the definition of coordinate system see 2.1.2.

Supports are generally arranged in the intersec-tions of structural elements of strong sub-structures for moreeffective taking up and distribution of concentrated reactionforce, obtained in the node of support.

D.2.1.5.3.2 Boundary conditions may be also prescribedthrough the spring system, where displacement depends ofthe given spring stiffness value in the relevant node. Thespring system enables static stability of the model and betterpresentation of the effect of the remaining structure to theevaluated model.

Equivalent stiffness of the spring elementsshould substitute stiffness of actual substructures as realisti-cally as possible:

- deck, bottom and inner bottom at hori-zontal bending,

- longitudinal bulkheads, side, double sideat vertical bending,

by means of which the remaining structure is supporting themodel.

In this case, stiffness effect of smaller girders(girder in double bottom, deck girders and stringers) may bedisregarded and consequently the springs need not to be gen-erated at the positions of such elements.

Stiffnesses of springs supporting substructures,such as bottom, inner bottom, decks, sides, longitudinalbulkheads, are to be calculated on the basis of elementaryformulae for beam shear stiffness.

Length of substructure D corresponds to trans-verse bulkhead spacing. Substructure has the shear surface As(only plating is to be taken in the section area) and shearmodulus G.

Rod elements of d in length, section area a,with Young's modulus of elasticity E, connecting substruc-ture node to the node, where all displacements are sup-pressed, have the function of springs. Specified nodes deter-mine the direction of spring's effect through their coordi-nates.

Spring stiffness kspring is determined by formula:

DAGc

daEk S

spring⋅⋅

=⋅

=

Where rod element section area is determinedby formula:

SADd

EGca ⋅⋅⋅=

where:Constant c is taken as c=1/n,


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n = number of springs within substructure sec-tion, to which its stiffness is to be distrib-uted.

D.2.1.5.3.3 For modelling of response due, the springs tovertical and horizontal bending of ship's hull are to be ap-plied at both model ends, in the positions of at least onestrong substructure. The springs are to be distributed alongthe substructure at least in two positions, see FiguresD.2.1.5.3.3-1 and D.2.1.5.3.3-2:

- vertical springs (global axis Y direction):on the bottom and longitudinal bulkheadtop, side or double side,

- transverse spring (global axis Z direc-tion): on the positions of deck, bottometc. at left (and starboard) side,

- longitudinal springs (global axis X direc-tion): to be placed as needed on the posi-tions as for transverse springs. Small un-balanced longitudinal forces are to begenerally taken up by fitting rigid sup-ports in appropriate neutral lines.

Figure D.2.1.5.3.3-1 Example of spring system in tankersstructure

y

x

z

Mt

Mt

Figure D.2.1.5.3.3-2 Ship's hull spring system

D.2.1.5.3.4 For modelling of response due to torsion ofship's hull:

- transverse and vertical springs are to beplaced in the intersections of transversebulkheads with longitudinal substructures.In such a case, rotation of bulkhead to oneof the model ends is to be enabled, by ap-plying spring supports in the symmetryplane of the model, and at the other end thespring supports are to be provided on thepositions of all strong longitudinal sub-structures.

- longitudinal springs for longitudinallyasymmetric load cases, such as torsion, areto be modelled due to controlled restrictionof structural warping. They are to be in-stalled at the intersections of strong verticaland horizontal substructures.

As to the more complex problems regardingasymmetric loads, possibility and advantage of full shipmodel is to be considered, with respect to modelling ofequivalent stiffness in the sections of smaller partial models.In all such cases, the agreement with the Register is to beobtained.

D.2.1.6 3-D FEM full ship hull model - model D

D.2.1.6.1 The present models should be produced for theships:

- where there is unequal distribution ofstructural elements along the ship's hull,

- where the load conditions require control ofstructural integrity at several locations,

- where there is problematic determination ofboundary conditions in partial 3D FEMmodels, see D.2.1.5.

The following ships are included into thisgroup:

- passenger and cruise ships,- multi-deck(car carriers, Ro-Pax) and multi-

hull ships,- containers ships,- high-speed ships,- naval ships,- special sea-going objects such as pontoons,

docks, etc.Any other non-standard ship's structures, re-

garding the size and extent of the model, will be agreed withthe Register.

These models are obligatory for multi-deckships (passenger and Ro-Pax ships) where the degree of par-ticipation of a superstructure deck into the longitudinalstrength, is unknown.

Long superstructures of such ships are to befully modelled in a way that their effect to the ship's longitu-dinal strength is correctly applied.

Short superstructures which are not includedinto the longitudinal strength are to be modelled in a way thatdistribution of their own weight, is correctly presented.

Specified models are intended for the calcula-tion of the primary and secondary response by FEM.

Tertiary response may be calculated by analyti-cal method and then superimposed to the primary and secon-dary response.


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Coarse mesh of macroelements, defined inD.2.1.5.2 a), is the most rational approach to modelling solarge FEM models. Characteristic model of large passengership is shown in Figure D.2.1.6-1.

