Rules for Class and Construction..Ship Technology..Uw Technology..Part 1 Diving System and Diving Simulators

Rules for Classification and Construction

I Ship Technology

5 Underwater Technology

1 Diving Systems and Diving Simulators

Edition 1998

The following Rules come into force on June 1st , 1998.

"General Terms and Conditions" of the respective latest edition will be applicable

(see Rules for Classification and Construction, I – Ship Technology, Part 0 – Classification and Surveys).

Reproduction by printing or photostatic means is only permissible with the consent of Germanischer Lloyd.

Germanischer Lloyd AG

Head Office Hamburg

Vorsetzen 35, D-20459 Hamburg

Telefon +49 40 3 61 49-0

Telefax +49 40 3 61 49-2 00

[email protected]

http://www.gl-group.com

Published by: Germanischer Lloyd AG, Hamburg Printed by: Gebrüder Braasch GmbH, Hamburg

mailto:[email protected]

http://www.gl-group.com/

Table of Contents

Section 1 Rules for Classification of Diving Systems and Diving Simulators

A. Classification and Characters of Classification .......................................................................... 1- 1

B. Classification of Diving Systems built or converted under the Survey of and in Accordance with the Rules of GL .............................................................................................. 1- 2

C. Classification of Diving Systems not built under the Survey of GL ........................................... 1- 2

D. Surveys of Maintenance of Class ............................................................................................... 1- 3

E. Surveys other than for Classification .......................................................................................... 1- 5

Section 2 Rules for Construction of Diving Systems

A. General Rules and Instructions ................................................................................................... 2- 1

B. Principles for the Design and Construction of Diving Systems .................................................. 2- 7

C. Pressure Vessels and Apparatus ................................................................................................. 2- 9

D. Pipes, Valves, Fittings, Hoses and Umbilicals ........................................................................... 2- 13

E. Compressors ............................................................................................................................... 2- 17

F. Life Support Systems ................................................................................................................. 2- 19

G. Automation, Communication and Locating Equipment ............................................................. 2- 22

H. Electrical Equipment .................................................................................................................. 2- 25

I. Fire Protection ............................................................................................................................ 2- 30

J. Handling, Transfer and Mating Equipment ................................................................................ 2- 32

K. Hyperbaric Evacuation System .................................................................................................. 2- 33

L. Wet Bells .................................................................................................................................... 2- 34

Section 3 Rules for Construction of Diving Simulators


B. Principles of Design and Construction of Diving Simulators ..................................................... 3- 6

C. Pressure Vessels and Apparatus ................................................................................................. 3- 8

D. Pipes, Valves, Fittings and Hoses .............................................................................................. 3- 9

E. Compressors ............................................................................................................................... 3- 10

F. Life Support Systems ................................................................................................................. 3- 10

G. Automation and Communications Equipment ............................................................................ 3- 13

H. Electrical Equipment .................................................................................................................. 3- 14

I. Fire Protection ............................................................................................................................ 3- 14

J. Hyperbaric Evacuation System .................................................................................................. 3- 16

Section 4 Rules for Construction of Diver Pressure Chambers


B. Principles for Design and Construction ...................................................................................... 4- 3

Appendix A Calculation and Pressure Hulls under External Pressure

A. Introduction ................................................................................................................................ A- 1

B. Stiffened and Unstiffened Cylindrical Shells ............................................................................. A- 1

C. Ring Stiffeners ............................................................................................................................ A- 4

I - Part 5 GL 1998

Table of Contents Chapter 1Page 3

D. Stiffened and Unstiffened Conical Shells ................................................................................... A- 8

E. Dished Ends and Spheres ............................................................................................................ A- 8

F. Openings and Discontinuities ..................................................................................................... A- 10

G. Elasticity Moduli ......................................................................................................................... A- 10

H. Out-of-Roundness of Cylinders and Spheres .............................................................................. A- 11

I. Tolerances of Ring Stiffeners ..................................................................................................... A- 13

J. Program Sequences for Iterative Calculations ............................................................................ A- 14

K. Symbols and Units ...................................................................................................................... A- 17

L. References ................................................................................................................................... A- 19

Appendix B Acrylic Plastic Windows

A. General ........................................................................................................................................ B- 1

B. Material ....................................................................................................................................... B- 1

C. Manufacture of Windows ............................................................................................................ B- 1

D. Window Shapes and Sizes .......................................................................................................... B- 2

Appendix C Design and Manufacture of GRP Constructions

A. Principles for the Manufacture of GRP Constructions ................................................................ C- 1

B. Company Authorization .............................................................................................................. C- 1

C. Workshop Requirements ............................................................................................................. C- 1

D. Construction Process ................................................................................................................... C- 2

E. Materials ..................................................................................................................................... C- 3

Chapter 1 Page 4

Table of Contents I - Part 5GL 1998

Index

A

Access openings ..................................................................................................................................................... 3-9

Access ports ......................................................................................................................................................... 2-10

Acrylic plastic windows ................................................................................................................................ 2-12, 3-9

Air ...................................................................................................................................................................... 2-22

Alarm systems ...................................................................................................................................................... 2-31

Analyzers ............................................................................................................................................................. 3-13

Analyzing equipment ........................................................................................................................................... 2-21

Ancillary equipment ............................................................................................................................................... 2-5

Annual survey ................................................................................................................................................. 1-3, 1-4

Antechambers ........................................................................................................................................................ 4-1

Apparatus ............................................................................................................................................................... 2-5

Application for classification ................................................................................................................................. 1-2

Area of installation of diving system ........................................................................................................... 2-30, 2-31

Area of installation of the diving simulator ................................................................................................. 3-14, 3-15

Areas not subject to an explosion hazard ............................................................................................................... 2-9

Areas subject to explosion hazard ................................................................................................................... 2-1, 3-1

Assignment of class ................................................................................................................................................ 1-3

Authorized workshop ............................................................................................................................................. 1-3

Automation .............................................................................................................. 2-2, 2-4, 2-6, 2-22, 3-2, 3-3, 3-5

Automation and communications equipment ....................................................................................................... 3-13

Automation equipment ......................................................................................................................................... 3-13

Average commissioner ........................................................................................................................................... 1-3

B

Ballast weights ....................................................................................................................................................... 2-5

Bayonet locks ......................................................................................................................................................... 2-3

Block diagrams ...................................................................................................................................................... 2-3

Bolts ..................................................................................................................................................................... 2-12

Bottles ..................................................................................................................................................... 2-1, 3-1, 3-2

Breathing connection ............................................................................................................................................. 4-1

Breathing gas ......................................................................................................................................................... 2-6

Breathing gas supply ............................................................................................................................................ 2-35

Breathing gas systems ..................................................................................................................................... 2-2, 3-2

Breathing gas treatment and mixing ..................................................................................................................... 2-20

Breathing gas/breathing mixture ..................................................................................................................... 2-1, 3-1

I - Part 5 GL 1998

Index Chapter 1Page 5

Breathing rate per minute AMV ................................................................................................................. 2-19, 3-10

Buoyancy ............................................................................................................................................................... 2-5

Bursting pressure ................................................................................................................................................... 2-6

C

Cables ........................................................................................................................................................... 2-6, 2-29

Calculation of pipe wall thicknesses ........................................................................................................... 2-15, 2-16

Calculations ......................................................................................................................................................... 2-12

Cast steel .............................................................................................................................................................. 2-15

Category A machinery space ................................................................................................................................. 2-2

Central control position ............................................................................................................ 2-20, 2-21, 2-22, 3-11

Certificate of classification ............................................................................................................................. 1-1, 1-3

Certification ........................................................................................................................................................... 1-5

Chamber conditions ............................................................................................................................................... 3-7

Chamber equipment ........................................................................................................................................ 2-9, 3-7

Chamber windows ................................................................................................................................. 2-10, 3-5, 4-2

Change of vessel .................................................................................................................................................... 1-3

Characters of classification ............................................................................................................................. 1-1, 1-3

Circuitry ............................................................................................................................................................... 2-23

Class renewal survey ............................................................................................................................... 1-2, 1-3, 1-4

Classification ......................................................................................................................................................... 1-1

CO ............................................................................................................................................................ 2-22, 3-13

CO2 ..................................................................................................................................................................... 2-22

CO2 analyzing system ......................................................................................................................................... 2-21

CO2 levels ........................................................................................................................................................... 2-21

Communication systems ................................................................................................................................. 2-2, 3-2

Communications ............................................................................................................ 2-4, 2-6, 2-22, 2-24, 4-2, 4-5

Communications equipment ............................................................................................... 2-24, 3-3, 3-5, 3-13, 3-14

Compact umbilicals ................................................................................................................................. 2-2, 2-6, 3-2

Components ........................................................................................................................................................... 2-6

Compressed air ...................................................................................................................................................... 4-5

Compressed air storage .......................................................................................................................................... 4-1

Compression chamber system ................................................................................................................................ 1-4

Compression chamber windows .............................................................................................................. 2-5, 3-5, 4-2

Compression chambers ................................................................. 2-1, 2-2, 2-9, 2-20, 2-31, 3-1, 3-2, 3-8, 3-11, 3-16

Compressors ................................................................................................. 2-3, 2-5, 2-17, 2-18, 3-2, 3-5, 3-10, 4-2

Conditioning of chamber atmosphere ......................................................................................................... 2-20, 3-11

Conditions in chamber ........................................................................................................................................... 2-8

Construction ........................................................................................................................................................ 2-11

Chapter 1 Page 6

Index I - Part 5GL 1998

Constructional test ................................................................................................................................................. 2-5

Consul .................................................................................................................................................................... 1-3

Control .................................................................................................................................. 2-2, 2-20, 3-11, 4-2, 4-5

Control equipment .............................................................................................................................. 2-22, 3-2, 3-13

Control position ................................................................................................................................................... 2-22

Control station ...................................................................................................................................................... 2-35

Cooling .................................................................................................................................................................. 2-4

Copper ................................................................................................................................................................. 2-15

Copper alloys ....................................................................................................................................................... 2-15

Corrosion protection ............................................................................................................................. 2-9, 2-10, 3-7

Coupling clamps .................................................................................................................................................... 2-3

D

Damage survey ................................................................................................................................................ 1-3, 1-5

Deck compression chambers ........................................................................................................................... 4-1, 4-4

Demand breathing system ...................................................................................................................................... 4-1

Depth .............................................................................................................................................................. 2-2, 3-2

Description of the system ....................................................................................................................................... 2-3

Design and construction of diving systems ............................................................................................................ 2-7

Design pressure ...................................................................................................................................................... 2-5

Design principles ................................................................................................................................................... 2-9

Detection ......................................................................................................................................................... 2-3, 3-2

Disposal system ..................................................................................................................................................... 2-4

Diver heating systems ..................................................................................................................................... 2-2, 3-2

Diver pressure chambers ................................................................................................................................. 4-1, 4-2

Diving bells .................................................................................................................... 2-2, 2-5, 2-9, 2-10, 2-20, 3-2

Diving procedure ................................................................................................................................................... 2-3

Diving simulators ............................................................................................................. 1-1, 3-1, 3-2, 3-6, 3-7, 3-11

Diving support vessels ........................................................................................................................................... 2-1

Diving system certificate ......................................................................................................................... 1-1, 1-2, 1-3

Diving systems ................................................................................................................. 1-1, 2-1, 2-2, 2-5, 2-7, 2-31

Documents ............................................................................................................................................................. 1-4

Documents for approval .......................................................................................................................... 2-3, 3-2, 4-1

Door leaves ............................................................................................................................................................ 2-3

Door leaves and frames .......................................................................................................................................... 3-3

Doors ................................................................................................................................................................... 2-10

Drawings ................................................................................................................................................................ 2-5

Drawings of consoles ............................................................................................................................................. 2-3

Drawings of supply and disposal systems .............................................................................................................. 2-3

Duration of class .................................................................................................................................................... 1-1

I - Part 5 GL 1998


E

Earthing ............................................................................................................................................................... 2-29

Electrical equipment ................................................................................................. 2-4, 2-6, 3-4, 3-5, 3-14, 4-3, 4-5

Electrical Equipment ........................................................................................................................................... 2-25

Electrical machines ................................................................................................................................................ 2-6

Electrical penetrations ......................................................................................................................................... 2-29

Electrical systems .................................................................................................................................................. 2-2

Electrical systems and equipment .......................................................................................................................... 3-2

Emergency communication ................................................................................................................................. 2-25

Emergency lighting .............................................................................................................................................. 2-30

Emergency location ............................................................................................................................................. 2-24

Emergency power supply ..................................................................................................................................... 2-27

Enclosures for electrical equipment ..................................................................................................................... 2-28

Ends ..................................................................................................................................................................... 2-11

Energy balance ...................................................................................................................................................... 2-4

Engine plant ........................................................................................................................................................... 2-1

Environmental conditions ............................................................................................................................... 2-8, 3-7

Equipment list ........................................................................................................................................................ 2-3

Evacuation chamber ............................................................................................................................................ 3-16

Evacuation system ............................................................................................................................................... 2-34

Evacuation units .................................................................................................................................................. 2-33

Expert .................................................................................................................................................................... 1-3

Extinguishing equipment ................................................................................................................................ 2-3, 3-2

F

Facilities ................................................................................................................................................................ 3-7

Fire behaviour ........................................................................................................................................................ 2-6

Fire detection ....................................................................................................................................................... 2-31

Fire detection and alarm systems ......................................................................................................................... 3-15

Fire detection systems ................................................................................................................................. 2-31, 3-15

Fire extinguishing equipment .............................................................................................................................. 3-15

Fire extinguishing systems ................................................................................................................................... 2-31

Fire loads ...................................................................................................................................................... 2-9, 2-31

Fire prevention ............................................................................................................................................... 2-3, 3-2

Fire protection ........................................................................................................ 2-4, 2-6, 2-30, 3-4, 3-6, 3-14, 4-3

Fire protection equipment .................................................................................................................... 2-32, 3-16, 4-6

Fire surveillance ......................................................................................................................................... 2-31, 3-15

Fittings ........................................................................................................................... 2-2, 2-9, 2-13, 2-14, 3-2, 3-9

Fixed system .......................................................................................................................................................... 2-2

Chapter 1 Page 8


Foundation drawings .............................................................................................................................................. 2-3

Frames .................................................................................................................................................................... 2-3

Functional efficiency .............................................................................................................................................. 1-2

Functional test ........................................................................................................................................................ 2-5

G

Gas analysis ........................................................................................................................................................... 2-3

Gas analyzing systems .................................................................................................................................... 2-2, 3-2

Gas bottles ..................................................................................................................................... 2-2, 2-7, 2-13, 3-9

Gas distribution ........................................................................................................................................... 2-19, 3-10

Gas mixers ...................................................................................................................................................... 2-3, 3-2

Gas piping .............................................................................................................................................................. 2-5

Gas storage facilities ........................................................................................................................... 2-5, 2-19, 3-10

Gas storage facility ................................................................................................................................................ 3-1

Gas supply ............................................................................................................................. 2-2, 2-3, 2-19, 3-3, 3-10

Gas supply system ................................................................................................................................................ 3-10

Gas venting system .............................................................................................................................................. 2-19

Gas-air mixture ...................................................................................................................................................... 2-1

Guidelines for the explosion protection of electrical equipment ............................................................................ 2-9

H

Handling ................................................................................................................................. 2-3, 2-4, 2-6, 2-7, 2-32

Handling and transfer systems ........................................................................................................................ 2-1, 3-1

Handling system ........................................................................................................................... 2-2, 2-5, 2-33, 2-34

Hatch trunks ......................................................................................................................................................... 2-10

Hatches ......................................................................................................................................................... 2-10, 3-9

He/N2/CO2 mixtures ........................................................................................................................................... 2-22

Heating ................................................................................................................................................................... 2-4

Helium reclaim system .................................................................................................................................... 2-3, 3-2

Helium-oxygen mixtures ...................................................................................................................................... 2-22

Hose lines ............................................................................................................................................................. 2-14

Hoses ............................................................................................................................... 2-2, 2-6, 2-13, 3-2, 3-5, 3-9

Hull ........................................................................................................................................................................ 2-1

Hydraulic pressure test .................................................................................................................................... 2-5, 2-6

Hydrocarbons ....................................................................................................................................................... 3-13

Hyperbaric evacuation system ....................................................... 2-2, 2-3, 2-4, 2-7, 2-33, 2-34, 3-2, 3-4, 3-6, 3-16

Hyperbaric evacuation units ................................................................................................................................. 2-33

Hyperbaric self-propelled lifeboats ...................................................................................................................... 2-33

I - Part 5 GL 1998


I

IMO code of safety ................................................................................................................................................ 2-1

Impact energy ...................................................................................................................................................... 2-10

Inclined positions ................................................................................................................................................... 2-8

Indicating instruments ......................................................................................................................... 2-21, 3-12, 4-5

Installation drawings .............................................................................................................................................. 2-3

Instrumentation .................................................................................................................................. 2-20, 3-11, 3-12

Insulation ............................................................................................................................................................. 2-31

Insurance company ................................................................................................................................................ 1-3

Integral opening reinforcements ............................................................................................................................ 2-3

Interior lighting .................................................................................................................................................... 2-30

Interiors ...................................................................................................................................................... 2-31, 3-15

Intermediate survey ........................................................................................................................................ 1-3, 1-4

Internal facilities .................................................................................................................................................... 2-3

Internal survey ....................................................................................................................................................... 1-3

Interrogator/receiver ............................................................................................................................................ 2-25

ISO V-notch ........................................................................................................................................................ 2-10

L

Launching devices ............................................................................................................................................... 2-35

Leaks ..................................................................................................................................................................... 2-5

Life support systems ................................................................................................... 2-2, 2-3, 2-5, 2-6, 3-2, 3-3, 3-5

Life Support Systems .................................................................................................................................. 2-19, 3-10

Lifting equipment .................................................................................................................................................. 2-4

Lifting point ......................................................................................................................................................... 2-10

Lighting ............................................................................................................................................................... 2-30

Lines .................................................................................................................................................................... 2-29

Living compartment ................................................................................................................................. 2-2, 3-2, 3-8

Living compartment of compression chambers ..................................................................................................... 2-9

Locating equipment ........................................................................................................................ 2-2, 2-4, 2-6, 2-22

Location ................................................................................................................................................................. 2-9

Lock for materials .................................................................................................................................................. 3-8

Locking mechanism ............................................................................................................................................. 2-10

Locks ............................................................................................................................................................ 2-10, 3-8

Log-book ............................................................................................................................................................... 1-1

Lowering ................................................................................................................................................................ 2-6

M

Main chambers ...................................................................................................................................................... 4-1

Main components of a diving system .................................................................................................................... 2-2

Chapter 1 Page 10


Main power supply .............................................................................................................................................. 2-27

Manufacture ......................................................................................................................................................... 2-11

Manufacturer .......................................................................................................................................................... 1-2

Manufacturer's works ............................................................................................................................................. 1-3

Marking ................................................................................................................................................... 2-7, 3-6, 4-3

Marking of gas systems ................................................................................................................................... 2-7, 3-6

Material testing ........................................................................................................................................... 2-11, 2-15

Materials ..................................................................................................................................................... 2-10, 2-15

Materials test certificates ....................................................................................................................................... 2-5

Mating .................................................................................................................................................................... 2-6

Mating and handling systems ............................................................................................................................... 2-34

Mating appliances .................................................................................................................................................. 2-7

Mating device ................................................................................................................................................. 2-1, 3-1

Mating equipment ................................................................................................................................................ 2-32

Mating systems ....................................................................................................................... 2-3, 2-4, 2-6, 2-34, 4-3

Maximum operating depth ..................................................................................................................................... 2-5

Maximum operating depth of the diving system ............................................................................................. 2-2, 3-1

Maximum permissible operating voltages ............................................................................................................ 2-26

Maximum permissible working pressure ........................................................................................................ 2-5, 4-1

Mechanical strength ............................................................................................................................................... 1-2

Minimum pipe wall thickness .............................................................................................................................. 2-16

Mixed gas ............................................................................................................................................................... 2-8

N

Name plate ............................................................................................................................................................. 2-7

National regulations ............................................................................................................................................... 2-1

NO ............................................................................................................................................................. 2-22, 3-13

Nodular cast iron .................................................................................................................................................. 2-15

Non-destructive testing of welds ............................................................................................................................ 2-5

Non-metals ........................................................................................................................................................... 2-15

NOx ............................................................................................................................................................ 2-22, 3-13

Nozzles ................................................................................................................................................................ 2-12

O

Office of authority .................................................................................................................................................. 1-3

Operator ................................................................................................................................................................. 1-2

Oxygen ................................................................................................................................................................... 2-6

Oxygen supply ....................................................................................................................................................... 4-5

Ozone ................................................................................................................................................................... 3-13

I - Part 5 GL 1998


P

Performance of surveys ......................................................................................................................................... 1-4

Permissible stress ........................................................................................................................................ 2-16, 2-17

Pipe classes .......................................................................................................................................................... 2-14

Pipe connections .................................................................................................................................................. 2-14

Pipes ............................................................................................................................................... 2-2, 2-13, 3-2, 3-9

Piping diagrams ..................................................................................................................................................... 2-3

Piping systems ................................................................................................................................ 2-6, 2-13, 3-5, 4-2

Power distribution ............................................................................................................................................... 2-27

Power supply .............................................................................................................................................. 2-23, 2-26

Pressure chambers ................................................................................................................................. 2-33, 4-1, 4-2

Pressure drop ......................................................................................................................................................... 2-5

Pressure vessels ................................................................................................................. 2-1, 2-2, 2-5, 2-7, 3-1, 3-2

Pressure vessels and apparatus ......................................................................... 2-5, 2-9, 2-13, 3-3, 3-4, 3-8, 3-9, 4-2

Procedure for classification ................................................................................................................................... 1-3

Purity test ............................................................................................................................................................... 2-6

R

Raising ................................................................................................................................................................... 2-6

Reclassification survey .......................................................................................................................................... 1-2

Register book ........................................................................................................................................... 1-1, 1-2, 1-3

Reinforcement of cutouts ..................................................................................................................................... 2-11

Release .................................................................................................................................................................. 2-6

Repairs ................................................................................................................................................................... 1-3

Replacements ......................................................................................................................................................... 1-3

Rescue chambers ............................................................................................................................................ 4-1, 4-6

Retaining rings ....................................................................................................................................................... 2-3

Rules of construction ............................................................................................................................................. 2-1

S

Safety equipment ............................................................................................................................................ 2-5, 4-2

Sanitary systems ............................................................................................................................................. 2-2, 3-2

Screws ................................................................................................................................................................. 2-12

Sea trials ................................................................................................................................................................ 2-5

Shower ................................................................................................................................................................... 2-9

Shutoff-devices .................................................................................................................................................... 2-14

Signalling systems ............................................................................................................................................... 2-24

SOLAS .................................................................................................................................................................. 2-2

Sources of ignition ............................................................................................................................................... 2-31

Special survey ................................................................................................................................................. 1-3, 1-5

Chapter 1 Page 12


Stability .................................................................................................................................................................. 2-5

Steel ..................................................................................................................................................................... 2-15

Storage batteries ................................................................................................................................................... 2-27

Structural fire protection ............................................................................................................................. 2-30, 3-14

Supervision during construction ............................................................................................................................ 1-2

Supply locks .................................................................................................................................................... 2-3, 4-4

Supply systems ..................................................................................................................................................... 2-26

Surface compression .............................................................................................................................................. 2-9

Surface compression chamber ........................................................................................................ 2-1, 2-2, 2-8, 2-31

Surveillance ........................................................................................................................................................... 3-2

Surveillance system ................................................................................................................................................ 2-2

Survey by special agreement .................................................................................................................................. 1-5

Surveyor ................................................................................................................................................................. 1-2

Surveyor's report on the assignment of class .......................................................................................................... 1-3

Surveys ................................................................................................................................................................... 1-3

Surveys of maintenance of class ............................................................................................................................ 1-3

Surveys other than for classification ...................................................................................................................... 1-5

Surveys relating to the safety of equipment ........................................................................................................... 1-5

Switchgear ........................................................................................................................................................... 2-27

Switching and protective devices ......................................................................................................................... 2-28

T

Television surveillance equipment ....................................................................................................................... 3-14

Temporary system .................................................................................................................................................. 2-2

Test chambers ................................................................................................................................................. 3-2, 3-8

Test pressure .......................................................................................................................................................... 4-1

Test pressure/time curve ...................................................................................................................................... 2-30

Test schedule ......................................................................................................................................................... 2-3

Tests ....................................................................................................................................................................... 2-5

Tightness test ......................................................................................................................................................... 2-6

Toilet ...................................................................................................................................................................... 2-9

Total system ........................................................................................................................................................... 2-3

Transfer .......................................................................................................................................... 2-3, 2-4, 2-6, 2-32

Transponder ......................................................................................................................................................... 2-24

Transporting ........................................................................................................................................................... 2-7

Treatment and mixing of breathing gases ............................................................................................................ 3-11

Trials ...................................................................................................................................................................... 2-5

I - Part 5 GL 1998


U

Umbilicals .................................................................................................... 2-2, 2-3, 2-6, 2-13, 2-14, 2-34, 3-2, 3-5

Underwater plug connections .............................................................................................................................. 2-29

V

Valves ................................................................................................................................... 2-2, 2-13, 2-14, 3-2, 3-9

View ports ........................................................................................................................................... 2-10, 2-12, 3-8

Voice communication systems .................................................................................................................... 2-24, 3-13

W

Water supply .......................................................................................................................................................... 2-4

Water systems ........................................................................................................................................................ 3-2

Weight ................................................................................................................................................................... 2-5

Welded structures ................................................................................................................................................ 2-10

Welding ............................................................................................................................................................... 2-11

Welding gas absorbers ........................................................................................................................................... 3-2

Wet bells ............................................................................................................................... 2-2, 2-5, 2-7, 2-34, 2-35

Wet test chambers .................................................................................................................................................. 3-8

Window flanges ..................................................................................................................................................... 2-3

Windows ................................................................................................................................. 2-3, 2-12, 3-3, 3-5, 4-2

Working gas .......................................................................................................................................................... 3-1

Working pressure ................................................................................................................................................... 4-1

X

X-ray test ............................................................................................................................................................... 2-6

Chapter 1 Page 14


Section 1

Rules for Classification of Diving Systems and Diving Simulators

A. Classification and Characters of Classification

1. Classification

1.1 The following Rules for Classification and Construction constitute the basis for the classification of diving systems on seagoing ships and for diving simulators.

The term "Rules for Construction" includes Rules for Materials and Welding as well as other Rules for Con-struction issued by Germanischer Lloyd (GL).

1.2 For the purpose of these Rules, diving sys-tems comprise:

Diving systems which are permanently installed on a ship or similar floating structure.

Diving systems which are assembled to meet particular service requirements and are installed for a limited period on a ship or similar floating structure.

1.3 The classification covers all equipment of the ship, machinery and electrical installation of diving systems.

1.4 The Certificate of Classification for diving systems is issued by the Managing Directors of GL or by their Representatives. It is to be kept on board ship.

1.5 Diving systems classified by GL are entered in the Register Book with a note of the relevant char-acter of classification and are included in the list of chips with a diving system certificate.

1.6 The ship is required to carry a diving system log-book in which are entered details of diving opera-tions, repairs etc. The diving system log-book is to be submitted to the Surveyor on request.

1.7 Diving systems which are not to be classified by GL but which are constructed in accordance with the Rules and under the Survey of GL may receive an appropriate Diving System Certificate from GL (cf. Subsection E.).

1.8 Diving simulators are not generally subject to classification by GL. Where a plant is to be classified at the request of the operator, the Rules for Classifica-tion of Diving Systems shall be applied as and where relevant.

1.9 For the purpose of these Rules, diving simu-lators are pressure chambers or pressure chamber sys-tems in which diving conditions can be simulated.

2. Characters of classification

2.1 The character of classification is:

TAZ

2.2 For diving systems of non-standard design, GL reserves the right to subject the systems to addi-tional tests, to order a special survey schedule and to make special entries in the diving system certificate and the Register Book.

2.3 Diving systems built under the survey and in accordance with the Rules of GL using materials and components tested by GL in conformity with its Rules receive the notation in front of the character of classification.

2.4 Diving systems built under the survey and in accordance with the rules of another recognized classi-fication society receive, on being awarded GL classifi-cation, the notation in front of the character clas-sification.

3. Duration of class

3.1 The validity of the class of permanently in-stalled diving systems is always identical to that of the machinery plant of the ship or floating structure. The class will be maintained as long as the diving system is subjected to all prescribed surveys, and any modifications and repairs found to be necessary are carried out to the satisfaction of GL.

3.2 If the diving system is not subjected to the prescribed surveys at their due dates, the class will be suspended.

3.3 If the diving system has suffered damage affecting its class or if such damage may be assumed, a survey must be performed before diving operations begin. The Society is to be notified of such damage as a matter of course.

3.4 Where it is found that the diving system no longer complies with the requirements of the Rules on the basis of which the class was assigned, or if the

I - Part 5 GL 1998

Section 1 Rules for Classification of Diving Systems and Diving Simulators Chapter 1Page 1–1

A

operator fails to carry out repairs or alterations consid-ered necessary by GL within a specified period to be agreed upon, the diving system will lose its class.

3.5 If the repairs or modifications required by GL have been carried out and the system is subjected to a Reclassification Survey, the original character of clas-sification may be reinstated. This survey is to be car-ried out in accordance with the requirements for a Class Renewal Survey.

3.6 If for some reason the class has expired or has been withdrawn by GL, this will be indicated in the Register Book. The Certificates of Classification shall be returned to GL.

B. Classification of Diving Systems built or converted under the Survey of and in Ac-cordance with the Rules of GL

1. General

1.1 Application for the classification of a diving system is to be submitted to GL in writing by the manufacturer or operator.

1.2 In general, particulars of the diving system are to be submitted to GL in triplicate for examination.

1.3 Any deviation from the approved drawings and documents are subject to the approval of GL be-fore work is commenced.

1.4 The Surveyor is to be advised in good time of tests to be performed under the supervision of GL:

1.5 On the completion and successful testing of the diving system, GL will issue the Diving System Certificate.

2. Supervision during construction

2.1 Proof is to be provided that the materials to be used for new constructions, replacements and repaired parts have been tested in accordance with the requirements of GL Rules for Materials.

2.2 Parts of the diving system requiring approval will be checked during manufacture for conformity with the approved documents.

2.3 The separate components of the diving system are to be tested on the manufacturer's test bed for mechanical strength and, where appropriate, for functional efficiency. Where components are novel in design or have not yet sufficiently proved their effi-ciency on board ship or in diving systems, GL may demand more extensive tests.

2.4 The Surveyors of GL will supervise the as-sembly of the diving system, will examine the work-manship and will carry out the required tightness and service tests.

2.5 Upon completion, the entire diving system will be subjected to a final test under working condi-tions in accordance with the Rules for Construction, Section 2, A.5.

2.6 To enable the Surveyor to fulfil his duties, he is to be given free access to the ship and the work-shops where parts requiring approval are manufac-tured, assembled or tested. To enable the Surveyor to carry out the required tests, the shipyard or the manu-facturers are to give him every assistance by providing the staff and equipment necessary for such tests.

C. Classification of Diving Systems not built under the Survey of GL

1. General

1.1 Applications for the classification of diving systems not built under the survey of GL are to be submitted to GL in writing.

1.2 With the application for classification docu-ments relating to the diving system are to be submitted for examination the scope of which shall be as stated in the Rules for Construction. The documentation relating to functional tests is to be submitted and, where necessary, individual tests are to be repeated.

1.3 Particulars are to be submitted as to existing class and period of class, as well as any requirements upon which the maintenance of the existing class has been made conditional.

1.4 Where the diving system has existing class awarded by a recognized classification society, it may in exceptional cases be sufficient to forward a set of the necessary documents.

2. Procedure for classification

2.1 For the assignment of class the diving system is to be surveyed in accordance with the provisions for a Class Renewal Survey.

2.2 If the diving system holds the class of another recognized classification society, GL may not require all parts to be surveyed, and the survey of individual parts may be deferred pending the next due date of a regular survey. GL may then consent to a survey in accordance with at least the requirements of an Annual Survey.

Chapter 1 Page 1–2

Section 1 Rules for Classification of Diving Systems and Diving Simulators I - Part 5GL 1998

C

2.3 A Diving System Certificate will be issued on the basis of a satisfactory Surveyor's Report on the assignment of class. Once a diving system has been classed with GL, the same regulations will apply as for diving systems built under survey of GL.

D. Surveys of Maintenance of Class

1. Kinds of surveys

Diving systems classed with GL are to be subjected to the following surveys, if their class is to be main-tained:

1.1 Annual survey (cf. 3.1).

1.2 Intermediate survey (cf. 3.2).

The intermediate survey falls due nominally 2,5 years after commissioning and each class renewal and may be carried out on the occasion of the second or third annual survey.

1.3 Class Renewal Survey after five years (cf. 3.3).

1.4 Damage survey, where the diving system has been damaged or where the hull or parts of the ma-chinery plant have suffered damage liable to affect the diving system (cf. 3.4).

1.5 Special Survey, before the start of diving operations with a modified diving system or after re-assembly or change of vessel in the case of a mobile diving system (cf. 3.5).

1.6 GL reserve the right to demand surveys to be held between the due dates of regular surveys, if this is considered necessary. Such surveys may be taken into account for the prescribed regular surveys.

1.7 If it is either impracticable or excessively costly to prepare units and components for internal survey on board, surveys may also, on application by the operator, be performed in the manufacturer's works or other authorized workshop.

2. Explanatory notes on surveys

2.1 The locally responsible Surveyor of GL is to be given timely notice when regular surveys become due or when it is intended to carry out repairs or al-terations, so that the work can be supervised.

2.2 The records of each survey, as well as special requirements upon which the maintenance of class has been made conditional, will be entered in the Diving System Certificate. In addition to the character of classification and the month and year of classification,

The Register Book shall also state the month and year of the last Annual Survey or the last Class Renewal Survey.

2.3 The reports prepared by the Surveyors are checked by GL. The results of surveys carried out are published in the Register Book, Part 2, upon accep-tance.

