Hellenic Register CHAPTER3

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HELLENIC REGISTER OF SHIPPING

Survey Procedures Manual

Chapter 3

Hull and Equipment

a. Existing Ships

April 1997



Hull and Equipment Chapter 3a

HELLENIC REGISTER OF SHIPPING[1]

Contents

SECTION 1 General

2 Safety precautions

3 Classification Surveys

4 Miscellaneus Surveys

5 Equipment









SECTION 1General

1.1 Advice of surveys and repairs

1.1.1 An Owner is normally advised about forthcoming surveys by means of a letter or a QuarterlyNotice, and his attention is drawn, by a Footnote, to the fact that non-compliance with classificationrequirements may jeopardize not only the Class of the Ship but also the validity of certain statutorycertificates and ultimately result in the withdrawal of such certificates by the National Administration or Certifying Authority.

1.1.2 The Surveyor should keep himself informed of ships arriving in his district in order to ensurethat satisfactory attention is given to all overdue and due surveys and/or conditions of class, and giveattention to surveys shortly becoming due. In this respect, full use of the records must be made andHull, Machinery and Statutory Surveys should be synchronized. Guidance should be given to the

Owner on requirements to be carried out with a view to preventing unnecessary expense andinconvenience.

1.1.3 The Surveyor is to keep Head Office advised of every arrangement made by the Owner or hisagent for submitting ships to Survey.

1.1.4 Before carrying out a survey, the Surveyor should be prepared so as to familiarize himself with the current survey position.

1.2 Recommendations following a survey

1.2.1 Temporary or postponed repairs

When temporary repairs or postponement of repairs until the arrival of the ship at home port or at aport more convenient for repairs, are requested, the Surveyor must satisfy himself that the ship is inan efficient condition for the contemplated voyage. In case of any doubt advice should be sought fromHead Office.

1.2.2 Repairs or structural conversions

It is important to attend classed ships before repairs or conversions are commenced in order to fullyunderstand the reason for the work. Any structural conversions are subject to the Surveyor's approvaland alterations. All conversions necessitating changes in the Register Book are to be reported

1.2.3 Additional strengthening

Where it is considered necessary to recommend additional strengthening to the hull structure becauseof suspected weakness, Head Office is to be advised or consulted so that the circumstances may befully investigated.

1.2.4 Advice of necessary repairs to the Owner

If it is considered that repairs are required the Owner or his agent should be advised immediately. If the Owner disagree with the Surveyor's recommendations he may ask for further attendance by aSenior or Principal Surveyor. In case of continued disagreement the Owner may appeal to HeadOffice, but should the original opinion of the Surveyor be upheld the Owner is responsible for all feesand costs in connection with the additional survey.





1.2.5 It is stressed that recommendations and observations should be made only to the Owner'srepresentative. This is especially important at dockings for change of ownership where the Surveyor

may be accompanied by both the Owner's and Buyer's representatives. The Surveyor should becareful during such surveys not to be unduly influenced by the Buyer's representative in hisrecommendations for repairs.

1.2.6 The following instructions must be followed in all cases:

(a) When in the opinion of the Surveyor, essential repairs are not being done, or are beingimproperly effected, the Owner is to be promptly advised. If this unsatisfactory situationcontinues Head Office should be advised urgently, and the Owner should be made aware thatthis has been done and that the Technical Council may take action in respect of class.

(b) In addition cabled advice is to be sent to Head Office if a ship leaves port without theSurveyor's recommendations having been carried out or without the ship being submitted to

any survey which the Committee had decided must be held for maintenance of class, beforecommencement of the voyage

1.2.7 The Surveyors should always have in mind the following requirements:

(a) All repairs necessary for the ship to retain her class are to be carried out to the satisfaction of the Society's Surveyors.

(b) Any damage, defect or breakdown, which could affect the ship's class is to be immediatelyreported to the Society.

(c) The ship shall be properly loaded and handled.

(d) The ship shall not be operated in environmental conditions more severe than those agreedwhen the ship was classed, unless with prior approval.

1.3 Partial surveys and repairs

1.3.1 Part survey held

When damage can only be partially surveyed due to cargo, fuel or ballast on board, the Surveyor mustinspect and report on the condition of the ship so far as examined and the extend of examination is tobe clearly indicated in the corresponding Survey Report. If any doubt exists as to the efficiency of inaccessible structure, removal of cargo, fuel or ballast, as necessary, must be recommended. TheSurveyor at the port where the survey is to be completed should be advised of any part survey heldand the recommendations made.

1.3.2 Part Special Surveys

When a Part Special Survey is held all parts accepted for the Special Survey should be shown on theProvisional Certificate, a copy of which is to be placed on board before the ship sails. In this waySurveyors at another port, where the Special Survey may be advanced or completed, will have up todate advice of parts already examined.





1.4 Reporting and certificates

1.4.1 Provisional Certificates

Provisional Certificates are to be issued whenever a survey is held and a copy is to be placed onboard for the information of Port Authorities and Surveyors at subsequent surveys. In specialcircumstances a hand-written copy will be acceptable. In the event that a ship sails before a copy canbe placed on board, the Owner or his agent should be asked to forward a copy to the ship and whenthe ship is proceeding to another port for further survey a copy should be sent to the Surveyorsconcerned.

1.4.2 The Surveyors are to specify distinctly in the Survey Reports the actual condition of those partof the ship surveyed. Vague statements such "good where seen" are not to be used; where items areonly part examined this is to be declared.

1.4.3 It is essential that all relevant information is included in the report of a defect or failure, either in the report itself or, if of a controversial nature, in a separate letter, and the Surveyor must ensure,by carefull checking, the accuracy of the details.

1.4.4 Defects and damages shown in the reports are recorded in Head Office and coded for subsequent analysis from the Research and Development Department of the Society.

1.4.5 Certificates of class

Except for Special Periodical Surveys of hull and machinery it is not usual to issue certificates of classification or letters confirming the classification position unless specially requested by the Owner or his representative. Requests for statements of this nature are to be referred to Head Office.

SECTION 2Safety precautions

2.1 General precautions

2.1.1 The Surveyor must pay due attention to his own personal safety as well as that of other persons on board.

2.1.2 Before commencing any survey, the Owner and all personnel involved in the survey mustensure that appropriate safety procedures are specified. Safety standards often vary from owner toowner and vessel to vessel. While many Owners maintain strict onboard safety procedures, survey

personnel must still be aware of what constitutes minimum acceptable standards for tanker inspectionto protect themselves from potentially hazardous working conditions.

2.1.3 In pump rooms where cargo vapours may occur due to leakages, pump rooms should beventilated at least 15 minutes before entering or before the pumps are started. As more cargo vapoursare heavier than air , lower explosive limits and /or toxic concentration measurements have also to betaken at floor level and below if inspections are necessary in this area.

2.1.4 Compartments normally not entered, as cofferdams, pipe tunnels, etc., which have usually nofixed ventilation system, should be ventilated by portable equipment. Especially double bottoms inchemical tankers or product carriers, where a risk of minor leakages from cargo tanks above alwaysexists, the double bottoms should always be opened at both manhole covers forward and aft and





thoroughly ventilated before entering. Then the contents of oxygen, petroleum vapours and/or possible toxic cargoes should be tested before making final access. The first person entering such a

compartment should use a breathing apparatus and a life line suitably attached for emergency rescue. A standby team should be trained for this purpose. A good practice prior to inspecting those doublebottom tanks is to fill them with seawater, keep them filled, and pump it out directly before entering.

2.1.5 For access to double bottom tanks, pipe tunnels, wing tanks, e.t.c. it is necessary that bothmanholes should be opened and prepared because it enables natural ventilation and easier means of escape.