Figure D.2.1.6.1 Coarse mesh of macroelements for 3-DFEM ship's full hull model

These models also generate displacementboundary conditions for direct calculations of structural de-tails, by means of fine FEM meshes, see D.2.1.7.

D.2.1.6.2 Displacement boundary conditions for thesemodels are intended to prevention of ship's motion as a rigidbody, and may be applied in accordance with TableD.2.1.6.2.

Table D.2.1.6.2

DISPLACEMENTBOUNDARY CON-

DITIONSTRANSLATIONS ROTATIONS

u v w θx θy θz

Fore collisionbulkhead, keelnode

1 1 1 0 0 0

Node of transom(or aft collisionbulkhead), deck(around N.L.) andport side

0 1 1 0 0 0

Node of transom(or aft collisionbulkhead), deck(around N.L.) andstarboard side

0 1 0 0 0 0

1= restrained; 0= freeNote: for the definition of coordinate system see 2.1.2.

Boundary conditions of half models in thesymmetry level are given in Table D.2.1.5.3.1

D.2.1.6.3 Balancing the model

FEM model is to be in quasi-static condition ofbalance at any considered loading cases.

Unbalanced forces in fiction supports in direc-tion of all three axes, are to be small, not more than 0.5 % ofthe ship's displacement.

Unbalanced moments are to be below 6% ofthe maximum bending moment, for each of the loading case.

Variations from the values of displacement,trim and vertical bending moment are considered satisfac-tory, if within the following tolerances:

- 0.5 % of displacement,- 0.1° of trim angle,- 5 % of still water bending moment.

D.2.1.7 2-D and 3-D fine and very fine FEM mesh ofstructural details– E model

Stress concentrations are not possible to be ob-tained from the previously described FEM models (A-D),where lesser mesh density as well as model simplificationshave been applied, or from the equivalent modelling of stiff-ness, respectively, where local geometry of structural com-ponents has been neglected.

Stress level and distribution are restricted byformulation of applied finite element (order of used shapefunctions). In order to reach required accuracy of maximumstresses amount and their correct position, refinement of ele-ments mesh is to be performed (fine and very fine mesh).

D.2.1.7.1 Structural details are to be modelled, with veryfine mesh of finite elements, at the locations where can ap-pear:

- increased stress level (as required by theRegister),

- increased stress level in the elements ofcoarser models, see D.2.1.3 to D.2.1.6, thatcan result in high stresses within structural


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details, included by the same, but are notmodelled in details.

D.2.1.7.2 Before commencement of modelling, the list ofstructural details is to be agreed with the Register, which is tobe modelled by very fine meshes, subject to the kind of detailand type of ship, so that appropriate mesh for correct deter-mination of boundary conditions could be ensured.

D.2.1.7.3 Mesh density of finite elements is defined sub-ject to the kind of structural detail. In principle, the followingnotes should be followed:

- transitions from coarse to fine mesh or veryfine mesh are to be performed gradually,reducing size of finite elements when ap-proaching considered structural detail("spider's web” mesh, etc.),

- element's dimensions are not to be less thanits thickness,

- element's dimensions are not to exceed 20 tor 200 mm, where t is element's thickness,

- special care is to be given to modelling ofcurved contour (e.g. bracket free edge)

- model extent is to be such that ends of finermodel, to which boundary conditions areapplied, are to be sufficiently spaced fromthe considered detail, for the reduction ofeffect of boundary conditions to the results– St. Venant principle,

- the model ends are recommended to corre-spond to the locations of substructures orstrong girders,

- local geometry (lightening openings, addi-tional framing, brackets and other details)are to be modelled in accordance with clas-sification and/or workshop documentation.

Examples of very fine FEM mesh of structuraldetails are shown in Figure D.2.1.7.3.

Figure D.2.1.7.3 3-D FEM models of ship's structural de-tails (very fine mesh)

D.2.1.7.4 One of the following models is applied in thecalculation of the stress concentration by means of very fineFEM models, see Figure D. 2.1.7.4:

D.2.1.7.5 Fine mesh model loads are prescribed directlyto the model, in accordance with considered load cases, fromwhich displacement boundary conditions have been taken(may be applicable as force boundary conditions, wheremore appropriate).

D.2.2 Selection of elements and/ormacroelements and mesh density

Type of finite element and mesh density is se-lected according to expected response field, which is to beaccurately presented, see D.2.3. Generally, mesh of macroelements (complex finite elements) corresponds to the meshof strong girders in the structure.

Likewise, strong girders at the edges of macro-elements provide boundary conditions for automatic controlof feasibility of individual macroelement (buckling). In thiscase, macroelement (stiffened panel, strong girder) is not tocomprise more than 4 spacing of stiffeners.


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METHOD CHARACTERISTICS

Sub-model method (top-down approach)

GLOBALMODEL

LOCALMODEL

At the model level with coarsermesh displacement boundaryconditions for finer models aregenerated. Minimum linear in-terpolation of field displace-ment to boundary conditions isrequired (− − − −) according tothe displacement in the nodesof coarser mesh.