2.4 Where defects are repaired provisionally only, or where the Surveyor does not consider imme-diate repairs or replacements necessary, the class of the diving system may be confirmed for a certain lim-ited period by marking an entry in the Certificate of Classification. Upon withdrawal of such restrictions, a corresponding record will be entered in the Certificate of Classification.

2.5 Where parts are damaged or worn to such an extent that they no longer comply with the require-ments of GL, they are to be repaired or replaced.

2.6 If a diving system has to be surveyed in a port where, or near which, there is no Agent or Surveyor of GL, the locally responsible Consul, a competent Office or Authority, or the Average Commissioner of the Insurance Company concerned is to be requested to cause a survey by an expert. The commission of the expert is to be confirmed by the Consul, the Office of Authority, or the Average Commissioner. The expert shall be requested to forward to GL forthwith a report on the condition of the diving system and on the repairs as well as on the decision arrived at. A copy of the report is to be retained on board ship. The decision of the expert is subject to the approval of GL, who will decide on whether the diving system has to be surveyed again.

3. Performance of surveys

3.1 Annual Survey

The Annual Survey of the diving system shall include at least the following tests and checks:

3.1.1 Examination of the documents relating to the diving system and scrutiny of the operational records.

3.1.2 The entire compression chamber system in-cluding all fixtures, penetrations, doors and covers, seals, locking systems etc. is to be inspected for visible damages, cracks, deformation, corrosion attacks and fouling.

3.1.3 All other pressure vessels and apparatus, valves, fittings and safety equipment are to be sub-jected to external inspection.

3.1.4 The entire power supply system, including the emergency supply, of the diving system is to be subjected to external inspection.

I - Part 5 GL 1998


D

3.1.5 Switching from the main to the emergency electricity supply is to be tested.

3.1.6 Insulation measurements are to be performed on the electrical equipment.

3.1.7 The accuracy of all important instrument readings is to be checked (e.g. depth gauge, gas ana-lyzer, etc.).

3.1.8 All emergency systems are to undergo a functional test (e.g. the autonomous gas supply of the diving bell).

3.1.9 The handling system is to be checked for visible damages, cracks and deformations and is to undergo a functional test including a brake test (power failure).

3.1.10 All high-pressure gas supply and charging hoses and the hoses belonging to the heating system and the umbilical are to be checked for visible damage and tightness.

3.2 Intermediate Survey

An Intermediate Survey is an Annual Survey extended as follows unless it coincides with the Class Renewal Survey in accordance with 3.3:

3.2.1 Performance of a tightness test on the com-pression chamber system at maximum permissible operating pressure using air.

3.2.2 Verification of the set pressures and reset pressures of compression chamber relief valves and of safety and warning systems.

3.2.3 Functional tests on mechanical and electrical equipment.

3.2.4 Functional tests on life support systems

3.2.5 Functional tests on fire warning and extin-guishing systems.

3.2.6 Functional tests on all alarm systems.

3.2.7 Functional test and purity check on all breathing gas compressors.

3.2.8 After ten years, all compression chambers are to undergo a hydrostatic internal pressure test.

3.2.9 Check of acrylic viewport windows (maximum service period: 10 Years).

3.3 Class Renewal Survey

A Class Renewal Survey is performed every five years. The following tests and examinations are to be carried out in addition to the inspections called for under 3.2:

3.3.1 A tightness test is to be performed on the compression chamber system at 1,1 times the maxi-mum permissible operating pressure using air.

3.3.2 Dimensional checks and non-destructive wall thickness tests are to be performed on the diving bell. Where necessary, buoyancy aids, cladding and layers of thermal insulation are to be removed for this pur-pose.

3.3.3 Emergency ballast release and buoyancy tests are to be performed with the diving bell.

3.3.4 Pressure vessels and apparatus not capable of satisfactory internal inspection and those whose satis-factory condition cannot be definitely established by internal inspection are to be inspected by another non-destructive method of examination or are to be sub-jected additionally to a hydraulic pressure test.

3.3.5 Acrylic viewport windows are to be dis-mounted and examined for incipient cracks. Window seatings are to be examined for corrosive attack.

3.3.6 If, within the period of class, surveys are performed on a diving system or parts thereof which are equivalent in scope to a Class Renewal Survey, the regular Class Renewal Survey of the parts concerned may, on application by the operator, be deferred ac-cordingly.

3.4 Damage Survey

3.4.1 If a diving system has suffered damage af-fecting its class or if such damage may be assumed, or if the hull or parts of the machinery of the support vessel have received damage affecting the diving sys-tem a Damage Survey is to be carried out.

3.4.2 Following damage, the diving system is to be presented for survey in such a way that a satisfactory inspection can be carried out. The extent of the Dam-age Survey will be determined by GL in each individual case.

3.5 Special Survey

3.5.1 When any modification is made in respect of design, mode of operation or equipment, and after major repairs to pressure vessels, the diving system is to be subjected to a Special Survey.

3.5.2 In addition, mobile diving systems are to undergo a Special Survey equivalent in scope to an Extended Annual Survey after each re-assembly and whenever there is a change of ship.

3.5.3 A further check shall be made to ensure that the diving system is properly installed and secured on the ship or floating structure.


Section 1 Rules for Classification of Diving Systems and Diving Simulators I - Part 5GL 1998

D

E. Surveys other than for Classification

1. Survey by special agreement

Where surveys are required by official ordinances, international agreements or other provisions, GL will undertake them on application, or by official order in accordance with the relevant provisions.

2. Surveys relating to the safety of equipment

2.1 For all components with an important safety aspect (e.g. pressure vessels and apparatus etc.), GL will, on application, examine the drawings, carry out

all the necessary surveys, acceptance tests and pres-sure tests and issue the relevant certificates.

2.2 On application, the Society will also perform the subsequent surveys required for pressure vessels and apparatus.

3. Certification

On application, GL will issue an appropriate certi-ficate in respect of diving systems or parts thereof which, while not classified by GL, are built under the survey of and in accordance with the Rules of GL or other recognized rules for the construction of diving systems.

I - Part 5 GL 1998


E

Section 2

Rules for Construction of Diving Systems

A. General Rules and Instructions

1. General

1.1 The following Rules of Construction apply to diving systems which are permanently installed on a ship or similar floating structure and which are classi-fied by GL.

They also apply to diving systems which are classified by GL but which are assembled and installed on a ship or similar floating structure for a limited period as required by the operating conditions.

They likewise apply to diving systems subject to a declaration of class equivalent by GL.

1.2 The hull and engine plant of diving support vessels are subject to GL Rules for the Classification and Construction, Part 0 – Classification and Surveys and Part 1 – Seagoing Ships.

1.3 Designs differing from the Rules of Con-struction may be permitted provided their suitability has been verified by GL and they have been recog-nized as equivalent.

1.4 Diving systems and parts thereof whose de-velopment is based on new principles and which have not yet been sufficiently tested in practical operation require special approval by GL.

1.5 In the case mentioned in 1.3 and 1.4 GL is entitled to require the submission of additional docu-mentation and the performance of special tests.

1.6 GL reserve the right to impose demands additional to those contained in the Rules in respect of all types of systems when such action is necessitated by new knowledge or practical experience or for the purpose of sanctioning departures from the Rules in specially justified cases.

1.7 National regulations existing alongside GL's Rules are unaffected.

1.8 Diving systems conforming to these Rules for Construction also comply with the requirements of the IMO Code of Safety for Hyperbaric Evacuation Sys-tems, Resolution A.831(19) of 23 November 1995.

2. Definitions

For the purpose of these Rules the terms used have the meanings defined in the following paragraphs unless expressly provided otherwise:

2.1 Mating device

The equipment necessary for the connection and dis-connection of a diving bell to a surface compression chamber.

2.2 Breathing gas/breathing mixture

All gases/mixtures which are used for breathing dur-ing diving operations.

2.3 Handling and transfer systems

The plant and equipment necessary for raising, lower-ing and transporting the diving bell between the work location and the surface compression chamber.

2.4 Surface compression chamber

A pressure vessel for human occupancy with means of controlling and monitoring the pressure within the chamber.

2.5 Pressure vessel

A container capable of withstanding an internal work-ing pressure of 1 bar or over.

2.6 Bottle

A pressure container for the storage and transport of gases under pressure.

2.7 Compression chamber

A pressure vessel for human occupancy under pres-sure.

2.8 Areas subject to explosion hazard

Those locations in which an explosive gas-air mixture is continuously present, or present for long periods (zone 0), in which an explosive gas-air mixture is likely to occur in normal operation (zone 1); in which an explosive gas-air mixture is not likely to occur and, if it does, will persist for only a short time (zone 2).

2.9 Fixed system

A diving system installed permanently on ships or floating structures.

I - Part 5 GL 1998

Section 2 Rules for Construction of Diving Systems Chapter 1Page 2–1

A

2.10 Maximum operating depth of the diving system

The depth in metres of seawater equivalent to the maximum pressure for which the diving system is designed.

2.11 Main components of a diving system

Surface compression chamber, diving bell, handling system and fixed gas storage facilities.

2.12 Hyperbaric evacuation system

A system whereby divers under pressure can be safely evacuated from a ship or floating structure to a posi-tion where decompression can be carried out.

2.13 Compact umbilical

A link cable with a protective sheath combining in one assembly the power supply, surveillance and commu-nication lines, the breathing gas and hot water hoses and the hoisting and lowering strength member.

2.14 Life support system

The gas supply, breathing gas system, surveillance system and equipment required to provide a safe envi-ronment for the diving crew in the diving bell and the surface compression chamber under all possible pres-sures and conditions to which they may be exposed during diving operations.

2.15 Category A machinery space

Category A machinery space means spaces and pas-sageways as defined in the 1974 International SOLAS Convention.

2.16 Wet bell

Open submersible device, including accessories, for the carriage of divers at the ambient pressure prevail-ing between a mobile or stationary platform and the underwater site.

2.17 Diving bell

A submersible compression chamber, including its ancillary equipment, for transfer of divers under pres-sure between the work location and the surface com-pression chamber.

2.18 Diving system

The whole plant and equipment necessary for the con-duct of diving operations using transfer under pressure techniques.

2.19 Depth

The pressure, expressed in metres of seawater to which the diver is exposed during a dive or inside a surface compression chamber or diving bell.

2.20 Temporary system

A diving system installed on ships or floating struc-tures for a period not exceeding one year.

2.21 Umbilical

The link between the diving support unit and the div-ing bell which may contain surveillance, communica-tion and power supply cables, breathing gas, and hot water hoses. The strength member for hoisting and lowering the diving bell may be part of the umbilical.

2.22 Living compartment

The part of the surface compression chamber which is intended to be used as the main habitation for the di-vers during diving operations and which is equipped for such purpose.

3. Components of diving systems

Where present, the following components form part of the diving system and are to be designed, constructed and tested in accordance with these Rules:

– Compression chambers

– Wet bells

– Diving bells

– Permanently installed gas bottles

– Pressure vessels

– Pipes, valves, fittings and hoses

– Umbilicals

– Breathing gas systems

– Life support systems

– Diver heating systems

– Sanitary systems

– Communication systems

– Control, automation and locating equipment

– Gas analyzing systems

– Electrical systems and equipment

– Fire prevention, detection and extinguishing equipment

– Compressors

– Gas mixers

– Helium reclaim system

– Handling, transfer and mating systems

– Hyperbaric evacuation system.


Section 2 Rules for Construction of Diving Systems I - Part 5GL 1998

A

4. Documents for approval

4.1 General

4.1.1 Before the start of manufacture, plans and drawings of all components subject to compulsory inspection, to the extent specified below, are to be submitted to Germanischer Lloyd in triplicate.

4.1.2 The drawings must contain all the data neces-sary to check the design and the loading of the equip-ment. Wherever necessary, calculations relating to components and descriptions of the system are to be submitted.

4.1.3 Once the documents submitted have been approved by GL, they become binding on the manu-facturer. Any subsequent modifications require GL's consent before they are implemented.

4.2 Total system

The following documents are to be submitted.

4.2.1 A description of the system together with the essential design data including:

– Diving procedure

– Maximum diving or observation depths, as ap-plicable

– Maximum operating time

– Maximum number of divers per diving bell

– Maximum number of divers in system.

4.2.2 General arrangement drawings of the diving system (block diagrams)

4.2.3 Installation drawings

4.2.4 Foundation drawings showing fixed points

4.2.5 Drawings of supply and disposal systems (water and electricity)

4.2.6 Drawings of consoles showing controls and instrument displays

4.2.7 Test schedule

4.3 Pressure vessels and apparatus

4.3.1 Drawings are to be submitted of pressure vessels and apparatus giving full details for appraising the safety of the equipment.

The information provided shall include the following:

– Application of equipment

– Capacities of individual compartments

– Media contained, together with operating pres-sures and temperatures

– Proposed materials, thermal insulation materials, paints, buoyancy material

– Welding specifications

– Heat treatment

– Manufacturing tolerances

– Non-destructive tests.

4.3.2 Drawings are also to be submitted of individ-ual items of vessel equipment such as:

– Windows, window flanges, retaining rings

– Door leaves and frames

– Bayonet locks

– Coupling clamps

– Integral opening reinforcements

– Supply locks

– Internal facilities.

4.4 Gas supply

4.4.1 Piping diagrams, block diagrams and de-scriptions are to be furnished for the entire gas supply system, including a list of valves and fittings.

4.4.2 Details of the umbilical structure.

4.4.3 Description of proposed cleaning procedure for breathing gas system.

4.4.4 Details of the gas analysis, including an equipment list.

4.4.5 Description of compressors and compressor drives including longitudinal and transverse sectional drawings of the compressors and a workshop drawing of the compressor crankshaft.

4.5 Life support systems

The following documents are to be submitted:

4.5.1 Piping diagrams, block diagrams and descrip-tions of systems and equipment.

4.5.2 Calculations of the cooling and heating re-quirements.

4.5.3 Description and drawings of the water supply and disposal system.

4.5.4 Description and design details of the diver heating system.

4.6 Automation, communications and locating equipment


I - Part 5 GL 1998


A

4.6.1 General arrangement drawings/block dia-grams of control equipment, including lists of meas-uring points.

4.6.2 Equipment list covering sensors, indicating instruments etc.

4.6.3 Drawings and descriptions of electronic com-ponents such as instrument amplifiers, computers and peripheral units.

4.6.4 General arrangement drawings and equip-ment lists for communications systems and signalling equipment.

4.6.5 Arrangement drawing and description of the TV system.

4.7 Electrical equipment


4.7.1 A general arrangement drawing of the electri-cal equipment containing at least the following infor-mation:

– Voltage rating of systems

– Power or current ratings of electrical consumers

– Switchgear, indicating settings for short-circuit and overload protection; fuses with details of current ratings

– Cable types and cross-sections.

4.7.2 The energy balance of the main and emer-gency power supply systems for diving systems with their own generating plant.

4.7.3 Drawings of switchgear and distribution equipment.

4.7.4 Complete documentation for electric motor drives with details of control, measuring and moni-toring systems.

4.7.5 Battery installation drawing with details of battery types, chargers and battery room ventilation.

4.7.6 Details of electrical penetrations through compression chamber walls.

4.7.7 Drawings and descriptions of all electrical components installed in compression chambers.

4.8 Fire protection


4.8.1 A description of the preventive fire protection measures taken.

4.8.2 Details of the fire loads in the system.

4.8.3 Drawings and descriptions of:

– Fire detection system

– Fire extinguishing system(s)

– Fire alarm equipment.

4.9 Handling, transfer and mating systems

4.9.1 A description of the system with details of operating conditions.

4.9.2 Installation drawing.

4.9.3 Construction drawings of:

– Transfer equipment

– Lifting equipment

– Mating equipment

– Substructures of handling gear, including winches.

4.9.4 Detailed drawings of interchangeable compo-nents and fittings.

4.9.5 Drawings of mechanical equipment items such as winches, drives etc.

4.9.6 Piping and instrumentation diagrams of the hydraulic or pneumatic system, as applicable.

4.9.7 Control system diagram and description of safety equipment.

4.9.8 Details or ratings and protection class of electrical appliances.

4.9.9 Details of hoisting and guide ropes.



4.10.1 Description of system

4.10.2 Arrangement drawing

4.10.3 Construction drawing of evacuation system

4.10.4 Drawing of the handling system, including a description of the power supply.

4.11 Wet bells

To be submitted:

4.11.1 System description

4.11.2 Arrangement plan

4.11.3 Construction drawings (bell, handling sys-tem, control platform, gas supply, umbilical, electrical equipment)



A

5. Tests and trials

5.1 General

5.1.1 Diving systems and their ancillary equipment are subject to constructional and material tests as well as to pressure and tightness tests and trials. All the tests called for in the following paragraphs are to be performed under GL supervision.

5.1.2 For series-manufactured parts, test proce-dures other than those prescribed may be agreed with GL provided that they are recognized as equivalent by GL.

5.1.3 Germanischer Lloyd reserves the right to extend the scope of the tests where necessary and also to subject to test those parts for which testing is not expressly prescribed in the Rules.

5.1.4 Parts subject to compulsory inspection are to be replaced with tested parts. The same also applied to spare parts.

5.1.5 After the compression chambers and ancillary equipment have been installed on board, the diving system together with its ancillary plant is to be sub-jected to functional test. All items of safety equipment are to be tested except where an adequate trial has already been performed on the manufacturer's prem-ises in the presence of GL's representatives.

5.1.6 During sea trials the handling system is to be subjected to a test in which the diving bell loaded to its maximum weight is lowered to its maximum op-erating depth. Thereafter, the diving bell is to be in-spected for leaks and the communication system is to be tested.


5.2.1 On completion, pressure vessels and appara-tus are to be subjected to a constructional test.

The constructional test includes verification that the vessel conforms to the approved drawings and that the workmanship is satisfactory. All components must be accessible to allow adequate inspection.

5.2.2 The materials test certificates for the materi-als used and the reports on the non-destructive testing of welds are to be submitted together with the results of inspections of workmanship and evidence of the heat treatments applied, where appropriate.

5.2.3 A hydraulic pressure test is to be performed prior to insulation and preservation treatment of the vessels. Each compression chamber compartment is to be tested individually. The walls may exhibit no per-manent deformation or leakage.

5.2.4 For vessel and apparatus, the test pressure shall normally be equivalent to 1,5 times the maxi-mum permissible working pressure.

5.2.5 Diving bells and vessels which may be ex-posed to an external pressure in service are also re-quired to undergo an external pressure test. The exter-nal test pressure used shall normally be equivalent to 1,3 times the design pressure.

5.2.6 The weight and buoyancy of diving bells are to be measured and their stability in normal and emer-gency operation is to be checked. The release of bal-last weights and the operation of the device for the emergency release of the hoisting rope and the umbili-cal are to be tested in shallow water.

5.2.7 The gas storage facilities, diving system and life support systems including the gas piping are to be subjected to a tightness test at the maximum permissi-ble working pressure using the appropriate breathing gas or a gas mixture with similar properties.

The maximum permissible leakage rate is represented by a 1 % pressure drop in 24 hours for the entire com-pression chamber system.

5.3 Compression chamber windows

5.3.1 Each compression chamber window must undergo a hydraulic pressure test which may be per-formed after installation together with the compres-sion chamber or in a testing device. The test pressure shall normally be equivalent to 1,5 times the design pressure.

5.3.2 After the pressure test windows may exhibit no scratches, cracks or permanent deformations.

5.4 Compressors

5.4.1 Compressor components subjected to pres-sure are to undergo a hydraulic pressure test at a test pressure equal to 1,5 times the delivery pressure of the compressor stage concerned.

5.4.2 On completion, compressors are to be sub-jected to a tightness test at their maximum working pressure. In addition, a performance test is to be car-ried out in which the final moisture content and any possible contamination of the compressed gas are to be determined. The safety devices are to be checked.

5.5 Piping systems

5.5.1 On completion of manufacture but before insulation or painting, all piping systems are to un-dergo a hydraulic pressure test at 1,5 times the design pressure.

5.5.2 For the tightness test, see 5.2.7.

5.5.3 Wherever possible, all butt welds in LSS piping systems are to be subjected to 100 % X-ray test.

5.5.4 Piping systems for breathing gas and oxygen are to be subjected to a purity test.

I - Part 5 GL 1998


A

5.6 Hoses, umbilicals

5.6.1 Evidence of the bursting pressure of each hose type is to be submitted to GL. For liquids, hoses must withstand at least 4 times, and for gases at least 5 times, the maximum permissible working pressure.

5.6.2 Each hose is to be subjected to a hydraulic pressure test at least 2 times the maximum permissible working pressure.

5.6.3 For hoses exposed to external pressure, proof is required that a differential ratio of 1,5 between the internal and external pressures can be withstood with-out failure.

5.6.4 As proof of their mechanical properties, com-pact umbilicals are to be subjected to alternating bend tests and rupture tests.

In addition, compact umbilicals are to undergo a tight-ness test in which all hoses are to be subjected simul-taneously to their maximum permissible working pres-sure and the electrical lines are to be checked for com-pliance with the specified insulation and impedance values.


A functional test is to be carried out to verify the satis-factory functioning of the life support systems under normal and emergency conditions.

5.8 Automation, communications and locating equipment

5.8.1 Indicating and monitoring instruments are to be tested for the accuracy of their readings and their limit value settings.

5.8.2 Automatic control systems are to be checked for satisfactory performance under service conditions.

5.8.3 Normal and emergency communications equipment is to be subjected to a functional test. The effectiveness of the helium speech unscrambler is to be demonstrated for the maximum operating depth of the diving system.

5.8.4 Proof is required of the autonomy of the safety systems.


5.9.1 Electrical machines, components, cables and lines are to be tested in the manufacturer's works in accordance with the Rules for Classification and Con-struction, Part 1 – Seagoing Ships, Chapter 3 – Elec-trical Installations.

5.9.2 All electrical systems and equipment are to be inspected and tested before the diving system is put into service.

5.9.3 Electrical protective devices are to be checked; in addition, an insulation test is to be per-formed on the electrical equipment in the compression chambers.

5.10 Fire protection

5.10.1 The fire behaviour of the chamber equipment is to be checked by reference to the relevant test cer-tificates and symbols, as applicable.

5.10.2 A check is to be made as to whether the elec-trical heating systems and heaters are fitted with pro-tection against overheating.

5.10.3 Fire alarm, detection and extinguishing appli-ances are to be subjected to a functional test.

5.11 Handling, transfer and mating systems

5.11.1 After installation on board, the handling sys-tem is to be loaded statically with a test load equal to 2,2 times the working load. In addition, a dynamic load test (braking test) is to be carried out at 1,25 times the working load.

5.11.2 A test is to be performed to ensure that the mating, release, transfer, lowering and raising of the diving bell proceed smoothly and safely under normal and emergency operating conditions.

5.11.3 A test is to be performed to verify that the mating device can be released and the diving bell transported only when the trunk is not under pressure.


A functional test is to be performed to demonstrate that the hyperbaric evacuation system is able to con-vey divers under pressure from the ship or floating structure to a safe position where they can be moni-tored and supplied.

5.13 Wet bells

During operational trials proofs are to be furnished of:

– Launching and recovery of wet bell under maximum load and, where practicable, down to maximum depths

– Main and emergency breathing gas supply, in-cluding control and monitoring equipment

– Equipment for salvaging divers heaving suffered an accident

– Communication equipment.

6. Marking

6.1 All diving bells and surface compression chambers are to be fitted in a prominent position with a permanently mounted name plate containing at least the following details:

– Name of manufacturer



A

– Serial number and year of manufacture

– Maximum permissible working pressure or operating depth

– Test pressure

– Capacity (in litres) (of each chamber compart-ment)

– Maximum permissible number of divers

– Date of test and test stamp.

6.2 All other pressure vessels and gas bottles are to be prominently and permanently marked with the following details:



– Capacity (in litres)

– Test pressure (bar)

– Empty weight (of gas bottles)


6.3 Permanently installed gas bottles, gas con-tainers and gas piping systems are, in addition, to be marked with a permanent colour code in accordance with Table 2.1 and with the chemical symbol desig-nating the type of gas concerned. The marking of gas bottles must be visible from the valve side.

Table 2.1 Marking of gas systems

Type of gas Chemical

symbol Colour code

Oxygen O2 white

Nitrogen N2 black

Air --- white & black

Helium He brown

Oxygen/ Helium-Gas mixture

O2/He white & brown

6.4 All valves, fittings, controls, indicators and warning devices are to be provided with identification plates made of a material which is at least flame retar-dant. The identifying marks are to be clear and un-mistakable (e.g. stating the short designation and/or the function of the item concerned).

6.5 The handling, transporting and mating appli-ances are to be fitted with a prominent and perma-nently mounted name plate containing at least the following information in easily legible characters:



– Static test load

– Operational test load

– Maximum working load


B. Principles for the Design and Construction of Diving Systems

1. General principles

1.1 Wherever expedient and feasible, diving systems are to be designed and constructed in such a way that failure of any single component cannot give rise to a dangerous situation.

1.2 Diving systems and their components are to be designed to meet the service conditions stated in the specification of the system.

1.3 Diving systems are to be constructed to en-sure that persons under pressure can be safely con-veyed from the surface compression chamber to the underwater work location (and back).

1.4 Diving systems are to be designed and built to ensure safe operation and facilitate proper mainte-nance and the necessary surveys.

1.5 All parts of a diving system are to be de-signed, constructed and mounted in such a way as to facilitate cleaning and desinfection.

2. Environmental conditions

2.1 Diving systems together with their accesso-ries and ancillary equipment are to be designed for the environmental conditions likely to occur at the pro-posed point of installation or work location. As a minimum requirement, allowance is to be made for the following conditions:

2.2 The inclined positions stated in Table 2.2.

2.3 The other environmental conditions stated in Table 2.3.

3. Conditions in chamber

3.1 Diving systems are to be so equipped that a breathable atmosphere can be maintained in surface compression chambers and diving bells throughout the entire operating period.

3.2 Facilities must be provided for keeping the partial pressure of the CO2 in the chamber atmosphere permanently below 0,005 bar assuming a CO2 produc-tion rate of 0,05 Nm3/h per diver.

I - Part 5 GL 1998


B

Table 2.2 Inclined positions

Angle of inclination [°]

Components Athwarthships For-and-aft

static dynamic static dynamic

Compression chambers and other deck installations on ships on semi-submersible

± 15 ± 15

± 22,5 ---

± 5 ± 15

± 10 ---

Diving bells ± 22,5 ± 45 --- ---

Table 2.3 Environmental conditions

Location Temperature Humidity Other conditions

In chambers 5 to 55 °C 100 %

Outside chambers in air 1 2 - 10 to + 55 °C 100 % salty air

Outside chambers in water - 2 to + 32 °C --- salt water containing

3,5 % salt

Control rooms 5 to 55 °C 80 % ---

1 In the case of facilities installed on the open deck, allowance is to be made for icing and temporary inundation with salt water and spray.

2 Other values may be permitted for installation in closed spaces.

In diving bells it must be possible to keep the partial pressure of the CO2 below 0,015 bar as a minimum requirement. Under emergency conditions it must be possible to hold the partial pressure of the CO2 below 0,02 bar for at least 24 h.

3.3 Diving systems using mixed gas and de-signed for operating periods of more than 12 hours at a time must be capable, under steady conditions, of keeping the temperature in the surface compression chamber constant to ± 1 °C in the 27 - 36 °C range while maintaining a relative humidity of at least 50 %.

3.4 Surface compression chambers are to be designed and equipped in such a way that a homoge-neous atmosphere (CO2 and O2 concentrations, tem-perature and humidity) can be maintained in the cham-ber.

3.5 In the steady state, the permanent noise level (over 8 hours) in the living compartment and surface compression chamber may not exceed 65 dB(A).

4. Location

4.1 Diving systems on ships and other floating structures may only be located and operated in areas not subject to an explosion hazard. In exceptional cases, installation subject to special conditions may be permitted in zone 2 as defined in VI – Additional Rules and Guidelines, Part 8 – Electrical Technology,

Chapter 2 – Guidelines for the Explosion Protection of Electrical Equipment.

4.2 As far as possible, the area in which the div-ing system is installed is to be kept free of fire loads.

In addition, only those electrical cables needed to operate the diving system should be routed through this area.

4.3 Diving systems and breathing gas storage facilities may not be located in engine rooms unless the engine plant is connected to the diving system.

4.4 Diving systems and breathing gas storage facilities are to be located in spaces which can be adequately ventilated and provided with suitable elec-tric lighting.

4.5 Where parts of the diving system are located on the open deck, these are to be protected against damage due to other shipboard activities.

5. Chamber equipment and fittings

5.1 The equipment and fittings of surface com-pression chambers and diving bells must be suitable for operation in hyperbaric atmospheres. Under these conditions they shall not give off any toxic or strongly irritant gases. The same also applies to protective coatings and paints used inside the chambers.

5.2 Only incombustible or at least flame retardant materials should be used in the chambers (cf. I.2.2.1).



B

6. Corrosion protection

6.1 Diving systems and all their accessories are to be effectively protected against corrosion.

6.2 Anti-corrosion coatings exposed to the con-ditions within the chambers must conform to the re-quirements stated in 5. In addition, they may not tend to blister of flake under hyperbaric conditions.

C. Pressure Vessels and Apparatus

1. Compression chambers and diving bells

1.1 General

1.1.1 The following Rules are applicable to com-pression chambers and diving bells which are used in diving systems and in which persons live in breathable atmosphere at pressures exceeding atmospheric pres-sure.

1.1.2 The documents to be submitted to GL for approval are listed in A.4.

1.1.3 The necessary tests and markings are stated in A.5. and A.6.

1.2 Design principles

1.2.1 Compression chambers

1.2.1.1 Each compression chamber or compartment thereof is to be so equipped that it is fully protected against excessive working pressures and inadmissible pressure drops.

1.2.1.2 Compression chambers are to be so designed that at least two persons can simultaneously pass in or out through the locks without exposing the other di-vers in the system to a pressure change.

1.2.1.3 In diving systems where divers are required to remain under pressure for a continuous period of more than 12 hours, the living compartment of the compression chamber is to be so designed and equipped that persons are able to stand upright in it and each diver is provided with a bunk on which he is able to stretch out comfortably. A toilet and shower are also to be provided. The toilet and shower are to be accommodated in a separate compartment. Toilet facilities capable of discharging the waste to outside are to be equipped with suitable interlocks to prevent pressure losses in the chamber system.

1.2.1.4 The living compartment of compression chambers and other compression compartments are to be provided with a lock through which provisions, medicines and equipment items can be passed to and for without exposing the occupants of the chamber to a pressure change.

1.2.1.5 Locks are to be designed to prevent acci-dental opening under pressure: if necessary, suitable interlocks are to be fitted.

1.2.1.6 Each compression chamber compartment is to be provided with view ports enabling all occupants to be observed from outside.

1.2.1.7 Wherever necessary, compression chamber windows are to be protected against mechanical dam-age from inside and outside.

1.2.1.8 Each compression chamber compartment is to be adequately lit.

1.2.2 Diving bells

1.2.2.1 Each diving bell is to be so equipped that it is fully protected against excessive working pressures and inadmissible pressure drops.

1.2.2.2 Each diving bell is to be provided with an extra lifting point designed to take the entire dry weight of the bell including ballast and equipment plus the weight of the persons inside the bell.

1.2.2.3 Close to main lift attachment, the diving bell is to be provided with spare connections for hot water (3/4" NPT female thread) and breathing gas (1/2" NPT female thread). The manifold is to be clearly marked and effectively protected.

1.2.2.4 Diving bells are to be designed to allow entry and exit even in an emergency.

1.2.2.5 Diving bells are to be equipped with a device for the recovery of an unconscious diver.

1.2.2.6 The dimensional design of diving bells shall be such as to provide adequate space for the proposed number of divers and their equipment.

1.2.2.7 Seating is to be provided for each diver in the diving bell.

1.2.2.8 Diving bells are to be provided with view ports so that divers working outside the bell can be observed from within the chamber.

1.2.3 Doors and access ports

1.2.3.1 Diving bell hatches and mating devices which are not sealed by pressure are to be fitted with a locking mechanism which precludes opening under pressure. The locking mechanism is to be so designed that the correct closure position is clearly apparent before pressure is applied.

1.2.3.2 Devices are to be fitted to enable doors to be opened from both sides. Hatch trunks are to be fitted with pressure compensating valves.

1.2.3.3 Doors and hatches for persons are required to have a clear opening at least 500 mm in diameter. For diving bell lockout/-in hatches the clear diameter shall be at least 600 mm.

I - Part 5 GL 1998


C

1.2.3.4 The length of the hatch trunk should not ex-ceed the hatch diameter.

1.3 Materials

1.3.1 General requirements

1.3.1.1 The materials for pressure vessels must be suitable for the proposed application and must con-form to the Rules for Classification and Construction, II – Materials and Welding, Part 1 – Metallic Materi-als and Part 2 – Non-metallic Materials. Unless other-wise specified, the stipulated impact energy is to be verified on ISO V-notch specimens at the following test temperatures:

Product thickness Test temperature [°C]

≤ 20 mm > 20 ≤ 40 mm > 40 ≤ 60 mm > 60 mm

0 - 20 - 40

by agreement

1.3.1.2 For parts welded directly to pressure vessel walls, e.g. reinforcing rings, mountings, brackets etc., use is to be made of materials with guaranteed weld-ing properties which are compatible with the base material.

1.3.1.3 Welded structures are also subject to the Rules for Classification and Construction, II –Mate-rials and Welding, Part 3 – Welding.

1.3.1.4 For corrosion protection, see B.6. of these Rules.

1.3.2 Approved materials

The materials stated in Table 2.4 are to be used for compression chambers and diving bells.

1.3.3 Material testing

1.3.3.1 Tests in accordance with the Rules for Clas-sification and Construction, II-Material and Welding Technology, Part 1 and 2, are performed on materials for:

– all walls subjected to pressure with the excep-tion of small parts such as welding lugs, rein-forcing plates, pipe connections and flanges with DN ≤ 32 mm

– forged flanges where the product of PB [bar] DN [mm] is > 2500 or the nominal bore DN is > 250 mm

– screws and nuts of size M 30 and over where made of steels with a tensile strength of more than 500 N/mm2 and for sizes > M 16 in the case of nuts over 600 N/mm2 and screws made of alloy or quenched and tempered steels.