2.2 Gas testing for tank entry

2.2.1 Entry of tanks for survey should not be permitted until testing indicates that the followingcriteria are met:

- Gas reading 1% Lower Explosive Limit (LEL) or less (by explosimeter).- Maximum Benzene (C6H6) 10 ppm (by Draeger Tube or equal).- Maximum Hydrogen Sulphide (H2S) 10 ppm (by Draeger Tube or equal).

(This figure is under review and likely to be lower).- Minimum Oxygen (O2) 21% by volume (Oxygen Analyser).- Maximum Hydrocarbons no greater than the Threshold Limit Value - Time Weighted Average

(TLV-TWA) for the actual mixture encountered (by Draeger Tube or equal).NOTE:The (TLV-TWA) for hydrocarbon varies depending on the cargo carried. For gasoline the TLVis 300 ppm corresponding to about 2% LEL. Therefore if the (TLV-TWA) is unknown, a valueof about 150 ppm should be used.

- Other limits specific to dangerous cargoes (chemical products), if applicable.

2.2.2 For vessels with inert gas systems, trace amounts of various toxic gases may increase thehazard of exposure for personnel. Normally, a steady 21% by volume of oxygen reading will besufficient to dilute these gases below their TLV's. However personnel should be aware of the followinglimits:

- Maximum Carbon Monoxide (CO) 50 ppm (by Draeger Tube or equal).- Maximum Nitrogen Dioxide (NO2) 3 ppm (by Draeger Tube or equal).- Maximum Nitric Oxide (NO) 25 ppm (by Draeger Tube or equal).- Maximum Sulphur Dioxide (SO2) 2 ppm (by Draeger Tube or equal).

2.2.3 If gas readings are greater than 1% LEL (Explosimeter), or if other limits are exceeded, thesurvey team should be instructed not to enter the tank or, if already in it, to stop working andimmediately vacate the tank. The Explosimeter used should be calibrated with a low level full scale

reading of 0 to 10% LEL. The team should arrange with the master to have the tank frequently testedfor gas at several locations, say every 2-3 hours. In addition, a member of the team should verify thereadings from time to time.

2.2.4 To aid the detection of any local pockets of gas, or lack of oxygen, team members should beencouraged to carry portable hydrocarbon and oxygen detectors with audible alarm features.

2.3 Tank preparation

2.3.1 Continuous forced ventilation should be supplied to the tank during the inspection. Anadequate number of deck fans should be used to supply this air. The fans should, where possible, beducted to supply fresh air to the tank bottom. The vent fans should be stopped during atmosphere





checks. The inert gas fans should not be used to provide fresh air ventilation because contaminantsfrom the inert gas lines could be introduced into the tanks. Inert gas branch lines should be blanked off

and the blanking flange interlocks checked at each tank if entry is required while inerting, or gasfreeing of other tanks is taking place, or if any other tanks are inerted or contain hydrocarbons. Analternative to pipe blanking would be to remove a section of the branch line.

2.3.2 All cargo pipelines leading to the tank should be checked for oil content and the valvessecured closed, immobilized and signposted. Any oil present in the lines should be removed.

2.3.3 All adjacent tanks should be in the same gas free condition as specified above or fullyballasted. Alternatively, and with the knowledge and approval of the owners and the agreement of thesurvey team, adjacent tanks may be fully inertred or partly ballasted /remainder inerted but with apressure reduced to a minimum. The survey team should be aware of the danger of potential leakageof inert gas through bulkhead fractures or faulty valves.

2.4 Safety watch and safety equipment

2.4.1 The survey team should not remain in a tank unless there is a safety watch by ship's staff withat least one individual stationed at the tank hatch throughout the inspection. The safety watch shouldhave the authority to order the evacuation of a tank and should be responsible for registering thesurvey team entering or leaving a tank. Communication should be maintained between the personnelin the tank and the safety watch. When underway, the safety watch should maintain communicationwith the bridge.

2.4.2 Rescue equipment including breathing apparatus, resuscitators, smoke masks, rescue lines, astrencher e.t.c. should be laid out at the tank hatch or, if more than one tank is being worked , at asuitable central location on deck.

2.5 Tank cleaning

2.5.1 Tanks and spaces to be surveyed must be sufficiently clean and free from water, scale dirtand oil residues to reveal excessive corrosion, significant deformation, fractures, damages and other structural deterioration. Tank cleaning can be performed with an existing Crude Oil Washing (COW)system.

2.5.2 Generally, tank surveys should be avoided in tanks in which de-sludging operations are takingplace since these operations can potentially raise gas levels.

2.6 Ballast transfer

2.6.1 The survey team should not enter or remain in any tank if ballast is being moved in or out of

that tank. Consideration should also be given to ballast movement in adjacent tanks.

2.7 Manoeuvring

2.7.1 The survey team should not enter or remain in any tank while the ship is manoeuvring incongested or confined waters.

2.8 Lighting

2.8.1 Whenever possible, natural lighting should be provided in the tank during surveys by openingall tank hatches. Suspended lighting should also be provided to supplement any natural lighting. Each





person should carry a torch of the high intensity beam type such as Wolf-lite or Halogen light. Torchesand lights should be of intrinsically safe design.

SECTION 3Classification Surveys

3.1 Annual and Indermediate Surveys

3.1.1 Part 1, Chapter 3,1 of the "Rules and Regulations for the Classification and Construction of Steel Ships" require Annual Classification Surveys to be held within three months before or after eachanniversary of the Special Survey and wherever practicable concurrently with the Statutory AnnualSurveys. The corresponding Survey Report should always be forwarded with a suitablerecommendation for fresh record of survey.

3.1.2 In the case of an incomplete survey the outstanding items are to be noted on the ProvisionalCertificate and the new date of the Annual Survey is to be recommended for assignment uponcompletion.

3.1.3 Where Annual Surveys are carried out concurrently with a Continuous Special Survey cycle itwill be necessary to complete those requirements of the Annual Survey which have not been coveredby the Continuous Survey.

3.1.4 Surveyor should check that the Passenger Safety Certificate or Cargo Ship Safety EquipmentCertificate is valid at the time of the classification surveys and the expiry dates of these certificates areto be recorded on the Survey Report. If the certificate is to expire shortly after the date of the surveythe Owner's intentions in this respect should be stated on the Survey Report. In the case of classed

ships where the certificates are issued by HRS on behalf of the National Administration and thecertificate has already expired at the time of the Classification Survey, the survey for renewal shouldbe held concurrently with the Classification Survey. In the case of classed ships where the certificatesare issued by a National Administration or on its behalf by any organization other than HRS, theSurveyors should satisfy themselves as to the condition of the main and emergency fire equipment.

3.1.5 In the case of any classed ship:

- being exempted from the requirements of Regulation 3 of Chapter 1- SOLAS 1960 or 1974,where the National authority does not conduct surveys, and

- ships registered in Non-Convention countries,

Surveyors are to satisfy themselves that a survey of the fire equipment has been carried out very

recently (i.e. within one month). If satisfactory evidence of survey is not available, information shouldbe obtained from Head Office as to wheater a survey of the fire equipment is due, and if so informed,procedure should be as follows:

- The equipment found on board is to be compared with the requirements of the Society's Rulesin force at the time the ship was built and the Surveyors are to be satisfied that thearrangements comply with the appropriate Rules.

- The Surveyor is to be satisfied that the equipment is in good condition and accordinglyrecords it on the Survey Report.





- An Interim Certificate should be placed on board the ship and a copy should be sent to theHead Office, attached to the Survey Report.

Ships in these categories should in general be non-passenger ships.

3.1.6 Steel hatch covers

(a) The Regulations for Annual Classification Surveys require the Surveyor to satisfy himself as tothe efficient condition of the means of ensuring weather tightness of steel hatch covers. Duecare is required to the examination of the condition of the sealing gasket, particularly at cross joints.