Superelement Method Model with fine mesh is stati-cally condensed and directlyincluded as stiffness intocoarser model through freedomdegrees connected to nodes(super nodes • ) and special-ised software is required.

Method of direct im-plementation of finemesh model to coarsemodel (D.2.1.3-D.2.1.6)

It is useful to a certain extent offine mesh density, but effec-tiveness and flexibility of cal-culation is reduced.

Figure D.2.1.7.4 Methods of stress concentration calcula-tion by very fine FEM models

D.2.2.1 Beam elements and macroelements

D.2.2.1.1 Standard beam element (characteristics):

(a) 6 (3) degrees of freedom by node, axialstiffness (rod), bending and torsion stiff-ness (beam),

(b) includes correction of deflection due toshear.

D.2.2.1.2 Beam macroelement (see also CREST CRS,ref. [2]):

(a) axial stiffness of bracket at the modeledges may be included through the superelement composed of three rod elements(bracket, free span, bracket) of differentsection area,

(b) rigid ends are included by standard pro-cedure of transition of vector displace-ment from the element end node to theinner end point of the rigid element part,on the basis of the following kinematicsassumptions:- rotation in both nodes is the same,- translation of inner node is sum of

translations of end node and productof its rotation with the length of rigidend (spacing between end and innernode).

D.2.2.2 Membrane finite elements

Standard membrane finite elements are trian-gles, rectangular and quadrilateral elements with ratio of ad-jacent sides less than 1:4.

If possible, triangle elements and acute anglesof all types of elements are to be avoided.

Angles of quadrangular elements are to begreater than 60°and less than 120°, while for triangular ele-ments are to be greater than 30° and less than 120°.

D.2.2.3 Finite Plate Elements

As ditto in D.2.2.2.

D.2.2.4 Macroelements of framed membranes andplates

As ditto in D.2.2.2.Stiffeners within the macroelement's field are

modelled on their actual positions (see computing systemCREST CRS [2]).

On agreement with the Register, exceptionallyin coarse meshes the following may be used:

- orthotropic elements with equivalent thick-ness in two directions,

- equivalent stiffeners at the edges of ele-ments with the stiffness corresponding tothe sum of stiffeners stiffness in the field.

D.2.2.5 Special Elements

Pillars are modelled with rod elements.

D.2.3 Equivalent modelling of the strucutralelement properties

Equivalent modelling is used for simplificationof a model for coarse and fine meshes.

Modelling is to provide actual stiffness of thestructure, but not necessarily the distribution of stresseswithin the equivalent structure.

Stress distribution and level around equivalentstructural part are to be unchanged.

Equivalent modelling is always to extend at thesafety side, i.e. obtained response is to exceed the actual onewhile capability is to be less than actual.

The following notes are to be considered:- beam girders in beam-membrane model are

modelled with effective width of plating atbending. Plating (membrane) and beam(rod) absorb the energy of axial load whilebending energy is absorbed only by beam(beam elements with effective width ofplating),

- for small eccentricities of ship's stronggirders, the nodes of element's mesh are tobe placed in the plating,

- small openings in the girders or plating areto be larger openings (e.g. manholes) maybe taken into consideration by deleting theelement or by reduction of girder's thick-ness, as follows:neglected,

- proportionally to the portion of openings inthe height of girder,


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- proportionally to the portion of opening inthe girder area,

- small brackets on the girders may be ne-glected,

- partial stiffeners may be also neglected.

D.2.4 Modeling procedure and verification ofthe model

Control of development and verification ofmodel the are essential for the application of FEM numericalmethod. Only the computing program with graphical pres-entation of model and response is acceptable and feature ofautomatic data generators is highly desirable, in order to re-duce effort and consequently inevitable failures.

For the purpose of ensuring modelling quality,the following is to be recommended:

- control of input of numerical data throughthe team work (i.e. checks, double-checks, etc.),

- visual verification of special data groups(plate thickness, type of material, profilecharacteristics etc.),

- application of test load (or actual load)for the verification of :consistency of model (potential “cracks”due to unconnected elements – freeedges)boundary conditions (e.g. illogical re-sponse), etc.

D.3 LOADING OF THE STRUCTURE

D.3.1 General

D.3.1.1 Selection of design loading conditions andloads cases

Design load cases (LCa) for given loadingconditions (LCo) are to include and all relevant load compo-nents, as prescribed in accordance with the Rules.

Design loading conditions for given loadingcondition are to set all essential structural elements into con-dition of the most significant (design) response, in relation towhich the capability of structural element is evaluated.

In principle, the most unfavourable responseswill be obtained by structural analysis for extreme sea load-ing conditions (sagging and hogging) of the hull girder andfor the inclined ship.

Loading conditions, related to longitudinalstrength, are specified in the Rules, 4.2.1.2.

Dynamic loads from the ship's motion as a rigidbody produce inertial structural loads. Masses of ship andcargo are multiplied by global vector of ship's translationalaccelerations (for heaving, swaying and surging), or alterna-tively, ship's local angular accelerations (pitching, rolling andyawing), subject to the mass position in relation to rotationcentre, are to be calculated.