1.3.3.2 For all parts not subject to materials testing by GL, some other proof of the material characteristics such as acceptance test certificates to EN 10204 - 3.1 B is to be supplied.

1.3.3.3 Components such as mountings, brackets and the like which are not subject to materials testing must be manufactured from materials compatible with their application in accordance with good engineering prac-tice.

Table 2.4 Approved materials

Material and product form Types of material in accordance with the Rules for Classification

and Construction, II-Materials and Welding, Part 1, Chapter 2

Steel plates, section and bars Plates of unalloyed steels to Section 1, E. Specially killed steels to Section 1, B. and C. (within inspection of each rolled plate). Austenitic stainless pipes to Section 1, C.

Pipes Seamless and welded pipes of ferritic steels to Section 2, B. and C. Austenitic stainless pipes to Section 2, E.

Forgings Forgings to Section 3, E.

Screws and nuts Screws and nuts to Section 6, C. recognized standards, e.g. DIN 367 or ISO 898

Steel castings To Section 4.

Non-ferrous metals Only with the Society's special consent

The use of materials not mentioned in this Table, e.g. special grain refined structural steels, is subject to the Society's special consent.



C

1.4 Principles of manufacture and construc-tion

1.4.1 Manufacturing processes

The manufacturing processes applied to materials must conform to good engineering practice. Materials whose grain structure has been impaired by hot or cold working are to be heat treated in accordance with Rules for Classification and Construction, II – Materi-als and Welding, Part 1 – Metallic Materials, Chap-ter 2 – Steel and Iron Materials, Section 6, A.

1.4.2 Welding

1.4.2.1 The execution of welds, the approval of welding ships and the testing of welders are subject to the Rules for Classification and Construction, II – Materials and Welding, Part 3 – Welding.

1.4.2.2 Welds are to be executed and inspected in such a way as to warrant the allocation of a weld fac-tor v = 1,0.

1.4.3 Reinforcement of cutouts

Due to allowance is to be made of the weakening of walls by cutouts, and reinforcement is to be provided where necessary (cf. Rules for Classification and Con-struction, Part 1 – Seagoing Ships, Chapter 2 – Ma-chinery Installations, Section 7a, D.

1.4.4 Ends

1.4.4.1 The nuckle area of dished ends shall not be unduly inhibited by fixtures of any kind such as re-straining plates, stiffeners etc. Supporting legs may only be fixed to ends which have been adequately dimensioned for this purpose.

1.4.4.2 Where covers or ends are secured by swing bolts, measures are to be taken to prevent these slip-ping off.

1.4.5 Nozzles

1.4.5.1 The wall thickness of nozzles must be de-signed to withstand safely any additional external loads. The wall thickness of welded-in nozzles shall be compatible with that of the component into which they are welded. The walls must be securely welded together.

1.4.5.2 Pipe connections in accordance with the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations, Section 11 are to be provided for nozzles.

1.4.6 Screws and bolts

1.4.6.1 Stud bolts screwed directly into the wall of a pressure vessel must have within the vessel wall a load-bearing length at least equal to the bolt diameter. Bolt holes shall not perforate the vessel wall.

1.4.6.2 For the testing of screws and bolts, see 1.3.3.

1.4.7 View ports

1.4.7.1 For the purpose of these Rules, view ports are sealed, pressure-tight windows of flat or curved acrylic plastic installed in the walls of surface com-pression chambers or diving bells and used respec-tively for observing the divers in the chamber and at the work location (cf. Appendix B).

1.4.7.2 In the design and construction of view port flanges it is to be borne in mind that the acrylic plastic windows make no contribution to reinforcing the cut-out in the wall of the compression chamber. Where the clear diameter of view port flanges is greater than 350 mm, the permissible radial deformation and the angular tolerances of the window seating are subject to more stringent requirements which are to be agreed with GL in each case.

1.4.7.3 The dimensions of the window seating in the view port flange shall be such as to provide adequate support for the window at maximum working pres-sure. The seating dimensions for various standard windows are specified in Appendix B.

1.4.7.4 For flat windows with a rectangular edge and an O-ring seal, the diameter of the seating in the view port flange is to be within + 0,25/- 0,00 mm of the nominal value; where a flat seal is used the tolerances are + 0,75/- 0,00 mm.

1.4.7.5 With spherical shell windows having a coni-cal seating, the larger diameter of the conical seating in the view port flange shall lie within + 0,002 Do/- 0,000 mm of the nominal value.

The included conical angle of the window seating of the view port flange shall be within + 0,000/- 0,25 degrees of the nominal value.

1.4.7.6 The surface roughness of the window seating shall not exceed 1,5 µm.

1.4.7.7 The window seating must be permanently protected against corrosion (e.g. a corrosion-resistant weld overlay).

1.4.7.8 A soft sealant may be used for the primary seal of standard windows according to Appendix B, Tables 2 and 3. The seal must be thick enough to ab-sorb reasonable deformation without permanent set.

1.4.7.9 For flat windows with a rectangular edge a second seal is required, which is to be stuck to the window seating using contact adhesive. The second seal also acts as the window supporting seal and may not be more than 3 mm thick.

1.4.7.10 Neither the window seating nor the metal flange seat may contain sealing grooves.

1.4.7.11 Retaining rings must be capable of sustaining the necessary initial compression of the window seals.

I - Part 5 GL 1998


C

1.4.7.12 When fitting acrylic plastic windows, care is to be taken to ensure the scrupulous cleanliness of all seating surfaces. The compatibility with acrylic plastic of cleaning agents, window seating greases and adhe-sives for window seals is to be checked before use.

1.5 Calculations

1.5.1 Principles of calculation

1.5.1.1 Pressure vessels, hatches, locks, windows, suspensions etc. are to be calculated in accordance with Germanischer Lloyd Rules (see 2. and Appen-dix B) of other engineering codes, and only the values stated in 1.5.3 are to be regarded as permissible stresses. Diving bells for external pressure are to be calculated according to Appendix A. The collapse loading case is not applicable.

1.5.1.2 The calculations underlying the dimensional design are to be submitted to GL. Where the calcula-tions are to be performed by computer, proof of the suitability of the programs is to be furnished to GL.

1.5.1.3 Load factors for dynamic loads are to be agreed with GL.

1.5.1.4 Allowance is to be made for the fatigue strength of the material. Surface compression cham-bers and diving bells are to be designed for at least 5000 operating cycles.

1.5.1.5 For the efficiency of welds, see 1.4.2.2.

1.5.1.6 The allowance (c) for corrosion and war is normally 1 mm. This allowance may be dispensed with in the case of plate with a thickness of 30 mm and over and with stainless steels and other corrosion-resistant materials.

1.5.1.7 The wall thickness of the casings and ends of seamless and welded vessels should not normally be less than 3 mm. A smaller wall thickness may be agreed for tubular and corrosion-resistant vessel cas-ings.

1.5.2 Design data

1.5.2.1 The design pressure (internal pressure, exter-nal pressure) is to be determined by reference to the system specification. Where applicable, allowance is to be made for additional forces. The design pressure is normally the maximum permissible working pres-sure or the maximum operating depth of the diving system as defined in A.2.10.

1.5.2.2 For pressure vessels subjected to external excess pressure, the calculation is to encompass the following cases:

– Buckling of the unstiffened shell

– Buckling of the shell reinforced with light stiff-eners

– Buckling of the shell reinforced with heavy stiffeners (where applicable, transverse bulk-heads or ends).

The safety factors against elastic buckling are speci-fied in Chapter 2 – Submersibles, Section 4, E.4.

1.5.2.3 For design temperatures, see B.2.3.

1.5.3 Permissible stresses

The lesser of the following two values is applicable:

m,20R

A° where Rm,20°

= guaranteed minimum ten-sile strength [N/mm2] at room temperature (may be dispensed with for es-tablished grain refined steels where ReH ≤ 360 N/mm2)

eH,tR

B° where ReH,t° = guaranteed yield point or

minimum value of 0,2 % proof stress at design temperature

Safety factors A, B see Table 2.5.

Table 2.5 Safety factors

Operation Test Material

A B B‘

Ferritic material Austenitic material Aluminium

2,7 2,7 3,0

1,7 1,7 –

1,1 1,1 1,1

2. Pressure vessels and apparatus and gas bottles

Pressure vessels and apparatus and gas bottles are to be manufactured in accordance with the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations, Section 8.

D. Pipes, Valves, Fittings, Hoses and Umbilicals

1. General

1.1 These Rules apply to piping systems, includ-ing valves and fittings, needed for the operation of the diving system and its ancillary equipment. All other pipelines are to conform to the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations, Section 11.

1.2 The documents to be submitted to GL for approval are listed in A.4.



D

1.3 The necessary tests and markings are stated in A.5. and A.6.

1.4 Pipes are subdivided in three pipe classes in accordance with Table 2.6

2. Design principles

2.1 Piping systems

2.1.1 Piping systems are to be constructed and manufactured on the basis of standards generally used in shipbuilding.

Table 2.6 Classification of pipes into "pipe classes"

Medium carried/ type of line

Design pressure PR [bar]

Air, gas

Lubricating oil

Hydraulic oil

Brine in refrigerating systems

PR > 40

PR ≤ 40

PR ≤ 16

Refrigerants --- all ---

Open-ended lines (with-out shutoff) such as drains, vent lines over-flow lines and blow-off lines

--- --- all

Pipe class I II III

2.1.2 Expansion in piping systems is to be com-pensated by pipe bends or compensators. Attention is to be given to the suitable siting of fixed points.

2.1.3 Means must be provided for the complete evacuation, drainage and venting of pipelines.

2.1.4 Pipelines which may be subjected in service to pressures higher than the design pressure must be fitted with overpressure protection.

2.1.5 Pipe penetrations in the compression cham-bers and diving bells must be fitted with 2 shut-off devices located immediately at the chamber wall. Wherever possible, one of these devices must be a non-return valve.

2.1.6 Suction ends in compression chambers and diving bells are to be protected against inadvertent covering and suction.

2.1.7 Pipelines carrying gas or oxygen under high pressure shall not be routed through accommodation spaces, engine rooms or similar compartments.

2.1.8 Pipelines for mixed gases containing more than 25 % oxygen are to be treated as pure oxygen lines.

2.1.9 Wherever possible, the pressure in oxygen lines is to be reduced at the gas storage facility to a pressure which is still compatible with an adequate gas supply to the diving system.

2.1.10 Gas lines and electrical cables are to be routed separately.

2.2 Pipe connections

2.2.1 Wherever possible, pipes should be joined by full-penetration butt welds.

2.2.2 Screwed pipe connections may only be made using bite joints approved by GL.

2.2.3 Flanged connections may be used provided that the flanges and flange bolts conform to a recog-nized standard.

2.3 Valves and fittings

2.3.1 Shutoff-devices must conform to a recog-nized standard. Valves with screw-down bonnets or spindles are to be protected against unintentional un-screwing of the bonnet.

2.3.2 Manually operated shutoff devices are to be closed by turning in the clockwise direction.

2.3.3 The closed and open positions of functionally important shutoff valves must be clearly indicated.

2.3.4 Oxygen lines may only be fitted with screw-down valves, although ball valves may be used for emergency shutoff at the chamber wall.

2.3.5 Hose fittings are to be made of corrosion-resistant material and are to be so designed that they cannot be disconnected accidentally.

2.4 Hose lines and umbilicals

2.4.1 Except for umbilicals, non-metal hoses are to be reduced to a minimum and are only to be installed in short lengths.

2.4.2 Hose lines, including their connectors, must be of proven suitability for the media, pressures and temperatures concerned. When selecting the material, special attention is to be paid to toxicity, incombusti-bility, gas permeability and, where applicable, to com-patibility with oxygen. Only types approved by GL may be used.

2.4.3 Hose lines for liquids/gases are to be de-signed for a bursting pressure equivalent to at least 4 and 5 times respectively the maximum permissible working pressure.

I - Part 5 GL 1998


D

2.4.4 Hoses are to be permanently coupled to their connectors.

2.4.5 Systems with hose lines are to be fitted with a device for relieving the pressure before the hoses are disconnected.

2.4.6 Unless equipped with load cables, umbilical hose lines must be fitted with load relieving devices.

2.4.7 Umbilicals must be protected against abra-sion and damage. Where protective sheathing is used, care is to be taken to ensure that minor leaks cannot lead to an internal pressure build-up. Metal inserts are to be avoided.

2.4.8 Electrical cables in the umbilical must con-form to the requirements stated in H.

3. Materials

3.1 General requirements

3.1.1 Materials must be suitable for the proposed application and must conform to the Rules for Classi-fication and Construction, II – Materials and Welding, Part 1 – Metallic Materials and Part 2 – Non-metallic Materials.

3.1.2 Welds are to conform to the Rules for Clas-sification and Construction, II – Materials and Weld-ing, Part 3 – Welding.

3.1.3 Materials for breathing gas systems shall not form any toxic or combustible products.

3.1.4 In oxygen systems, only those materials may be used which are approved for use with oxygen and which are suitable for the proposed operating condi-tions.

3.2 Approved materials

3.2.1 Steel

3.2.1.1 Carbon and carbon-manganese steels may be used for pipes, valves and fittings. Pipes belonging to classes I and II must be seamless drawn or produced by a welding procedure approved by GL.

3.2.1.2 For oxygen lines with an operating pressure of more than 40 bar, use is to be made of high-alloy CrNi steels with an aggregate chromium and nickel content of at least 22 %, or of CrSi steels with a chro-mium content of at least 22 %.

3.2.2 Copper and copper alloys

Copper and copper alloy pipes in pipe classes I and II must be seamless drawn pipes which meet the re-quirements of the Rules for Classification and Con-struction, II – Materials and Welding, Part 1 – Metal-lic Materials, Chapter 3 – Non-Ferrous Metals, Sec-tion 2 in respect of ductility, freedom from stress and resistance to hydrogen embrittlement. They may be used for systems carrying oxygen.

3.2.3 Nodular cast iron, cast steel

3.2.3.1 Ferritic nodular cast iron valves and fittings are permitted only in special cases.

3.2.3.2 Cast steel is approved for general application up to design temperatures of 300 °C.

3.2.4 Non-metals

Non-metal pipes, valves and fittings are permitted only in special cases.

3.3 Material testing

3.3.1 For piping systems belonging to class I and II the components listed below are to be subjected to tests in accordance with the Rules for Classification and Construction, II – Materials and Welding, Part 1 – Metallic Materials, Chapter 1 – Principles and Test Procedures, Section 2:

– Pipes, bends, fittings

– Valve bodies and flanges of nominal bore ≥ DN 32:

made of steel, cast steel or nodular cast iron where PB [bar] ⋅ DN [mm] is > 2500 or the nominal bore DN is > 250 mm;

made of copper alloy where PB [bar] ⋅ DN [mm] is > 1500

– Bolts and nuts of M 30 and above made from steel with a tensile strength above 500 N/mm2, 600 N/mm2 for nuts, and bolts made of alloy or quenched and tempered steels of M 16 and above.

3.3.2 For parts not subject to materials testing by GL, proof of quality is to be supplied in some other form e.g. Acceptance Test Certificate in accordance with EN 10204-3.1 B.

3.3.3 Welded joints in pipes of classes I and II are to be inspected in accordance with the Rules for Clas-sification and Construction, II – Materials and Weld-ing, Part 3 – Welding, Chapter 3 – Welding in the Various Fields of Application, Section 4, G.

3.3.4 Valves and fittings in pipe classes I and II are to be subjected to a hydraulic pressure test at 1,5 times the nominal pressure on the manufacturer's premises in the presence of a GL Surveyor. The tightness of the closure is to be tested with air at 0,5 bar and at 1,1 times the nominal pressure.

4. Calculation of pipe wall thickness

4.1 Minimum wall thickness

4.1.1 The minimum wall thicknesses stated in Ta-ble 2.7 are to be adhered to unless the strength calcu-lation demands greater wall thicknesses. Slightly smaller wall thicknesses can be permitted for pipes manufactured to a recognized standard.



D

4.1.2 Where it is proposed to use smaller wall thicknesses, elasticity calculations are required to prove that the permissible stresses specified in 4.3 are not exceeded when allowance is made for the internal excess pressure, deformations of the ship's hull, ther-mal expansion and the effect of the dead weight of the pipelines.

4.2 Calculation of pipe wall thicknesses

4.2.1 The following formula is applicable to the calculation of the wall thicknesses of cylindrical pipes and bends subjected to internal excess pressure:

s = so + c + b [mm] (1)

so = c

zul c

da p

20 v p

⋅⋅σ ⋅ +

[mm] (1a)

s [mm] = minimum wall thickness

so [mm] = calculated wall thickness

da [mm] = (nominal) outside diameter of pipe

pc [bar] = design pressure

σzul [N/mm2] = permissible stress

b [mm] = allowance for bends

v = weld efficiency factor

c [mm] = corrosion allowance

4.2.2 In the case of straight cylindrical pipes which are to be bent, an allowance b is to be made for the bending of the pipes. The value of b shall be such that the stress due to the bending of the pipe does not ex-ceed the permissible stress σzul. The allowance b can be calculated as follows:

b = 0,4 ⋅ ao

ds

R⋅ (2)

R [mm] = radius of bend

4.3 Permissible stress σzul

4.3.1 Steel pipes

The smallest of the following values is to be substi-tuted for the permissible stress σzul in formula (1a):

For design temperatures of ≤ 350 °C

m,20R

A° where Rm,20°

= guaranteed minimum tensile strength at room temperature

eH,tR

B where ReH,t

= guaranteed minimum yield point at design temperature

p0,2, tR

B where Rp02,t

= minimum value of 0,2 % proof stress at design temperature

For pipelines for which

– a detailed stress analysis recognized by GL is available and

– whose material has been tested by GL may, on application, approve the substitution of value of 1,5 for the safety factor B (for A and B, see Ta-ble 2.8).

4.3.2 Pipes of metals without a clear yield point

Table 2.9 is applicable to materials without a clear yield point. For other materials, the permissible stress is to be agreed with GL subject to the requirement that

m, tzul

R

4σ ≤

where Rm,t is the minimum tensile strength at design temperature.

Table 2.7 Minimum pipe wall thickness s [mm]

Outside diameter of pipe

da [mm] Steel Austenitic steels Copper Copper alloys

8 – 10 12 – 20 20 – 44,5 50 – 76,1 88,9 – 108

1,6 1,8 2,0 2,6 2,9

1,0 1,2 1,6 2,0 2,3

1,0 1,2 1,5 2,0 2,5

0,8 1,0 1,2 1,5 2,0

I - Part 5 GL 1998


D

Table 2.8 Factors A and B for determining the permissible stress σzul

Pipe class I II, III

Material A B A B

Unalloyed and alloyed carbon steel

2,7 1,6 2,7 1,8

Stainless rolled and forged steel

2,4 1,6 2,4 1,8

Steel with σs,20°1

> 400 N/mm2 3,0 1,7 3,0 1,8

Nodular cast iron --- --- 5,0 3,0

Cast steel 3,2 --- 4,0 ---

1 Minimum yield point or minimum 0,2 % proof stress at 20 °C.

4.4 Design temperature

The design temperature is the maximum temperature of the medium carried.

4.5 Weld efficiency factor v

4.5.1 For seamless pipes v = 1,0.

4.5.2 For welded pipes, the value of v shall be that determined by GL's qualification test.

4.6 Corrosion allowance c

4.6.1 The value substituted for the corrosion allow-ance c shall be that shown in Table 2.10. With GL's consent, the corrosion allowance for steel pipes with

effective corrosion protection, may be reduced, though not by more than 50 %.

4.6.2 With GL's consent, the corrosion allowance may be dispensed with in the case of pipes made of corrosion-resistant materials (e.g. austenitic steels and copper alloys).

4.7 Tolerance allowance t

The negative wall thickness tolerances allowed by pipe manufacturer's supply specifications are to be added to the calculated wall thickness (so) as the stated tolerance allowance (t). This allowance can be calculated as follows:

oa

t s100 a

= ⋅−

[mm] (3)

a [%] = negative wall thickness tolerance

so [mm] = wall thickness calculated in accordance with 4.2.1.

E. Compressors

1. General

1.1 These Rule apply to compressors, including valves, used in diving systems for compressing breath-ing gases.

Where the compressors are electrically driven, the motors and other electrical equipment must comply with the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Instal-lations.

Table 2.9 Permissible stress σzul for copper alloys (material condition soft annealed) 1

Pipe material Minimum

tensile stress

Permissible stress σzul [N/mm2]

[N/mm2] 50 °C 75 °C 100 °C 125 °C 150 °C 175 °C 200 °C

Copper 215 41 41 40 40 34 27,5 18,5

Aluminium brass CuZn20Al

325 78 78 78 78 78 51 24,5

CuNi10Fe CuNi10Fe

275 68 68 67 65,5 64 62 59 Copper-Nickel- alloys CuNi30Fe 365 81 79 77 75 73 71 69

1 For other material conditions higher strength values may be permitted.



E

Table 2.10 Corrosion allowance c for carbon steel pipes

Nature of pipe system Corrosion allowance c [mm]

Compressed air 1

Fresh water 0,8

Seawater 3,0

Hydraulik oil 0,3


1.3 The necessary tests are stated in A.5.


2.1 Compressors are to be designed for the re-quired delivery rates, types of gas and delivery pres-sures.

2.2 Compressors are to be so designed that no lubricating oil can penetrate the gas circuit.

2.3 Compressors are to be so installed that no harmful gases can be sucked in.

2.4 Where a compressor is used for the divers' air supply, a receiver must be interposed for the compen-sation of pressure variations.

2.5 Oxygen compressors are to be installed in separate spaces with adequate ventilation.

3. Materials

3.1 The materials of compressor parts must be suitable for the application concerned. They are to be specified with due attention to the operating condi-tions and the nature of the gas. Rules for Classification and Construction, II – Materials and Welding, Part 1 and 2 are to be complied with. Compliance with the Oxygen Safety Regulations (UVV-Sauerstoff-VBG 62) is also required in the case of oxygen compres-sors.

3.2 Proof is to be furnished of the quality of the materials used for all components under pressure.

3.3 A materials test is to be performed on the crankshafts of reciprocating compressors with a cal-culated crank pin diameter of more than 50 mm.

Finished shafts are to undergo magnetic particle in-spection.

4. Equipment

4.1 Compressors must be equipped with ade-quately designed suction filters, coolers and water separators.

4.2 Each compressor stage must be equipped with a pressure relief valve or rupture disc, neither of which can be disabled. This safety device must be designed and set in such a way that the specified pres-sure in the compressor stage concerned cannot be exceeded by more than 10 %. The setting must be safeguarded against unauthorized alteration.

4.3 Each compressor stage must be provided with a suitable pressure gauge indicating clearly the final pressure of that stage.

4.4 Where a compressor stage comprises more than one cylinder and each cylinder can be closed off individually, a pressure relief valve and a pressure gauge must be provided for each cylinder.

4.5 Cooling liquid systems with a shutoff device must be so designed that the specified coolant pressure cannot be exceeded.

4.6 Dry-running reciprocating compressors must be equipped at each stage with a device which acti-vates a warning signal and shuts down the drive motor if the final compression temperature stated in the oper-ating instructions is exceeded.

4.7 Diaphragm-type compressors must be equipped at each stage with a diaphragm rupture indi-cator which shuts down the compressor as soon as damage occurs to the drive or compressor diaphragm.

5. Marking

A manufacturer's data plate containing the following details must be permanently fixed to each compressor:

– type designation

– manufacturer's name

– serial number

– year of manufacture

– capacity

– delivery pressure

– revolutions per minute

F. Life Support Systems

1. General

1.1 These Rules apply to all those plant compo-nents and parts which are needed to ensure life support

I - Part 5 GL 1998


F

and a safe environment for the occupants of a diving system.



2. Gas supply

2.1 Gas storage facilities

2.1.1 Each diving system is to be provided with a permanently installed gas storage facility or with a suitable place for the storage of portable gas contain-ers.

2.1.2 The capacity of the gas store shall be such that, for all the planned diving operations, a sufficient number and quantity of gas mixtures are available to supply all the compression chambers, diving bells and divers with an adequate quantity of the correct gases at all operating depths and under normal and emergency conditions (for determining the minimum quantities of gas required, see European Diving Technology Com-mittee: Guidance Notes for Safe Diving, Appendix 2 to Chapter 5, p. 70, Oct. 1984).

2.1.3 The gas supply for the provision of emer-gency breathing gas is to be stored separately in bot-tles which must not be opened for normal operation.

2.1.4 The diving bell is to be provided with its own bottles so that the occupants of the chamber can in an emergency be supplied with a sufficient quantity of breathing gas mixture for at least 24 hours at the maximum operating depth. An oxygen bottle for sup-plementing the oxygen supply is also to be carried on the diving bell.

2.1.5 Oxygen bottles are to be placed in well ven-tilated positions and may not be stored close to com-bustible materials.

2.1.6 Spaces in which oxygen is stored must be separated from the adjoining spaces by bulkheads and decks of Type "A"-60 and must be arranged to facili-tate speedy exit in case of danger.

2.2 Gas distribution

2.2.1 General

2.2.1.1 The gas supply is to be designed so that a pressure increase up to 2 bar in the living compart-ment of the compression chamber can be effected at a rate of at least 2 bar/min followed by a rate of 1 bar/min.

2.2.1.2 The gas venting system is to be designed so that the pressure in a compression chamber or diving

bell can be reduced to 1 bar at a rate of at least 1 bar/min.

2.2.1.3 Sets of breathing apparatus which, activated by respiration, supply breathing gas to persons ex-posed to excess pressures and also remove exhaust gas independently of the chamber atmosphere are to be designed for a gas flow equal to 3 times the required breathing rate per minute (AMV).

The required breathing rate per minute depends on the proposed activity and the environmental conditions.

When designing the supply and exhaust facilities for breathing masks, the number of persons simultane-ously connected to the system is to be allowed for as follows:

Number of persons Quantity of breathing gas

[operating litres/min]

1 2 3 4 5 6 7 8

z > 8

1 x AMV x 3 2 x AMV x 1,8 3 x AMV x 1,6 4 x AMV x 1,4 5 x AMV x 1,3 6 x AMV x 1.2 7 x AMV x 1,1 8 x AMV x 1,1 z x AMV x 1,0

2.2.1.4 The gas circulating systems are to be so de-signed that the chamber conditions stated in B.3. are maintained.

2.2.1.5 Each compression chamber compartment and each diving bell is to be equipped with at least the following gas systems:

– 2 independent gas supply systems for compres-sion which may deliver into a single inlet pipe immediately at the chamber

– 1 chamber exhaust gas system

– 1 built in breathing systems (BIBS)

– 1 mask exhaust gas system

– 1 gas circulating system for maintaining the breathable chamber atmosphere.

Where pure oxygen or gas containing more than 25 % O2 by volume is supplied to the chamber, a separate piping system is to be provided for this purpose.

2.2.1.6 Valves in gas systems are to be so arranged that a valve leakage cannot lead to an unintended mixture of gases and oxygen or oxygen-like gas can-not penetrate into lines intended for other gases. Inter-sections between oxygen and non-oxygen systems are to be isolated by twin shutoffs with venting valves in between.



F

2.2.1.7 Filters and automatic pressure reducers are to be so arranged that they can be dismounted without interrupting vital gas supplies.


2.2.2.1 At least one breathing mask is to be provided for each occupant inside each separately pressurized chamber compartment.

2.2.2.2 The masks are to be connected to the mask gas supply and exhaust gas system either permanently or by plug and socket connectors.

2.2.2.3 The exhaust gas (exhalation line) side of the masks is to be protected against any inadmissible pres-sure drop or inadmissible pressure difference.

2.2.2.4 The supply of gas to the chamber is to be arranged so as to ensure a homogeneous gas distribu-tion inside the chamber is achieved as quickly as pos-sible.

2.2.3 Diving bells

2.2.3.1 Besides their normal breathing gas supply diving bells and divers in the water must also carry an independent reserve gas supply.

2.2.3.2 The supply of breathing gas to the diving bell is to be designed in such a way that, should the diving bell umbilical fail, the reserve chamber supply can be switched manually or automatically to the divers with-out flowing back into the chamber umbilical.

2.2.3.3 The divers' umbilical system is to be so de-signed that each diver has his own independent sup-ply.

2.2.3.4 In the diving bell at least one breathing mask is to be provided for each diver, and this must be con-nected to both the normal and the reserve gas supply. Divers' masks and helmets with a gas supply may be recognized as breathing masks.

2.2.3.5 Automatic pressure reducers are to be pro-vided for the breathing masks.

2.2.3.6 The emergency oxygen supply is to be fitted with a dosage system to enable the oxygen in the div-ing bell to be maintained at the correct partial pres-sure.

2.2.3.7 The diving bell is to be equipped with two independent exhaust gas lines, which must be ar-ranged to avoid flooding of the electrical equipment. An exhaust gas valve is to be mounted close to the divers' exit.

2.3 Conditioning of chamber atmosphere

2.3.1 Each compression chamber living compart-ment is to be equipped with an oxygen dosing device and a chamber gas circulating unit in which the CO2 can be absorbed and the air temperature and humidity

can be regulated. The rate of circulation shall be such as to satisfy the conditions stated in B.3.

2.3.2 Each diving system is to be equipped with at least 2 chamber gas treatment units so arranged that they can be switched to adjacent chambers.

2.3.3 Diving bells are to be equipped with a cham-ber gas treatment unit and also with an autonomous reserve CO2-absorption unit for emergency use.

2.3.4 Diving bells are to be equipped with a heat-ing system provided with redundant supplies and so designed that the divers in the diving bell and in the water are maintained in a thermal balance. For diving operations at depths greater than 100 m breathing gas preheaters are also to be provided for the divers in the water.

2.3.5 Measures are to be taken to enable the divers within the diving bell to be maintained in a safe ther-mal balance for at lest 24 hours in an emergency.

2.4 Breathing gas treatment and mixing

The use of closed breathing gas circuits, gas mixing systems for direct breathing gas supply and helium reclaim systems requires GL's approval.

3. Control and instrumentation

3.1 Central control position

3.1.1 Diving systems are to be so arranged and equipped that centralized control of the safe operation of the system can be maintained under all weather conditions.

3.1.2 For monitoring and controlling the diving system, a central control position is to be provided at which all important data relating to the chambers and the operating states of the ancillary equipment are displayed and where the chamber pressures can be controlled and the gases distributed to the various chambers.

3.1.3 At the Central Control Position are to be grouped all the controls needed for the operation of the diving system, including the TV monitoring and communications equipment.

3.1.4 Only those items of equipment may be in-stalled at the Central Control Position which are es-sential to the operation of the diving system and do not impair its surveillance and control.

3.1.5 The Central Control Position is to be sepa-rated from the other spaces in the ship or floating structure by bulkheads and decks of type "A"-60.

3.1.6 The Central Control Position is to be equipped with a separate ventilation system, the intake duct of which must be routed from an area not subject to an explosion hazard.

I - Part 5 GL 1998


F

3.2 Instrumentation

3.2.1 Indicating instruments

3.2.1.1 Instruments for the surveillance, control and operation of the diving system are to be grouped and arranged in the Central Control Position in accordance with the principles of safety technology and ergonom-ics.

3.2.1.2 The Central Control Position is to be equipped with suitable instruments for the surveillance of each manned compression chamber compartment and each diving bell (cf. Table 2.11).

3.2.1.3 The instrument indicating the pressures in compression chambers and diving bells must be accu-rate to ± 0,3 % of the whole scale with a maximum deviation of 30 cm water column. All other pressure readings shall be accurate to ± 1 % of the whole scale.

3.2.1.4 The Central Control Position is also to be equipped with indicating instruments for the following parameters:

– pressure of connected breathing gas receiv-ers/bottles

– pressure downstream of pressure reducers

– oxygen content in supply lines to:

umbilical

chamber compartments

breathing masks in chambers

3.2.1.5 Inadmissible deviations from the reference values of the vital parameters shall actuate a visual and audible alarm at the Central Control Position. Automatically actuated switching operations in the gas supply system and similar functions shall also trip such alarm.

3.2.1.6 The compartments of compression chambers are to be fitted with pressure and temperature gauges which can be read from inside.

Diving bells are to be equipped with instruments indi-cating the internal and external pressure and the pres-sure of the independent gas supply. In addition, the diving bell is to be equipped with an autonomous unit for monitoring the oxygen and CO2 levels.

3.2.1.7 Pressure gauges connected directly to the compression chamber system are to be fitted with a shutoff valve.

3.2.2 Analyzing equipment

3.2.2.1 Each diving system is to be equipped with at least one oxygen and one CO2 analyzing system.

3.2.2.2 Throughout the entire operating period, the oxygen analyzing system must give a reading accurate to ± 0,015 bar partial oxygen pressure.

3.2.2.3 Throughout the entire operating period the CO2 analyzing system must give a reading accurate to ± 0,001 bar partial CO2 pressure.

3.2.2.4 In addition, autonomous instruments for monitoring the oxygen and CO2 levels are to be pro-vided in diving bells and the living compartments of compression chambers.

3.2.2.5 Where gases other than air, helium-oxygen mixtures or He/N2/CO2 mixtures are used for diving operations, the instrumentation required shall be agreed with GL in each case.

3.2.2.6 A system is to be provided for analyzing the chamber atmosphere for impurities such as CO, NO, NOx and hydrocarbons. Test tubes may be recognized for this purpose.

3.3 Control equipment

3.3.1 The Central Control Position is to be fitted with controls fore at least the following functions:

– pressurization and pressure control for each compression chamber compartment capable of independent operation and for each diving bell

Table 2.11 Operating parameters to be monitored

Parameter Compression chamber

compartments Diving bell

Pressure or depth 1 X X 2

Temperature 1 X

Humidity X

O2 partial-pressure 1 X X

CO2-partial pressure X X

1 These parameters are to be displayed continuously. 2 The pressure or depth inside and outside the diving bell are to be indicated.



F

– decompression of each compression chamber compartment capable of independent operation and of each diving bell

– pressure equalization between chamber com-partments

– supply of oxygen to the chamber compartments

– control of gas supply to breathing masks

– control of temperature and humidity in com-pression chambers

3.3.2 To the gas distribution control position is to be fitted a mimic diagram showing the functions of the various valves and the different gas lines in colour.