(b) When examining hatch covers the Surveyor is to pay particular attention to possibledeterioration in the thickness of the top, side and end plating of each section of the covers. Inconjunction with the examination of the end plates, attention should also be given to the cross

joint gasket. A chalk test should be carried out if considered necessary. On completion of theexaminations the covers are to be hose tested in according with Pt. 3, Chapt. 1, 4.4 of theRules.

(c) In cases of ships whose hatch covers are not required to have gaskets hose testing is notrequired.

(d) Care should be taken, especially when examining cross joints of steel hatch covers, to ensurethat the covers are stable and restrained from movement.

(e) In cases where a ship's commitments are such that all the required repairs to steel hatchcovers can not be completed before sailing, the Surveyor should remember that the efficiencyof the closing appliances is a requirement of the Load Line Convention 1966 as well as a

class item.

(f) Provided that the strength of the covers is not in question, the weather tightness of the hatchcovers can be ensured by fitting two tarpaulins of adequate strength and size to cover each of the affected hatches, after the closing and fastening of the steel covers. When thisarrangements adopted on ships with B-60 freeboards, the draught may need to be decreased.It is stressed that the above arrangement is acceptable only as a last resort and is valid onlyfor a single voyage.

3.1.7 Intermediate Surveys

For Intermediate Surveys reference is made to the Rules, Part 1, Chapt. 3, Sec. 2.2.

3.2 Docking Surveys

3.2.1 Requirements for Docking Surveys are given in Part 1, Chapt. 2, 7.4 of the Rules. Specialattention should be given to ships on coastal service which are particularly liable to bottom shelldamage.

3.2.2 The underwater bottom should be carefully examined for hogging, sagging, groundingdamage, or distortion possibly indicative for structural weakness. One old way to sight for deformationis to bend over and look through the legs upside down at the bottom. Any hills or valleys seem tostand out better from this viewpoint. Optical keel sights or checking with a tight string may be called for and to this purpose the Surveyor should carry two small magnets and a length of string. The bottomand sideshell plating in the midship area, should be closely examined for the possible presence of





transverse deformation between frames. It is important to look carefully for signs of deformationpossibly attributable to structural weakness as differentiated from grounding or striking indents.

3.2.3 Unfair or set-in plating is common forward. A fair degree of deformation, say up to 75mm, of the underwater bottom plating forward ordinarily may be accepted without resulting in seriousimpairment of structural strength provided the internal framing in way is not significantly "tripped" or rendered ineffective. However for transversely framed ships, severe or sharp transverse buckling of bottom plating within the amidships half-length, can significantly affect longitudinal strength of the hullgirder. As might be expected, the greater the athwartship extent of such buckling, the greater theimpairment of hull strength. Any appreciable buckle of sufficient athwartship extent so as to cross thekeel strake and centre vertical keel, or say two strakes including an inner bottom girder is serious.Such a buckle should be corrected by replacement of plating and the buckled portion of affectedgirders. If there is no evidence to indicate the buckle was caused by grounding or other excessiveconcentrating loading, or that is associated with excessive wastage, it may be an indication of need for providing additional internal reinforcement, i.e. a design deficiency. In such instances the Principal

Surveyor should be advised of the circumstances and Head Office contacted for suitable correctivemeasures. Buckles of shorter athwartship extent may also require correction, depending upon their depth and sharpness, the number of buckles and their respective locations. Obviously, several bottombuckles within the same frame space transversely are more serious than the same number of bucklesdistributed randomly. These are indicative of advanced localised stress, which experience indicatesmay lead to cracking. In such cases, plating replacement may be called for even though thedeterioration may be less than the allowable wastage. In such cases it may be feasible to replace lessthan full length plates.

3.2.4 Stern frame

The stern frame should be closely examined for fractures particularly at the forward end of the skegconnection to plating. Local eroded and corroded areas are often found in the rudder or horn just aft

of the propeller blade tips. If not too severe they may be scaled and filled with epoxy. If the conditionappears to be progressing rapidly, waster plates should be fitted over the affected area. The top of thestern frame should also be examined for leakage in way of the core hole closing plates and for anysuspicious bulges at the top. Water entering the hollow part of the stern frame, either from the aftpeak or through a leaking closing plate, may freeze in cold weather causing the frame to fracture. If water is present it should be drained out and the void space pressure-filled with an inert non-freezingfiller.

3.2.5 Rudder

(a) Clearances

Rudder pintle bearing clearances are to be taken by the Surveyor at each drydocking. The bearing

clearances are maximum clearances measured on the diameter. The feeler gauge to be used shouldbe of ample length to ensure justified wear measures and not only "edge wear". Measurements shouldbe taken port-starboard and for-aft. The greatest total clearance value measured on the diameter should be used for evaluation in Fig. 3.3.(1) and 3.3.2.

(b) Survey guidance

The rudder and rudder stock should be visually checked for fractures so far as accessible, tightness of the palm boats (or the covering cement intact), condition of external rudder stops, presence of rudder lift prevention arrangements, weardown of the carrier bearing, condition of securing arrangement andclearance of the gudgeons and pintles. A number of rudders have been lost due to pintle nuts backingoff allowing the pintle to come out. Pintles install with the nut and tapper upwards are especially





susceptible to this problem. Sometimes the pintle simply unscrews out of the nut leaving the nut inplace, because the stopper arrangement did not include both nut-to-pintle and nut-to-casting welding.

Such welding on large vessels incidentally, needs to be relatively heavy to survive the vibration andcorrosion until the next drydocking.

If no external damages are revealed the rudder need not be lifted. For vessels having their rudder lifted the following should be taken into account.

- Synthetic materials are not to replace bronze or stainless steel unless a check of the bearingpressure has been carried out.

- When mounting the pintles, care should be taken to ensure that sealings are fitted inaccordance with approved document.

- Securing of the nut to the pintle housing will not prevent unscrewing of the pintle. A flat bar

bent over the end of the pintle and strongly welded to nut and pintle is recommended.

- Securing with split pin should only be accepted if the pin penetrates both pintle and nut. Cover plate bolted or tack welded under a bearing is not to be considered as part of any securingarrangement.

3.2.6 Propeller and tailshaft

The propeller should be removed from the shaft in order to examine the tailshaft taper, if there is anyevidence of looseness or water leaking from the forward or after and of the hub assembly or damageto the oil seals. Sea water contact greatly reduces the fatigue limit of a tailshaft. Stern tube bearingwear down should be measured and the stern tube bearing rebushed or replaced if the clearance is inexcess of the Rule or manufacturer's allowance. For the recommended maximum and minimum

clearances for propeller shafts see Part 1, Chap. 3, Sec. 17.4 of HRS Rules. Any damage to thepropeller sealing arrangement, stern tube bushing or securing arrangement for same, should beimmediately repaired. Minor deformation of propeller blade tips is best left alone, but small cracksshould be stopper-hole drilled to prevent their progression. A propeller cannot be properly repair-welded in place as repairs involving heat will necessitate its removal from the shaft





0 200 400 600 800 1,000Diameter, mm

1

2

3

4

5

6

C l e a r a n c e , m m

A

B

C

A : Renewal necessaryB : Renewal recommended

C : New / repaired

Lign. Vitae, Synth. Fibre, etc.

Fig. 3.3.(1)

0 200 400 600 800 1,000

Diameter, mm

0

2

4

6

C l e a r a n c e , m m

A

B

C

A : Renewal necessaryB : Renewal recommendedC : New / repaired

Stainless Steel, Bronze, etc

Fig. 3.3.(2)





3.2.7 Overboard discharge pipes, their shell reinforcement rings and external shell plating beneaththe outless should be checked for excessive corrosion. Sea chests should be examined for fractures

particularly in way of corners, for aerated water corrosion, and the condition of the stainers and their securing devices.