For simplified determination of design loadcases, it is recommended that load cases are prescribed byconcentrated masses or distribution of mass (structure andcargo) instead of local pressures/forces.

Vector of ship's acceleration is stated in theRules, 3.5, or is obtained by sea-keeping calculation, previ-ously approved by the Register.

For determination of load cases for selectedloading condition, the application of Turkstra's rule may beconsidered, so that only one of the components in the consid-ered case has the extreme value, since the simultaneousmaximum of more load components is not probable, unlessexpressly prescribed by the Rules.

D.3.1.2 Determination of design load cases

As specified in D.3.1.1, design load cases are tobring structural elements into condition of maximum possible(design) response. It will require control of the sagging andhogging condition of the elements with structurally possibleboundary conditions at their edges, respectively:

- that the elements will be loaded by pres-sure or masses in both directions of thenormal to the element, in case this ispermissible by loading cases,

- bending of adjacent elements will definedegree of elastic restraint of the consid-ered element, and thus for adjacent ele-ments load in both directions or unloadedcondition is to be considered.

Example 1: Outer shell plating panel in double bottom –design load cases:

- maximum draught and empty doublebottom will produce critical hogging ofthe shell plating panel,

- maximum tank filling in double bottomand minimum draught will produce criti-cal sagging of the shell plating panel.

Specified load cases are to be additionally con-sidered with respect to the:

- boundary conditions effect (adjacenttanks, full and/or empty),

- appropriate level of superimposed pri-mary stresses.

Example 2: For evaluation of panel boundary conditions weconsider joining node (cross joint) of four spaces a, b, c and dseparated e.g. by longitudinal and transverse watertight bulk-heads (LWB or TWB) or joining node (A) three spaces(tank) a, b and c separated e.g. by inner bottom plating andwatertight floor, see Figure D.3.1.2. For combination full(=1) and empty (=0) in the first case 16 different load casesmay be obtained (abcd = 1000, 1001, 1010, 1011,..., 0111),and in the second case eight different load cases (abc= 100,101, 110, 111,...,011).


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a b

c d

TWB TWB TWB

L WB

L WB

LC

LWB - longitudinal watertight bulkheadTWB - transverse watertight bulkhead

side

side

a

T WB T WB T WB

P

b c

LWB - longitudinal watertight bulkheadTWB - transverse watertight bulkhead

floor floor

deck

inner bottom

bottom

Figure D.3.1.2

Each of the specified cases produces differentstate of deformation in bulkheads or inner bottom plating,from which some will be critical, while some of them cannotappear at all for the assigned loading conditions.

The designer is to consider sufficiency andadequacy of load cases in relation to the stated conditions,especially for sagging (resulting buckling or plastic defor-mation of plating) and hogging of panel (resulting bucklingor plastic deformation of stiffener flange). For the selectionof load cases, special attention is to be given to the most in-convenient combination, resulting in the most significantlevel of primary stresses.

In the case of a part of inner bottom plating a-b,see Figure D.3.1.2, it is evident that among critical (design)load cases there will be combinations 101 (sagging) and 010(hogging), related to unfavourable boundary conditions,stated in node (A).

The Register may require control of omittedload cases, if considered critical.

D.3.2 Load components

Load components applied in direct calculationare to be in accordance with the Rules and given load condi-tions.

For specific types of ships, other than loadsspecified in this Section, additional requirements for loadsare to be considered and applied, in accordance with theRules, Section 17-21, subject to the type of ship.

D.3.2.1 Load from lightship weight

Load from lightship weight is to be taken intoconsideration for all types of direct calculations. If actualstructural mass is known (Trim and Stability Book), idealizedmass, obtained through FEM model, is to be adapted to theactual structural mass. Lightship weight is obtained by mul-tiplying structural mass with adequate acceleration vectors,according to D.3.2.4.

D.3.2.2 Hydrostatic and hydrodynamic externalsea loads

Subject to the design load condition and ship'sdraught, as defined in D.3.1, values of the load to the shellplating and upper deck are to be determined in accordancewith the Rules, 3.2.

D.3.2.3 Loads from cargo in tanks and decks

Subject to the design loading condition, theload of tank's structure is calculated in accordance with theRules, 3.4. Deck load from cargo and accommodation deckload are to be determined in accordance with the Rules, 3.3.It is recommended to recalculate the pressures (force per unitarea) to masses per unit area, see D.3.1.1.

D.3.2.4 Loads from ship's motion

Dynamic loads due to ship's motion are giventhrough acceleration vector components, in accordance withthe Rules, 3.5. Rotation centre may be placed at 0.05⋅L fromamidships toward stern.

D.3.2.5 Loads from wave moments and transverseforces

For all types of direct calculations in the con-sidered section, bending moments and shear forces, specifiedin the text below, are to be applied and/or achieved.

D.3.2.5.1 Vertical bending moments MS and shear forcesFS in still water are to be determined in accordance with theRules, 4.2.1.

D.3.2.5.2 Vertical bending moments MW and shear forcesFw induced by waves, are to be determined in accordancewith the Rules, 4.2.2 and 4.2.3.