G. Automation, Communication and Locating Equipment

1. General

1.1 The following Rules supplement the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations and Chapter 4 – Automation and are to be applied to the construction and use of surveillance, control, commu-nications, TV monitoring and locating equipment in diving systems holding GL class.

1.2 The documents to be submitted to GL are listed in A.4.

1.3 The necessary tests and markings are stated in A.5. and A.6. Only components and units approved by GL may be used.

2. Automation equipment


2.1.1 All equipment for the automatic surveillance and control of diving system operating parameters is to be designed and constructed so that it works prop-erly under the design and environmental conditions specified for the diving system.

2.1.2 All items of surveillance and control equip-ment are to be clearly inscribed and identified.

2.1.3 Indicating instruments and synoptic displays are to be designed and inscribed in such a way that they can be read quickly and clearly.

2.1.4 Any fault or failure which may occur in the automation system shall not provoke a critical operat-ing condition in the compression chamber or diving bell.

2.1.5 As far as possible, automation equipment is to be safeguarded against faulty operation.

2.1.6 Automation equipment must be compatible with the operating conditions of the diving system.

2.1.7 Any inadmissible variations in the operating parameters must actuate an automatic /visual and audible) alarm at the Central Control Position. The same shall also occur in the event of automatic switch-ing operations in the gas and power supply systems or faults in the control and surveillance system.

2.1.8 In addition to electronic control and surveil-lance equipment, independent safety devices must be fitted which prevent a fault in one system from pro-voking an improper response in another system.

2.1.9 Automatic surveillance and control equip-ment must be capable of being switched to manual operation at all times.

2.1.10 The response values of automation equipment must be so coordinated with each other that, when a threshold is reached, a warning is initiated, followed, after a certain warning period or if the process variable continues to change at a preset speed, by the actuation of safety devices.

2.1.11 The integral operation of automation systems must be designed to take account of the lags and time constants of the units and elements making up the system (e.g. by allowing for the length and cross-sec-tion of piping systems and the response times of gas analyzers).

2.1.12 It must be possible to check the function of important indication lamps during operation.

2.2 Construction

2.2.1 Electronic automation systems should com-prise easily replaceable assemblies, of the plug-in type wherever possible. Standardization of units is to be encouraged and the number of assembly types is to be kept small in order to minimize the spare parts inven-tory.

2.2.2 Plug-in cards must be clearly marked or coded to prevent inadvertent confusion.

2.2.3 Measures must be taken to prevent condensa-tion inside electronic units, even when switched off. Shutdown heating is recommended.

2.2.4 Wherever possible, automation equipment should be capable of operation without forced ventila-tion. Any cooling system used is to be monitored.

2.2.5 Components must be effectively secured. Any mechanical loading of wires and soldered con-nections due to vibration or jolting is to be reduced to a minimum.

2.2.6 The construction of systems and units is to be simple and straightforward. Good accessibility is to be ensured to facilitate measurements and repairs.

I - Part 5 GL 1998


G

2.3 Circuitry

2.3.1 Signalling equipment and control systems with a safety function must be designed on the fail-safe principle, i.e. faults due to short-circuit, earthing or circuit breaks shall not be capable of provoking situations hazardous to personnel and/or the system. In this respect, it is to be assumed that faults occur sin-gly.

The failure of one unit, e.g. due to short-circuit, shall not result in damage to other units.

2.3.2 In stored-program control systems, the elec-trical characteristics of the signal transmitters shall conform to the safety requirements for instruction and control devices. This means principally

– activation at H level, i.e. by energization across NO contacts

– deactivation at L level, i.e. by deenergization across NC contacts

The requirements of 2.3.1 are unaffected.

2.3.3 Instruction and control units for safety func-tions, e.g. emergency stop buttons, shall be independ-ent of stored-program control systems and shall act directly on the output unit, e.g. the STOP solenoid.

2.3.4 Stored-program control systems should be reactionless and, in case of fault, should cause no malfunctions in program-independent safety interlocks or stepped safety circuits for fixed subroutines.

2.3.5 Freely accessible potentiometers and other units for equipment trimming or operating point set-tings must be capable of being locked in the operation position.

2.3.6 Interfaces with mechanical switchgear must be so designed that the operation of the system is not adversely affected by contact chatter.

2.3.7 Conductive tracks forming part of circuits which extend outside the enclosure housing the circuit boards must have qualified short-circuit protection, i.e. in case of an external short-circuit only the safety devices provided may respond without destroying the conductive tracks.

2.3.8 The equipment shall not be damaged by brief overvoltages in the ship's power supply, due for exam-ple to switching operations. The design is to allow for overvoltages equal to approximately 2,5 times the rated voltage and lasting 1 ms.

Where systems are supplied by static converters, it may be necessary to make allowance for periodic voltage pulses lasting about 0,5 ms. The pulse ampli-tude depends on the converter type and is to be inves-tigated in each case.

2.4 Power supply

2.4.1 Mains units for automation equipment must contain at least one short-circuit protection and one overload protection device.

2.4.2 The reference conductor system is to be de-signed to preclude circuit breaks as far as possible. This may, for example, be achieved by duplicating exposed reference conductor joints and connections.

2.4.3 Automation equipment must be capable of reliable operation under the conditions of voltage and frequency variation stated in the Rules for Classifi-cation and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations, Section 3.

2.5 Tests

Automation equipment of novel design must have been type-tested by GL.

The nature and scope of the type-test will be deter-mined by GL in each case.

3. Communication equipment

3.1 Voice communication systems

3.1.1 Diving systems are to be equipped with a suitable communication system providing direct voice communication between the control stand and

– divers in water

– diving bell

– each compartment of the chambers

– diving system handling position

– dynamic positioning room

– bridge, ship's command centre or drilling floor

3.1.2 In diving systems using helium, gas mixtures, each compression chamber compartment and the div-ing bell are to be connected to a speech unscrambler. The unscrambling devices should be designed to achieve maximum noise suppression and the auto-matic compensation of sound level fluctuations.

3.1.3 It is recommended that the Central Control Position should be equipped to record all voice com-munications with the divers.

3.1.4 Voice communications between the compres-sion chamber compartments and the Control Position and between the diving bell and the Control Position must be provided by a communication system with loudspeaker which is permanently switched to "Re-ceive" on the control console. Switches for reversing the direction of communication must be of the self-resetting type. In addition, each compression chamber compartment is to be provided with at least one head-set.



G

3.1.5 A telephone link independent of the mains power supply must also be provided in addition to the communication system specified in 3.1.4.

3.1.6 Electrically powered voice communication systems shall be provided with a reliable power sup-ply. This normally means that the equipment shall be supplied from a storage battery with a parallel con-nected mains unit and battery charger supplied with energy in accordance with H.

3.1.7 In wet rooms microphone and receiver sys-tems must be constructed to prevent the penetration of water. Where considerations of design render this impossible, the penetration of water shall not perma-nently impair the serviceability of the equipment.

3.1.8 Microphone and receivers in diver's masks and helmets are to be functionally separated from each other.

3.2 Television surveillance equipment

3.2.1 Diving bells are to be equipped with an inde-pendent underwater communication systems for use in emergencies.

3.2.2 Suitable alternative communication equip-ment (e.g. a 3-button signalling system) is to be pro-vided in all compression chamber compartments and in the diving bell.

3.3 Other signalling systems

3.3.1 Diving bells are to be equipped with an inde-pendent underwater communications system for use in emergencies.

3.3.2 Suitable alternative communications equip-ment (e.g. a 3-button signalling system) is to be pro-vided in all compression chamber compartments and in the diving bell.

4. Emergency location and communication

4.1 Emergency locating equipment

Subject to the IMO Code of Safety for Diving Sys-tems, Resolution A.831(19) of 23 November 1995, each diving bell is to be equipped with an emergency locating device with a frequency of 37,5 kHz designed to enable contact to assist personnel on the surface in establishing and maintaining contact with the sub-merged diving bell, if the umbilical to the surface is severed. The device should include the following components:

4.1.1 Transponder

4.1.1.1 The transponder should be provided with a pressure housing capable of operating to a depth of at least 200 m containing batteries and equipped with salt water activation contacts. The batteries should be of the readily available "alkaline" type and, if possi-

ble, be interchangeable with those of the diver and surface interrogator/receiver.

4.1.1.2 The transponder should be designed to oper-ate with the following characteristics:

common emergency reply frequency

37,5 kHz

individual interrogation frequency

– channel A – channel B

38,5 ± 0,05 kHz 39,5 ± 0,05 kHz

receiver sensitivity + 15 dB referred to 1µ bar

minimum interrogation pulse width

4 ms

turnaround delay 125,7 ± 0,2 ms

reply frequency 37,5 ± 0,05 kHz

interrogation rates:

– more than 20 % of battery life remaining

– less than 20 % of battery life remaining

once per second

once per 2 seconds

minimum transponder output power

85 dB referred to 1 µ bar at 1 m

minimum transducer polar diagram

- 6 dB at ± 135° solid angle, centred on the transponder vertical axis and transmitting towards the surface

minimum listening life in water

10 weeks

minimum battery life re-plying at 85 dB

5 days

4.1.2 Diver-held interrogator/receiver

4.1.2.1 The interrogator/receiver should be provided with a pressure housing capable of operating to a depth of at least 200 m with pistol grip and compass. The front end should contain the directional hydro-phone array and the rear end the 3-digit LED display readout calibrated in metres. Controls should be pro-vided for "on/off receiver gain" and "channel selec-tion". The battery pack should be of the readily avail-able "alkaline" type and, if possible, be inter-changeable with that of the interrogator and trans-ponder.

4.1.2.2 The interrogator/receiver should be designed to operate with the following characteristics:

common emergency reply frequency

37,5 kHz

I - Part 5 GL 1998


G

individual interrogation frequencies:

– channel A – channel B

38,5 kHz 39,5 kHz

minimum transmitter out-put power

85 dB referred to 1 µ bar at 1 m

transmit impulse 4 ms

directivity ± 15°

capability to zero range on transponder

maximum detectable range more than 500 m

4.2 Emergency communication

In addition to the communication systems referred to above, a standard bell emergency communication tapping code should be adopted, as given below, for use between persons in the bell and rescue divers.

A copy of this tapping code should be displayed inside and outside the bell and also in the dive control room.

Tapping code Situation

3.3.3 Communication opening procedure

1 Yes or affirmative or agreed

3 No or negative or disagreed

2.2 Repeat please

2 Stop

5 Have you got a seal?

6 Stand by to be pulled up

1.2.1.2 Get ready for through water trans-fer (open your hatch)

2.3.2.3 You will not release your ballasts!

4.4 Do release your ballast in 30 min-utes from now!

1.2.3 Do increase your pressure

3.3.3 Communication closing procedure

H. Electrical Equipment

1. General

1.1 The following Rules supplement the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations and are to be applied to the construction of diving systems hold-ing GL class.




2.1 General principles

2.1.1 All electrical systems and equipment are to be constructed and installed in such a way that they are serviceable and perform satisfactorily under the design conditions specified for the diving system.

2.1.2 Provision must be made for maintaining the diving system in a normal operating condition without recourse to the emergency power supply.

2.1.3 Even under emergency conditions, the opera-tion of equipment important to the divers' safety must be guaranteed.

2.1.4 Measures must be taken to exclude any elec-trical hazards either to divers or to personnel operating diving systems.

2.2 Materials and insulation

2.2.1 The materials used in the construction of electrical machines, cables and apparatus must be resistant to moist and salty sea air, seawater and oil vapours. They may not be hygroscopic and must be flame-retardant and self-extinguishing. In addition, materials installed inside compression chambers and diving bells must be approved for operation in hyper-baric atmospheres and shall not liberate toxic gases or fumes under these conditions.

2.2.2 Materials with high tracking resistance are to be used for the supports of live parts.

Leakage paths and air gaps are to be calculated in conformity with IEC rules.

2.2.3 Materials and insulations for electrical equipment used in water are to be agreed with GL in each instance.

2.3 Supply systems

2.3.1 Approved supply systems are:

– direct current and single-phase alternating cur-rent:

2 conductors insulated from ship's hull

– three-phase alternating current: 3 conductors insulated from ship's hull

2.3.2 The use of the diving system, the ship's hull or parts thereof for the return of electrical current is not permitted.

2.3.3 Systems earthing is not permitted.



H

Exceptions may be allowed in the case of subsystems using isolating transformers and high-resistance sys-tems earthing.

2.4 Maximum permissible operating voltages

2.4.1 The following maximum voltages are per-mitted for electrical equipment inside compression chambers (only in dry chamber compartments):

– for permanently installed electrical drives and heating systems: 250 V rms

– for lighting networks and socket circuits, com-munications and display equipment and all con-sumers supplied via cables not permanently in-stalled: 30 V rms

2.4.2 30 V is the maximum permissible voltage for all electrical equipment in diving bells and wet cham-bers.

2.4.3 Voltages higher than those stated in 2.4.1 and 2.4.2 may be approved where additional safety meas-ures are taken which afford an equivalent level of safety.

2.4.4 The permissible voltages for electrical equipment used in water are to be agreed with GL in each case.

2.5 Protective measures

2.5.1 All electrical equipment is to be protected in accordance with the Rules for Classification and Con-struction, Part 1 – Seagoing Ships, Chapter 3 – Elec-trical Installations, Section 1.

2.5.2 To protect divers against excessive contact voltages and electric shock, additional safety measures are to be taken to avoid or restrict dangerous fault currents. These measures are to be agreed with GL in every distance.

3. Power supply

3.1 Principles

3.1.1 All electrical equipment important to the safety of divers and diving operations is to be con-nected to a mutually independent main and emergency power supply.

3.1.2 Where provision is made for automatic switching from the main to the emergency power supply, each such switching operation must actuate in the diving system control room a (visual and audible) signal requiring acknowledgement. An indicator must show which supply is connected.

3.1.3 The main power supply to the diving system can be taken direct from the main switchboard of the support vessel or from the main power source of the diving system.

3.1.4 The following may be used as an independent emergency power source:

– an electrical generator with its own drive

– an emergency battery of sufficient capacity

– the emergency power supply of the support vessel provided that this is designed to meet the additional emergency power requirements of the diving system

3.1.5 The emergency power source for the diving system must be installed in a space separated from the main power source and the main switchboard so that it remains operational in case of a fire or other major damage affecting the main power supply.

3.2 Main power supply

3.2.1 A power balance must be prepared to prove that units for the generation, storage and conversion of electric power are adequately rated. This balance shall take account of the full power consumption of those consumers which are permanently required in service.

3.2.2 The power consumption of consumers which are connected for limited periods may be determined by applying a simultaneity factor.

3.2.3 Evidence is required of the availability of reserve capacity to meet the power requirements dur-ing brief peak loads, e.g. when motors are started automatically.

3.2.4 The main power supply must be designed to ensure that an adequate supply of energy to all con-sumers important to the operation of the diving system can be maintained should a generator or its prime mover fail.

3.2.5 The generating equipment of the main power supply is to be so designed that the voltage and fre-quency variations allowed by the provisions of the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations, Section 3.

3.3 Emergency power supply

3.3.1 The emergency power supply must be able to meet the emergency power requirements of the diving system for a period of at least 48 hours.

3.3.2 The emergency power supply must be able to meet simultaneously the requirements of at least the following items of equipment:

– emergency lighting systems in compression chambers and diving bells

– emergency communication systems

– emergency life support systems

– emergency diving system handling equipment

– emergency surveillance and alarm systems

I - Part 5 GL 1998


H

3.3.3 In the design of the emergency power supply system, appropriate reserve capacity is to be provided to meet peak loads (e.g. caused by the starting of elec-tric motors).

In determining the necessary battery capacity, allow-ance is also to be made for the cut-off voltage and voltage drop of battery.

3.3.4 Diving bells are to be equipped with their own independent emergency power supply capable of meeting the power requirements of the autonomous life support system of the diving bell for at least 24 hours.

3.4 Storage batteries

3.4.1 When installing storage batteries, the relevant provisions of the Rules for Classification and Con-struction, Part 1 – Seagoing Ships, Chapter 3 – Elec-trical Installations, Section 2 are to be complied with.

3.4.2 In the case of battery installations equipped with a catalytic converter which ensures that at least 95 % of the hydrogen produced is recombined, sepa-rate ventilation of the battery room can be dispensed with. The same applies when gastight battery casings are used.

4. Power distribution

4.1 Distribution and switchgear

4.1.1 Electrical distribution systems are to be so designed that a fault or failure in one circuit cannot impair the operation of other circuits or the power supply.

4.1.2 The following consumers at least are to be supplied via individual circuits equipped with all nec-essary safety devices and switchgear from a distribu-tion panel supplied direct from the main switchboard of the support vessel:

– the diving system handling equipment on the support vessel

– the compression chamber and diving bell light-ing system

– the electrical consumers of the life support sys-tems

– the communication systems

4.1.3 In normal operation the emergency power distribution system may be supplied via a transfer line from the main power distribution system.

4.1.4 Distribution boards with their own individual feed circuits may not be mounted in a shared casing, i.e. each of these switchgear units must have its own enclosure.

4.1.5 Effective measures are to be taken to prevent the occurrence of vagabond voltages inside switch-

gear. Circuits at protective low voltage may not be routed with circuits at higher voltage in a joint con-ductor bundle or cable duct.

Terminals for different voltage levels are to be ar-ranged separately and are to be clearly identified.

4.1.6 Switchgear units for a connected load of 100 kW and over are to be tested in the manufacturer's works in the presence of a GL Surveyor. The test shall be performed in accordance with the Rules for Classi-fication and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations, Section 5, H.

4.1.7 Switchgear units for a connected load of less than 100 kW are to undergo an internal works test of the same scope. These tests are to be certified by a Works Test Certificate issued by the manufacturer. Test certificates are to be submitted to GL not later than the trial of the diving system. For voltage ratings below 60 V, the voltage test is to be performed at a power-frequency withstand voltage of 500 V plus twice the rate voltage.

4.2 Switching and protective devices

4.2.1 Each circuit is to be protected against over-load and short-circuit.

4.2.2 All consumers circuits are to be fitted with switches. The switching action must be on all poles.

4.2.3 Electrical switches for circuits with a current rating above 0,5 A are permitted inside compression chambers and diving bells only subject to the use of additional safety features (such as pressurized enclo-sure in protective gas).

4.2.4 Electrical fuses may not be located inside compression chambers and diving bells. Wherever possible, fuses for the independent emergency power supply to the diving bell are to be located outside the chamber. If installed inside the diving bell, special protective measures are necessary. The fuses shall in any case be protected against intervention by the occu-pants of the chamber.

4.2.5 Electric motors installed inside chambers are to be fitted with an overcurrent alarm. The alarm must be tripped in good time before the motor protection responds. This does not apply to those electric motors which cannot be endangered by overcurrent. For mo-tors in the diving bell, the alarm may take place in the diving bell.

4.2.6 Devices are to be fitted which, in the event of danger, enable the power supply to all the electrical consumers in the compression chamber to be quickly disconnected. The switches needed for this purpose are to be mounted at the Central Control Position. Means must be provided to enable the disconnection separately for each chamber.



H

4.2.7 All unearthed distribution systems, including the groups of consumers and individual consumers supplied via isolating transformers, safety transform-ers, rectifiers and inverters, are to be equipped with a continuously operating insulation monitoring system. For systems using protective low voltage, an alarm must be actuated at the Central Control Position if the insulation value drops below a preset limit. For higher voltage systems, the insulation monitor must trip an alarm at the Central Control Position when a prede-termined fault current is reached, and the system con-cerned must be automatically disconnected.

For the electrical equipment of the diving bell, the alarm actuated by the insulation monitoring system may take place in the diving bell.

Note:

The current/time characteristics of insulation moni-toring systems directly concerned with personnel safety must meet the requirements of diver protection. In assessing the time characteristics, account is to be taken of the response time of the insulation monitoring system and of the tripping time of the switching de-vices which it actuates.

4.3 Enclosures for electrical equipment

4.3.1 All items of electrical equipment belonging to a diving system are to be encased or sealed in a suitable enclosure compatible with their nature, loca-tion and protection class.

4.3.2 The enclosures of electrical equipment in-stalled inside compression chambers and diving bells or operated in water must have been approved by GL.

4.3.3 Pressure-tight enclosures inside compression chambers and diving bells are to be tested at 1,5 times the maximum working pressure of the chamber. En-closures mounted on the outside of diving bells are to be tested at 1,3 times the design pressure of the diving bell.

4.4 Earthing

4.4.1 Diving bells are to be equipped with an earthing and potential equalizing system. Connections for external earthing are to be provided in all cham-bers.

4.4.2 The connections between the earthing con-ductor and the chamber and to the ship's earth are to be made with corrosion-resistant screw unions effec-tively safeguarded against accidental loosening. The dimensions of the screw unions are to be compatible with the requisite cross-sections of the earth conductor to be connected and may not be used for other pur-poses.

4.4.3 All metal parts of electrical installations – with the exception of live components – are to be earthed. The casings of electrical equipment mounted directly against the inside wall of compression cham-

bers and diving bells are considered to be effectively earthed only if the contact surfaces are permanently free from rust, scale and paint and the casings are fastened with at least two corrosion-resistant screws secured to prevent accidental loosening.

If these conditions are not met, earthing must be ef-fected by separate earthing conductors.

4.4.4 The casings of electrical equipment in water are always to be earthed by an earthing conductor included in the supply cable. Where this is not possi-ble, casings mounted on the outside of the diving bell may also be provided with a separate external earth. In this case, however, the entire earth connection (con-necting screws and earthing conductor) is to be corro-sion-resistant.

4.4.5 Earth connections must be accessible for maintenance and inspection. Wherever possible, they are to be marked. Earthing conductors in multi-core cables are to be marked green and yellow, at least at the terminals.

4.4.6 Earthing conductors are to be provided with corrosion protection compatible with their place of installation.

4.4.7 Copper earthing conductors are subject to the following minimum cross-sections:

– external connections on ship and water: 10 mm2

– external connections inside chambers and living compartments: 6 mm2

– separate earthing conductors inside switchgear and casings: 4 mm2

– Earthing conductors in multi-core cables up to a conductor cross-section of 16 mm2 must corre-spond to the cross-section of the main conductor subject to a minimum of 1 mm2.

– earthing conductors in multi-core cables with a conductor cross-section of more than 16 mm2 equal to at least half that of the main conductor

If other materials are used, the minimum cross-section is to be determined by the ratio of the electrical con-ductivity of these materials to the electrical conductiv-ity of copper.

4.4.8 Cable sheaths and armouring may not be used as earthing conductors.

4.5 Cables and lines

4.5.1 Cables and lines for diving systems must be suitable for the proposed application. Their use is subject to approval by GL.

4.5.2 The selection, dimensions and installation of cables and lines shall comply with the provisions of the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations, Section 12 and 20, E.

I - Part 5 GL 1998


H

4.5.3 In addition, the materials of cables and lines inside compression chambers and diving bells and in water must meet the requirements stated in 2.2.

4.5.4 Underwater cables and lines must be de-signed for an external hydrostatic excess pressure equal to 1,3 times the maximum permissible operating depth. The pressure resistance is to be verified by pressure-testing each made-up length after the con-nectors have been fitted.

4.5.5 Electric umbilicals are to be tested in the manufacturer's works in the presence of a Ger-manischer Lloyd Surveyor.

4.5.6 In cables for winding on drums, no mechani-cal forces may be transmitted by electrical compo-nents of the cable.

4.6 Electrical penetrations in compression chamber walls, underwater plug connec-tions

4.6.1 Penetrations in compression chamber walls must be gas- and watertight. Their tightness must be guaranteed even should the connected cables be dam-aged or shorn off.

4.6.2 compression chamber wall penetrations and underwater plug connections must have been type-tested.

Type-testing is performed, on application, in the manufacturer's works and comprises at least the fol-lowing individual tests:

– hydraulic pressure test, in which the test pres-sure must equal twice the design pressure. The test is to be conducted in accordance with the test pressure/time curve shown in Fig 2.1, the changes in pressure being applied as quickly as possible.

– gastightness test with shorn, open cable ends. This test may be performed alternatively under air or helium pressure. If compressed air is used, the test pressure must be equal 2 times the de-sign pressure; if helium is used, 1,5 times.

0 5 15 20 25 30 35 40 45 50 55

0

10

P [b

ar]

t [min]

Fig. 2.1 Test pressure/time curve

In all pressure and tightness tests on compres-sion chamber wall penetrations, the pressure must in each case be applied from the pressure side of the wall penetration.

– high-voltage test at an AC voltage of 1000 V plus twice the rated voltage. This test is per-formed at the rated frequency and is to be car-ried out for 1 minute in each case between all the conductors mutually and between the con-ductors and the casing. The test is performed in the disconnected state. The connection side of the compression chamber wall penetration may be fully wired for the high-voltage test. The sealing of the connector shells and the like is permitted where this is stipulated by the manu-facturer in the relevant data sheet.

The test voltage for plug connections rated at more than 500 V is to be agreed with GL.

– measurement of insulation resistance

The minimum value of the insulation resistance between the conductors mutually and between the conductors and the casing shall be 4 MΩ.

The insulation resistance is to be measured with an instrument using 500 V DC.

With wet plug connections, the minimum insu-lation resistance is also to be measured after the connection has been made once in salt water.

– visual check against manufacturer's documenta-tion.

4.6.3 All electrical penetrations in compression chamber walls and all plug connections are to be sub-jected to individual inspection by the manufacturer. A Works Test Certificate is to be issued by the manu-facturer in respect of this inspection.

4.6.4 The necessary test conditions applicable to plug connections in medium voltage systems are to be agreed with GL in each case.

4.7 Interior lighting in compression chambers and diving bells

4.7.1 Each compression chamber compartment and each diving bell is to be equipped with a suitable nor-mal and emergency lighting system.

4.7.2 The normal lighting system is to be so de-signed and installed that the intensity of the lighting inside the chamber is at least 300 lux. As far as possi-ble, interior lighting should be free from glare.

4.7.3 The emergency lighting system is to be de-signed and installed in such a way that a diver inside the chamber is fully able to take readings and operate controls in every compartment.

4.7.4 Safeguards against the bursting of light fit-tings are to be agreed with GL in each case.



H

I. Fire Protection

1. General

1.1 The Rules of this Section apply to the fire protection of diving systems holding GL class which are permanently or temporarily installed on a ship or similar floating structure.



2. Structural fire protection

2.1 Area of installation of diving system

2.1.1 The ship or floating structure on which the diving system is installed is required to conform to the fire protection regulations of the classification society responsible and, where applicable, to the relevant provisions of the 1974 International Convention for the Safety of Life at Sea.

2.1.2 In the areas of installation of the diving sys-tem, the gas storage facility and the control room, sources of ignition and fire loads must be reduced to a minimum. As far as possible, materials which are at least flame-retardant are to be used. Heat insulation is to be made of incombustible materials.

2.1.3 Diving systems on ships and other floating structures may only be installed and operated in areas not subject to an explosion hazard in accordance with B.4.

2.1.4 Where diving systems or parts thereof are installed in enclosed spaces, these spaces are to be separated from the deck and the rest of the ship by partitions of type "A"-60.

2.1.5 Enclosed spaces for diving systems or parts thereof are to be provided with a forced ventilation system capable of effecting at least 8 changes of air per hours. The air must be drawn from an area not subject to an explosion hazard.

2.2 Interiors of compression chambers and diving bells

2.2.1 As far as possible, all materials used in com-pression chambers or diving bells must be at least flame-retardant (for the purpose of these Rules, "flame-retardant" refers to materials which do not continue to burn spontaneously in a compressed air atmosphere of at least 6 bar).

2.2.2 As far as possible, fire loads and sources of ignition are to be avoided. Electrical heating appli-ances and heaters are to be fitted with protection against overheating.

2.2.3 Components and materials are to be selected with a view to minimizing the danger of static charges.

3. Fire surveillance

3.1 Fire detection and alarm systems

3.1.1 Interior spaces containing diving equipment such as surface compression chambers, diving bells, gas storage facilities, compressors and control stands are to be monitored by an automatic fire detection system.

3.1.2 The occurrence of fire must be signalled visually and audibly in at least one permanently manned control room.

3.1.3 The fire alarm may be actuated manually from the permanently manned control room or may be automatically activated by the fire detection system.

3.2 Fire detection systems

3.2.1 Fire detection systems including central fire detection stations, fire detectors and the wiring of the detection loops require the approval of GL.

3.2.2 Fire detection systems must be so constructed that any fault, e.g. supply failure, short-circuit or wire breakage in the detection loops, or the removal of a detector from its base triggers a visual and audible signal at the central fire detection station.

3.2.3 The design and arrangement of fire detection and alarm systems are to conform to the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations, Section 9, C. and Chapter 4 – Automation.

4. Fire extinguishing systems

4.1 Area of installation of diving system

4.1.1 Every ship or floating structure on which a diving system is installed must be equipped with a general water fire extinguishing system as well as with portable and mobile fire extinguishers and extinguish-ing equipment in accordance with the Rules for Clas-sification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations, Section 12.

4.1.2 Where pressure vessels are situated in en-closed spaces, a permanently installed water spray

system having an application rate of 10 /m2/minute

related to the horizontal projected area is to be pro-vided for cooling in the event of fire. These water spray systems may be manually activated and oper-ated.

I - Part 5 GL 1998


I

4.1.3 For pressure vessels installed on the open deck, cooling by means of fire hoses connected to the general fire extinguishing system is permitted.

4.1.4 Interior spaces containing diving systems or parts thereof are to be additionally equipped with ap-proved manual fire extinguishers. One of the portable fire extinguishers shall in every case be situated close to the entrance to the space concerned.

4.2 In compression chambers

4.2.1 Each compartment of a surface compression chamber is to be equipped with suitable means for extinguishing a fire in the interior by providing for the rapid and efficient distribution of the extinguishing agent to any part of the chamber.

4.2.2 The fire extinguishing system is to be de-signed and constructed in such a way that it can safely deal with every conceivable outbreak of fire under all the environmental conditions for which the diving system is designed. Actuation of the fire extinguishing system may not cause any unacceptable pressure drop inside the chamber. The extinguishing system may be actuated by hand. It must at all times be possible to stop the extinguishing operation from the chamber and from the control room.

4.2.3 Water is the preferred extinguishing agent. Extinguishing agents with a toxic or narcotic effect are not permitted.

5. Other fire protection equipment

Diving system control rooms are to be equipped with at least one independent compressed air respirator of approved design having an operating capability of at least 30 minutes and fitted with equipment for voice communication with the divers.

J. Handling, Transfer and Mating Equip-ment

1. General

1.1 These Rules apply to all equipment for the handling, transfer and mating of the diving bells of diving systems holding GL class.




2.1 Diving systems are to be provided with han-dling and transfer equipment capable of ensuring the

safe transfer of the diving bell between the work loca-tion and the surface compression chamber

2.2 The handling system shall provide means for the safe and easily controllable transport of the diving bell.

2.3 For the eventuality of single component fail-ure in the main handling system, an alternative means is to be provided to enable the divers to be brought back to the surface compression chamber. This alter-native system must be supplied with power independ-ently of the main handling system. In addition, provi-sion is to be made for emergency retrieval of the bell should both the main and alternative systems fail.

Diving bells whose emergency ascent is initiated by the release of ballast must be equipped with devices for releasing the hoisting and lowering strength mem-ber/umbilical and the ballast weight. The equipment shall be so designed that two mutually independent operating actions have to be performed inside the chamber to initiate the release of ballast.

After release of the ballast weights, the diving bell, at its maximum service weight and with its trunk flooded, must exhibit a positive buoyancy equal to at least 3 % of its displacement at maximum operating depth. In these circumstances, the bell should have sufficient stability to maintain a substantially upright position.

2.4 The mating system shall enable the connec-tion and disconnection of the diving bell and surface compression chamber to be effected easily and se-curely even under conditions where the support ship is rolling, pitching or listing to predetermined degrees.

2.5 Where a power actuating system is used for mating operations, an auxiliary power actuating sys-tem or an appropriate means is to be provided to con-nect the diving bell to the surface compression cham-ber in the event of failure of the normal power actuat-ing system.

2.6 The mating system is to be provided with a safety interlock between the diving bell and the sur-face compression chamber.

2.7 Unless otherwise stated in the following Sec-tions, the mechanical equipment of the handling sys-tem is to conform to VI – Additional Rules and Guide-lines, Part 2 – Life Saving Appliances, Lifting Appli-ances, Accesses, Chapter 2 – Guidelines for the Con-struction and Survey of Lifting Appliances, Section 9.

3. Calculations

3.1 The "working load" of the handling system comprises the weight of the diving bell, the total weight of the fully equipped divers at 150 kg each, the weight of the equipment and the ballast weights.



J

The "dead load" is the weight of the handling system.

3.2 Regardless of the tape of handling system and the size of the working load, the dimensional design of the handling system is to allow for a working load factor Ψ = 2,7 and a dead load factor ϕ of 1,5. It is assumed here that the use of the system in a seaway will be limited to significant wave heights of 2 m or less. Where it is proposed that handling operations should be performed in even more unfavourable con-ditions, previous agreement with GL is necessary.

3.3 Calculations are to be based on the assump-tion that the angle of engagement of the hoisting and lowering strength member may be 12° off perpen-dicular in any direction.

3.4 The maximum static tensile stress imposed on steel wire ropes by the working load may not ex-ceed 1/8 of the proven rupture strength of the ropes.

3.5 Where ropes made of natural or synthetic fibres are used, the maximum static tensile stress im-posed by the working load may not exceed 1/10 of the proven rupture strength of the ropes.

3.6 The stress limits for components are specified in VI – Additional Rules and Guidelines, Part 2 – Life Saving Appliances, Lifting Appliances, Accesses, Chapter 2 – Guidelines for the Construction and Sur-vey of Lifting Appliances, Section 2.

4. Construction

4.1 The handling system must be provided with suitable means for preventing any excessive rotation of the diving bell (e.g. non-spin rope).

4.2 The use of fibre ropes is permitted only in special cases with the consent of GL:

4.3 Precautions are to be taken to prevent the diving bell from jarring against the ship's hull or the handling gear.

4.4 All interchangeable components such as blocks, hooks, shackles etc. are to conform to recog-nized standards and must be designed for twice the working load.