3.2.8 Special attention is required during the examination of bilge keels and their attachment to thehull for fractures or corrosion grooving of the shell plating in way of any discontinuities.

3.2.9 If cargo spaces are cleared, the Surveyor should make some internal inspections in order tosatisfy himself regarding their general condition. It should be borne in mind that it is necessary to hosetest steel hatch covers in container ships at Docking Surveys.

3.2.10 When a ship is placed in dry dock for sale and the Surveyor is requested to attend, great caremust be taken to avoid discussing any aspect of the ship's condition with the Buyer's representative.It must be remembered that, usually, if repairs to underwater parts are found at this docking, they will

be to the Owner's account and entail the Owner paying for the drydocking.

3.2.11 Examination of large pontoons

(a) In view of the difficulties experienced in obtaining drydocking facilities for pontoons over 30min breadth, it has been agreed by the Classification Committee that such pontoons, up to theage of 15 years, may need to dry dock only once in five years, the Docking Survey coincidingwith the Special Survey.

(b) In addition, during the period between 2 years and 3 years after the last Special Survey a fullinternal examination of the bottom plating and structure is to be carried out afloat.

3.3 In-water surveys

3.3.1 The requirements of this type of survey are set out in Part 1, Chapt. 3, 2.4 of the Rules.However the requirements should not be taken to indicate that ships without approved means of identification are automatically precluded from carrying out In-water surveys. If enquiries are receivedfrom the Owner, advice should be sought from Head Office.

3.3.2 At each In-water Survey, the rudder pintle upper stock bearing and tailshaft clearances are tobe measured, unless the design precludes that.

3.4 Special Surveys

3.4.1 Requirements for Special Surveys are given in Part 1, Chapt. 3 of the Rules.

3.4.2 The purpose of the Special Survey, which includes the requirements of Annual andDrydocking Survey, is to examine all parts in which the Society has an interest, and then torecommend the necessary work to enable the vessel to operate for another four to five years inapparent good order.

3.4.3 All surveys are to be carried out by Exclusive Surveyors unless alternative arrangements areagreed with Head Office.

3.4.4 The Special Survey is the one time that a vessel's hull has the opportunity of being cleanedand painted and the Surveyor should encourage this being done, if for no other reason than to enableproper examination of the structure. The condition of bilge wells or tank top margins is difficult toascertain if covered with rust, water oil or dirt. In addition , oil and debris in the bilges is a fire hazard





that must be eliminated during the Special Survey. If the Owners of the vessel have not had the vesselcleaned for Special Survey it is most probable that it has not been cleaned or recoated during the past

four years and is apt to be in poor condition.

3.4.5 The Special Survey is the proper time to overhaul all the closing appliances on the decks andin the vessel's sides. These items are generally examined every year but gradually deterioratebetween Special Surveys. Their failure in an emergency can have dire consequences. Leaking or holed scupper valves in way of cargo holds may cause serious cargo damage.

3.5 Postponement of Special Surveys

3.5.1 All requests received from Owners for postponement of Special Surveys are to be submittedin the first instance to Head Office for consideration.

3.5.2 Decisions regarding the postponement of a Special Survey or of the completion thereof can

only be made by the Technical Council, after the consideration of the circumstances and of thetechnical recommendations. Surveyors are not permitted to agree such postponements with theOwner without having obtained approval from Head Office.

3.5.3 In every case, irrespective of the urgency of the matter, the request for postponement must bereferred to the Head Office.

3.5.4 Normally, a general examination of sufficient extent of the vessel's hull is to be required inorder to be assured that the ship's condition is satisfactory for the period of grace desired. It isstressed, however, that this general examination is not to be commenced until definite instructionsfrom Head Office have been required.

3.5.5 At the aforementioned general examination the Surveyor should satisfy himself that the

condition of the ship is such as to warrant his recommendation that the Special Survey be postponedfor a specific period not exceeding 12 months beyond the due date. The extent of the generalexamination will depend largely on the history of the ship and known defects.

3.5.6 In certain circumstances it may not be justifiable for the Surveyor to recommend the full periodof postponement without extensive repairs being carried out. In such cases he should reportimmediately to Head Office the maximum period for which he considers the ship's condition to besuitable in relation to the repairs effected.

3.5.7 For postponement of the first Special Survey the requirements of an Annual ClassificationSurvey are to be complied with. This is applicable to all ships.

3.5.8 In bulk carriers and OBOs over five years old, ballast tanks forward, amidships and aft are to

be examined with particular attention being given to topside tanks.

3.5.9 In tankers over five years old, selected cargo tanks should be examined to enable theSurveyor to satisfy himself as to the general condition of the internal structure of the tanks. Theexamination should include, at least, one cargo tank forward, amidships and aft, together with all thepermanent water ballast tanks.

3.5.10 For postponement of subsequent Special Survey on ships under 15 years old, the inspectionshould include, in addition to the Annual Survey, as complete an internal and external examination aspracticable of selected holds and bilges, weather decks and 'twin decks, bunkers, structure belowboilers, peak tanks and spaces, machinery spaces and casings. The main and auxiliary steering gear and their connections and the windlass should also be examined.





3.5.11 For postponement of Special Survey on ships over 15 years old, in addition to the above thefollowing items are to be generally examined:

(a) Holds and bilges.

(b) A few frame spaces of the ballast double bottom tanks immediately forward of and abaft themachinery space. If, in the opinion of the Surveyor the above examination make it necessary,additional double bottom tanks should be similarly examined.

(c) Pipe casings removed, if considered necessary by the Surveyor.

(d) The Surveyor should satisfy himself regarding shell and deck scantlings by gauging if considered necessary.

3.5.12 For postponement of Special Survey for ships over 20 years old or over, in addition to the

above, the following should be taken into account:

(a) A very thorough general examination should be made of the hull and this should include aninternal examination of all water ballast deep tanks. Special attention should also be given tothe possibility of grooving of the shell in way of the frame connections and wastage of bilgeshell plating and structure in way.

(b) Anchor and cables are to be ranged and gauged.

3.6 Areas for special examination

3.6.1 Although it is not possible to define a standard pattern of probable defects for the varioustypes of ships, there are some structural elements of the hull that require special attention should be

given from the Surveyors to the following areas:

3.6.2 Tankers

(a) The upper part of the topside structure, including plating, longitudinals, transverses and their associated connections. The Surveyor should bear in mind that the ability of the deck to resistcompression strongly depends upon the efficiency of the longitudinals. Waviness of the deckplating is a sign of probable deterioration of the deck longitudinals.

(b) The bottom plating at the ends of longitudinals should be closely examined for signs of incipient fractures.

(c) Where longitudinal framing is continuous through transverse bulkheads forming tank

boundaries, a careful examination is required of the welded connections of the longitudinalsin order to ascertain their freedom from fractures.

(d) The following items should also be given special attention for evidence of cracking, buckling or excessive corrosion:

(i) Connections of longitudinals to bulkheads.(ii) Connection of bottom and side longitudinals to webs.(iii) The junctions of the brackets from the longitudinal bulkheads.(iv) The continuity of deck and bottom longitudinals in way of oil-tight transverse

bulkheads.(v) Cross tie junctions.(vi) The bottom shell plating in way of transverse oil-tight bulkheads.





(e) It should be noted that on tankers corrosion is of two types, general overall corrosion and

pitting which is usually localized. Tank wastage depends on several factors, one of the mostimportant being the use of particular tanks for salt water ballast. If the ship has been carryingcrude oil, the corrosion most often takes the form of deep pitting on the bottom plating,particularly at the aft end of the tanks, under suction bellmouths, in way of drainage slots anddirectly below the Butterworth openings. If gasoline or other light products have been carried,the top members of the tank are mostly corroded.