D.3.2.5.3 Additional bending moments caused by slam-ming MSL are to be determined in accordance with the Rules,4.5.1.

D.3.2.5.4 Wave induced horizontal bending momentsMWH are to be determined in accordance with the Rules,4.5.2.

D.3.2.5.5 Torsional loads respectively distribution oftwisting moments for ships with “open” sections (containerships, bulk carriers, etc.), catamarans, semi-submersibles etc.,are to be specially considered on agreement with the Regis-ter. Torsion stiffness at pure torsion, torsion stiffness with re-strained warping and centre of torsion are to be determinedby FEM procedure from CREST CRS system [2] or anyother acceptable analytical method.

D.3.2.6 Other Loads

Loads of heavier equipment, main engine,containers, etc. are to be modelled at their actual positions,taking into account distance of the mass centre of gravityfrom the supporting points. Inertial forces taken up by sup-


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porting points are to be correctly distributed, subject to thetype of support.

Wheeled loads in Ro-Ro ships should be spe-cially considered and applied in agreement with the Register.

D.3.2.7 Special notes for loads of 3-D FEM full shipmodel

D.3.2.7.1 Where 3-D FEM full ship model loads aregiven, the notes specified in D.2.1.6.3 (relating to modelbalancing), as well the following instructions will be valid:

- if distribution of actual light ships mass isknown (from the Trim and StabilityBook), idealized mass obtained by FEMmodel is to be adapted to the actual mass(addition for mass of neglected stiffening,painting, welds, pipes, etc.),

- wave load for these models is given in theagreement with the Register.

D.3.2.7.2 Loads to wetted surface of global 3D FEMmodel could be given simultaneously or separately in twoforms:

(1) Sinusoidal quasi-static static design waveof length λ, including correction forSmith's effect:

p=pw e -kd

where:

pw = wave hydrostatic pressure,

k = 2π / λ wave number,

d = distance of the considered point fromthe wave axis. It is assumed that designwave defined in this manner generateswave bending moments as specified inD.3.2.5.2.

In this manner primary (hull girder bending)and secondary (coupled bending of structural girder andplating) stresses within shell plating panels (membranestresses) are obtained from FEM model.

(2) By means of design pressures, accordingto the Rules, 3.2, for obtaining realistictotal stresses (primary + secondary +tertiary) due to bending of plating andpanel stiffeners, for the calculation ofshell plating panel feasibility (interactionformulae, see Section D.5).

In the feasibility formulae greater of the valuesspecified under (1) and (2) is relevant.

D.3.3 Determination of equivalent loads in themodel nodes

For the continuous loads (by side, by area or byvolume) the equivalent nodal loads are to be determined us-ing the work equivalency principle between work of the dis-tributed load on the displacement field of the respective ele-ment and the work of equivalent nodal forces on the corre-sponding nodal displacement field.

Specified transformation is to be used by theapplied computer program.

D.3.4 Force boundary conditions in thepartial model sections

D.3.4.1 Hull bending and torsion moments, sec-tional stress distribution

Depending on the prescribed boundary mo-ments of the vertical and horizontal bending and torsion mo-ment or angles of twist, the equivalent distribution of forceboundary conditions (normal stresses distribution) is ob-tained for the end sections of partial models, including:

- vertical bending σV,

- horizontal bending σH,

- restrained warping σW (warping stress).

Distribution of force boundary conditions isgiven in accordance with extended beam theory (see com-puting program CREST CRS) or on the basis of analyticalmethod of sufficient accuracy.

For the case of hull girder bending, normalstresses σV and σH are to be corrected due to influence of theshear stress, i.e. in the sheer strake and deck stringer.

For the case of torsion with restrained warping,distribution of normal stresses σW (determined by the meansof second derivations of the angle of twist obtained from thehull girder torsion calculation (to be submitted to the Regis-ter) is to be imposed.

Distribution of normal stresses for plates andprofiles of adequate scantlings is to be converted into distrib-uted load, and in accordance with D.3.3 it is to be convertedinto equivalent FEM model nodal forces.

D.3.4.2 Transverse forces due to hull bending andtorsion and their distribution

On the basis of prescribed transverse forces dueto (1) vertical and (2) horizontal bending at the model endsand (3) angles of twist and its derivations in torsion with re-strained warping, equivalent shear stress distribution repre-senting force boundary conditions, is obtained at end sectionsof partial models, namely:

- vertical and horizontal bending τV, τH,

- primary shear stresses (pure torsion) τ1,

- secondary shear stresses (restrainedwarping) τ2.

Distribution of specified boundary stresses isgiven in accordance with extended beam theory (see com-puting program CREST CRS) or according to analyticalmethod of appropriate accuracy.

Distribution of shear stresses for plates and pro-files of adequate scantlings are converted into distributedload and in accordance with D.3.3 it is converted intoequivalent FEM model nodal forces.