4.5 The driving power of the handling system must be sufficient to lift 1,5 times the working load.

The strength of the mechanical brake must be suffi-cient to hold the test loads specified in A.5.11.

4.6 Before assembly, all interchangeable compo-nents are to be subjected to individual component load testing.

4.7 The rupture strength of ropes is to be verified by a full tensile breaking test.

K. Hyperbaric Evacuation System

1. General

1.1 With reference to the "Guidelines and Speci-fications for Hyperbaric Evacuation Systems", Reso-lution A.692(17) of 6 November 1991, the IMO Code of Safety for Diving Systems, Resolution A.831(19) of 23 November 1995 stipulates for diving systems in-stalled on board ships or offshore platforms an evacuation system enabling divers in saturation to be rescued in the event of their having to abandon the ship or the platform.

1.2 Depending on the local, geographical and other service conditions, different kinds of evacuation systems are conceivable, including:

1.2.1 Hyperbaric self-propelled lifeboats

1.2.2 Towable hyperbaric evacuation units

1.2.3 Hyperbaric evacuation units, which may or may not be towable, suitable for offloading onto an attendant vessel

1.2.4 Transfer of the diving bell to another facility

1.2.5 Transfer of the divers from one diving bell to another when in the water and under pressure

1.2.6 Negatively buoyant unit with inherent re-serves of buoyancy, stability and life support capable of returning to the surface to await independent recov-ery.

1.3 If a self-propelled or towable hyperbaric evacuation system permanently connected to the div-ing system is provided, the following requirements are to be applied.

1.4 The necessary tests are stated in A.5. Official regulations may necessitate further tests.


2.1 Pressure chamber

2.1.1 The pressure chamber of the hyperbaric evacuation system shall be so designed that all the divers in the diving system can be rescued simultane-ously at maximum operating depth. At least one seat with safety harness is to be provided for each diver.

2.1.2 The pressure chamber is to be equipped with a supply lock.

2.1.3 The connection flange of the pressure cham-ber is to be so designed that it is also able to mate to a different system.

I - Part 5 GL 1998


K

2.1.4 The pressure chamber is to be fitted with view ports in such a way that, wherever possible, all the occupants can be observed from outside.

2.1.5 The pressure chamber is to be provided with the necessary connections to enable the internal pres-sure, temperature, gas composition and humidity to be maintained.

2.1.6 The pressure chamber is to be adequately lit.


2.2.1 The hyperbaric evacuation system is to be so designed that its behaviour in a seaway corresponds to that of an enclosed lifeboat.

2.2.2 The system must be self-propelled and capa-ble of navigation or must be provided with means (e.g. suitably equipped ancillary boat) enabling the hyper-baric evacuation system to be towed away quickly after launching.

2.2.3 The hyperbaric evacuation system must be equipped with its own life support system enabling the pressure, temperature, humidity and gas composition in the pressure chamber to be maintained for at least 72 hours. The life support systems are to be provided with connections for external supply and surveillance.

2.2.4 The hyperbaric evacuation system must be equipped with the controls needed to maintain a safe environment for the divers.

2.2.5 The hyperbaric evacuation system must be equipped with a communication system for talking to the divers.

2.2.6 The hyperbaric evacuation system is to be equipped with its own power supply capable of keep-ing the electrical installations in operation for at least 72 hours.

2.2.7 The hyperbaric evacuation system is to be provided with lifting attachments enabling it to be hoisted by a standard ship's crane.

2.2.8 The hyperbaric evacuation system must be constructed of materials which are at least flame-retar-dant and must be equipped with a water spray system for cooling the surface in the event of fire.

2.3 Mating and handling systems

2.3.1 The mating system of the hyperbaric evacua-tion system must be designed to permit rapid and safe connection and disconnection.

2.3.2 The design and testing of the handling system must conform to VI – Additional Rules and Guide-lines, Part 2 – Life Saving Appliances, Lifting Appli-ances, Accesses, Chapter 1 – Guidelines for Life Sav-ing Launching Appliances and, where applicable, to the relevant national regulations.

2.3.3 The handling system must be capable of safely launching the hyperbaric evacuation system and, where applicable, of effecting also the retrieval and mating operatings.

2.3.4 Disconnection and launching of the system must also be possible in the event of failure of the ship's power supply.

L. Wet Bells

1. General

1.1 Wet bells serve the purpose of safely carrying divers and their equipment from a ship's deck or a platform to and from the site, using either compressed air or gas mixtures as breathing gas, depending on the depth, however, without saturation being reached.

1.2 The documents to be submitted to GL for approval are listed in A.4.11.

1.3 The testings required are defined in A.5.13.


2.1 Wet bells should be designed for the carriage of at least two divers, including their equipment. Nor-mally, they consist of an upper part at head and shoul-der level supporting a gas pocket and an open lower part provided with a platform enabling the divers to stand safely.

2.2 Wet bells and the persons inside are to be adequately protected against impacts during lowering or recovering.

2.3 The supply lines for breathing gas, hot water, etc. are to be arranged from the surface through the wet bell to the divers. Alternatively, supply by a joint umbilical is possible, which is connected to the bell connections for the individual diver umbilicals.

The bell is to be equipped with devices for opening up the diver supply lines.

2.4 Wet bells are to be provided with emergency supplies of breathing gas sufficient to supply the di-vers at maximum depth for a period of two hours and with an emergency breathing mask for each diver.

2.5 The upper part of the bell supporting the gas pocket must be equipped for scavenging with the re-spective breathing gas employed.

2.6 The wet bells must be equipped with appro-priate devices for the salvaging and securing of divers having suffered an accident.



L

2.7 Lighting is to be installed in the wet bell for working and for emergency purposes. In addition a surface communication line is to be provided.

2.8 Wet bells are to be provided with appropriate devices ensuring indication of the respective diving depth in the surface control station.

3. Launching devices

3.1 Launching devices for wet bells have to safe-guard safe launching and recovery under all admissi-ble seaway and weather conditions.

3.2 The launching device must facilitate the de-compression stops in the water to be reliably and ex-actly observed. Jerky motions of the wet bell due to ropes becoming slack in a seaway are to be avoided by appropriate structural measures.

3.3 Where the hoisting rope and the supply lines are arranged separately appropriate measures are to be taken for preventing these from twisting and from damaging each other during launching and/or recovery operations.

3.4 It is to be ensured that upon recovery the wet bell will be deposited on deck without jerks and im-pacts.

4. Equipment for breathing gas supply

4.1 For the wet bell system in accordance with the design diving depths and service periods supplies

of breathing gas of appropriate composition are to be kept available.

4.2 Where during a diving operation and the pertinent decompression phases different kinds of breathing gas are employed, it is to be ensured that each of the gases employed can at any time be identi-fied at the control station.

5. Control station

The control station at the surface is to be equipped with all necessary devices ensuring that the parameters quoted below are at any time adhered to and moni-tored:

– supply of divers with adequate quantities of the proper breathing gas

– possibly supply of divers' thermal suits with an adequate quantity of hot water of adequate tem-perature

– indication of diving depth of bell

– adherence to decompression stops and periods

– uninterrupted communication with divers

– insulation values of the wet bell's electrical equipment

Visual monitoring of the bell and the operating site by VHF TV system.

I - Part 5 GL 1998


L

2.1.4 The pressure chamber is to be fitted with view ports in such a way that, wherever possible, all the occupants can be observed from outside.

2.1.5 The pressure chamber is to be provided with the necessary connections to enable the internal pres-sure, temperature, gas composition and humidity to be maintained.

2.1.6 The pressure chamber is to be adequately lit.


2.2.1 The hyperbaric evacuation system is to be so designed that its behaviour in a seaway corresponds to that of an enclosed lifeboat.

2.2.2 The system must be self-propelled and capa-ble of navigation or must be provided with means (e.g. suitably equipped ancillary boat) enabling the hyper-baric evacuation system to be towed away quickly after launching.

2.2.3 The hyperbaric evacuation system must be equipped with its own life support system enabling the pressure, temperature, humidity and gas composition in the pressure chamber to be maintained for at least 72 hours. The life support systems are to be provided with connections for external supply and surveillance.

2.2.4 The hyperbaric evacuation system must be equipped with the controls needed to maintain a safe environment for the divers.

2.2.5 The hyperbaric evacuation system must be equipped with a communication system for talking to the divers.

2.2.6 The hyperbaric evacuation system is to be equipped with its own power supply capable of keep-ing the electrical installations in operation for at least 72 hours.

2.2.7 The hyperbaric evacuation system is to be provided with lifting attachments enabling it to be hoisted by a standard ship's crane.

2.2.8 The hyperbaric evacuation system must be constructed of materials which are at least flame-retar-dant and must be equipped with a water spray system for cooling the surface in the event of fire.

2.3 Mating and handling systems

2.3.1 The mating system of the hyperbaric evacua-tion system must be designed to permit rapid and safe connection and disconnection.

2.3.2 The design and testing of the handling system must conform to VI – Additional Rules and Guide-lines, Part 2 – Life Saving Appliances, Lifting Appli-ances, Accesses, Chapter 1 – Guidelines for Life Sav-ing Launching Appliances and, where applicable, to the relevant national regulations.

2.3.3 The handling system must be capable of safely launching the hyperbaric evacuation system and, where applicable, of effecting also the retrieval and mating operatings.

2.3.4 Disconnection and launching of the system must also be possible in the event of failure of the ship's power supply.

L. Wet Bells

1. General

1.1 Wet bells serve the purpose of safely carrying divers and their equipment from a ship's deck or a platform to and from the site, using either compressed air or gas mixtures as breathing gas, depending on the depth, however, without saturation being reached.

1.2 The documents to be submitted to GL for approval are listed in A.4.11.

1.3 The testings required are defined in A.5.13.


2.1 Wet bells should be designed for the carriage of at least two divers, including their equipment. Nor-mally, they consist of an upper part at head and shoul-der level supporting a gas pocket and an open lower part provided with a platform enabling the divers to stand safely.

2.2 Wet bells and the persons inside are to be adequately protected against impacts during lowering or recovering.

2.3 The supply lines for breathing gas, hot water, etc. are to be arranged from the surface through the wet bell to the divers. Alternatively, supply by a joint umbilical is possible, which is connected to the bell connections for the individual diver umbilicals.

The bell is to be equipped with devices for opening up the diver supply lines.

2.4 Wet bells are to be provided with emergency supplies of breathing gas sufficient to supply the di-vers at maximum depth for a period of two hours and with an emergency breathing mask for each diver.

2.5 The upper part of the bell supporting the gas pocket must be equipped for scavenging with the re-spective breathing gas employed.

2.6 The wet bells must be equipped with appro-priate devices for the salvaging and securing of divers having suffered an accident.



L

2.7 Lighting is to be installed in the wet bell for working and for emergency purposes. In addition a surface communication line is to be provided.

2.8 Wet bells are to be provided with appropriate devices ensuring indication of the respective diving depth in the surface control station.

3. Launching devices

3.1 Launching devices for wet bells have to safe-guard safe launching and recovery under all admissi-ble seaway and weather conditions.

3.2 The launching device must facilitate the de-compression stops in the water to be reliably and ex-actly observed. Jerky motions of the wet bell due to ropes becoming slack in a seaway are to be avoided by appropriate structural measures.

3.3 Where the hoisting rope and the supply lines are arranged separately appropriate measures are to be taken for preventing these from twisting and from damaging each other during launching and/or recovery operations.

3.4 It is to be ensured that upon recovery the wet bell will be deposited on deck without jerks and im-pacts.

4. Equipment for breathing gas supply

4.1 For the wet bell system in accordance with the design diving depths and service periods supplies

of breathing gas of appropriate composition are to be kept available.

4.2 Where during a diving operation and the pertinent decompression phases different kinds of breathing gas are employed, it is to be ensured that each of the gases employed can at any time be identi-fied at the control station.

5. Control station

The control station at the surface is to be equipped with all necessary devices ensuring that the parameters quoted below are at any time adhered to and moni-tored:

– supply of divers with adequate quantities of the proper breathing gas

– possibly supply of divers' thermal suits with an adequate quantity of hot water of adequate tem-perature

– indication of diving depth of bell

– adherence to decompression stops and periods

– uninterrupted communication with divers

– insulation values of the wet bell's electrical equipment

Visual monitoring of the bell and the operating site by VHF TV system.

I - Part 5 GL 1998


L

Section 3

Rules for Construction of Diving Simulators


1. General

1.1 The following Rules of Construction apply to diving simulators which are permanently installed in a building or similar structure and which are built under the survey and in accordance with the Rules of GL with a view to the issue of an appropriate Certificate.

1.2 On application by the operator, diving simu-lators built in accordance with 1.1 may also be classi-fied by GL.

1.3 Buildings, power generating plants, fuel stor-age and gas storage facilities etc. are required to com-ply with the relevant national regulations of the coun-try in which the facilities are established.

1.4 Designs other than those stated in the Rules of Construction may be approved provided their suit-ability has been verified by GL and they have been recognized as equivalent.

1.5 GL reserve the right to impose requirements additional to those contained in the Rules in respect of all types of facility should this become necessary in the light of new knowledge or practical experience. GL likewise reserves the right to sanction exceptions to the Rules in specially justified cases.

1.6 National regulations existing alongside the GL Rules are unaffected.

2. Definitions

For the purpose of these Rules the terms used therein shall have the following meanings in the absence of an express statement to the contrary:

2.1 Mating device

The equipment necessary for the connection and dis-connection of a diving bell to a surface compression chamber.

2.2 Working gas

All gases needed for performing underwater opera-tions such as torch work, cutting, welding etc.

2.3 Breathing gas/breathing mixture

All gases/mixtures which are used for breathing during diving operations.

2.4 Handling and transfer system

The plant and equipment necessary for raising, lower-ing and transporting the diving bell between the work location and the surface compression chamber.


A pressure vessel for human occupancy equipped with means for controlling and monitoring the pressure within the chamber.

2.6 Pressure vessel

A container capable of withstanding an internal work-ing pressure of 1 bar or over.

2.7 Bottle

A pressure container for the storage and transport of gases under pressure.


A pressure vessel for human occupancy under pres-sure.

2.9 Areas subject to explosion hazard

Those locations in which an explosive gas-air mixture is continuously present, or present for long periods (zone 0); in which an explosive gas-air mixture is likely to occur in normal operation (zone 1); in which an explosive gas-air mixture is not likely to occur and, if it does, will persist for only a short time (zone 2).

2.10 Gas storage facility

Bottles permanently installed in the open or inside which contain the store of breathing and working gases needed for operation of the simulator.

2.11 Maximum operating depth of the diving system

The depth in metres of seawater equivalent to the maximum pressure for which the diving system is designed.

I - Part 5 GL 1998

Section 3 Rules for Construction of Diving Simulators Chapter 1Page 3–1

A


A system whereby divers under pressure can be safely evacuated to a position where decompression can be carried out.

2.13 Compact umbilical

A link cable with a protective sheath combining in one assembly the power supply, surveillance and commu-nication lines, the breathing gas and hot water hoses and the hoisting and lowering strength member.

2.14 Life support system

The gas supply, breathing gas system, surveillance system and equipment required to provide a safe envi-ronment for the diving crew in the diving simulator under all possible pressures and conditions to which they may be exposed during diving operations.

2.15 Diving bell

A submersible compression chamber, including its ancillary equipment, for transfer of divers under pres-sure between the work location and the surface com-pression chamber.

2.16 Diving simulator

A compression chamber system in which both manned and unmanned tests can be carried out in a wet or dry environment under conditions simulating those at sea.

2.17 Depth

The pressure, expressed in metres of seawater, to which the diver is exposed at any time during a dive or inside a compression chamber.

2.18 Umbilical

The link between the diving support unit and the div-ing bell which may contain surveillance, communica-tion and power supply cables, breathing gas and hot water hoses. The strength member for hoisting and lowering the diving bell may be part of the umbilical.

2.19 Test chamber

A compression chamber in which manned and un-manned tests can be carried out under the conditions prevailing in the sea.

2.20 Living compartment

The part of the surface compression chamber which is intended to be used as the main habitation for the di-vers during diving operations and which is equipped for such purpose.

3. Components of diving simulators

3.1 Where present, the following components form part of the diving simulator system and are to be designed, manufactured and tested in accordance with these Rules:

– compression chambers

– bottles

– pressure vessels

– pipes, valves, fittings and hoses

– breathing gas systems

– life support systems

– welding gas absorbers

– diver heating system

– sanitary systems

– communication systems

– surveillance, automation and control equipment

– gas analyzing systems

– electrical systems and equipment

– fire prevention, detection and extinguishing equipment

– compressors

– gas mixers

– helium reclaim system

– water systems

– hyperbaric evacuation system


4.1 General

4.1.1 Before the start of manufacture, plans and drawings of all components subject to compulsory inspection, to the extent specified below, are to be submitted to Germanischer Lloyd in triplicate.

4.1.2 The drawings must contain all the data neces-sary for checking the design, the loads and the stresses imposed. Where necessary, design calculations relat-ing to components and descriptions of the plant are also to be supplied.



Section 3 Rules for Construction of Diving Simulators I - Part 5GL 1998

A

4.2 Total system


4.2.1 Description of plant stating the essential de-sign parameters such as:

– purpose of the diving simulator

– diving or operating procedure

– maximum operating depth

– maximum operating period

– maximum number of divers in system

– maximum rates of pressure change

4.2.2 General arrangement drawings of the diving simulator (block diagram).

4.2.3 Installation drawings.

4.2.4 Foundation drawings, showing fixed points.

4.2.5 Drawings of supply and disposal systems (water and electricity).

4.2.6 Identification system

4.2.7 Test schedule.


4.3.1 Drawings are to be submitted of pressure vessels and apparatus giving full details for appraising the safety of the equipment.

The information provided shall include the following:

– application

– capacities of individual compartments

– media contained, together with operating pres-sures and temperatures

– proposed materials, thermal insulation materials, paints, buoyancy material

– welding specifications

– heat treatment

– manufacturing tolerances

– non-destructive tests

4.3.2 Drawings are also to be submitted of individ-ual items of vessel equipment such as:

– windows, window flanges, retaining rings

– door leaves and frames

– bayonet locks

– coupling clamps

– integral opening reinforcements

– internal facilities

4.4 Gas supply

4.4.1 Piping diagrams and descriptions are to be furnished for the entire gas supply system, including a list of valves and fittings.

4.4.2 Description of proposed cleaning procedure for breathing gas system.

4.4.3 Details of gas analysis, including an equip-ment list.

4.4.4 Description of compressors and compressor drives together with longitudinal and transverse sec-tional drawings of the compressor crankshaft.


The following are to be submitted:

4.5.1 Piping diagrams, block diagrams and descrip-tions of systems.

4.5.2 Descriptions of system components and equipment.

4.5.3 Calculation of cooling and heating require-ments.

4.5.4 Description and drawings of the water supply, disposal, circulation and treatment systems.

4.5.5 Description and design details of the diver heating system.

4.6 Automation and communications equip-ment


4.6.1 General arrangement drawings/block dia-grams of control equipment, including lists of meas-uring points.

4.6.2 Equipment list for sensors, indicating instru-ments etc.

4.6.3 Drawings and descriptions of electronic com-ponents such as instrument amplifiers, computers and peripheral units.

4.6.4 General arrangement drawings and equipment lists for communication systems and signalling equip-ment.

4.6.5 Arrangement drawing and description of the TV system.

I - Part 5 GL 1998


A



4.7.1 A general arrangement drawing of the elec-trical equipment containing at least the following in-formation:

– voltage rating of systems

– power or current ratings of electrical consumers

– switchgear, indicating settings for short-circuit and overload protection; fuses with details of current ratings

– cable types and cross sections

4.7.2 The energy balance of the main and emer-gency power supply system.

4.7.3 Drawings of switchgear and distribution equipment part lists.

4.7.4 Complete documentation for electric motor drives with details of control, measuring and monitor-ing systems.

4.7.5 Battery installation drawing with details of battery types, chargers and battery room ventilation.

4.7.6 Details of electrical penetrations through compression chamber walls.

4.7.7 Drawings and descriptions of all electrical components installed in compression chambers.

4.7.8 Drawing showing the utilization of electrical penetrations through compression chamber walls.

4.8 Fire protection


4.8.1 A description of the preventive fire protection measures taken.

4.8.2 Details of the fire loads in the system.

4.8.3 Drawings and descriptions of:

– fire detection system

– fire extinguishing system(s)

– fire alarm equipment

– building

– drawings of fire protection and fire escapes



4.9.1 Description of system.

4.9.2 Arrangement drawing.

4.9.3 Construction drawings of evacuation system.

4.9.4 Drawings of mating and handling system.

5. Tests and trials

5.1 General

5.1.1 Diving simulators and their ancillary equip-ment are subject to constructural and materials tests as well as to pressure and tightness tests and trials. All the tests called for in the following paragraphs are to be performed under GL supervision.

5.1.2 For serial manufactured parts, test procedures other than those prescribed may be agreed with GL provided that they are recognized as equivalent by the Society.

5.1.3 GL reserve the right to increase the scope of the tests, if necessary, and also to extend tests to parts for which testing is not expressly required according to the Rules.

5.1.4 Parts requiring approval are to be replaced with tested parts. The same applies to spare parts.

5.1.5 After the compression chambers and their ancillary equipment have been installed in the opera-tions building, the diving simulator and its auxiliary systems are to be subjected to a functional test. All items of safety equipment are to be tested except where an adequate test has already been carried out in the manufacturer's works in the presence of a repre-sentative of GL.


5.2.1 On completion, pressure vessels and appara-tus are to be subjected to a constructural test.

This test covers verification that the vessel conform to the approved drawings and that the workmanship is satisfactory. All components must be accessible to allow proper inspection.

5.2.2 The materials test certificates for the materi-als used, the reports on the non-destructive testing of welds and, where applicable, the results of inspection of workmanship are to be submitted together with evidence of any heat treatments applied.

5.2.3 A hydraulic pressure test is to be performed prior to insulation and preservation treatment of the vessels. Each compression chamber compartment is to be tested individually. The walls may exhibit no per-manent deformation or leakage.



A

5.2.4 The test pressure normally applied to vessels and apparatus shall be 1,5 time the maximum permis-sible working pressure.

5.2.5 Diving bells and vessels which may be ex-posed in service to external excess pressure are, in addition, to be subjected to an external pressure test. The external test pressure shall normally be equal to 1,3 times the design pressure.

5.2.6 Gas storage facilities, diving simulator and life support systems, including piping systems, are to be subjected to a tightness test at the maximum per-missible working pressure using the appropriate breathing gas or gas mixture possessing similar prop-erties.

The maximum permissible leakage rate is equivalent to a 1 % pressure drop in 24 hours for the whole com-pression chamber system.


5.3.1 Each compression chamber window must be subjected to a hydraulic pressure test which may be performed in a testing device or on the window and compression chamber together after assembly. The test pressure shall normally be equal to 1,5 times the de-sign pressure.

5.3.2 After the pressure test, the windows shall not exhibit any scratches, cracks or permanent deforma-tion.

5.4 Compressors

5.4.1 Compressor components subjected to pres-sure are to undergo a hydraulic pressure test at a test pressure equal to 1,5 times the delivery pressure of the stage concerned.

5.4.2 On completion, compressors are to be sub-jected to a tightness test at the maximum permissible working pressure applicable. A performance test shall also be performed during which the final moisture content and any possible contamination of the com-pressed gas shall also be determined.

5.5 Piping systems

5.5.1 On completion but before the application of insulation or paint, all piping systems are to be sub-jected to a hydraulic pressure test at 1,5 times the design pressure.

5.5.2 Tightness test, cf. 5.2.6.

5.5.3 Wherever possible, all butt welded joints in LSS gas lines are to be subjected to 100 % X-ray ex-amination.

5.5.4 Piping systems for breathing gas and oxygen are to be subjected to a purity test.

5.6 Hoses, umbilicals

5.6.1 Proof of the bursting pressure of each type of hose is to be submitted to GL. For liquids, hoses must be able to withstand at least 4 times, and in the case of gases at least 5 times, the maximum permissible work-ing pressure.

5.6.2 Each hose is to be subjected to a hydraulic pressure test at least 2 times the maximum permissible working pressure.

5.6.3 Where hoses are subjected to external pres-sure, proof is required that a differently ratio of 1,5 between the internal and external pressures can be withstood without failure.


A functional test is to be performed to demonstrate the satisfactory operation of the life support systems under normal and emergency operating conditions.

5.8 Automation and communications equip-ment

5.8.1 Indicating and monitoring instruments are to be checked for the accuracy of their readings and their limit settings.

5.8.2 The satisfactory operation of automatic con-trol systems is to be checked under service conditions. Proof is required of the autonomy of safety systems.

5.8.3 The communications equipment for normal and emergency operation is to be subjected to a func-tional test. The suitability of the helium speech un-scrambler is to be verified at the maximum operating depth of the facility.


5.9.1 Electrical machines, components, cables and lines are to be subjected to testing in the manufac-turer's works in accordance with the Rules for Classi-fication and Construction Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations.

5.9.2 All electrical systems and equipment are to be surveyed and tested before the diving simulator is placed in service.

5.9.3 The electrical safety devices are to be tested and, in addition, the electrical equipment in the com-pression chambers is to be subjected to an insulation test.

5.10 Fire protection

5.10.1 The fire behaviour of the chamber equipment is to be checked by reference to the relevant test cer-tificates and symbols.

I - Part 5 GL 1998


A


5.10.3 Fire alarm, detection and extinguishing appli-ances are to be subjected to a functional test.


A functional test is to be carried out to demonstrate that the hyperbaric evacuation system is able to convey divers under pressure to a safe position where they can be supplied and kept under surveillance.

6. Marking

6.1 A name plate containing at least the following details is to be permanently fitted to all compression chambers in a prominent position:

– name of manufacturer

– serial number and year of manufacture

– maximum permissible working pressure or oper-ating depth

– test pressure

– capacity (in litres) of each chamber compartment

– maximum permitted number of divers

– date of test and test stamp




– capacity (in litres)

– test pressure (bar)

– empty weight (of gas bottles)


6.3 Permanently installed gas bottles, gas con-tainers and gas piping systems are also to be perma-nently colour-coded in accordance with Table 3.1 and are to bear the chemical symbol of the type of gas concerned. The marking of gas bottles must be visible from the valve side.

6.4 All valves, fittings, controls, indicators and warning devices are to be fitted with identification plates made of material which is at least flame-retar-dant. The marking shall be easily legible and clear (i.e. abbreviated designation and/or functional description).

Table 3.1 Marking of gas systems

Type of gas

Chemical symbol

Colour code

Oxygen O2 white

Nitrogen N2 black

Air --- white and black

Helium He brown

Oxygen/ Helium Gas mixture

O2/He white and brown

B. Principles of Design and Construction of Diving Simulators


1.1 Wherever appropriate and practicable, diving simulators are to be designed and built in such a way that the failure of any single component cannot cause a dangerous situation.

1.2 Diving simulators and their components are to be designed for the conditions of service described in the equipment specification.

1.3 Diving simulators are to be so designed that the proposed tests can be performed with maximum safety for the simulator crew.

1.4 Diving simulators for technical experiments are to be equipped with suitable test chambers which must be separable from the remaining chamber system in respect of operating services, pressure and atmos-pheric conditions.

The living compartment of the simulator is to be so arranged that its occupants are not endangered or in-convenienced by the experiments.

1.5 Diving simulators which can be operated with simultaneously differing chamber pressures must be provided with effective means of preventing any un-intentional pressure drift within the chamber system.

1.6 Diving simulators must be designed in such a way that injured divers can be carried on a stretcher inside the compression chamber system.

1.7 It is recommended that diving simulators be equipped with a hyperbaric evacuation system.



B

1.8 Diving simulators are to be designed and built to facilitate safe operation, adequate maintenance and necessary surveys.

1.9 All parts of a diving simulator are to be de-signed, constructed and mounted in a way which fa-cilitates cleaning and disinfection.

2. Environmental conditions

Diving simulators, including their accessories and ancillary equipment, are to be designed for the envi-ronmental conditions likely to be encountered at the operating site or under the planned test conditions.

3. Chamber conditions

3.1 Diving simulators are to be equipped in such a way that a breathable atmosphere can be maintained in the compression chambers throughout the period of operation.

3.2 Means must be provided for keeping the partial pressure of CO2 below 0,005 bar at all times and for this purpose a CO2 production of 0,05 Nm3/h per diver shall be assumed.

3.3 Under steady conditions, diving simulators must be capable of keeping the temperature in the compression chamber constant to ± 1 °C in the range from 27 to 36 °C while maintaining a relative atmo-spheric humidity of at least 50 %.

3.4 Compression chambers are to be so arranged and equipped that a uniform chamber atmosphere can be maintained (CO2 and O2 levels, temperature and humidity).

3.5 Under steady conditions, the permanent noise level (over 8 hours) in the living and compression chambers shall not exceed 65 dB(A).

3.6 Deviations from the aforementioned chamber conditions are permitted where this is essential to the performance of the tests and where additional meas-ures are taken to ensure the divers' safety.

4. Arrangement

4.1 Diving simulators may only be installed and operated in areas not subjected to an explosion hazard.

4.2 As far as possible, the area of installation of diving simulators is to be kept free of fire loads.

4.3 Diving simulators and breathing gas storage facilities are to be located in areas which can be ade-quately ventilated and provided with suitable electric lighting.

4.4 The area of installation of diving simulators is to be separated from other operational facilities. The partition must, as a minimum requirement, possess Class F 30 fire resistance as defined in DIN 4102.

5. Chamber equipment and facilities

5.1 Compression chamber equipment and facili-ties must be suitable for operation in hyperbaric at-mospheres. Under these conditions they shall not lib-erate any toxic or strongly irritant gases. This also applies to protective coatings and paints used inside chambers.

5.2 Only incombustible, or at least flame-retar-dant, materials should be used in the chambers (cf. Section 2, I.2.2.1).

5.3 Permanently installed chamber facilities are to be so designed that they suffer no damage when the chamber is subjected to hydraulic pressure tests.

5.4 Equipment items in experimental chambers are to be designed and installed in such a way as to minimize the danger of injury to the divers and leave sufficient room for movement. In addition, chamber equipment and experimental apparatus shall not pre-vent or limit unduly the possibility of observing the divers from outside the test chamber, where necessary with the aid of TV equipment.

5.5 Ancillary systems and equipment needed to perform tests or create experimental boundary condi-tions are to be designed and constructed so that they are able to perform their functions safely without dan-ger to the divers. The relevant requirements will be stipulated by GL in each case.

6. Corrosion protection

6.1 Diving simulators and all their ancillary com-ponents are to be effectively protected against corro-sion. The corrosion protection must be capable of being repaired or retouched at a later stage.

6.2 Anti-corrosion coatings exposed to the cham-ber conditions must meet the requirements stated in 5. In addition, they shall not tend to blister or flake off under hyperbaric conditions. In wet test chambers it may be necessary to make special provision for the effect of helium-saturated seawater.

6.3 Wet test chambers are to be provided with an adequate anodic protection system.

I - Part 5 GL 1998


B

C. Pressure Vessels and Apparatus

1. Compression chambers

1.1 General

1.1.1 The following Rules apply to pressure vessels used as compression chambers in diving simulators.

1.1.2 The documents to be submitted to GL for approval are listed in A.4.

1.1.3 The necessary tests and markings are stated in A.5. and A.6.



1.2.1.1 Each compression chamber and chamber compartment is to be equipped with reliable safe-guards against an excessive working pressure and any inadmissible pressure drop.

1.2.1.2 Compression chambers are to be designed to allow at least two persons to pass in or out simultane-ously through the locks without subjecting the other divers in the system to a change of pressure.

1.2.1.3 The living compartment of compression chambers shall be so designed and equipped that the occupants can stand upright and each diver is provided with a bunk on which he is able to stretch out com-fortably. A toilet and shower are also to be provided. The toilet and shower are to be located in a separate space. Toilets with arrangements for the external dis-charge of human waste are to be equipped with suit-able interlocks to prevent pressure losses in the cham-ber system.

1.2.1.4 The living compartment of compression chambers and other compartments used for decom-pression are to be provided with a lock through which provisions, medicines and equipment can be passed in and out without subjecting the occupants of the cham-ber to a change of pressure.

1.2.1.5 Locks are to be designed to prevent acci-dental opening under pressure; if necessary, suitable interlocks are to be provided.

1.2.1.6 Each compression chamber compartment is to be fitted with view ports so that, wherever possible, all the occupants can be observed from outside.

1.2.1.7 Wherever necessary, the view ports of com-pression chambers are to be protected internally and externally against mechanical damage. View ports are also to be protected against ultraviolet radiation and unacceptably high temperatures.

1.2.1.8 Each compression chamber compartment is to be adequately lit.

1.2.2 Test chambers

1.2.2.1 Test chambers are to be designed and built in such a way that the proposed tests can be performed safely and any danger to the rest of the chamber sys-tem is avoided.

1.2.2.2 The dimensional design of test chamber walls is to allow for possible additional loads due to test equipment.

1.2.2.3 Test chambers are to be separated by double doors from the rest of the chamber system.

1.2.2.4 Manned test chambers for technical experi-ments are to be provided with a lock for materials.

1.2.2.5 Test chambers compartment are to be pro-vided with sufficient mountings for experimental equipment. Adequate means are also to be provided for the transport and handling of experimental equip-ment.

1.2.2.6 Each test chamber compartment is to be equipped with separate gas analysis connection.

1.2.2.7 All open penetrations for gas, measurements and analysis are to be protected by replaceable filters mounted on the inside of the chamber.

1.2.2.8 Each test chamber compartment is to be pro-vided with separate connections for communications equipment. In addition, at least one blind flange each is to be fitted for power and data transmission.

1.2.2.9 Where water partitions are fitted in wet test chambers, an access opening with a clear diameter of at least 800 mm must be provided. The water level control system is to be so designed, that no water can penetrate into dry compartments in the event of pres-sure variations.

1.2.2.10 Test chambers are to be provided with drain-age connections at their lowest points. Sumps and other drains are to be protected to prevent impurities being sucked in.

1.2.2.11 Water circuits for test chambers are to be designed and constructed so that switching from high-pressure to low-pressure circuits cannot cause any inadmissible pressure drop in the test chamber. Fur-thermore, such switching operations shall not cause any unacceptable rise in pressure in low-pressure cir-cuit.