3.6.3 Bulk carriers

(a) It is stressed that cargo hold frames should be closely examined by the Surveyor in order toestablish the degree of their corrosion. For this purpose, access facilities to allow to reach atleast to the lower part of the hold frames should be provided. It should be noted that thedeficiency of the cargo hold frames due to corrosion has been the cause of many structural

failures during recent years. It should be referred that studies have shown that the corrosion of hold frames is heavier in ships engaged in the carriage of coal but more often casualtieshappened when vessels were carrying ore in bulk, because this corresponds to a severeloading condition.

(b) The weldments of the cargo hold frames to the side shell is to be examined for evidence of fractures.

(c) The side-shell plating is to be examined for incipient cracks. It is reminded that the deficiencyof the cargo hold frames may lead to the creation of cracks on the side shell, which propagate,both, in the horizontal and vertical direction, and finally to the drop off of large side shellpanels.

(d) Deck longitudinals with their associated brackets and connections, through transverses andend connections at bulkheads.

(e) The topside tank connections at the engine room bulkhead.

(f) The topside tank connections at transverses and bulkheads.

(g) The topside tank bottom shelf plate connection to side shell.

(h) The hopper tank top shelf plate connection to side shell.

(i) Cross tie junctions.

3.6.4 OBOs and ore/oil carriers

The recommended examination areas for tankers and bulk carriers also apply to these ships sincethe basic structural arrangements are similar.

3.6.5 All ships

(a) Where a fracture has been found in main hull structure on one side of the ship and the causeis other than contact damage, an examination of the corresponding structure on the oppositeside of the ship should be made to ensure that a similar failure has not taken place. Thisprecaution is especially important in cases where corrosion is associated with the failure. In allsuch cases of failure the Surveyor should make particular reference in his report to the





examination of the structure on the opposite side of the ship and whether or not a similar defect was found.

(b) Special attention should be given to water ballast tanks, because in these tanks it is expectedincreased degree of corrosion.

(c) During the examination of tanks or bilges the Surveyor should see that a doubling plate or equivalent is fitted under all sounding pipes.

(d) The chain lockers should be cleaned of all mud and debris, including the section in way of thebilge suctions and then recoated.

(e) When examining refrigerated cargo compartments, holes should be drilled to ascertain thecondition of the insulation and also the condition of the steel deck or bulkhead behind it. Onehole should be drilled near the top of the compartment to see that the insulation is not

"packing down" and another should be drilled just above the deck to make sure that theinsulation has not become wet, or the steel excessively corroded.

3.7 Thickness determination

3.7.1 The structural elements of the hull to be measured according to the type of survey and thetype of vessel are specified in Part 1, Chapter 3 of the Rules. Where special reasons exist, theSurveyor may demand additional thickness measurements.

3.7.2 All thickness measurements are to be made immediately at the start of the Survey concerned.The results of scheduled thickness measurements, i.e. those specified in the Rules, are to becommunicated at once to Head Office in order that they may be assessed and any appropriatemeasures taken before the completion of the survey.

3.7.3 Parallel with the consideration by Head Office, the Surveyor for his part shall assess themeasurements by reference to the drawings available on board and shall at once require anyobviously necessary replacements. In case of components with a reduced original thicknesscombined with effective corrosion protection, the assessment is to be based on the unreducedregulation thickness.

3.7.4 If the assessment by Head Office does not arrive in good time prior to the departure of theship, the Surveyor is to include in the Survey Report a reservation with regard to the examination andapproval of the thickness measurements by Head Office, e.g. "Thickness measurements are subjectto approval by Head Office".

3.7.5 In general, thickness measurements are made with an ultrasonic wall thickness gauge.

3.7.6 The measurements shall only be performed by suitably trained and competent personnel.

3.7.7 A gauging plan is to be prepared. The plan is to give the position of each measuring point, thethickness measured as well as corresponding original thickness. Furthermore, the plan is to give thedate when the measurements were carried out, type of measuring equipment names of personnel andtheir qualifications. It is advisable to enter the results obtained by the measurements into part prints of the respective drawings. In selecting positions for gauging, a careful overall assessment is to be madeutilizing shell expansion and deck plans in order to avoid local reinforcements, doublers, or any other obstruction, both on the deck and at the shell. If individual plates show excessive deteriorationadditional gaugings should be made forward and aft to ascertain the extent of such deterioration.3.7.8 The Surveyor shall make random measurements to verify the results. Attention is to be paid tothe satisfactory operation and settings of the gauge, the proper preparation of the measuring points





and the satisfactory coupling of probe and material. If the verifying measurements deviatesubstantially from the initial results, the scope of the verification may be extended until it equals that of

the initial measurement schedule.

3.7.9 Where the measurement of plating produces individual results which lie below the minimumthickness, further measurements are to be carried out in the area surrounding these points and are tobe continued in a similar manner until such time as satisfactory values are registered which enable theextent of the necessary replacement to be determined.

3.7.10 Renewals

(a) The design of ships varies so much that only a broad generalization is possible. However, thepercentage diminutions with respect to the corresponding Rule thickness given in Table3.3.(1) should not be exceeded. Assessments of the percentage deterioration of the topsides(deck plating, stringer and sheer strake) and bottom (keel, bottom and bilge strakes) are to be

made by summing the thickness of individual strakes of plating and comparing these with thesums of the Rule thickness. If the deterioration in way of belts of topside or bottom plates or associated longitudinals is then found still to be in excess of the values given for items 2 or 3of the Table, renewals extending over the midship half length of the appropriate number of strakes and longitudinals should be made. Where conditions warrant it , doublings of therequisite area extending over the midship half length may be fitted as a substitute for renewalof the plating.

(b) The estimated thickness of a plate or panel is normally based on the average of threegaugings, or five gaugings for heavilly corroded areas, these gaugings will normally be takenas indicated in Fig. 3.3.3, but not at the bottom of pittings.

(c) Particular attention is drawn to the need to maintain the buckling resistance of longitudinals,

especially at the deck of a tanker, which is normally in compression when the ship is loaded.Longitudinals must be renewed if there is any evidence of buckling or if the diminution hasreached the values given in Table 3.3.(1). Deck doublings can not be accepted as a substitutefor the renewal of deck longitudinals.

(d) In addition, when the diminution is found to be in excess of the values given in Table 3.3.(1) atany station within the half length amidships the longitudinals in way will require to be gaugedand reported upon.





Figure 3.3.3: Estimation of the average thickness of a plate

3.7.11 Irrespective of the preliminary transmission of the results of the measurements in accordancewith 3.7.2 records/sketches of thickness measurements are to be prepared as annexes to the relevantSurvey Report and are to be forwarded to Head Office together with the report.

3.7.12 A greater diminution may be permitted over 0.5 L amidships provided the hull girder sectionmodulus, using the actual gauged thicknesses, is not less than 90 % of the Rule section modulus asnew ship.

L

12

34

5 W

0.1L

0.1W





Table 3.3.(1): Maximum allowable diminution with respect to the corresponding Rulethickness

L ≥ 100 m L < 100 m

Structural Item0.5 L

amidships0.075 L

from ends0.5 L

amidships

0.075 Lfromends

1. Individual Plates

Deck plating, shell plating, tank top plating, plating of longitudinal bulkheads and corrugated watertight

transverse bulkheads, topside tank sloping plating, tank topplating, inner hull plating, web plating of girders and

transverses within the cargo region, hold shell frames and

bracket connection in dry bulk cargo ships.