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D.3.5 Verification of loads model

D.3.5.1 For 3-D FEM models of ship's part, seeD.2.1.5, and full ship, see D.2.1.6, the following data relatedto the verification of load model, should be submitted:

.1 diagrams of vertical transverse forces andbending moments, obtained from loadsapplied on FEM model for all load cases,

.2 diagrams of horizontal transverse forcesand bending moments as well as twistingmoments, obtained from loads applied onFEM model, where such load cases areconsidered,

.3 table with bending moment and shearforce values for individual sections,

.4 applied acceleration components,

.5 graphical or tabular presentation of exter-nal sea load distribution upon the platingand model exposed deck,

.6 graphical or tabular presentation of theload (pressure) distribution upon the tankplating and/or model deck,

.7 resulting unbalanced forces and momentsin the sections.

D.4 STRUCTURAL RESPONSECALCULATION BY FINITE

ELEMENTS METHOD

D.4.1 General

Boundary conditions may be provided by e.g.excluding relevant rows and columns from the stiffness ma-trix or modification of stiffness of diagonal matrix elementand load vector, etc.

For half hull models and transversely asymmet-ric loads, the following will be allowed:

(1) decomposition of asymmetric load vectorto symmetric and anti-symmetric compo-nent,

(2) equations system is to be solved sepa-rately for adequate symmetry and anti-symmetry boundary conditions,

(3) resulting displacement vector is to beobtained by inverse transformation in re-lation to (1).

Transversely asymmetric structures are to bemodelled in full (both sides).

Solution of FEM equation system is to be con-sistent, whilst stiffness matrix is to be positively definitive(internal control in the equation system solver).

Values of reaction forces are to be within per-missible tolerances, especially for full ship model, seeD.2.1.6.3.

Partial models calculation results, see D.2.1.5,in the zones adjacent to model section, are not to be consid-ered in accordance with St. Venant principle, but are to be

reasonable. When using sub-model, see D.2.1.7, the sameprinciple is to be applied.

D.4.2 Calculation and presentation ofstructural displacements

For presentation of displacements, the follow-ing should be submitted:

- graphical layout (plot) of deformedstructure and visual verification of physi-cal acceptability of model displacementin sufficient number of views,

- table of significant nodal displacementwith control of permissible displacementvalues (e.g. displacements of deck) withrespect to linear theory of small dis-placements. Control of displacements iscarried out in relation to the selected ref-erence items (boundary conditions,structural rigid parts, etc.)

D.4.3 Calculation and presentation ofstructural stresses

For presentation of stresses, the load levels in-cluded into calculation are to be clearly presented (primary,secondary, tertiary).

Components of the stress tensor are presentedin the local coordinate system of elements and are calculatedfor the following reference points:

- element centre of gravity,

- element boundary nodes,

- Gauss points for numerically integratedelements.

Where stresses are presented with unique col-our by element or contour lines for given stress level (socalled iso-lines), the type of the stress tensor component, ref-erence point and used type of presentation are to be stated(mean value or maximum on element).

Graphical layout of stresses for coarse and finemesh should include the following stress components byelement:

- mean normal stresses in both directions(σx, σy),

- mean shear stresses (τ),

- equivalent stresses (σVM, where is222 3τσσσσσ +−+= yxyxVM )

Presenting of principal stresses (σ1, σ2) by ele-ment in relation with local coordination system (stress tra-jectory), may be used as alternative method.

Graphical layout of the stress components is tobe presented in sufficient number of views, so that all rele-vant structural elements can be visible.

Structural parts with increased stress level areto be graphically presented in details by means of so calledcontour layout.


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Structural detail models with very fine meshare to be clearly indicated with any relevant stress compo-nents : principal stresses-σ1, σ2, …) in sufficient number ofviews.

D.5 CALCULATION OFSTRUCTURAL FEASIBILITY

ACCORDING TO CRS CRITERIA

D.5.1 Basic principles

D.5.1.1 Structural Elements Safety Criteria - Gen-eral

Library of safety criteria includes mathematicalformulation of different failure modes (serviceability andstructural collapse) in the form of design constraints. Theconstraints are forming the envelope in the design space withfeasible combinations of structural variables, which meet allrestrictions.

Feasibility is determined by the relation of:

- increased or extreme load (D=δ Dc),where δ is given load factor, whilst Dc ischaracteristic load or response obtainedfor that load,

- usable capability or capacity of structure(C = ε Cmax), where ε is given utility fac-tor, whilst Cmax is combination of loads orresponses (load effects) causing structurallimit state.

Loads D (demand) are set directly as forces ormoments to the considered structural components or as re-sponses/ stresses at the structural element. They are con-nected via equilibrium equation of acting force and resultingstresses so the criteria may defined as F < Fcrit or as σ < σcrit,taking account of F = σ A.

Plastic capability or capacity is Cmax= σY = ReHor Cmax= FY or Cmax= Mult , depending on selected material.

Calculation of capability C for different meth-ods of buckling (σcrit or Fcrit) is given in the Rules, 4.6.