1.2.2.12 Test chambers are to be provided with exter-nal insulation compatible with the test conditions and with the environmental conditions at the locations where the simulator is installed.

1.2.3 Hatches and access openings

1.2.3.1 Hatches and mating devices in diving simu-lators which are not sealed by pressure are to be equipped with a closing mechanism which precludes



C

opening under pressure. The closing mechanism is to be so designed that the correct position of closure is clearly indicated before pressure is applied.

1.2.3.2 Means are to be provided to enable hatches to be opened from both sides.

Hatch trunks are to be provided with pressure equal-izing valves.

Devices are to be fitted which hold hatches in the open position.

Hatches which open or close under their own weight are to be so designed that divers are not endangered when operating them.

1.2.3.3 Hatches and access openings for persons should have a clear diameter of at least 500 mm, or at least 700 mm in the case of test chambers.

1.2.3.4 The length of hatch trunks should not exceed the trunk diameter.

1.2.3.5 For hatches in wet test chambers, the sealing groove and seal counterface should be made of non-corroding materials.

1.2.3.6 Hydraulically operated hatches have to meet the following additional requirements:

– The hatches must be capable of being opened manually if the hydraulic system fails.

– Steps must be taken to ensure that hatches which open under their own weight if the hydraulic sys-tem fails cannot endanger the divers.

– Steps must be taken to ensure that the opening action can only be initiated after the pressure has been equalized.

– Operating elements fitted outside chambers are to be arranged so that the operations of opening and closing the hatch can be observed through the view ports provided in the chamber.

The design and dimensions of the hydraulic system for internal hatches shall be compatible with the specified working pressures and with the boundary conditions of the compression chamber system. The hydraulic fluid must be suitable for use in the chambers and shall not under hyperbaric conditions release gas or va-pours which are toxic or capable of supporting combustion.

1.3 Materials

The materials used for diving simulators are required to comply with the provisions of Section 2, C.1.3 of these Rules.

1.4 Principles of manufacture and construc-tion

Pressure vessels for diving simulators are to be manu-factured and constructed in accordance with Section 2, C.1.4 of these Rules.

1.5 Calculations

Calculations relating to diving simulator pressure vessels are to be performed in accordance with Sec-tion 2, C.1.5 of these Rules.

1.6 Acrylic plastic windows

Acrylic plastic windows are to be designed and manu-factured in accordance with Appendix B of these Rules.

2. Pressure vessels and apparatus and gas bottles

Pressure vessels and apparatus and gas bottles are to be manufactured in accordance with the Rules for Classification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations, Section 8.

D. Pipes, Valves, Fittings and Hoses

Pipes, valves, fittings and hoses for diving simulators are to be designed and manufactured in accordance with Section 2, D. of these Rules.

E. Compressors

Breathing gas compressors for diving simulators are to be designed and manufactured in accordance with Section 2, E. of these Rules.

F. Life Support Systems

1. General

1.1 These Rules apply to all parts and compo-nents of the system which are necessary to ensure the life support and safe environment of the occupants of a diving system.



I - Part 5 GL 1998


F

2. Gas supply

2.1 Gas storage facilities

2.1.1 Each diving system is to be provided with a permanently installed gas storage facility or with a suitable location for the storage of mobile gas bottles.

2.1.2 The capacity of the gas storage facility shall be such that a sufficient number and quantity of gas mixtures are available for all planned diving opera-tions to ensure that an adequate volume of the appro-priate gases can be supplied to all compression cham-bers and divers at all operating depths under both nor-mal and emergency conditions (for determination of the minimum quantities of gas required, see: European Diving Technology Committee: Guidance Notes for Safe Diving, Appendix 2, to Chapter 5, p. 70, Oct. 1984).

2.1.3 The emergency breathing gas supply is to be stored separately in bottles which shall not be opened for normal operation.

2.1.4 Wherever possible, the gas storage facility is to be housed in a separate building. Rooms for the storage of oxygen must be constructed of components having at least class F 30 fire resistance to DIN 4102.

2.1.5 The gas storage facility is to be separated from adjoining rooms by fireproof partitioning (F 90 to DIN 4102) if these rooms are subject to a fire or ex-plosion hazard.

2.1.6 The roofing of the gas storage facility must have adequate resistance to airborne incandescent particles and radiant heat. The floor covering must be at least flame-retardant.

2.1.7 Gas store-rooms must be adequately venti-lated. The exits are to be so arranged that it is possible to quit the rooms quickly in case of danger.

2.1.8 No combustible materials may be stored in the gas storage facility.

2.1.9 Gas stores in the open must be established in such a way that they are protected from mechanical damage and the action of outside fires. The containers must be readily accessible from all sides. The valves must be capable of being operated from a fixed control point.

2.1.10 Gas storage facilities are to be safeguarded against unauthorized entry. In addition, warning no-tices are to be mounted prohibiting the introduction of mobile fire loads as well as the use of open fires and smoking inside the gas store.

2.2 Gas distribution

2.2.1 General

2.2.1.1 The gas supply system shall be so designed that the pressure in the living compartment of the compression chamber can be raised at a rate of at least 2 bar/min up to 2 bar and thereafter at a rate of 1 bar/min.

2.2.1.2 The gas venting system shall be so designed that the pressure in a compression chamber or diving bell can be lowered to 1 bar at a rate of at least 1 bar/min.

2.2.1.3 Sets of breathing apparatus activated by respi-ration which supply breathing gas to persons under pressure and also remove the exhaust gas independ-ently of the chamber atmosphere are to be designed for a gas flow equivalent to 3 times the required breathing rate per minute (AMV).

The required breathing rate per minute depends on the activity to be performed and the environmental condi-tions (where heavy work is performed in open water, the rate may be as much as 75 operating li-tres/min/person).

When designing the breathing mask gas supply and exhaust gas disposal system, the number or persons simultaneously connected to the system is to be al-lowed for as follows:

Number of persons Quantity of breathing gas

[operating litres/min]

1 2 3 4 5 6 7 8

z > 8

1 x AMV x 3 2 x AMV x 1,8 3 x AMV x 1,6 4 x AMV x 1,4 5 x AMV x 1,3 6 x AMV x 1,2 7 x AMV x 1,1 8 x AMV x 1,1 z x AMV x 1,0

2.2.1.4 The gas circulating systems are to be so de-signed that the chamber conditions stated in B.3. are maintained.

2.2.1.5 Each compression chamber compartment and each diving bell is to be equipped with at least the following gas systems:

– 2 independent gas supply systems for compres-sion which may deliver into a single inlet pipe immediately at the chamber

– 1 chamber exhaust gas system

– 1 built in breathing system (BIBS)



F

– 1 mask exhaust gas system

– 1 gas circulating system for maintaining a breathable chamber atmosphere

Where pure oxygen or gas containing more than 25 % O2 by volume is supplied to the chamber, a separate piping system is to be provided for this purpose.

2.2.1.6 Valves in gas systems are to be arranged so that a leaking valve cannot cause any unintended mix-ing of gases and no oxygen or oxygen-like gas can penetrate into lines intended for other gases. Inter-sections between oxygen and non-oxygen systems are to be isolated by twin shutoff valves with a vent valve placed between them.

2.2.1.7 Filters and automatic pressure reducers are to be fitted in such a way that they can be dismounted without having to interrupt major gas supply lines.

2.2.1.8 All gas supply and exhaust lines are to be effectively protected against mechanical damage. When routed through zones subject to fire hazard they shall, in addition, be provided with fireproof cladding.


2.2.2.1 At least one breathing mask is to be provided for each occupant of each separately pressurized chamber compartment.

2.2.2.2 The masks are to be joined either perma-nently or by plug connectors to the mask gas supply and exhaust system.

2.2.2.3 The exhaust gas (exhalation line) side of the masks is to be protected against any inadmissible pres-sure drop or inadmissible pressure difference.

2.2.2.4 The supply of gas to the chamber is to be arranged so as to ensure that a homogeneous gas dis-tribution inside the chamber is achieved as quickly as possible.

2.3 Conditioning of chamber atmosphere

2.3.1 Each compression chamber living compart-ment is to be equipped with an oxygen dosing device and a chamber gas circulating unit in which the CO2 can be absorbed and the air temperature and humidity can be regulated. The rate of circulation shall be such as to satisfy the conditions stated in Section 2, B.3.

2.3.2 Each diving simulator is to be equipped with at least 2 chamber gas treatment units which are to be so arranged that they can be switched to adjoining chambers.

2.3.3 Test chambers for the performance of manned experiments in which gases, vapours, dust or fumes injurious to health are generated are to be equipped with extraction systems capable of aspirating the harm-ful substances as close as possible to their point of origin.

Such test chambers are also to be provided with purifi-cation systems (welding gas absorbers) for keeping the chamber atmosphere breathable, inert and within the permitted temperature limits, e.g. during welding op-erations. In addition to this, such test chambers must be equipped with a personal breathing system and respirators independent of the chamber atmosphere. Additional equipment is to be provided to enable not only the chamber atmosphere but also the breathing gases supplied to the divers to be permanently moni-tored directly at the mask when work or tests are being carried out in a non-breathable atmosphere.

2.4 Treatment and mixing of breathing gases

The use of closed breathing circuits, gas mixing sys-tems for direct breathing gas supply and helium re-claim systems is subject to approval by GL.

3. Control and instrumentation

3.1 Central Control Position

3.1.1 Diving simulators are to be arranged and equipped in a manner which enables the entire simu-lator operation to be centrally monitored.

The Central Control Position must be equipped with all the necessary means for the surveillance, control and coordination of the various operating functions.

Measures are necessary to ensure that:

– the Central Control Position is adequately shielded from other service rooms (protection against noise and visual interference, separate ventilation system, no access or thoroughfare to other service rooms)

– the Central Control Position is free from items of equipment and components which do not belong to, or are not needed in the Central Control Po-sition

– the Central Control Position is provided with effective all-round fire protection

– the atmosphere in the Central Control Position is regulated to provide optimum conditions for human beings and equipment

– the Central Control Position is designed on er-gonomic principles and the main units are laid out and arranged in a manner compatible with the test work to be performed (e.g. relative posi-tioning of the chamber control consoles)

– the Central Control Position is provided with a sufficiently secure emergency power supply (electricity, compressed air)

– the Central Control Position is provided with a sufficiently bright emergency lighting system with a back-up power supply

I - Part 5 GL 1998


F

– as far as possible, the pipes and cable runs in the Central Control Position are installed separately according to system so that faults in one system cannot lead to the failure of others

– the Central Control Position has communication links not only with the compression chambers but also with the ancillary units and general op-erations rooms

– the Central Control Position contains the central fire alarm station for the compression chamber fire detection system, where such a system is in-stalled, as well as the release valves of the com-pression chamber water spray extinguishing sys-tem

– the Central Control Position is itself provided with a fire detection system and with the means for combating effectively a fire in the Central Control Position without endangering the safe operation of the compression chamber system as a whole

– effective stops are taken to prevent operations in the Central Control Position from being im-paired by telephones, the activation of alarms and general noise.

3.2 Instrumentation

3.2.1 Indicating instruments

3.2.1.1 The instruments for the surveillance, control and operation of the diving simulator are to be grouped and arranged in the Central Control Position in accordance with the principles of safety technology and ergonomics.

3.2.1.2 In the Central Control Position a separate control console is to be provided for each independ-ently operated compression chamber compartment. For test chambers, an additional independent control stand should be placed in the immediate vicinity of the test chambers.

3.2.1.3 At least the following operating parameters are to be displayed at the Central Control Position for each manned compression chamber compartment:

– pressure or depth

– temperature

– humidity

– partial oxygen pressure

– partial CO2 pressure

– pressure of connected breathing gas contain-ers/bottles

– pressure at pressure reducer outlets

– oxygen content in supply lines to

– chamber compartments

– breathing masks in chambers

3.2.1.4 The instrumentation of compression cham-bers used exclusively for unmanned tests shall be compatible with the test conditions.

3.2.1.5 The pressure gauges of compression cham-bers must give a reading accurate to ± 0,3 % of the full instrument scale subject to a maximum deviation of 30 cm water column. All other pressure readings may be accurate ± 1 % of the full instrument scale.

3.2.1.6 Inadmissible deviations from reference values of the vital parameters shall actuate a visual and audi-ble alarm at the Central Control Position. Automati-cally actuated switching operations in the gas supply system and similar functions shall also trip such alarms.

3.2.1.7 Compression chamber compartments are to be equipped with pressure and temperature gauges which can be read from inside.

3.2.1.8 Pressure gauges connected directly to the compression chamber system are to be fitted with a shutoff valve.

3.2.2 Analyzers

3.2.2.1 Each diving simulator is to be equipped with at least one oxygen and one CO2 analyzing system.

3.2.2.2 Throughout the entire period of operation, the oxygen analyzer must give a reading accurate to at least ± 0,015 bar partial oxygen pressure.

3.2.2.3 Throughout the entire period of operation, the CO2 analyzer must give a reading accurate to at least ± 0,001 bar partial CO2 pressure.

3.2.2.4 Compression chamber living compartments are to be equipped in addition with independent in-struments for monitoring the oxygen and CO2 levels.

3.2.2.5 Where gas mixtures other than air or helium-oxygen are to be used for diving, suitable additional equipment is to be provided for analyzing the gases used.

3.2.2.6 Test chambers in which welding operations are performed are to be equipped with analyzers for continuously monitoring the chamber atmosphere for impurities such as CO, NO, NOx, hydrocarbons and ozone. It is necessary to ensure that the analyzers are also able to monitor the chamber atmosphere of the other compression chambers. Apparatus is also to be provided for the analysis of the pure gases. The breathing gas mixtures and the purified helium gases.

3.2.2.7 The accuracy of the analyzer readings shall be such that the discrepancy between the partial pres-sure in the gas and the partial pressure readings on the instrument does not exceed 10 %.

3.2.2.8 For diving simulators where the chamber atmosphere is not subject to contamination as a result



F

of technical experiments, test tubes may be recognized as a suitable means of monitoring the chamber atmos-phere for contamination.

3.3 Control equipment

3.3.1 The Central Control Position is to be equipped with controls for at least the following func-tions:

– pressurization and pressure control of each inde-pendently operated compression chamber com-partment and each diving bell

– decompression of each independently operated compression chamber compartment and each diving bell

– pressure equalization between chamber com-partments

– oxygen supply to the chamber compartments

– control of gas supply to breathing marks

– control of temperature and humidity in the com-pression chambers

3.3.2 The control stand for the gas distribution system is to be provided with a mimic diagram show-ing the functions of the various valves and the differ-ent gas lines marked in colour.

G. Automation and Communications Equip-ment

1. General

1.1 The following Rules supplement of GL Rules Part 1 – Seagoing Ships, Chapter 3 – Electrical Instal-lations are to be applied to the construction and appli-cation of equipment for the surveillance and control of diving simulators and their communications and TV monitoring systems.


1.3 The necessary tests and markings are stated in A.5. and A.6. Only components and units which have been approved 'by GL may be installed.

2. Automation equipment

Automation equipment for diving simulators is to be designed and constructed in accordance with Sec-tion 2, G.2. of these Rules.

3. Communications equipment

3.1 Voice communication systems

3.1.1 Diving simulators are to be equipped with a suitable communications systems allowing direct communication between the control stand and:

– each compartment of compression chambers and test chambers

– test equipment control positions

– test chamber control stands

– ancillary units

– offices and service rooms (e.g. the operations manager's office and mechanical and electrical workshops)

3.1.2 Where diving simulators are operated with helium gas mixtures, each compression chamber com-partment is to be connected to a helium speech un-scrambler. The speech unscramblers should be de-signed for maximum noise suppression and automatic compensation of changes in signal level.

3.1.3 It is recommended that the Central Control Position be equipped to record all communications with the divers.

3.1.4 Voice communications between the compres-sion chamber compartments and the Control Position must be provided by a communication system with loudspeaker which is permanently switched to "Re-ceive" at the control console. Switches for reversing the direction of communication must be of the self-resetting type. In addition, each compression chamber compartment is to be provided with at least one head-set.

3.1.5 A mains-independent telephone link must be provided in addition to the telephone system called for in 3.1.4.

3.1.6 Electrically powered telephone systems are to be provided with a reliable power supply. This nor-mally means that they are to be supplied from a stor-age battery with a parallel-connected mains unit and battery charger supplied with energy in accordance with Section 2, H.

3.1.7 In wet rooms microphone and receiver sys-tems must be designed to prevent the penetration of water. Where this cannot be ensured by the design, the penetration of water shall not render the equipment permanently unserviceable.

3.1.8 The microphone and receiver in diver's masks and helmets are to be functionally separated from each other.

I - Part 5 GL 1998


G

3.2 Television surveillance equipment

3.2.1 Diving simulators are to be equipped with a television surveillance system.

3.2.2 The number of cameras and their angles of view shall be chosen to give, wherever possible, a complete picture of the whole interior of the diving simulator. In test chambers, allowance is to be made for the fact that the chambers may be partially filled with water and adjustable test equipment may obstruct the view.

3.2.3 A sufficient number of TV monitors must be provided. Each TV monitor must indicate clearly which compartment is being viewed at any time.

3.2.4 The image reproduced on the monitors must show up the necessary detail.

3.2.5 It is recommended that a video recorder is installed.

3.3 Other communications equipment

3.3.1 All compression chamber compartments are to be provided with suitable alternative communica-tions equipment (e.g. a 3-button signalling system).

3.3.2 Diving simulators should be provided with equipment for transmission of radio, television and video programmes which can, if necessary, carry op-erational telephone communications as priority traffic.

H. Electrical Equipment

Electrical installations and equipment for diving simu-lators are to be designed and constructed in ac-cordance with Section 2, H. of these Rules.

The electrical components and equipment to be in-stalled outside compression chambers must, as a minimum requirement, conform to a recognized stan-dard, e.g. VDE, DIN or IEC standards.

I. Fire Protection

1. General

1.1 The following Rules apply to the fire protec-tion of diving simulators built in accordance with the Rules of GL.



2. Structural fire protection

2.1 Area of installation of the diving simulator

2.1.1 Buildings for diving simulators and their ancillary units are to be designed and constructed in accordance with the building regulations in force at the site where the diving simulator is to be installed.

2.1.2 Diving simulators may only be installed and operated in areas not subject to an explosion hazard.

2.1.3 The rooms in which the diving simulator, the Central Control Position and the gas storage facility are installed are to be separated from other service rooms by floors and walls with class F 30 fire protec-tion to DIN 4102. If the adjoining rooms are consid-ered to be subject to a fire hazard, the relevant parti-tions are to be fireproof (F 90).

2.1.4 The rooms in which diving simulators and their ancillary units are installed are to be provided with forced ventilation systems capable of effecting at least 8 changes of air per hour. The air must be aspi-rated from an area not subject to an explosion hazard.

The rooms are also to be equipped with an effective smoke extraction system.

2.1.5 In the area of installation of the diving simu-lator, the gas storage facility and the Central Control Position, sources of ignition and fire loads must be reduced to a minimum. Wherever possible, materials which are at least fire-retardant are to be used. Heat insulation is to be made of non-combustible materials.

2.2 Compression chamber interiors

2.2.1 Wherever possible, all materials used in com-pression chambers must be at least flame-retardant. (For the purpose of these Rules, flame-retardant refers to materials which do not spontaneously sustain com-bustion in a compressed air atmosphere of at least 6 bar).

2.2.2 As far as possible, fire loads and sources of ignition are to be avoided. Electrical heating appli-ances and heaters are to be fitted with protection against overheating.

2.2.3 Components or materials are to be selected with a view to minimizing the acquisition of static charges.

3. Fire surveillance

3.1 Fire detection and alarm systems

3.1.1 The rooms in which diving simulators and their ancillary units are installed are to be protected by an automatic fire detection system.



I

3.1.2 The fire detection system must trip visual and audible signals in at least one permanently manned control room.

3.1.3 The fire alarm can be activated manually from the permanently manned control room or auto-matically by the fire detection system.

3.2 Fire detection systems

3.2.1 Fire detection equipment such as the central fire detection station, the detectors and the wiring of the detection loops must have the approval of GL.

3.2.2 Fire detection systems must be constructed so that any faults, e.g. failure of the power supply, short-circuit or wire breakage in the detection loops or the removal of a detector from its base, trip visual and audible signals in the central fire detection station.

3.2.3 The installations and arrangement of fire detection and signalling systems are to conform to GL Rules for Classification and Construction Part 1 – Seagoing Ships, Chapter 3 – Electrical Installations, Section 9 and Chapter 4 – Automation.

4. Fire extinguishing equipment

4.1 Area of installation of the diving simulator

4.1.1 The area of installation of the diving simula-tor and its ancillary units is to be equipped with a water fire extinguishing system as well as with port-able and mobile fire extinguishers and extinguishing appliances.

4.1.2 The water fire extinguishing system is to be fed by a wet 100 mm ID ring main in the building. The ring main is to be fitted with hose connections in a way which ensures that a fire inside the building can be effectively and safely combated. Hose connections are to conform to DIN 14461, Part 3. Suitable hose boxes (e.g. to DIN 14461, Part 1) containing hoses and noz-zles are to be placed close to the hose connections.

In addition, a non-freeze water hydrant is to be placed close to the diving simulator operations building (e.g. an underfloor hydrant to DIN 3221 or an above-floor hydrant to DIN 3222).

4.1.3 In the case of diving simulators without a hyperbaric evacuation system, the compression cham-ber system is to be provided with means of cooling in case of fire in the form of a permanently installed water spray system with a capacity of at least

10 /m2/minute related to the projected horizontal area

concerned. The water spray system must encompass at least all the living areas. These spray systems may be activated and operated by hand.

4.1.4 The rooms in which diving simulators and their ancillary units are installed are to be equipped

with approved hand extinguishers. In each case, one of the portable extinguishers is to be mounted close to the entrance to the room concerned.

4.1.5 Where the room in which the diving simulator is installed is also used wholly or in part as a work-shop, the room in question is to be additionally equipped with at least one mobile 50 kg dry extin-guisher.

4.2 In compression chambers

4.2.1 Each compartment inside a compression chamber is to be equipped with suitable means of extinguishing a fire in the interior and such means shall be capable of applying the extinguishing agent quickly and effectively to all parts of the chamber.

4.2.2 The fire extinguishing system is to be de-signed and constructed in such a way that it is fully able to deal with any conceivable case of fire under all the environmental conditions for which the diving simulator is designed. Activation of the fire extin-guishing system shall cause no inadmissible loss of pressure in the chamber. The extinguishing system may be activated by hand.

4.2.3 The preferred extinguishing agent is water. Extinguishing agent with a toxic or narcotic effect are not allowed.

5. Other fire protection equipment

The Central Control Position of the diving simulator is to be provided with at least one independent com-pressed-air respirator of approved design having an operating capability of at least 30 minutes and fitted with equipment for voice communication with the divers.

J. Hyperbaric Evacuation System

1. General

1.1 Where a hyperbaric evacuation system per-manently connected to the diving simulator is pro-vided, the following Rules are to be applied.

1.2 Where the evacuation chamber is also to be used as a compression chamber the relevant sections of the Rules of Construction for Diving Simulators are also to be applied.

1.3 The documents to be submitted to GL for approval are listed in A.4. The necessary tests are stated in A.5.

I - Part 5 GL 1998


J


2.1 Evacuation chamber

2.1.1 The hyperbaric evacuation chamber is to be designed for the simultaneous rescue of all the divers in the diving simulator at the maximum operating depth. At least one seat with safety harness is to be provided for each divers.

2.1.2 The evacuation chamber is to be provided with a lock for supplies.

2.1.3 The evacuation chamber is to be equipped with view ports enabling all the occupants to be ob-served from outside.

2.1.4 The chamber connections for gas, water and electricity are to be designed for rapid coupling and uncoupling.

2.1.5 The evacuation chamber is to be adequately lit.

2.1.6 The evacuation chamber must be equipped with an autonomous life support system enabling the pressure, temperature and gas composition in the com-pression chamber to be maintained for at least eight hours. The life support system or the evacuation

chamber is to be provided with connections for exter-nal supply and surveillance.

2.1.7 The evacuation chamber must be equipped externally with regulating and control devices enabling a safe environment for the divers to be maintained.

2.1.8 The evacuation chamber is to be equipped with a telephone system allowing communication with the divers.

2.1.9 The evacuation chamber is to be provided with its own power supply enabling the electrical sys-tem to be kept operational for at least eight hours.

2.1.10 The evacuation chamber is to be so designed that it can be operated in the open air.

2.1.11 The evacuation chamber is to be equipped with a mating and handling system enabling it to be quickly and safely connected and disconnected and conveyed to a position of safety without external power.

2.1.12 The evacuation chamber is to be provided with attachment points enabling it to be hoisted by a standard crane.



J

Section 4

Rules for Construction of Diver Pressure Chambers


1. Scope

1.1 The following Rules apply to diver pressure chambers (deck compression, rescue chambers) which are intended for the treatment or rescue of sick divers under pressure in accordance with UVV "Taucherar-beiten" (VBG 39) (Accident Prevention Regulations for Work Performed by Divers), and which are con-structed under survey of and in conformity with the Rules of GL and are to be certified accordingly. They also apply to all equipment necessary to the safe op-eration of the diver pressure chambers.

1.2 Diver pressure chambers, including their ancillary equipment, which are constructed in accor-dance with 1.1 may also be classified by GL on appli-cation by the operator.

2. Definitions

2.1 Breathing connection

Connection between the demand breathing system and the user's respiratory passages.

2.2 Working pressure

The internal excess pressure in part of the system intended to facilitate the performance of one or more basic operations.

2.3 Deck compression chamber

Diver pressure chamber intended for the treatment of sick divers under pressure.

2.4 Pressure chamber

Pressure vessel for human occupancy.

2.5 Compressed air storage

Total quantity of stored compressed air.

2.6 Main chamber

Part of pressure chamber used for carrying out treat-ment under pressure.

2.7 Demand breathing system

Respiration-controlled metering system.

2.8 Test pressure

The excess pressure to which a component is sub-jected for test purposes.

2.9 Diver pressure chamber

Pressure chamber intended for the treatment or rescue of sick divers under pressure in accordance with UVV "Taucherarbeiten".

2.10 Rescue chamber

Pressure chamber intended for the transport of sick divers to a treatment chamber under pressure.

2.11 Antechamber

Part of pressure chamber for the lock in and out of persons and equipment.

2.12 Maximum permissible working pressure

The maximum permissible working pressure dictated by safety considerations.


3.1 General

3.1.1 Before the start of manufacture, plans and drawings of all components subject to compulsory inspection are to be submitted to GL in triplicate.

3.1.2 The drawings must contain all the data neces-sary to check the design and the loading of the equip-ment. Wherever necessary, calculations relating to components and descriptions of the system are to be submitted.


3.2 Pressure chambers, pressure vessels and apparatus

3.2.1 Drawings are to be submitted of pressure chambers, pressure vessels and apparatus giving full details for appraising the safety of the equipment. Component drawings of the equipment of pressure chambers and vessels are also to be submitted.

I - Part 5 GL 1998

Section 4 Rules for Construction of Diver Pressure Chambers Chapter 1Page 4–1

A

3.2.2 Plans, block diagrams and descriptions, in-cluding lists of valves and fittings are to be submitted for the supply, operating and control systems.

4. Test and trials

4.1 General

4.1.1 Diver pressure chambers and their ancillary equipment are subject to preliminary examination, constructional and materials tests as well as to pres-sure and tightness tests and trials. All the tests called for in the following paragraphs are to be performed under GL supervision.

4.1.2 After the diver pressure chambers and ancil-lary equipment have been installed on board, the sys-tem is to be subjected to functional test, and all items of safety equipment are to be tested except where this has already been done on the manufacturer's premises in the presence of GL's representatives.

4.2 Diver pressure chambers, pressure vessels and apparatus

4.2.1 On completion, pressure chambers, pressure vessels and apparatus are to be subjected to a con-structional test.

The constructional test includes verification that the vessel conforms to the approved drawings and that the workmanship is satisfactory. All components must be accessible to allow adequate inspection.

4.2.2 The materials test certificates for the materi-als used and the reports on the non-destructive testing of welds are to be submitted together with the results of inspections of workmanship and evidence of the heat treatments applied, where appropriate.

4.2.3 A hydraulic pressure test is to be performed prior to preservation treatment of the vessel. Each pressure chamber compartment is to be tested indi-vidually. The walls may exhibit no permanent defor-mation or leakage.

4.2.4 The test pressure shall normally be equivalent to 1,5 times the maximum permissible working pres-sure.

4.2.5 The gas storage facility and the diver pressure chamber including the gas piping are to be subjected to a tightness test using air at the maximum permissi-ble working pressure.

4.2.6 Gas bottles are to be checked to determine whether they bear the test date and marking applied by a recognized expert and whether the test period has not yet expired.


4.3.1 Each compression chamber window must undergo a hydraulic pressure test which may be per-formed after installation together with the compres-sion chamber or in a testing device. The test pressure shall normally be equivalent to 1,5 times the design pressure.

4.3.2 After the pressure test, windows may exhibit no scratches, cracks or permanent deformation.

4.4 Compressors

Compressors are to be subjected to a tightness test at their maximum working pressure. In addition, a per-formance test is to be carried out in which the final moisture content and any possible contamination of the compressed gas are to be determined. The safety devices are to be checked.

4.5 Piping systems

On completion of manufacture but before insulation or painting, all piping systems are to be subjected by the manufacturer to a hydraulic pressure test at 1,5 times the design pressure and are to be cleaned. A certificate in accordance with EN 10204-2.2 is to be issued to this effect.

4.6 Control, communications and safety equipment

4.6.1 Indicating and monitoring instruments are to be tested for the accuracy of their readings and their limit value settings.

4.6.2 Automatic monitoring systems are to be checked for satisfactory performance under service conditions.

4.6.3 Normal and emergency communications equipment is to be subjected to a functional test.

4.6.4 Proof is required of the autonomy of the safety systems.


4.7.1 All electrical systems and equipment are to be inspected and tested before the diver pressure chamber is put into service.

4.7.2 Electrical protective devices are to be checked; in addition, an insulation test is to be per-formed on the electrical equipment in the pressure chambers.

4.8 Fire protection

4.8.1 The fire behaviour of the chamber equipment is to be checked by reference to the relevant test cer-tificates and symbols, as applicable.


Section 4 Rules for Construction of Diver Pressure Chambers I - Part 5GL 1998

A


4.8.3 Fire extinguishing appliances are to be sub-jected to a functional test.

4.9 Mating systems

A check is to be carried out to verify that the bayonet flange connection cannot be subjected to pressure until the inner ring of the bayonet mechanism has turned fully home, and that the bayonet flange connection cannot be opened until the pressure has been relieve.

Furthermore, the pressure relief device of the flange connection is to be checked.

5. Marking

5.1 All diver pressure chambers are to be fitted in a prominent position with a permanently mounted name plate containing at least the following details:



– maximum permissible working pressure

– test pressure

– capacity (in litres) (of each chamber compart-ment)

– maximum permissible number of persons (in the case of deck compression chambers)





– capacity (in litres)

– test pressure (bar)

– empty weight (of gas bottles)


5.3 All valves and fittings, operating elements, indicators and warning devices are to be clearly and plainly marked.

B. Principles for Design and Construction


1.1 Diver pressure chambers are to be designed and built to ensure safe operation and facilitate proper maintenance and the necessary surveys.

1.2 All parts of diver pressure chambers are to be designed, constructed and mounted in such a way as to facilitate cleaning and disinfection.

1.3 Diver pressure chambers must be so designed that a working pressure of at least 5 bar can be reached and maintained without fail. Provision must be made for raising the working pressure form 0 bar to 5 bar within 6 minutes. A pressure reduction from 0,4 bar to 0,2 bar must be possible within one minute.

1.4 Diver pressure chambers must be equipped with a suitable safety device which automatically prevents the maximum permissible working pressure from being exceeded by more than 10 %.

In addition, diver pressure chambers must be equipped with a reliable safeguard against any inadmissible pressure drop.

1.5 Safety valves must be so designed that they respond only when the maximum permissible working pressure has been exceeded and close before the pres-sure drops below this level.

Safety valves are to be mounted in such a way that they are protected from mechanical damage and acci-dental operation.

The connection of safety valves on diver pressure chamber are to be so designed that they cannot be sealed off unintentionally.

1.6 Instead of the pressure relief device, equip-ment may be fitted which automatically interrupts the pressure supply when the maximum permissible work-ing pressure is exceeded and simultaneously trips a visual and audible alarm. The alarm signal shall be such that it is at all times clearly perceptible to the operating personnel.

1.7 The door opening of diver pressure chamber shall allow the passage of a patient laying flat on a stretcher to DIN 13024. Round door openings must have a clear diameter of at least 0,70 m. Doors fitted with an interlock must be capable of being operated from both sides when the pressure has been equalized.

Diver pressure chambers operated on ships, floating structures or in containers have to be fitted with a device that avoids swinging of the doors also in the open position.

I - Part 5 GL 1998


B

1.8 Diver pressure chambers are to be fitted with observation windows giving a good view of all the occupants of deck compression chambers and of the head of the occupant of rescue chambers. The win-dows must be made of acrylic plastic.

1.9 Each pressurized gas supply and exhaust line must be fitted with a shutoff valve immediately at the pressure chamber wall. This shutoff valve may be deleted if the connection between the pressure cham-ber and the line valve is short and well protected.

1.10 Diver pressure chambers are to be so de-signed and equipped that the noises in the chamber do not exceed a peak level of 90 dB(a) measured as an A(pulse) acoustic pressure level to DIN 45645, part 1, or an evaluation level (to DIN 45645, part 1, over 3 hours) of 70 dB(A). These values apply to the head level of persons seated in the deck compression cham-ber and to the head area of the person in the rescue chamber.

1.11 The interior equipment of diver pressure chambers should be made of materials which are at least flame-retardant (class B1 to DIN 4102 or to ISO 6941). The use of plastics for the interior equipment of chambers is to be kept to a minimum.

2. Deck compression chambers

2.1 General requirements

2.1.1 Deck compression chambers must comprise at least a main chamber and an antechamber. They should also be equipped with a connecting flange for rescue chambers subject to DIN 13256, Part 6, (NATO flange).