Remaining structure including oiltight and deep tankbulkheads and plane watertight bulkheads and stiffeners

and longitudinals

20%

25%

20%

25%

30%

25%

30%

25%

2. Topsides

(deck, outside line of openings for dry cargo

ships, stringer and sheer strake,

Plating 15% 20% 20% 30%

including roundedgunwales, together withassociated longitudinals) Longitudinal

s20% 25% 25% 30%

Single bottom 15% 20% 15% 30%

3. Bottom

(keel, bottom and bilgeplating together with

associated longitudinals)

Plating

Double

bottom

20% 25% 25% 30%

Longitudinals 20% 25% 25% 30%





3.8 Corrosion control

3.8.1 When scantlings have been reduced on account of an approved system of corrosion control,the notation (cc) will be made in the Register Book.

3.8.2 At the inspection of anodes at Special Surveys, Surveyors must ensure that the system of cathodic control is providing satisfactory protection (see 3.8.5 and 3.8.6).

3.8.3 Where protection is provided by an approval coating of paint, the surface should be examinedat Special Surveys and bare or thin regions recoated to avoid severe local corrosion. General remarkson the condition in each tank should be included in the Special Survey report.

3.8.4 Where a breakdown in the paint is found to have occurred and the Owner is unwilling to cleanand recoat as necessary, an appropriate recommendation should be made in the Report to the effect

that the (cc) notation should be amended to read ((cc)) indicating that the corrosion control system

has not been maintained.

3.8.5 All thickness determination surveys on ships having a ((cc)) notation, or where this notation isto be recommended, the Surveyor should compare his gaugings with the original Rule thicknessesand not the reduced scantlings which were approved in association with a (cc) notation. If theseoriginal thicknesses are not available, they should be requested from Head Office.

3.8.6 Renewals of anodes

When renewals of anodes or coatings are made, the tanks protected and the particulars of the anodesor coatings with the name of the manufacturers should be reported. This is applicable whether or not a(cc) notation has been assigned.

3.8.7 Support and location of anodes

(a) The Surveyor should examine the anodes and supports at Special Surveys, particularly anyfitted under the deck head.

(b) Anodes are to be attached to the structure so that they remain secure during service.

(c) The owner will generally renew the anodes before they are totally consumed, because thedegree of protection afforded by an anode is reduced approximately in proportion to theamount remaining.

(d) When anodes are renewed the replacements are to be of an approved type.

(e) Special attention is to be paid to the attachment of anodes to higher tensile steel structure, toavoid damage to the edges of longitudinals and face bars. The anode connections are to becontinuously welded using suitable electrodes.

3.9 Continuous Special Surveys

3.9.1 Where Continuous Special Surveys are approved the following conditions are to be compliedwith:

(a) The first cycle of Continuous Survey should commence after the previous Special Survey hasbeen completed.





(b) Examination and testing of hull items should be so arranged that twenty per cent of thecomplete Special Survey is to be carried out each year. Each item is to be examined at

intervals of not more than five years. A general arrangement or capacity plan of the shipincluding a plan view of all tanks is to be approved prior to the commencement of the survey.It should show the Owner's proposed arrangements of carrying out the Survey over five yearsand a record of this procedure will be retained in Head Office to enable the necessary recordsof surveys to be kept.

(c) An identical plan is to be kept on board for use at the ship all times and is to be ensured thatthe nomenclature used in reporting spaces examined and/or tested is the same on board asthat originally approved. Head Office is to be notified of any proposed alterations at an earlydate.

(d) If the survey is completed before the due date, the actual date of completion will berecommended for assignment of the Continuous Survey notations. If it is completed later than

the due date, then the due date will be recommended.

SECTION 4Miscellaneous Surveys

4.1 Transfer of class

4.1.1 The transfer of ship from one Classification Society to another is usually a matter of urgencyand it is required to be carried out without disruption of the ship's commitments. The Owner is advisedof the Society's requirements for the transfer and the Surveyors are provided with guidance notes.

4.1.2 In the case of a transfer to HRS Class, the Society has to be satisfied that the ship and itsmachinery comply with HRS Rules for Ships. Hull and machinery plans are required to be submittedfor approval, together with documentary evidence that the materials used are equivalent to thoserequired by the Society.

4.1.3 The current survey position is scrutinized and, if the transfer is from a recognizedClassification Society, the survey requirements for transfer of class may be modified.

4.1.4 The Owner should be advised to retain the existing class until the Society is in position toissue the certificates necessary for the ship to continue trading.

4.1.5 During Transfer of Class Surveys, the Surveyor should ensure that no controversialstatements, which may reflect upon the previous Society, are made.

4.2 Damage Surveys

4.2.1 A damage survey should if possible be made jointly with the Owner's Representative,Underwriter's Surveyor, Repairer and the Classification Surveyor. A representation of the flag Administration may also be present. Normally the procedure is as follows:

(i) They all examine the damage and the Class Surveyor makes his recommendations as to theextend of repairs that will be required to retain Classification.

(ii) The administration inspector may be satisfied with this or add on items, as will the Owner if hethinks he is entitled to more under his insurance cover.





(iii) The Surveyor representing Underwriters then may advise the Owner as to which items hefeels are or are not attributable to the alleged cause and which repairs are considered

reasonable and necessary to place the vessel back into equivalent condition as before thedamage incident.

(iv) The Owner then reviews these positions and places the work order with the Repairer as hedeems necessary.

4.2.2 The Surveyor must be aware that he should be extremely careful not to makerecommendations for repairs that are not the concern of Classification. The Surveyor should make hisrecommendations only to the Owner's Representative and never directly to the Repairer.

4.2.3 If a vessel has suffered damage such as from heavy weather, grounding or collision, and putsinto a port of refuge to make temporary repairs before continuing on her voyage, it is of the utmostimportance that the Surveyor develop as complete information as possible on the extend of thedamage before fixing his opinion on the fitness of the vessel to proceed. This may require a Diver's

inspection or removal of part of the cargo and should in all cases, call for sounding of the tanks or cargo holds and an examination of past soundings in the log. Normally a Surveyor should not endorsethe fitness of a vessel suspected of grounding damage, particularly where bad whether may beexpected, without a thorough survey of the structure for cracks and a Diver examination of the bottom.

4.2.4 The damage survey report ending must state clearly what repairs were carried out, whatremains to be carried out, and any limitations or outstanding recommendations. When the final surveyand repairs are carried out, the Surveyor must note clearly that the previous outstandingrecommendation has now been complied with.

SECTION 5

Equipment

5.1 Anchors and chain cables

5.1.1 Anchors and chain cables are to be in a generally good condition without large visiblecorroded areas or marked reduction of dimensions.

5.1.2 Anchors and chain cables are to be lowered in drydock sufficiently to permit survey of theanchors, especially including anchor shackles, the outboard shots and the connecting shacklesbetween anchor and outboard shot as well as the outboard shot and first length.

5.1.3 At Special Survey No 2 the chain cables are to be ranged so that they can be examinedthroughout their length. The anchors are to be cleaned and placed in an accessible position for

inspection.

5.1.4. At Special Survey No 3 and also subsequent Special Surveys the cross sectional area of theanchor chain cables is to be determined by measuring approximately three typical links per length of 27.5 m at the ends of the length in way of the maximum wear.

5.1.5 If the measurements show that the section has been reduced beyond the permitted limit, theSurveyor should specify that the lengths concerned are to be replaced and should notify the Owner'srepresentative accordingly. If the replacement length can not be procured at once, the Surveyor maysanction a postponement compatible with the circumstances. A corresponding recommendation shallthen be included in the Report.5.1.6 The weight of the anchors should be checked. In practice an external inspection will oftensuffice to show with sufficient certainty that the reduction in weight has not been substantial. In cases





of heavy corrosion or wear, or where there are other grounds for doubt, e.g. the suspicion that aninadequate replacement anchor has been fitted, the actual weight is to be ascertained by weighting.