Yielding criteria are given in D.5.2 for differentstructural parts. Buckling criteria are given in D.5.3

D.5.1.2 Determination of feasibility criteria

Criteria (constraints, limit states) are deter-mined in the following ways:

- through realised safety margin M = ε Cmax - δDc; (M > 0),

- through realised safety factor γ = ε Cmax / δ Dc= Cmax / (γHRB Dc ); (γ > 1),

where:

- Cmax is capability (capacity) for givenelement, whilst Dc is its load for consid-ered load case. In factor γHRB, the utilityfactor εHRB and load factor δHRB are im-plicitly included.

Factor γ shows size of additional safetybeyond prescribed factor γHRB. through

- realised adequacy factor (or adeqacyparameter [2, 4]) g = (γ-1)/(γ+ 1);(g>0)

D.5.1.3 Structural adequacy factor (normalisedsafety factor)

In direct calculation, feasibility is expressed inthe simplest way through adequacy factor, since thus theunique approach for all criteria is provided (plasticity, buck-ling).

Adequacy factor g may assume the value

-1 < g < 1.

Value g = 0 corresponds to the limit or failuresurface, separating feasible structures from unfeasible ones.

Realised safety factor is obtained from the fol-lowing formula:

γ = (1 +g) / (1 - g)

based on adequacy factor g given in output re-sults (e.g. CREST CRS [2]).

Direct relation of calculated capability andcharacteristic load of structural elements is obtained from thefollowing formula:

Cmax / Dc = γ γHRB = (1 +g) / (1 - g) γHRB

D.5.2 Library of feasibility criteria - yielding

Criteria of structural feasibility, related to per-missible stress levels (Yield), are stated in Table D.5.1.1.

The permissible stresses σdop are specified inTable D.5.2-1, in accordance with the Rules, subject to mate-rial coefficient k, see the Rules, 1.4.2 and Table 1.4.2.2.

Factor γHRB for yielding is calculated from theformula Cmax = ReH and from permissible stresses:

γHRB = ReH / σdop

where ReH = material yield point, whilst σdop ispermissible stress as per the Rules. Factor γHRB is specified inTable D.5.2-2.

Where feasibility calculation is performed byusing γHRB (e.g. by CREST CRS program) the minimumvalue of the permissible adequacy factor amounts:

gmin = 0.

Where feasibility calculation is performed forγHRB = 1, the minimum value of the permissible adequacyfactor is to be corrected for actual γHRB as per the followingformula:

gHRB =( γHRB -1) / ( γHRB +1)

Minimum adequacy factors gHRB are stated inTable D.5.2-2.


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Table D.5.2-1

2D/3D FEM models – coarse and fine mesh

Permissible stresses σdop

No. Structural element Rule Demand D11), D22), D33)

σVM4)

equivalentσ5)

normalτ6)

shear1. - General 4.3.2

4.4.2.3D1 175/k

110/k2. PLATING

- bottom- side

5.1.25.2.1.25.3.1.2

D1+D2+D3D2+D3D2+D3

230/k125/k130/k

3. DOUBLE BOTTOM- floors- long. girders

7.2.8.2/3 D1+D2+D3D2 (p)D2 (p)

230/k150/k150/k

100/k100/k


7.2.8.2.17.2.8.2.1

D2pop +0.3 (D2uzd+ D1)D1+D2uzd +0.3 D2pop

170/k190/k

5. FRAMING- frames, web frames

- longitudinals

8.1.2.1.48.2.4.28.2.3.1

D2+D3

D2+D3D1+D2+D3

180/k

230/k

150/k

150/k

100/k

100/k6. DECK

- general- cantilever beams- beams- top of coaming- flange of girder- top of coaming- flange of girder- coaming at deck level

9.1.29.4.2.19.4.2.19.5.2.3

D2+D3D2+D3D2+D3D1+D2+D3

D2D2

180/k

180/k230/k

150/k125/k150/k200/k

150/k70/k

100/k80/k80/k90/k

7. TANKS- stiffeners and girders 11.2.3.2 D2+D3, (static-test)

180/k200/k

150/k180/k

100/k120/k

GENERAL8. STIFFENED PANEL

- plating

- stiffeners

D1+D2+D3

D1+D2+D3D2+D3

230/k

230/k180/k

210/k

210/k150/k

110/k

100/k100/k

9. STRONG TRANSVERSEGIRDER

D1+D2+D3 180/k 170/k 100/k

10. STRONG LONGITUDI-NAL GIRDER

D1+D2+D3 230/k 190/k 100/k

2D/3D FEM models - very fine mesh

Direct notch stress Dmax (D1+D2+D3 ) 1.1 ReH

Notes:1) D1 = primary loads (demand) calculated as per D.1.3.12) D2 = secondary loads (demand) calculated as per D.1.3.23) D3 = tertiary loads (demand) calculated as per D.1.3.34) 222 3τσσσσσ +−+= yxyxVM

5) σ = normal stresses, including all stress components (bending + axial) in different directions subject to element type,6) τ = mean shear stresses by element.