2.1.2 The inside diameter of the deck compression chamber should be at least 1,48 m.

2.1.3 The configuration of the main chamber shall provide space for one person laying down and two persons seated.

The number of occupants allowed in the main cham-ber is to be stated on a plate prominently and perma-nently fixed above the entrance.

2.1.4 Seats must be provided in sufficient number for the number of persons admitted. Seats must be designed to provide each person with a seat width of at least 0,5 m and a seat depth of at least 0,4 m and must avoid loss of body heat due to contact with cold surfaces.

2.1.5 After deduction for interior equipment, the chamber must provide at least 0,5 m3 of space for each person to be accommodated.

2.1.6 The main chamber must be equipped with means of changing the air.

2.1.7 Each person to be accommodated must be provided in the main chamber with a source of oxygen supplying at least 75 /min at atmospheric pressure. The oxygen is to be supplied to the breathing connec-tion via a demand breathing system at the pressure prevailing in the chamber. The exhaled gas may not be introduced in the chamber atmosphere.

2.1.8 Main chamber and antechamber must be separately supplied with air and oxygen for breathing. Means must be provided to prevent the pressure in the antechamber exceeding that in the main chamber.

2.1.9 The main chamber must be equipped with heating. The heating capacity must be equivalent to at least 0,25 kW per m3 of chamber volume and must have at least 3 settings.

2.1.10 The main chamber is to be provided with a supply lock. The dimensions of the supply lock must not be less than 200 mm in diameter and 300 mm in length. The means of closure of the supply lock must be interlocked in such a way that they can on no ac-count open simultaneously. Pressure equalizing aper-tures must be safeguarded to prevent them from being rendered ineffective by obstructions. The pressure in the supply lock chamber must be indicated by a pres-sure gauge mounted externally close to the lock con-trols.

2.1.11 The vessel wall of the main chamber must be fitted with at least one DN 80 blind flange for later installations.

2.1.12 The main chamber must be provided with easily accessible means of mounting a pressure gauge for test purposes.

2.1.13 The configuration of the antechamber shall be such that it can accommodate two seated persons.

2.2 Compressed air and oxygen supply

2.2.1 A supply of compressed air is to be provided for the operation of the deck compression chamber which is sufficient to

– raise the pressure in the main chamber once and in the antechamber twice from 0 bar to 5 bar ex-cess pressure

– hold an overpressure of 5 bar in the main cham-ber for 30 minutes with an adequate rate of air-change

– hold an overpressure of 1 bar in the main cham-ber for 300 minutes with an adequate rate of air-change

The design of the air-change system is adequate if it is capable of exchanging 40 litres of air per minute per person at working pressure.



B

In the main chamber it must be possible to effect the aforementioned pressure rise within 6 minutes.

2.2.2 The air supply system is also to be equipped with an air compressor at least capable of meeting the air-change requirements stipulated in 2.2.1.

2.2.3 The capacity of the air compressor called for in 2.2.2 may be reduced provided that the deck com-pression chamber is equipped with an efficient CO2 absorber and suitable quantities of lime are carried.

2.2.4 Notwithstanding 2.2.2 an air compressor may be dispensed with if an additional emergency air sup-ply is carried in compressed air containers which cor-responds to at least 50 % of the quantity of air speci-fied in 2.2.1.

2.2.5 The air supply system is to be provided with an additional inlet for compressed air.

2.2.6 The air supplied to the deck compression chamber must conform at least to the purity require-ments specified in EN 12021 "Compressed Air for Breathing Apparatus".

2.2.7 For oxygen treatment a supply of oxygen of at least 20 m3 has to be provided.


2.3.1 All electrical equipment including lighting must conform to DIN 57100 part 706/VDE 0100 part 706 and VDE 0100.

2.3.2 All electrical equipment is to be safeguarded to prevent overheating.

2.3.3 The lighting in the antechamber and main chamber of deck compression chambers must provide a nominal illuminance of at least 200 lux at the seating level. It must be possible to illuminate lying surfaces with an illuminance of 500 lux (e.g. by adjustable spotlight).

2.3.4 An emergency power supply must be pro-vided to illuminate the deck compression chamber, the control console and all consumers necessary to opera-tional safety. In case of mains failure, this must take over the power supply to the consumers and must ensure continued operation for at least 5 hours.

2.4 Controls and indicating instruments

2.4.1 The controls and indicating instruments for the antechamber and main chamber must be grouped in one control console. They must be clearly marked, arranged according to function and must be illumi-nated in accordance with DIN 5035, part 2. The nomi-nal illuminance required is 300 lux.

2.4.2 The pressure in each antechamber and main chamber must be indicated by at least one class 0,25 pressure gauge.

2.4.3 A facility must be provided for continuously recording the pressure in the main chamber. The sys-tem must register pressure variations of 0,03 bar and time intervals of 1,0 min in a manner which enables the data to be evaluated. The pressure variations over the previous 2 hours must be visible.

2.4.4 The console is also to be fitted with indica-tors registering the following:

– the pressure in the compressed air storage con-tainers

– the pressure in the oxygen storage containers

– the air-change flow rate

– the inside temperature in the main chamber

– the volumetric concentration or partial pressure of the oxygen

2.4.5 A clock with a second hand, independent of the mains supply, must be mounted where it can be seen by the operator at the control console. Clocks with a digital display as the sole indicator are not per-mitted.

2.5 Communications

2.5.1 A communication system with loudspeaker must be provided between antechamber and control console and between main chamber and control con-sole. The communication system must be permanently switched to "Receive" on the control console, and reversal of the direction of communication shall be possible only by self-resetting switches.

2.5.2 A telephone link independent of the mains supply must be provided in addition to the communi-cation system called for in 2.5.1.

2.5.3 At least one emergency signalling system each must be installed between the antechamber and the control console and between the main chamber and the control console. The signal buttons in the chambers must be clearly marked and easily accessi-ble.

2.6 Fire protection equipment

Deck compression chambers are to be equipped with suitable fire-extinguishing appliances (e.g. deluge system, bucket spray, fire-extinguishing blanket).

3. Rescue chambers

3.1 For consideration of safety the use of one-man rescue chambers should no longer be envisaged. In addition to the sick diver the rescue chamber should be capable of accommodating a non-injured person.

I - Part 5 GL 1998


B

Apart from the General Principles according to 1. the following requirements apply.

3.2 Rescue chambers must have an inside length of at least 2,0 m and must have an access port with a clear diameter of at least 0,5 m.

3.3 It must be possible to lodge the diver in the rescue chamber securely enough to prevent injury due to motions during transfer. Suitable restraints are to be provided.

3.4 Rescue chambers must regarding their total weight and dimensions be designed such that they can be carried or moved otherwise by helpers over short distances and loaded onto a transport vehicle without the assistance of a crane.

3.5 Rescue chambers must be equipped with lifting handles, at least two fastening eyes and the necessary hoisting sling.

3.6 Rescue chambers are to be fitted with a bayo-net flange connection as per DIN 13256, Part 6, to enable them to be coupled to a deck compression chamber.

3.7 The design must ensure that, in normal op-eration, the means of closure of the rescue chamber cannot be opened until it is subjected to the same pres-sure from inside and out.

3.8 Rescue chambers are to be equipped with compressed air containers with at least 8000 litres air supply.

This supply of air is intended for the sole purpose of renewing the atmosphere in the event of an interrup-tion of the normal air supply. Adequate renewal of the atmosphere means 25 litres per minute per person measured at the maximum pressure in the vessel.

3.9 Rescue chambers must be equipped with at least the following controls and monitoring instru-ments:

– air inlet valve

– exhaust air valve

– pressure gauge (class 0,25) for chamber pressure

– pressure-reducing valve, with inlet and outlet pressure gauge, to which the compressed air containers called for in 3.8 are connected

– an additional means of connection, with shutoff device, comprising a suitable high-pressure hose at least 1,5 m in length for connecting the opera-tional compressed air supply to the pressure-re-ducing valve

– measuring instrument for monitoring of the oxygen volume concentration or partial pressure

3.10 The controls and indicating instruments must continue to be capable of being operated or observed when the rescue chamber is coupled to the deck com-pression chamber. They are to be located close to a window in the vessel in such a way that the operating personnel can observe the occupants of the rescue chamber without having to change position.

3.11 It must be possible to adjust the flow of re-newal air to at least 25 litres per minute per person (measured at the chamber pressure) at each pressure stage.

3.12 For the purpose of scavenging rescue cham-bers may be operated only with breathing air meeting the purity requirements as per EN 12021, "Com-pressed Air for Breathing Apparatus". Connections for sources of oxygen as per 2.1.7 are to be provided.

3.13 A communication system with loudspeakers must be provided between the inside of the rescue chamber and the outside controls. On the outside, the system must be permanently switched to "Receive", and reversal of the direction of communication shall only be possible by the operation of a self-resetting switch mounted on the outside. On the outside the communication system must also be equipped with a head-set.

3.14 Rescue chambers are to be provided with a supply lock as per 2.1.10.

4. Materials

The materials used for walls subjected to pressure are subject to the requirements set out in Section 2, C. of these Rules.

5. Manufacture

5.1 The manufacture of diver pressure chambers is subject to the requirements set out in Section 2, C. of these Rules with the following exceptions.

5.2 A weld factor of 0,85 is sufficient for welded seams on diver pressure chambers provided that at least all intersections of longitudinal and circumferen-tial seams are subjected to X-ray inspection.

5.3 Flat disk windows which have only been machined professionally on the edges do not have to be subjected to heat treatment after manufacture.

6. Calculations

Calculations relating to diver pressure chambers are subject to the requirements set out in Section 2, C.1.5 of these Rules.



B

Appendix A

Calculation and Pressure Hulls under External Pressure

A. Introduction

A method of calculation for designing the pressure hulls of submersibles is described below, which can be used for the three loading conditions:

– nominal diving pressure pN

– test pressure pP

– collapse pressure pZ

to investigate the stresses in the pressure hull and the corresponding states of stability:

– asymmetric buckling between stiffeners (axial buckling)

– symmetric buckling between stiffeners (circular buckling)

– general instability of pressure hull design

– tripping of stiffening rings

– buckling of dished ends.

The method of calculation presented takes limited account of fabrication relevant deviations from the ideal shape of the shell (out-of-roundness). Methods of verifying the roundness of hull shells are also de-scribed.

Conical shells are calculated in sections, each of which is treated as a cylindrical shell.

Overall collapse of the design is regarded as buckling of the hull structure between bulkheads or dished ends.

With regards to the stresses in the pressure hull the permissible values are those stated in Chapter 2 – Submersibles, Section 4, E.

For the states of stability described, proof is required of sufficient safety in respect of the particular form of damage concerned.

When using the method of calculation it is to be re-membered that both elastic and elastic-plastic behav-iour can occur in the materials of the shell structure.

It is generally the case that:

– at nominal diving pressure, the stress is within the purely elastic range of the material;

– at test pressure, the stress may lie at the com-mencement of the elastic-plastic range of the material;

However, calculations relating to the permissi-ble stress being exceeded can be based on the

assumption that the behaviour of the material is elastic.

– at the collapse pressure, the stress may lie in the elastic or the elastic-plastic range of the mate-rial.

In the elastic-plastic range, use of the method requires the determination of values by a process of iteration. The modulus of elasticity E and the Poisson's ratio ν shall be substituted by the values E' and ν' according to G. The corresponding iteration techniques are shown as program sequences at the end of the Appen-dix (Figs. 9 - 11).

When calculating a pressure hull use is to be made of design data corresponding to the proposed service conditions of the submersible in accordance with Chapter 2 – Submersibles, Section 4, E. of these Rules.

It is advisable to use a programmable computer for performing the calculations.

Pressure hulls subjected to internal overpressure are, in addition to be designed in accordance with GL Rules for the Classification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations, Section 8.

B. Stiffened and Unstiffened Cylindrical Shells

1. General

For the loading conditions mentioned in A. Cylindri-cal shells are to be checked for excess stresses and asymmetric and symmetric buckling.

The method of calculation presented below is for stiff-ened cylindrical shells. In the case of unstiffened cy-lindrical shells with dished ends, the calculations are performed in a similar manner, the cross-sectional area of the ring stiffener being A = A1 = 0 and the spacing between stiffeners being defined by the ends. Where the spacing between stiffeners is defined by dished ends 40 % of the depth H of each dished end is to be added to the cylindrical length (see Fig. 1). The "general stability" state is considered in C.3.3.

for the calculation of buckling in the elastic-plastic range the modulus of elasticity E and the Poisson's ν is determined by applying formulae (65) - (68) and by means of the stress σi formula (1) in the centre of the section and the centre of the plate.

I - Part 5 GL 1998

Appendix A Calculation and Pressure Hulls under External Pressure Chapter 1Page A–1

B

The calculations allow for an out-of-roundness of the shell of maximum u = 0,005. If larger tolerances are planned, or if the method of measurement described in H.1 results in greater out-of-roundness values, then the permissible pressure is to be checked in accordance with H.2.

2. Stresses in the cylindrical shell

The stress intensity (at the centre of the plate at mid-bay position between ring stiffeners) is determined by applying formulae (1) - (14).

In formulae (2a) to (2d) the bending component is expressed by the plus sign on top for the outside of the cylindrical shell and by the minus sign below for the inside. The stresses in the centre of the plate are de-termined by omitting of the expressions after the plus/minus signs.

2 2i x xϕ ϕσ = σ + σ − σ ⋅σ (1)

op R

s

⋅σ = − (2)

In the centre of the section the following applies:

x o 10 11 41

C C F2

σ = σ ± ⋅ ⋅

(2a)

( )o 10 2 10 11 41 C F C C Fϕσ = σ − ⋅ ± ν ⋅ ⋅ ⋅ (2b)

In the area of stiffening the following applies:

x o 10 11 31

C C F2

σ = σ ± ⋅ ⋅

(2c)

( )o 10 10 11 31 C C C Fϕσ = σ − ±ν⋅ ⋅ ⋅ (2d)

2 28 9

1 cosh C sinhC cosC sin C8 8 9 95 C C6 7

cosh C cos C4F

C ⋅ ⋅

− = +

(3a)

cosh C sin C sinh C cosCC C

2 cosh C sinh C cosC sinCC C

8 9 8 97 6

8 8 9 96 7

F

⋅ ⋅

⋅ ⋅

+ = +

(3b)

( )coshC sinh C cosC sin C8 8 9 9

C C6 73 cosh C sinh C cosC sin C2 8 8 9 9

C C6 7

3F

1

− ⋅ ⋅

⋅ ⋅

+ = +− ν

(3c)

( )cosh C sin C sinh C cosC8 9 8 9

C C7 64 cosh C sinh C cosC sin C2 8 8 9 9

C C6 7

3F

1

⋅ ⋅

⋅ ⋅

− = +− ν

(3d)

L3

L2 L2 L2

L1

0,4 H

R

R

H H

R

s

s

0,4 H

s

ϕ

Fig. 1 Spacing between stiffeners in pressure vessel subject to external pressure

Chapter 1 Page A–2

Appendix A Calculation and Pressure Hulls under External Pressure I - Part 5GL 1998

B

2

1 2o

RA A

R= ⋅ (4)

5 1C L= α ⋅ (5)

61

C 1 G2

= − (6)

71

C 1 G2

= + (7)

8 5 6C C C= ⋅ (8)

9 5 7C C C= ⋅ (9)

110

11 1 1

A1

2 s LC

A b b1 F

s L L L

ν − ⋅ ⋅ =

+ + − ⋅

(10)

11 2

0,91C

1=

−ν (11)

( )2

2 2

2 s Ep*

R 3 1

⋅ ⋅=⋅ ⋅ −ν

(12)

pG

p*= (13)

( )2

42 2

3 1

s R

⋅ −να =

⋅ (14)

ox

K ϕσ=

σ (15)

3. Provision against excess stresses

The stress intensity for the three loading conditions is obtained from formula (1). Sufficient safety against exceeding the permissible stress is provided if the conditions (16a, b, c) are met. In formulae (2a) to (2d) where load p = pZ the binding component can be dis-regarded.

i Nk S (where p p )= ≥σ ⋅ = (16a)

i Pk S' (where p p )= ≥σ ⋅ = (16b)

i Zk (where p p )= ≥σ = (16c)

The program sequence (see Fig. 9) shows the method of calculation used to obtain, for the loading condi-tions collapse pressure, the stress intensity and the maximum permissible pressures for the permissible stresses.

4. Asymmetric buckling

The buckling pressure pn is calculated with formulae (17) - (19) for the integer value n ≥ 2 corresponding to the lowest value of pn. The relevant stresses of the centre of the plate are determined in accordance with 2.

The program sequence (see Fig. 9) shows the method of calculation used to determine the buckling pressure pn in the elastic-plastic range.

n1n

E sp

R

⋅ ⋅β= (17)

( )( )

( )

22 2 2 22 1

2 2 21

n1 2 21

s n 1n1

12 R 1

n 1 0,5

− ⋅ − + λ + + λ ⋅ ⋅ −ν β =− + ⋅λ

(18)

11

R

L

π⋅λ = (19)

5. Provision against asymmetric buckling

The buckling pressure for the three loading conditions is obtained from formula (17). Sufficient safety against asymmetric buckling is provided if the condi-tions (20a, b, c) are met.

n N kp p S≥ ⋅ (20a)

(for the nominal diving pressure load condition)

n P k N 1 kp p S ' p S S '≥ ⋅ = ⋅ ⋅ (20b)

(for the test diving pressure load condition)

n Z N 2p p p S≥ = ⋅ (20c)

(for the collapse pressure load condition)

6. Symmetric buckling

The buckling pressure pm is calculated with formulae (21) - (33) and (15) for the lowest integer value of m at which conditions (33) is met. The values Es and Et are determined in accordance with G. The relevant stresses of the centre of the plate are calculated in accordance with 2. In the elastic range Es = Et = E and ν' = ν.

The program sequence (see Fig. 10) shows the method of calculation used to determined the buckling pres-sure pm in the elastic-plastic range.

2 21 1

m o1 1

L 1 mp p** C

m 4 L

α ⋅ π⋅ = ⋅ ⋅ + ⋅ π⋅ α ⋅ (21)

( )2

s

2 2

2 s Ep**

R 3 1 '

⋅ ⋅=

⋅ ⋅ −ν (22)

I - Part 5 GL 1998


B

2 21 2 3

o 2

C C ' CC

1 '

⋅ −ν ⋅=

−ν (23)

22 4

11

H HC 1

H

⋅= − (24)

23 4

21

H HC 1

H

⋅= − (25)

2 3 4

1

H H HC3 1

' H

⋅ ⋅= +

ν ⋅ (26)

( )21 4 2H 1 H H 3 1 '2 = + ⋅ − ⋅ −ν (27)

( ) ( )2 oH 2 ' 1 2 ' K= −ν − − ν (28)

( ) ( )3 oH 1 2 ' 2 ' K= − ν − −ν (29)

( )

t

s4 2

1

E1

EH

4 1 ' K

−=

⋅ −ν ⋅ (30)

21 o oK 1 K K= − + (31)

232

4 1 1

1 2 2

CC3 v '

C C

s R

⋅ − ⋅ α =

⋅ (32)

( )1 1L mm 1

2

α ⋅≤ +

π (33)

7. Provisions against symmetric buckling

The buckling pressure pm for the collapse pressure condition is obtained from formula (21). Sufficient safety against symmetric buckling is provided if the conditions (34a, b, c) are met.

m N kp p S≥ ⋅ (34a)

m P k N 1 kp p S ' p S S '≥ ⋅ = ⋅ ⋅ (34b)

m Z N 2p p p S≥ = ⋅ (34c)

C. Ring Stiffeners

1. General

It is the purpose of ring stiffeners to reduce the buck-ling length of cylindrical shells. A distinction is made between "heavy" and "light" ring stiffeners. "Heavy" ring stiffeners are stiffeners which are able to reduce the significant mathematical length of the pressure hull as this relates to the failure described in 2.3. The dimensions of "heavy" stiffeners are not to be smaller than the "light" stiffeners.

For a terminal section, the length to be used is that between the end and the stiffener. (In the case of dished ends, the buckling length is to take account of the instruction in B.1 and Fig 1.)

For the loading conditions mentioned in A., stiffeners are to be designed for safety against excess stresses, buckling and tripping. Unreinforced cut-outs in the girth or web are to be considered for calculation.

2. "Light" stiffeners

2.1 Stresses in "light" stiffeners

The stresses are calculated using formulae (4), (14), (35 - (37) and the values of pn1 and n according to 2.3. If n = 2 determined also n = 3 has to be calculated. In formula (37), L = L1. Where the distances L1 to the two adjoining stiffeners are unequal, the calculation shall make use of the arithmetic mean value of both distances. In the elastic-plastic range the values E and ν are replaced by E' and ν' respectively. The elasticity modulus E' and the Poisson's ratio ν' are calculated in accordance with G. In relation to stress σf.

The program sequence (see Fig. 11) shows the method of calculation in the elastic-plastic range.

( )22

f

1 2 N

p R 1

AR s

b

ν

⋅α

⋅ ⋅ −σ = −

⋅ + +

(35)

( )( )

22

fb 2n o

p n 1 E e U

p p R

⋅ − ⋅ ⋅ ⋅σ = ±

− ⋅ (36)

( ) ( )( ) ( )

cosh L cos LN

sinh L sin L

α⋅ − α⋅=

α⋅ + α⋅ (37a)

N 1for L 5,5= α⋅ > (37b)



C

ew = b

b

ew

e fd w df

e f

df

d w

b

h

s

R R0

R1

e

e 2e 1

Le

A1

Area for which Ie is calculated

Fig. 2 Stiffeners

2.2 Provision against excess stresses

For the three loading conditions, formulae (35) and (36) give the stresses σf and σfb, the absolute values of which are related to the yield strength k in conditions (38a, b, c).

f fb k Nk S S (for p p )≥ σ ⋅ + σ ⋅ = (38a)

f fb k Pk S' S ' (for p p )≥ σ ⋅ + σ ⋅ = (38b)

f fb Zk (for p p )≥ σ + σ = (38c)

2.3 Buckling

The "light" stiffeners are to be calculated using for-mulae (39) - (45) for the integer n ≥ 2 which produces the lowest value of pn1. In formula (41) L = L2, and, in the absence of "heavy" stiffeners, L = L3. In the elas-tic-plastic range, E' according to G. is to be substituted for E in formulae (39) and (42). The necessary stress calculation is performed in accordance with 2.1.

n2o

E sp

R

⋅ ⋅β= (39)

( ) ( )4

2n2 22 2 2 2

2 2n 1 0,5 n

λβ =

− + ⋅λ ⋅ +λ (40)

2R

L

π⋅λ = (41)

( )2e

1 3o 1

n 1 E Ip

R L

− ⋅ ⋅=

⋅ (42)

n1 o 1p p p= + (43)

32e1

e 1AL s

1e

L sA eI I

121 ⋅

⋅⋅= + +

+ (44)

eL 2 R s b= ⋅ ⋅ + (45a)

In addition with light stiffeners

e 1L L≤ (45b)

2.4 Provision against buckling

The calculation of the buckling pressure pn1 for the three loading conditions is performed in accordance with 2.3. Sufficient safety against buckling is provided if the conditions (46a, b, c) are met.

n1 N kp p S≥ ⋅ (46a)


n1 P k N 1 kp p S ' p S S '≥ ⋅ = ⋅ ⋅ (46b)


n1 Z N 2p p p S≥ = ⋅ (46c)


I - Part 5 GL 1998


C

3. "Heavy" stiffeners

3.1 Stresses in "heavy" stiffeners

The stresses are calculated using formulae (35) - (37) and the values pg and n according to 3.3. In formulae (37) and (41) L = L2. If the distances L2 to the two adjoining stiffeners (or ends) are unequal, the calcula-tion shall make use of the arithmetic mean value of both distances. In the elastic-plastic range the values E and ν are replaced by E' and ν'. The elasticity modulus E' and the Poisson's ratio ν' are calculated in accor-dance with G. in the relation to the stress σf.

3.2 Provision against excess stresses

For the three loading conditions, formulae (35) and (36) give the stresses σf and σfb, the absolute values of which are related to the yield strength k in conditions (38a, b, c).

3.3 Buckling (general stability)

Using formulae (39) - (42) and (47) - (49), the overall stability of the design is to be calculated for the inte-ger n ≥ 2 at which the buckling pressure pg attains its lowest value. The calculation factor C4 in formula (47) becomes C4 = - 4 for internal stiffeners and C4 = n2 for external stiffeners. Where only one "heavy" stiffener is located midway between two bulkheads, the total buckling pressure pg formula (49) can be increased by a membrane stress element po in accor-dance with formulae (39) - (41) where L = L3. Where there are no "heavy" stiffeners, the buckling pressure pg is obtained from formula (43):

pg = pn1

( )( )

2e

2 2o 1 4 2

n 1 E Ip

R R e C L

− ⋅ ⋅=

+ ⋅ ⋅ (47)

o 2n2

o 2

p pp

p p

⋅=

+ (48)

g 1 n2p p p= + (49)

3.4 Provision against buckling

The calculation of the total buckling pressure pg for the three loading conditions is performed in accor-dance with 3.3. Sufficient safety against buckling is provided if the conditions (50a, b, c) are met.

g N kp p S≥ ⋅ (50a)


g P k N 1 kp p S ' p S S '≥ ⋅ = ⋅ ⋅ (50b)


g Z N 2p p p S≥ = ⋅ (50c)


4. Tripping of ring stiffeners

4.1 Tripping pressure and general conditions

The tripping pressure pk of flat bar stiffeners is to be calculated using formulae (4), (14), (37) and (51) and Fig. 3 or 4. The value of n is to be that used in 2.3 or 3.3 for calculations in the elastic-plastic range, E and ν in the aforementioned formulae are to be replaced by E' and ν' in accordance with G. The necessary stress calculation is performed in accordance with 2.1 or 3.1. The maximum allowable value of (k1/E) ⋅ (h/b)2 is 1,14 in each case.

Calculation of the tripping pressure using the formulae referred to above necessitates maintaining the toler-ances stated in I.

( )1 1

k 2 2N2

k R Ap s

bR 1 να

⋅= ⋅ + +−

(51)

The tripping pressure pk of L-, T- and I-section ring stiffeners can be calculated by the method described in [3] or [5] (see L. or 4.2).

4.2 Resistance of tripping

For flat bar stiffeners, the tripping pressure pk for the three loading conditions is obtained from formula (51). Sufficient resistance to tripping is provided if the conditions (52a, b, c) are met.

k1 N kp p S≥ ⋅ (52a)


k1 P k N 1 kp p S ' p S S '≥ ⋅ = ⋅ ⋅ (52b)


k1 Z N 2p p p S≥ = ⋅ (52c)




C

n = 2

0,050 0,10 0,15 0,20h/R

1,0

0,01

0,015

0,02

0,03

0,04

0,05

0,10

0,15

0,2

0,3

0,4

0,5

K 1E

hb

2

3

4

5

20

10

15

Fig. 3 Stresses k1 for the calculation of internal flat bar stiffeners

n = 2

10 98

7

6

5

4

3

0,050 0,10 0,15 0,20h/R

1,0

0,01

0,015

0,02

0,03

0,04

0,05

0,10

0,15

0,2

0,3

0,4

0,5

K 1E

hb

2

Fig. 4 Stresses k1 for the calculation of external flat bar stiffeners

I - Part 5 GL 1998


C

Proof of the sufficient resistance to tripping of L-, T- and I-section stiffeners can be provided by applying formula (53).

'1

k1

E Ik S

A R e

⋅⋅ ≤

⋅ ⋅ (53)

Proof can be dispensed with if minimum seven of the following eight conditions are met:

we s≥

f w fe e , e 2 s≥ ≤ ⋅

w w wd 20 e , d R / 2≤ ⋅ ≤

f f f w f wd 10 e , d d / 2, d d / 4≤ ⋅ ≤ ≥

D. Stiffened and Unstiffened Conical Shells

The procedure to be applied to conical shells is similar to that for cylindrical shells. Conical shells are re-placed in sections by cylinders having the mean di-ameter and by multiplying the actual external pressure by 1/cosϕ. It is assumed that the ends of the cone are fitted with "heavy" ring stiffeners. If not, a stress analysis has to be performed in accordance with F.1. Ring stiffeners are to be calculated in the manner de-scribed in C. The instructions given in B.1 are applica-ble to out-of-roundness values in conical shells.

E. Dished Ends and Spheres

1. General

Dished ends and spheres are to be examined for excess stresses and buckling under the loading conditions stated in A. In the case of dished ends, the stresses in the crown radius and in knuckle radius are to be inves-tigated. Spheres are to be treated in the same way as the crown radius of dished ends.

The calculation allow for out-of-roundness of the shell up to a maximum of u = 0,04 ⋅ s/R. If larger tolerances are planned, or if the method of measurement de-scribed in H.3 results in greater out-of-roundness val-ues, than the permissible pressure is to be checked in accordance with H.4.

2. Stresses

For the dished sections the stress is obtained by ap-plying formula (54). For the knuckle radius the stress is obtained with formula (55), the radius R being the radius of the adjoining cylindrical jacket. The coeffi-cient β are to be taken from reference [2] or Fig. 5. For hemispherical ends in the range of 0,5 s R⋅

beside the transition to the cylinder a coefficient β = 1,1 is valid.

R p

2 s

⋅σ = −⋅

(54)

p R 1,2

2 s

⋅ ⋅ ⋅βσ = −⋅

(55)

3. Provision against excess stresses

The stress for the three loading conditions is obtained by applying formula (54) and (55). Sufficient safety against excess stresses is provided if the conditions (56a, b, c) are met, allowing for the absolute values of σ.

Nk S (for p p )≥ σ ⋅ = (56a)

Pk S' (for p p )≥ σ ⋅ = (56b)

Zk (for p p )≥ σ = (56c)

4. Buckling

The buckling pressure pn in the dished section for the nominal diving pressure and test diving pressure load conditions is determined by applying formula (57).

2

ns

p 0,366 ER

= ⋅ ⋅

(57)

The buckling pressure pn in the dished section for the collapse pressure load condition is calculated with formula (58). The elasticity moduli Es and Et are cal-culated in accordance with G. allowing for the stress determined with formula (54).

2n s t

sp 0,84 E E

R = ⋅ ⋅ ⋅

(58)

5. Provision against buckling

The buckling pressure for the nominal diving pressure and test diving pressure load conditions is calculated with formula (57). Sufficient safety is provided if the conditions (59a, b) are met.

The buckling pressure for the collapse pressure load condition is calculated with formula (58). Sufficient safety is provided if conditions (59c) is met.

n N kp p S≥ ⋅ (59a)


n P k N 1 kp p S ' p S S '≥ ⋅ = ⋅ ⋅ (59b)


n Z N 2p p p S≥ = ⋅ (59c)




E

0,15 0,45 0,50,40,350,30,250,2

6,5

6,0

5,5

5,0

4,5

4,0

3,5

3,0

2,5

2,0

1,5

1,0

Ratio H / Da

Cal

cula

tion

coef

ficie

nt β

βο

s___ = Da

≥ 0,04

0,02

0,01

0,005

0,002

Fig. 5 Values of β for the calculation of dished ends

I - Part 5 GL 1998


E

F. Openings and Discontinuities

1. Discontinuities

Discontinuities such as

– Connections between cylinders and conical segments

– Reinforcing rings (rings other than the ring stiff-eners dealt with in C.)

– Flanges for fixing spherical shell windows

must be subjected to a stress and elongation analysis similar to that specified in [19] and [11] for the nomi-nal diving pressure and test diving pressure load con-ditions. The comparison stress is determined by ap-plying formula (1). Sufficient safety is provided if the conditions (16a, b) are met. In case of an interruption of stiffeners an adequate reinforcing has to be pro-vided.

2. Cylinder/cylinder penetrations

Cutouts in cylinders are to be made in accordance with the Rules Part 1 – Seagoing Ships, Chapter 2 – Ma-chinery Installations, Section 7a, D.2.3.4 and using as internal pressure a design pressure pc calculated by applying formulae (60) and (61) - minimum with the relevant pressure of the load case. Reinforcements are to be provided as integral reinforcements.

2N

cA

2 p R Sp

k F s

⋅ ⋅ ⋅=

⋅ ⋅ (60a)

2P

cA

2 p R S'p

k F s

⋅ ⋅ ⋅=

⋅ ⋅ (60b)

2Z

cA

2 p Rp

k F s

⋅ ⋅=

⋅ ⋅ (60c)

1 A

0,4 R RF 1 3 u 1

L s

⋅= + ⋅ ⋅ − ⋅

1Lfor 0, 4

R≥ (61a)

1LF 1 for 0,4

R= < (61b)

3. Sphere/cylinder penetrations

Cutouts in spheres are to be made in accordance with GL Rules for the Classification and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery In-stallations, Section 7a, D.4.3.3 and using as internal pressure an increased design pressure pc calculated by applying formula (62).

c Np 1,2 p= ⋅ (62a)

c Pp 1,2 p= ⋅ (62b)

c Zp 1,2 p= ⋅ (62c)

G. Elasticity Moduli

The elasticity modulus for calculations in the elastic region up to the limit of proportionality is to be taken from the standard specifications for the materials con-cerned. For design temperatures up to 50 °C, a value of E = 206.000 N/mm2 can generally be accepted for ferritic steels. For steel, a Poisson's ratio of ν = 0,3 is to be used.

In the elastic-plastic range, the elasticity moduli Esc and Et for steel between the limit of proportionality σe and the yield point k according to the stress-strain curve σ = f (ε, k, E) are to be determined by applying formulae (63) - (66).

ezk

σ=

( ) ( ) ( )E z

k z 1 z tgh1 z k 1 z

⋅ εσ = ⋅ + − ⋅ − − ⋅ − (63)

( ) ( ) ( )k z

z 1 z artghE 1 z k 1 z

σε = ⋅ + − ⋅ − − ⋅ − (64a)

mink

zE

ε = ⋅ (64b)

[maxk

Min max.remaining elongation ,E

ε = +

( )f kε= σ → (64c)

( ) ( ) ( )sk E z

E z 1 z tgh1 z k 1 z

⋅ ε= ⋅ + − ⋅ − ε − ⋅ − (65)

( ) ( )2

1E z

E E 1 tgh1 z k 1 z

⋅ε= ⋅ − − − ⋅ − (66)

For calculations in the elastic-plastic range which were originally developed for the elastic range, the term E is to be replaced by the term E' from formula (67).

s tE ' E E= ⋅ (67)

With GL's agreement, the stress-strain curve actually measured may b e used to determine the elasticity moduli in the elastic-plastic range.