5.1.7 Permissible reduction of cross sectional area of anchor chain cables is 20 percent.

5.2 Wire ropes

5.2.1 Inspection should be carried out on the full length of the wire rope as fully as possible. Duringinspection the following are to be established:

(a) Reduction of nominal rope diameter due to loss of core support, internal or external corrosionor wear of outside wires.

(b) Number of broken outside wires, the degree of distribution over a lengths of 15, alternatively30 wire diameters.

(c) Condition of end connections; corrosion, pittings, deformed or improperly fitted end.

(d) Severe kinking, crushing or distortion of rope structure.

(e) Evidence of damage by heat or chemicals.

5.2.2 Wire ropes must be discarded and replaced in the following cases:

(a) If damages such as wire extrusions, kinks, core protrusions, bends, flattened portions,increase or decrease in diameter etc. are noticed.

(b) If the diameter of the rope is reduced by 10 percent due to wear or corrosion.

(c) If a strand is broken.

5.2.3 Particular attention is to be given to the ISO Standard 4309 - 1990 (ELOT -891)

5.3 Cargo gear or crane surveys

5.3.1 Cargo Gear or Crane Surveys are not a requirement of Classification, they are Owner’soption, however if the Register is to be maintained, the cargo gear or cranes must be examined asthoroughly as with a Class survey. A less-than-thorough survey is not favor to anyone (although theOwner’s Representative may think otherwise at the time) and a possibly serious problem to allconcerned when the end result is injury to personnel or delay of the vessel due to restrictions by portor stevedore safety officials.

a) Always confirm that the vessel actually has a Cargo Gear or Crane Register prior to survey. Also,do not carry out an Annual Survey if the Quadrennial Survey is overdue.

b) At Annual Surveys of conventional swinging boom or burtoning-type gear with multiple booms,

lowering of two or three booms may be sufficient, together with observation from the deck, toconfirm the maintenance of the upper part of the gear. However if the condition of the gear looksdoubtful, have all the booms actually lowered for closer inspection.

c) Check all locking arrangements such as gooseneck and shackle cotter pins, lock washers and lock

nuts on block, shackle safety wires, hook “mousing”, etc. Binoculars can be of assistance inexamining the hard-to-reach upper parts of the gear.





d) On Quadrennial Surveys, all booms should be lowered for examination. Also, the lower end of atleast some of any conventional tubular-type booms should be lifted up a few inches so that the

gooseneck pins can be examined (and preferably dye penetrant examined under the shoulder) for cracks. Check that the Register is being properly maintained and for information on the correctcomplement and marking of loose gear, test loads, boom angles and any special riggingarrangements, such as for double or single block options. Boom positions and vang arrangementsassociated with burtoning should also be clarified if such certification is being maintained.

e) When examining blocks, check for wastage or grooving of the load-carrying parts such as the

becket straps and attached shackles, and for missing or damaged locking arrangements. Also, for excessive wear of the sheave bearing and pin, and the swivel pin shoulder inside the cheeks of swivel blocks.

f) Make sure that pad-eyes on the deck, on caprails and on the boom are not worn excessively and

have sufficient attachment-welding and structural support.

g) Gooseneck forks sometimes spread open and fracture at the base of the fork due to swinging of

the boom at too high an angle or when the gooseneck pin is frozen from lack of lubrication. Theinside corners of the forks should be examined for cracks, and gooseneck grease holes provedclear.

h) The upper portions of topping lifts are subject to stack gas corrosion and related breakage of

individual wires. Refer to the Requirements for guidance on broken wires. i) Watch for excessive corrosion where the wire rope enters socket-type fittings. The filler metals

used in such fittings is usually a zinc alloy (never lead) and is somewhat susceptible to electrolyticcorrosion in a salt atmosphere.

j) Where the condition of the wire is questionable, with the help of a fid or inspection clamp-bar,untwist the wire rope slightly at a few random locations and close to sockets and thimbles to checkfor inside corrosion and deterioration of filler core. Wire rope should also be checked for flattening,excessive wear, and signs of having been kinked. There should be no bolted cable clamps or splices in the wire rope (except at ends).

k) Little-used heavy-lift gear is prone to excessive corrosion from salt water entrapment and flue

gases, which may be obscured by cable slush or preservative grease. This may be revealed bycleaning and close visual examination. Loose-ends of wire sticking out of splices may be tested for the effects of corrosion by bending them back-and-forth a few times to see if they break easily.

l) Frequently, modern tubular booms are made of higher-strength materials requiring special heat

treatment when straightening or welding, or of multi-ply construction. A lattice-type boom is often

made up of several different grades of higher-strength steels. Check the materials identificationdata at front of Register or refer to Headquarters before attempting repairs.

m) Smooth bends in booms can often be straightened by “line heating”, if this can be done without

degrading the steel quality. Severe bends or indents usually must be cropped out and boomshortened accordingly, or a new section welded in against backing strips inside. A circumferentialdoubler may also be welded over the repair area if boom shows wastage inside or outside. Shortdoublers may have ends scalloped to “soften” the effect of the abrupt change-of-section. Repairsor reinforcements to either tubular or lattice type booms should always be kept symmetrical withrespect to the longitudinal axis of the boom; e.g., if a boom is reinforced on one side or on onecord, the same sort of reinforcement should be applied diametrically opposite.





n) During the Quadrennial Survey of Cranes, the swing circle or slewing ring bolting should bechecked for breakage, proper torquing and the slew ring bearings for damage or wear. The

onboard records and crane manufacturer’s manual should be referred to in connection with this. Actual torquing checks on some or all of the slew ring bolts may be required if deemed necessary. At each Annual Survey the slew ring arrangement should be generally checked for broken or loosebolts and damage and the crane records reviewed for damage repairs and ongoing maintenance.

o) We often receive inquiries on the possibility of postponement or extensions of cargo gear or crane

surveys, however there are presently no provisions in the published requirements for this. Thesesurveys are wholly voluntary on the part of the Owner, no action can be taken by Class if thesurveys are not carried out, the certificates we issue are simple statement of fact as to what wassurveyed and when.



HELLENIC REGISTER OF SHIPPING

Survey Procedures Manual

Chapter 3

Hull and Equipment

b. New Constructions

April 1997



Hull and Equipment Chapter 3b


Contents

SECTION 1 General

2 Types of imperfections

3 Material defects

4 Edge preparation errors

5 Welded joint defects

6 Shape imperfections of panels

7 Shape imperfections of stiffeners, girders and pillars

8 Gross imperfections & overall ship shape standards









SECTION 1General

Structural imperfections due to inherent errors in the fabrication techniques as well as to humanfactors are always present in ship structires. Even when up to date technology is used it is still notpossible to produce perfect structures.

In order to be able to accept inaccuracies up to such an extent that a ship is constructed economicallyand at the same time the strength of the structures is maintained a Quality Assurance Scheme isessential. The purpose of this chapter is to provide a brief procedure for specifying and acceptingstandards of workmanship.

The following have been considered in the development of this scheme:

i. Working practice is Shipyards and limitations in ship construction.

ii. Similar quality assurance schemes existing in Europe and Japan.iii. Effect of various imperfections on the strength of a member of the ship structure.iv. Consequences from the reduction of strength of the various members due to

imperfections.

The derived standards are stated in terms of "standard range" of defects and "tolerance limit". Theformer is expected not to be exceeded in 95% of the cases. This is about the same with two times thestandard deviation on either side of the mean of a normal distribution. The "tolerance limit" is not to beexceeded. Where the above are exceeded then the recommended corrective action is included.

SECTION 2

Type of imperfections

The various types of imperfections may be categorised as follows:

i. Material imperfections:

Surface defectsPlate Laminations

ii. Edge preparation imperfections

iii. Welded joints defects:

Mis-alignmentUndercut

iv. Shape imperfections of:

PanelsStiffener & GirdersPillarsOverall ship girder





SECTION 3Material defects

3.1 Surface defects

These are either isolated or in clusters. Scratches, grooves, spills, blisters, rolled scale, pitting,material overlaps and cracks are the most common ones.