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Table D.5.2-2

2D/3D FEM Models – Coarse and Fine MeshFactor γHRB and

min. adequacy factor (gHRB)for stress criteria

No.Structural element Rule Demand D1, D2, D3

Equivalentstress

Normal stress Shear stress

1. - General 4.3.24.4.2.3

D1 1.34 (0.145) 1.23 (0.103)

2. PLATING- bottom- side

5.1.25.2.1.25.3.1.2

D1+D2+D3D2+D3D2+D3

1.02 (0.010)1.88 (0.305)1.81 (0.288)


7.2.8.2/3 D1+D2+D3D2 (p)D2 (p)

1.02 (0.010)1.57 (0.222)1.57 (0.222)

1.35 (0.149)1.35 (0.149)


7.2.8.2.17.2.8.2.1

D2pop +0.3 (D2uzd+ D1)D1+D2uzd +0.3 D2pop

1.38 (0.160)1.23 (0.103)

5. FRAMING- frames, web frames

- longitudinals

8.1.2.1.48.2.4.28.2.3.1

D2+D3

D2+D3D1+D2+D3

1.31 (0.134)

1.02 (0.010)

1.57 (0.222)

1.57 (0.222)

1.35 (0.149)

1.35 (0.149)6. DECK

- general- cantilever beams- beams- top of coaming + flange of girder- top of coaming + flange of girder- coaming at deck level

9.1.29.4.2.19.4.2.19.5.2.3

D2+D3D2+D3D2+D3D1+D2+D3

D2D2

1.31 (0.134)

1.31 (0.134)1.02 (0.010)

1.57 (0.222)1.88 (0.306)1.57 (0.222)1.18 (0.083)

1.57 (0.222)3.36 (0.541)

1.35 (0.149)1.69 (0.257)1.69 (0.257)1.5 (0.200)

7. TANKS- stiffeners and girders 11.2.3.2

D2+D3D2+D3, (static-test)

1.31 (0.134)1.18 (0.083)

1.57 (0.222)1.31 (0.134)

1.35 (0.149) 1.13 (0.06)

GENERAL8. STIFFENED PANEL

- plating

- stiffeners

D1+D2+D3

D1+D2+D3D2+D3

1.02 (0.010)

1.02 (0.010)1.31 (0.134)

1.12 (0.057)

1.12 (0.057)1.57 (0.222)

1.23 (0.103)

1.35 (0.149)1.35 (0.149)


D1+D2+D3 1.31 (0.134) 1.38 (0.160) 1.35 (0.149)

10. STRONG LONGITUDI-NAL GIRDER

D1+D2+D3 1.02 (0.010) 1.23 (0.103) 1.35 (0.149)

2D/3D FEM models - very fine mesh11 Direct notch stress Dmax (D1+D2+D3 ) 0.91 (-0.047)

D.5.3 Library of feasibility criteria - buckling

Criteria for verification of feasibility at struc-tural buckling (Buckling) are specified in Table D.5.1.1, inaccordance with the Rules, 4.6.

The required safety factors are included intofeasibility criteria of CREST program, in accordance withthe Rules.

Global safety factor for buckling and adequacyfactor (gHRB) are specified in Table D.5.3.


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Table D.5.3

No. Structural element Rule Demand D1, D2, D3Safety factor and minimumadequacy factor for bucklingcriteria (gHRB)(valid for all models)

1. STIFFENED PANEL- plating (local buckling)- stiffeners

D1+D2+D3D1+D2+D3

1.0 (0.0)1.1 (0.048)


D1+D2+D3 1.1 (0.048)

3. STRONG LONGITUDINALGIRDER

D1+D2+D3 1.1 (0.048)

D.5.4 Presentation of the results of thefeasibility criteria verification (yieldingand buckling)

For presentation of feasibility criteria the fol-lowing is to be submitted:

- graphic layout of realised safety factor γ(adequacy factor g) for all elements inrelation to the given feasibility criteria inaccordance with the Rules, in sufficientnumber of views,

- identification (graphical and/or tabularlay out) of structural elements, load casesand feasibility criteria (yielding, buck-ling), where Rules requirements are notsatisfied,

- comment relating to those structural ele-ments for which the Rules requirementsare not met, with respect to feasibilitycriteria due to equivalent or simplifiedmodelling (especially for coarse meshmodels),

- detailed control of stress condition ofthose structural elements, for which theRules requirements for feasibility criteria(buckling or yielding) are not met,

- additional comments to the results

D.5.5 Modification of structural elements

All structural elements, which do not meet thefeasibility criteria, as per Section 5, should be modified bychanging their dimensions.

All changes should be clearly documented andsubmitted to the Register.

In case of performing new FEM calculation,the procedure for verification and presentation of results,should be repeated, in accordance with Sections 4 and 5, inthis case for the re-dimensioned structure.

D.6 REFERENCES

[1] CRS, Rules for the Classification of Ships, Part2 – Hull, 2013.

[2] CREST, Program Documentation and UserManual, Croatian Register of Shipping, Split, 2009.

[3] J. Uršić: Ship/s Strength 1, University ofZagreb, 1982.

[4] O.F.Hughes: Ship Structural Design, SNAME,1988 or later.

Documents

Rules for the classification of ships, Part 2, 2013 - crs.hr for the... · 11.7 construction and initial tests of watertight decks, ... annex d guidelines for direct calculations