The isolated surface defects should be treated individually by grinding or drilling followed by welding.The same should be applied to any "crack like" defects of any depth.

Those appearing in clusters can be left unrepaired when they are below the corresponding line of Figure 1. If they do exceed these standards but the deepest defect does not reduce the platethickness by 20% and are less than 13% of the total area of one side of Figure 1 they can be repaired.This can be done by grinding only if the defect is less than 3mm deep and 7% of the plate area and by

grinding or chipping followed by welding if the defect is larger.





When the limits stated earlier for repair are exceeded the plate is to be substituted or the damagedportion to be cropped and renewed as indicated in Figure 2.

3.2 Plate laminations

Observation of the thickness at the edges of plates can raise suspicions and ultrasonic testing can

reveal their extend. When these are isolated (less than 2% of total area of one side) and are near thesurface and on one side only can be shipped out and built up with welding. The same applies whenthese are 300 mm near the edges and extend up to 50% of the thickness. After the welding, nondestructive examination is essential. For larger entend of this defect substitution or part renewal of theplate is recommended as in Figure 2.





SECTION 4Edge preparation errors

When machine controlled gas cutting is not used the use of guides on magnet posts or wheels isrecommended. Free hand cutting should be avoided as far as possible. Irregularities in the gas flowand starting points should be grinded. Any edge with depth of irregularities more than the valuesindicated in Table 1 should be smoothened with grinding.

SECTION 5

Welded joint defects

5.1 Misalignemnt

The Japanese Shipubuilding Quality Standards JSQS produced by the Researche Committee onSteel Shipbuilding of the Society of Naval Architects of Japan have been considered and adopted toform the basis of the HRS Standards. Comparison with other sources and practices have been done.The produced HRS Standards are summarized in Table 2.









5.2 Recommended edge preparation

For butt welds abrupt changes in thickness should be avoided and taper 1 in 3 should be adopted. If the change of the thickness is less than 3 mm the joint can be made smooth with the welding withouttapering the thicker plate.

The edge preparation of butt joints depends on the thickness, welding process and position to thevertical. In Table 3 recommended joint configurations and limits for gap and root face are summarizedfor butt joints. Where root gaps are in excess of the said limits weld build-up should be applied up to alength equal to the plate thickness or 25 mm whichever is smaller. N.D.T.examination should follow. If this is not enough then part renewal of the plate is required. Suitable electrode diameter should beused for every joint.

Generally weldings should be separated, overhead welding reduced as much as possible and weldingsequence decided beforehand and observed during building. When overhead weldings is unavoilable

unsymetrical bevels should be adopted with the smaller down as type 9 of Table 3. The overheadwelding should be completed first followed by back gauging and welding the second side in thedownhand or flat position. For weldings running horizontally the type 3 and 4 of Table 3 should beused.

The recommended welding configurations for fillet joints are summarized in Table 4. The leg thicknessis recommended to be about 0.8 times the thickness of the thinner plate involved.

5.3 Undercut

For but welds undercut type weld defects can be left unrepaired when the depth does not exceed 0.8mm in connections of strength members in the midship area or 1.0 mm for other connections. For filletwelds maximum depth accepted is 1.0 mm. When the weld is subjected to tension normal to its

direction the above limits should be reduced by 20%.

Corrective action when these limits are exceeded is to be in the form of filling the undercut usingsmaller electrodes.













SECTION 6Shape imperfections of panels

The initial imperfections of a plate should be more strickly controlled when it is subjected tocompression. Smaller values should be accepted when there are at a location affecting thelongitudinal strength of the ship and/or when it is a slender member than a stocky one. The sameshould be required for members which produce consequencial damage and/or to those withoutpostbuckling strength reserve.

The size of the imperfection accepted on a compressed member is related to the "utilized strength"from it. Figure 3 shows that by accepting different levels of imperfections one can get from thismember different levels of strength. The safest idea in this case is to define the range of imperfectionsacceptable on the "plateau" of the curve so that small deviations do not produce dramatic changes of strength.

Permissible values of initial shape imperfections for plate panels with one half wave across and alongthe panel are indicated in Table 5. The relevant terms can be seen in Figures 4 and 5. Theseimperfections depend on span, thickness, and amount of welding. Normally thin plates are joined withlight interminent welding and thick ones with heavy continuous welding. Under these circumstances

the imperfection depends only on the span.













It is complicated to differentiate stress free initial imperfections and those cold forming and weldingstresses. The standards of Table 5 would be easily met except in cases where thin plates are joinedwith heavy continuous welding. Excessive unessesary welding should be avoided because bothstresses & imperfections are produced. Not well bended plates should not come into the desired

shape using jacks, clamps & welding. It is recommended that the frames and plates should not bedifferent than the mould loft lines by more than 2mm in one meter span of template. When buckling isthe expected mode of failure for a panel then the imperfections should be well within the limits of Table 5. Otherwise fairing is recommended at the expense of increasing the residual stresses.

When fairing is done using flame straightening the local temperature should not exceed 850oC i.e. just

a visible red heat. Cooling should be natural one (for normal ambient conditions), at least until theplate temperature has cooled back to 550

oC i.e. a black heat.





SECTION 7Shape imperfections of stiffeners, girders & pilars

Generally a stricter approach is required than for plate imperfections. Table 6 includes therecommended standards which have been produced by modifying and detailing the JapaneseStandars JSQS. It is important to estimate the strength required from a member in resisting axialcompression and tolerances to be accordingly. Those supporting lateral loads only, would not be verysensitive to imperfections & relaxations can be allowed.

Attention should be drawn to observe the limitations set in the rules regarding web height of flat bars &bulb plates, the web thickness to depth ratio & the flange slenderness to avoid local buckling. When amember is slender strickt imperfection tolerances should be adopted and/or antitripping bracketsshould be fitted.




SECTION 8Shape imperfections & overall ship shape standards

All the imperfections mentioned so far are expected to be found randomly on a ship structure andaffect the capability of the members locally. When their size is large they are to be assessed as grossimperfections or overall ship shape ones.

Discontinuities arising from prefabricated large building sections, lengthenings, jamboizings, joiningships from two parts afloat or from errors in bottom or deck construction are Gross imperfections. Ageneral idea is illustrated in Figure 6*. However each case should be assessed individually.

Overall ship shape imperfection can be the hull girder sag from the usual wedling sequence on abuilding berth or dock or distorsion in the horizontal sense due to unsymetrical sun heating during

assembly. The type of smooth overall shape imperfection is not important or detrimental from thelongitudinal strength point of view. The behaviour of this ship girder is that of a slightly curved beaminstead of straight one. For such large radius of curvature the structural behaviour is almost the same.However an excessive amount of sag can create drydocking problems and distortion in the horizontalplane will lead to steering problems and hydrodynamic defficiency. How much imperfection in thissense should be allowed has not been decided yet. In practice ship structures are built with an overallsag or hog of about LBP/4 mm.** There is no reason to insist on higher accuracy and on the other hand more imperfection than that would reflect worst than average workmanship.

It is important in any case to record those overall shape imperfections on ship delivery in order toavoid possible alarming suspicions, after years of operations, that the ship has suffered plasticdeformation.

*Total imperfections & fitting errors between prefabricated sections measured longitudinally should not exceed the followingvalues for a length of 6 m maximum:Bottom Side shell, main and Tween decks, superstructues: 15 mmDouble Bottom longit.girders, tank top & Long bulkheads: 17 mm

** (Where LBP is in meters)

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Hellenic Register CHAPTER3