In the elastic-plastic range, the Poisson's ratio is to be calculated using formula (68).

sE1 1'

2 2 E ν = − −ν ⋅

(68)



G

H. Out-of-Roundness of Cylinders and Spheres

Cylindrical shells and dished ends subjected to exter-nal pressure are to be checked for out-of-roundness. If the tolerances are exceeded, the permissible external pressure is to be reduced to the value p'.

1. Measuring the out-of-roundness of cylin-drical shells

The number of planes used for measuring the out-of-roundness of cylindrical pressure vessels is to be agreed with GL. For each plane, the number of meas-uring prints (J) shall be at least 24, and these shall be evenly distributed round the circumference. The height of arc x (j) is measured with a bridge extending over a string length y = 4 ⋅ π ⋅ (R + s/w)/J (cf. Fig. 6). Form the values x (j) and the influence coefficients C, the out-of-roundness values can be calculated by ap-plying formula (69). Table 1 gives the influence coef-ficients #C where J = 24. If the out-of-roundness U (j) at any measuring point exceeds a value of U = 0,005 ⋅ R, then a reduced permissible pressure p' is to be de-termined in accordance with 2.

γ

x

y

R'

j = 0

j = 1

j = 2

Fig. 6 Measuring the out-of-roundness of a cylindrical shell

J 1

j i i ji 0

U x C−

−=

= ⋅Σ (69)

Example of the out-of-roundness U at measuring point j = 2 where J = 24:

2 0 2 1 1 2 0 3 1U x C x C x C x C ...= ⋅ + ⋅ + ⋅ + ⋅ +

21 19 22 20 23 21x C x C x C+ ⋅ + ⋅ + ⋅

Table 1 Influence factors Ci where J = 24

i - j C i j− i - j C i j−

0 1 2 3 4 5 6 7 8 9 10 11

1,76100 0,85587 0,12834 – 0,38800 – 0,68359 – 0,77160 – 0,68487 – 0,47097 – 0,18614 0,11136 0,36793 0,54051

12 13 14 15 16 17 18 19 20 21 22 23

0,60124 0,54051 0,36793 0,11136 – 0,18614 – 0,47097 – 0,68487 – 0,77160 – 0,68359 – 0,38800 0,12834 0,85587

2. Calculation of permissible pressure for cylindrical shell with an out-of-roundness u > 0,005

The bending stress is determined for al measuring points by the choice of a reduced permissible pressure p' and by applying formula (70). The total stress is found with formula (74) and the reduced permissible pressure p' with formula /75) by a process of iteration, the n-related value for formula (17) being substituted for the pressure pn. The mean radius R' is to be deter-mined by measuring the circumference.

( ) ( )2J / 2

2b 2 2 n 2 1

E s Rn 1

L2 R 1 =

⋅ π⋅ σ = Σ − +ν − ν

( ) ( )n nn

p 'a sin n b cos n

p p '

⋅ ⋅ ⋅ ⋅ γ + ⋅ ⋅γ −

(70)

2i

J

⋅πγ = ⋅ (71)

( ) ( )J 1

n ii 0

2a R ' U sin n

J

−

== ⋅ Σ + ⋅ ⋅γ (72)

( ) ( )J 1

n ii 0

2b R ' U cos n

J

−

== ⋅ Σ + ⋅ ⋅γ

for n J / 2≠ (73a)

( ) ( )J 1

n ii 0

1b R ' U cos n

J

−

== ⋅ Σ + ⋅ ⋅γ

for n J / 2= (73b)

bp ' R

ks

⋅≥ + σ (74)

( )p 'S

max

p ' 0,005 Rp ' p

S U

⋅≥ + − ⋅ (75)

I - Part 5 GL 1998


H

3. Measuring the out-of-roundness of spheres

The height of arc x' is measured with a bridge gauge (cf. Fig. 7), the string length y being calculated with formulae (76) and (79). The out-or-roundness U is determined with formula (78). If the out-of-roundness is greater than u = 0,04 ⋅ s/R, a reduced permissible pressure p' is to be determined in accordance with 4.

δ

y

x

Ux'

s' s

R'

R + s/2

Fig. 7 Measuring the out-of-roundness of a sphere

R'

15° 30° 30°

Measuring point

Fig. 8 Distribution of measuring points over hemisphere

sy 2 R sin

2 = ⋅ + ⋅ δ

(76)

( )sx R 1 cos

2 = + ⋅ − δ

(77)

U x x ' u R= − = ⋅ (78)

( ) s22

1,1 s

R1δ = ⋅

+−ν (79)

the distribution of the measuring points is shown in Fig. 8. Two measurements are to be made at each point: one in the plane of the central axis, the other at right angles to it.

4. Calculation of permissible pressure for spheres with an out-of-roundness u > 0,04 ⋅ s/R

The reduced permissible pressure p' is calculated with formula (80) allowing for the actual radius of curva-ture R' and the minimum wall thickness s' occurring in the measuring range y (taking account of any reduc-tions for wear and corrosion). The radius of curvature R' is determined with formula (81).

2 2s2R s '

p ' p pR ' 2

+ = ⋅ ⋅ ≤ (80)

2x ' yR '

2 8 x '= +

⋅ (81)

I. Tolerances of Ring Stiffeners

A check is to be carried out on ring stiffeners to de-termine whether the following tolerances have been maintained:

– Girth width (on T-section flanges, the whole width): - 0/+ 5 mm

– Girth and web thickness: - 0/+ t

The tolerance t depends on the conditions of supply for the material. (If the material supply specification allows negative tolerances, these are to be allowed for in the calculations)

– Height of ring (in the case of built-up profiles the height of the entire ring): - 2 %/+ 5 % of the total height

– Uneveness of web and girth (measured over height of web and girth respectively): 0/1 % of web and girth height respectively

– Symmetry of flange in relation to web (applica-ble to I- and T-section stiffeners: the difference from the edge of the girth to the web on both sides of the web): 0/4 mm difference



I

– L1 distances (distances between "light" stiffen-ers and separating "light" from "heavy" stiffen-ers): - 5,0/+ 5,0 mm

– L2 distances (distances between "heavy" stiffen-ers or ends or separating "heavy" stiffeners from ends): - 15,0/+ 5,0 mm

– Angularity of web in relation to wall or main axis: - 2°/+ 2°

– Angularity of flange in relation to web: - 3°/+ 3°

All dimensional deviations are to be measured eight times on each stiffener at points equally spaces round the circumference. If the aforementioned tolerances are exceeded, corrective machining and/or manual work is to be carried out on the stiffener and/or the calculation is to be repeated with corrected dimen-sions.

I - Part 5 GL 1998


I

J. Program Sequences for Iterative Calculations

!"#""""$

% "

!

!

"&

'(

)

&

**+,)%-%.

+%&.%,-%.

&&,%

/00-%!),0&,)!,0&,12),),0)!,!!3,00,),4,0&4,0.,1

&&,%

Fig. 9 Cylindrical shells, stresses and asymmetric buckling in the elastic-plastic range



J

$+%&.%,-%.+,)%-%.

$

5

$6

789

$

5!).%$$

,

$

!"#"""

"$

"

!

!

"&

'(

)

$ $

&

Fig. 10 Cylindrical shells, symmetric buckling in the elastic-plastic range

I - Part 5 GL 1998


J

+,)%-%.

+%&.%,-%.

&&,%

&&,%

&

78

!$#

!!$#$"

!"#""""$

:%$;;

)

%

"

!

!!$#

"&

'(

Fig. 11 "Light" stiffeners in the elastic-plastic range



J

K. Symbols and Units

A [mm2] modified area of stiffener ring

A1 [mm2] cross-sectional area of stiffener ring

b [mm] width of stiffener ring in contact with shell

C [1] influence coefficient for calcu-lating out-of-roundness

C0... C3 [1] calculation factors for symmetric buckling

C4 [1] calculation factor for asymmetric buckling, "heavy" stiffener rings

C5... C11 [1] calculation factor for stress in cylindrical shell

df [mm] width of girth of L-, T- or I-stiff-ener ring from web to edge of flange

dw [mm] height of web L-, T- or I-stiffener ring

ef [mm] girth thickness of L-, T- or I-stiffener

ew [mm] web thickness of L-, T- or I-stiffener

e [mm] distance from stiffener ring cen-troid to centre of cylindrical wall

e1 [mm] distance from stiffener ring cen-troid to centre of cylinder wall including effective length of shell Le

e2 [mm] distance between stiffener ring centroid, including effective length of shell Le, and flange face facing away from cylinder wall

E [N/mm2] modulus of elasticity

E' [N/mm2] modulus of elasticity elastic-plastic range, see formula (67)

Es [N/mm2] secant modulus, see formula (65)

Et [N/mm2] tangent modulus, see formula (66)

F [1] factor for calculations in plastic range, see formula (61)

F1... F4 [1] geometric factors, see formulae (3a) to (3d)

G [1] pressure ratio, see formula (13)

h [mm] height of stiffener ring

H [mm] depth of dished end

H1... H4 [1] calculation factors for symmetric buckling

I1 [mm4] second moment of area of stiff-ener ring cross-section about axis through centroid parallel to cyl-inder axis

I1' [mm4] second moment of area of stiff-ener ring cross-section about axis through centroid vertical to cyl-inder axis

Ie [mm4] second moment of area of stiff-ener ring cross-section, including effective length of shell acting with stiffener ring, about axis through centroid parallel to cyl-inder axis

J [1] number of measuring points for checking out-of-roundness

j [1] number (0 ... J-1) of measuring point used to check out-of-roundness

k [N/mm2] yield strength ReH20

k1 [N/mm2] stress in flat bar, cf. formula (51) and Abb. 3 and 4

Ko [1] stress ratio, cf. formula (15)

K1 [1] stress coefficient, cf. formula (31)

L [mm] spacing between effective stiff-eners

L1 [mm] spacing between two "light" stiffeners

L2 [mm] spacing between two "heavy" stiffeners

L3 [mm] total length or length between bulkheads

Le [mm] effective length of shell

m [1] mode of collapse, symmetric buckling

n [1] mode of collapse, asymmetric buckling

N [1] coefficient, cf. formula (37)

p [N/mm2] external design pressure

p' [N/mm2] external pressure reduced owing to out-of-roundness

po [N/mm2] pressure, membrane stress part

pc [N/mm2] design pressure for calculation of opening

pe [N/mm2] pressure in which the stress reaches the elastic-plastic range

pg [N/mm2] total buckling pressure

pk [N/mm2] tripping pressure

I - Part 5 GL 1998


K

pm [N/mm2] buckling pressure, symmetric buckling

pn [N/mm2] buckling pressure, asymmetric buckling

pn1 [N/mm2] buckling pressure, asymmetric buckling, "light" stiffener

pn2 [N/mm2] buckling pressure, asymmetric buckling, "heavy" stiffener

pN [N/mm2] nominal diving pressure (1st load condition)

pP [N/mm2] test diving pressure (2nd load condition)

pZ [N/mm2] collapse pressure (3rd load con-dition)

p* [N/mm2] critical pressure, cf. formula (12)

p** [N/mm2] critical pressure, elastic-plastic, cf. formula (22)

R [mm] mean radius of wall

Ro [mm] radius of stiffener ring centroid including effective length Le

R1 [mm] radius of standing flange of stiff-ener ring

R' [mm] measured outside radius

s [mm] thickness of shell/sphere without abrasion and corrosion

s' [mm] measured wall thickness without abrasion and corrosion

sA [mm] thickness of shell/sphere adjoin-ing opening

S [1] safety factor applied to yield strength ReH20 at nominal pres-sure

S' [1] safety factor applied to yield strength ReH20 at test diving pressure

Sk [1] safety factor against instability at nominal pressure

S'k [1] safety factor against instability at test diving pressure

t [mm] tolerance

U [mm] out-of-roundness: U = u ⋅ R

u [1] out-of-roundness in relation to R

x [mm] theoretic height of arc

x' [mm] effective height of arc

y [mm] string dimension of measurement device

z [1] proportional ratio (= σe/k)

α 1

mm

shape factor, cf. formula (14)

α1 1

mm

shape factor, cf. formula (32)

β [1] coefficient for dished ends, cf. reference [2] or Fig. 5

βn1 [1] coefficient, cf. formula (18)

βn2 [1] coefficient, cf. formula (40)

γ [rad] angle used in increasing the out-of-roundness of cylinders

δ [rad] angle used in measuring out-of-roundness of spheres

λ [1] coefficient, cf. formulae (19), (41)

ν [1] Poisson's ratio, elastic

ν' [1] Poisson's elastic-plastic, cf. for-mula (68)

ϕ [rad] angle of cone (between wall and axis)

σb [N/mm2] bending stress in case of out-of-roundness

σe [N/mm2] proportional limit

σf [N/mm2] compression stress in girth

σfb [N/mm2] bending stress in girth

σi [N/mm2] stress intensity

σo [N/mm2] stress (calculate value)

σx [N/mm2] stress in longitudinal direction

σϕ [N/mm2] stress in circumferential direction

σzul [N/mm2] permissible stress

L. References

[1] Germanischer Lloyd: Rules for the Classifica-tion and Construction, Part 1 – Seagoing Ships, Chapter 2 – Machinery Installations

[2] AD Merkblätter, Reihe B, Berechnung von Druckbehältern, Herausgeber: Arbeitsgemein-schaft Druckbehälter

[3] The Stress Analysis of Pressure Vessels and Pressure Vessel Components, published by S.S. Gill, Pergamon Press, 1970



L

[4] John C. Pulos and Vito L. Salerno: Axisymmet-ric Elastic Deformations and Stresses in a Ring-Stiffened, Perfectly Circular Cylindrical Shell under External Hydrostatic Pressure, DTMB-Report No. 1497

[5] Development in Pressure Vessel Technology, published by R.W. Nichols, Applied Science Publishers, 1983

[6] European Recommendations for Steel Construc-tion: Buckling of Shells, published by ECCS-CECM-EKS, Brüssel, 1984

[7] DIN 4114, Blatt 2: Stabilitätsfälle (Knickung, Kippung, Beulung), 2.53 Edition

[8] Myron E. Lunchick: Plastic Axisymmetric Buckling of Ring-Stiffened Cylindrical Shells Fabricated from Strainhardening Materials and Subjected to External Hydrostatic Pressure, DTMB-Report No. 1393

[9] Krenske, Martin A. and Kierman, Thomas J.: The Effect of Initial Imperfections on the Col-lapse Strength of Spherical Shells, DTMB-Re-port No. 1757

[10] ASME Boiler and Pressure Vessel Code, Sec-tion VIII, Division 2, 1989 Edition

[11] Raymond J. Roark and Warren C. Young: For-mulars for Stress and Strain, MC Graw-Hill Book Company

[12] William F. Blumenberg: The Effect of Interme-diate Heavy Frames on the Elastic General In-stability Strength of Ring-Stiffened Cylinders Under External Hydrostatic Pressure, DTMB-Report No. 1844

[13] Thomas E. Reynolds: Inelastic Labor Buckling of Cylindrical Shells under External Hydrostatic Pressure, DTMB-Report No. 1392

I - Part 5 GL 1998


L

Appendix B

Acrylic Plastic Windows

A. General

1. For the purpose of these Rules, acrylic plastic windows are flat or curved windows for the view ports of pressure hulls which are made of cast, unlaminated polymethyl methacrylate plastic.

2. For acrylic plastic windows following operat-ing limits apply:

– designed service life 10 or 20 years (see explanatory notes below)

– temperature range - 18°C to + 66°C

– rate of pressurization max. 10 bar/sec

– pressure cycles at design pressure max. 10.000

– period under pressure at design pressure max. 40.000 h

– max. working pressure max. 1.380 bar

The design service life depends on numerous factors, in particular on the kind of loading. The maximum design service life to be assumed for spherical or cy-lindrical windows subjected to external overpressure, which are exclusively exposed to compressive stresses or minor bending stresses only, generally is 20 years, while for flat windows with flat fit it is 10 years.

Depending on the previous actual loads acting on the windows and following testings to be agreed with GL in detail, extension of the service life of acrylic plastic windows may be approved.

B. Material

1. The material of acrylic plastic windows must be manufactured in accordance with a recognized standard (e.g. ANSI/ASME PVHO 1, Section 2). The producer is required to certify this before manufacture commences.

2. Acrylic plastic windows must meet the mini-mum physical requirements stated in Table 1.

3. For each batch of acrylic plastic to be made into windows the manufacturer is to issue a material certificate containing at least the following details:

– number and date of certificate

– manufacturer's name and address

– designation and application of casting type

– batch number, quantity, shape and size of cast-ings

– marking of castings

– results of tests applied in accordance with Ta-ble 1

– stamp and signature

4. Where a material certificate of the kind re-quired is not available for the acrylic plastic or where the conditions for recognition of the material certifi-cate are not satisfied, the tests are to be extended in a manner to be agreed with GL in each case.

5. Each casting is to be provided at at least one point with a marking which identifies the type of cast-ing, the batch number, the date of manufacture and the name of the manufacturer.

C. Manufacture of Windows

1. The manufacture of acrylic plastic windows covered by these Rules may only take place in spe-cialized workshops which have been approved by GL for that purpose. Such approval can be granted only to those companies which employ properly trained spe-cialists and which have available the necessary techni-cal facilities enabling them to undertake the expert forming, machining, heat treatment and quality control of acrylic plastic windows.

Application for approval is to be made to GL before the manufacture of windows commences.

2. The acrylic plastic to be used must meet the requirements stated in B. After machining and any necessary forming operations, each window is to be subjected to heat treatment (tempering) in accordance with the acrylic plastic manufacturer's specification. After tempering no further mechanical polishing may be carried out on the window.

3. Window surfaces are to be polished in such a way as to meet the optical clarity requirement stated in Table 1.

I - Part 5 GL 1998

Appendix B Acrylic Plastic Windows Chapter 1Page B–1

C

4. For each window or series of windows the window manufacturer is to be issue a component cer-tificate specifying all the stages of manufacture such as cutting, sticking, polishing, forming and tempering. The certificate shall also indicate the tests carried out, the test results, the marking of the windows and the date of manufacture.

5. Each window is to be permanently marked with at least the following details:

– Design pressure [bar]

– Design temperature [°C]

– Germanischer Lloyd approval stamp

– Manufacturer's name or identifying mark

– Serial number and year of manufacture.

Wherever possible, the marking is to be engraved in the non-load-bearing portion of the window edge. The use of punches is not allowed.

6. The acrylic plastic windows are to be pre-sented to GL for an inspection of manufacture. In addition, each window is to be subjected, in the pres-ence of Germanischer Lloyd Surveyor, to a pressure test in accordance with Chapter 2 – Submersibles, Section 2, D.3.3 of these Rules.

D. Window Shapes and Sizes

1. the standard shapes and sizes shown in Ta-ble 2 and 3 are to be selected for the acrylic plastic windows.

For design pressure in general the nominal diving pressure is to be used.

2. Acrylic plastic windows of other shapes and sizes or for other ranges of pressure may be approved

by GL on application, provided that they are designed and manufactured to a recognized standard.

3. The design temperature to be assumed for acrylic plastic windows should be the mean value of the maximum external and internal temperatures to be expected under design pressure conditions.

4. Windows subjected to pressure from both sides are to be designed for the maximum pressure applied, regardless of whether this pressure is external or internal.

5. Pressure may only be applied to the convex side of spherical shell windows.

6. The thickness of the window must be every-where equal to, or greater than, the minimum value determined by reference to Tables 2 and 3.

7. With flat windows having right-angled edge and an O-ring seal, the outside diameter of the disk shall be within + 0,00/- 0,25 mm of the nominal value, or within + 0,00/- 0,75 mm where flat gasket seals are used.

8. The major diameter of the conical bearing surface of an acrylic plastic window shall be within + 0,000/- 0,002 Do of the nominal value.

The included conical angle of the window shall be within + 0,25/- 0,00 degrees of the nominal value.

9. The concave or convex surface of the win-dow shall not differ from an ideal spherical sector by more than ± 0,5 % of the nominal external spherical radius.

10. The surface roughness (Ra) of the window bearing surface shall be 0,75 µm or better.

Chapter 1 Page B–2

Appendix B Acrylic Plastic Windows I - Part 5GL 1998

D

Table 1 Mechanical and optical properties of acrylic plastic

Properties Specified values Test method ASTM

Ultimate tensile strength

Elongation at break (in relation to necking zone)

Modulus of elasticity measured by tensile test

≥ 62 N/mm2

≥ 2 %

≥ 2760 N/mm2

DIN 53 455 1 specimen type 3 test velocity II standard 23/50 atmosphere

DIN 53 457

D 638 1

Compressive yield strength

Modulus of elasticity measured by compression test

≥ 103 N/mm2

≥ 2760 N/mm2

DIN 53 454 1 standard 23/50 atmosphere size of test specimen: 25 x 12,5 x 12,5 mm

DIN 53457 1

D 695 1

Compressive deformation ≤ 1 % constant compressive stress 1 of 27,5 N/mm2 for 24 h at 50 °C test cube: 12,5 mm edge length

D 621 1

Ultraviolet transmittance ≤ 5 % UV-spectrophotometer wave length range: 290 - 370 nm thickness of specimen: 12,5 mm

E 308

Visual clarity legibility a25 x 25 mm standard layout comprising 7 lines of 16 letters each must be clearly legible through the acrylic plastic pane at a distance of 500 mm.

D 702

Total residual monomers methyl methacrylate ethyl acrylate

≤ 1,6 % gas chromatograph

1 The mechanical properties are to be verified on at least 2 specimens.

I - Part 5 GL 1998


D

Table 2 Standard dimensions for flat disk windows

!" # # $ %

#&

'%(

)

)

*

*

+

$

,

-

)*

+

$

)*

*

$)

,,

-

+

))

*

)

+$

,

-

)

)

)*

))*)**

)*

)+)

)$)

*+

$)

-

)

))

*)

)

+*

$*

-

)

)*

))-

)*

)+,

),)

)-,*

*$

**

*+

*

,,

+

*

)

+$

,

-

)

)*

)**

)+)

),)

*

*

**

*+*,

)-

+*

)

*

$

$*

-

)

)$

)-

)*

)$,

*

*$

*

*$+

**-

$)

-,

+

,,

+

)

,

)

)*

)**

)+)

),)

*

**

*,

-

-,

+)$

+$+

$$*

$-)

,)

,$

./ *./ ),./ ./ ++./

0



D

Table 3 Standard dimensions for spherical shell windows with conical seat

Designpressure

Pc

[bar]

Designpressure

Pc

[bar]

Minimum wall thickness /inside diameter of seat s/Di

where α = 60 ° at

5

10

15

20

25

30

35

40

45

50

60

70

80

90

100

110

120

130

140

150

160

170

0,090

0,090

0,090

0,090

0,090

0,097

0,104

0,112

0,119

0,126

0,140

0,153

0,166

0,179

0,191

0,203

0,215

0,227

0,238

0,248

0,259

0,269

10 °C

s

α

Ri

Di

Df

Range of application :

Opening angle : α ≥ 60 °

Minimum of wall thickness : s ≥ 12,5 mm

Minimum values for s/Ri :

Window seating : Di / Df ≥ 1,02

Maximum working pressure : p ≤ 170 bar

α ≥ 60° ≥ 90° s/Ri 0,09 0,06

24 °C 38 °C 52 °C 66 °C


where α = 90 ° at

10 °C 24 °C 38 °C 52 °C 66 °C

0,090

0,090

0,090

0,097

0,108

0,119

0,129

0,140

0,150

0,160

0,179

0,197

0,215

0,232

0,248

0,264

0,279

0,293

0,307

0,320

0,332

0,344

0,090

0,090

0,097

0,112

0,126

0,140

0,153

0,166

0,179

0,191

0,215

0,238

0,259

0,279

0,298

0,315

0,332

0,348

0,363

0,377

0,391

0,404

0,090

0,090

0,108

0,126

0,143

0,160

0,176

0,191

0,206

0,221

0,248

0,274

0,298

0,320

0,340

0,359

0,377

0,394

0,410

0,425

0,439

0,452

0,090

0,112

0,140

0,166

0,191

0,215

0,238

0,259

0,279

0,298

0,332

0,363

0,391

0,416

0,439

0,460

0,480

5

10

15

20

25

30

35

40

45

50

60

70

80

90

100

110

120

130

140

150

160

170

0,042

0,042

0,043

0,049

0,054

0,060

0,065

0,070

0,075

0,080

0,089

0,098

0,107

0,116

0,124

0,133

0,142

0,151

0,160

0,168

0,177

0,185

0,042

0,043

0,052

0,060

0,067

0,075

0,082

0,089

0,095

0,102

0,116

0,128

0,142

0,155

0,168

0,181

0,194

0,206

0,218

0,230

0,242

0,254

0,042

0,049

0,060

0,070

0,080

0,089

0,098

0,107

0,116

0,124

0,142

0,160

0,177

0,194

0,210

0,226

0,242

0,257

0,272

0,287

0,300

0,314

0,042

0,054

0,067

0,080

0,091

0,102

0,113

0,124

0,135

0,146

0,168

0,190

0,210

0,230

0,250

0,269

0,287

0,304

0,320

0,336

0,351

0,365

0,049

0,070

0,089

0,107

0,124

0,142

0,160

0,177

0,194

0,210

0,242

0,272

0,300

0,327

0,351

0,373

0,393

0,411

I - Part 5 GL 1998


D

Table 3 Standard dimensions for spherical shell windows with conical scat (contd.)

Range of application :

Opening angle : α ≥ 60 °

Minimum of wall thickness : s ≥ 12,5 mm

Minimum values for s/Ri :

Window seating : Di / Df ≥ 1,02

Maximum working pressure : p ≤ 170 bar

α ≥ 120° ≥ 180° s/Ri 0,06 0,03

5

10

15

20

25

30

35

40

45

50

60

70

80

90

100

110

120

130

140

150

160

170

0,021

0,025

0,030

0,034

0,038

0,042

0,046

0,050

0,054

0,059

0,067

0,075

0,083

0,092

0,100

0,108

0,117

0,123

0,131

0,138

0,146

0,153

10 °C

s

α

Ri

Di

Df

24 °C 38 °C 52 °C 66 °C 10 °C 24 °C 38 °C 52 °C 66 °C

0,023

0,030

0,036

0,042

0,048

0,054

0,061

0,067

0,073

0,079

0,092

0,104

0,117

0,127

0,138

0,149

0,161

0,171

0,182

0,193

0,204

0,214

0,025

0,034

0,042

0,050

0,059

0,067

0,075

0,083

0,092

0,100

0,117

0,131

0,146

0,161

0,175

0,190

0,204

0,218

0,232

0,245

0,259

0,272

0,028

0,038

0,048

0,059

0,069

0,079

0,090

0,100

0,110

0,119

0,138

0,157

0,175

0,193

0,211

0,228

0,245

0,262

0,278

0,294

0,310

0,325

0,034

0,050

0,067

0,083

0,100

0,117

0,131

0,146

0,161

0,175

0,204

0,232

0,259

0,285

0,310

0,334

0,357

0,379

0,400

5

10

15

20

25

30

35

40

45

50

60

70

80

90

100

110

120

130

140

150

160

170

0,018

0,019

0,023

0,026

0,030

0,034

0,038

0,041

0,045

0,049

0,056

0,064

0,071

0,079

0,086

0,094

0,101

0,108

0,115

0,122

0,129

0,135

0,018

0,023

0,028

0,034

0,039

0,045

0,051

0,056

0,062

0,068

0,079

0,090

0,101

0,112

0,122

0,132

0,142

0,152

0,162

0,172

0,182

0,191

0,019

0,026

0,034

0,041

0,049

0,056

0,064

0,071

0,079

0,086

0,101

0,115

0,129

0,142

0,155

0,168

0,182

0,194

0,207

0,220

0,232

0,244

0,021

0,030

0,039

0,049

0,058

0,068

0,077

0,086

0,096

0,105

0,122

0,139

0,155

0,172

0,188

0,204

0,220

0,235

0,250

0,264

0,278

0,292

0,026

0,041

0,056

0,071

0,086

0,101

0,115

0,129

0,142

0,155

0,182

0,207

0,232

0,256

0,278

0,299

0,319

0,337

0,352

0,366

Designpressure

Pc

[bar]


where α = 120 ° at

Designpressure

Pc

[bar]


where α = 180 ° at



D

Appendix C

Design and Manufacture of GRP Constructions

A. Principles for the Manufacture of GRP Constructions

Apart from the selection of suitable and approved materials, special attention is to be paid to be process-ing operation in view of its major influence on the characteristics of the product.

The instructions of the raw materials manufacturers and the requirements of the competent authorities and Berufsgenossenschaften are to be observed in the storage, preparation and processing of the reactive resin compounds and reinforcing media.

B. Company Authorization

The manufacture of GRP components for submersi-bles in accordance with these Rules may only take place in specialist companies which have been author-ized by GL to carry out such work. Authorization will be restricted to companies possessing suitably trained specialist personnel and the necessary technical equipment for moulding, machining, heat treating and quality assurance in accordance with the best modern practice.

Authorization by GL is to be applied for before manu-facture begins.

C. Workshop Requirements

1. General

The production and storage buildings are to be of suit-able construction and equipped to provide the required environment. Contamination is to be minimized by subdivision into separate materials storage and manu-facturing areas, or acceptable alternative arrangements are to be made.

Workshops and equipment are to be maintained in clean, efficient working order and are to be essentially free from hardened resin debris, surplus glass fibre and any other material or equipment not essential to the moulding process.

2. Moulding shop

Where the conventional hand lay-up process is used a uniform shop temperature of not less than 16 °C and in general not less than 25 °C is to be maintained

throughout the moulding area during the lay-up and curing periods. By agreement with the Surveyor a small deviation from the above temperatures will be considered depending on the resin manufacturer's recommendations.

Where other moulding processes are to be used, the moulding shop temperature will be determined ac-cordingly.

The relative humidity in the moulding shop is to be kept as low as practicable, preferably below 70 %, and no substantial variation shall be permitted which would cause moisture to condense on modulus and materials.

Temperature and humidity monitoring equipment is to be provided in sufficient quantity and appropriate locations. Where dictated by the environmental condi-tions, continuous recording monitoring equipment may be required. The measuring instruments are to be recalibrated at intervals of not more than 2 years.

The ventilation system shall not cause excessive evaporation of the resin monomer, and precautions are to be taken to ensure the exclusion of draughts.

The working areas are to be suitably illuminated. Pre-cautions are to be taken to prevent the resin cure from being affected by direct sunlight or artificial lighting.

Machines which generate dust may not be operated until the laminating and sticking phases have been fully concluded. It is recommended that machines of this type should be installed in separate rooms.

3. Storage areas

The resin are to be stored in dry, well ventilated con-ditions at temperatures between 10 °C and 20 °C or in accordance with the resin manufacturer's recommen-dations.

Where the resins are stored outside the moulding shop, they are to be brought into the moulding shop to allow the resin to reach the required working temperature before being used.

Catalyst and accelerators are to be stored separately in clean, dry and well ventilated conditions in accor-dance with the manufacturer's recommendations.

Fillers and additives are to be stored in closed contain-ers which are impervious to dust and humidity.

Reinforcements are to be stored in dust-free and dry conditions in accordance with the manufacturer's rec-ommendations.

I - Part 5 GL 1998

Appendix C Design and Manufacture of GRP Constructions Chapter 1Page C–1

C

Where the glass materials are stored outside the cut-ting area, they are to be brought into the cutting area to allow the material to reach the workshop tempera-ture before being used.

4. Materials handling

The arrangements for the reception and handling of materials are to be such that the materials suffer no contamination or degradation and are properly identi-fiable at all times. Storage is to be so arranged that materials are used in order of receipt, wherever possi-ble. Materials are not to be used after the manufac-turer's expiry date except with the prior agreement of the manufacturer of the material and the Surveyor.

The arrangements for the release of materials from store are to ensure that they are of the appropriate grade or formulation. Any surplus resin or ancillary material issued is not to be returned to the parent stock or bulk storage.

D. Construction Process

1. Moulds

Moulds are to be constructed of a suitable material and adequately stiffened to maintain their overall shape and fairness of form.

The materials used for the construction of the moulds are not to affect the resin curs.

Sufficient external and internal staging is to be pro-vided to allow satisfactory access to the work of lami-nation.

2. Laminating (hand lay-up process)

Moulds are to be thoroughly cleaned, dried and al-lowed to condition to the ship temperature before being treated with a suitable release system. Release agents are to have no inhibiting effect on the gel coat resin.

The gel coat resin is to be applied by brush, roller or spraying device to give a uniform film thickness of between 0,4 and 0,6 mm.

Gel coats are not be left exposed longer than is rec-ommended by the resin manufacturer before the appli-cation of the first layer of reinforcement. The gel coat is to be backed up by a lightweight reinforcement, not exceeding 450 g/m2 in weight, which is to be applied and consolidated by gentle rolling to give a glass con-tent not exceeding 0,4 by weight.

Sandwich constructions built on a male plug mould have to be given a heavy coat of resin or resin-based compound on the outer surface prior to painting.

All mouldings are to be manufactured from layers of reinforcement, laid in the approved sequence and di-rection, each layer being thoroughly impregnated and

consolidated to give the required glass content by weight.

The amount of material laid "wet-on-wet" is to be limited to avoid excessive heat generation.

Laminating is to be carried out in a sequence such that the time lapse between the application of the succes-sive layers is within the prescribed limits. Forming and bonding of structural members are to be kept within these limits, and, where this is not practicable, the surface of the laminate is to be abraded to improve the bond.

When laminating is interrupted, so that the exposed resin gels, the first of any subsequent layers of rein-forcement to be laid in that area is to be of the chopped glass fibre type.

Reinforcements are to be arranged to maintain a conti-nuity of strength throughout the laminate.

At joints and seams, each reinforcement layer must be overlapped by at least 25 mm for each 600 g/m2 of glass reinforcement. If it is impossible to avoid cutting into reinforcement layers, the cut edges must be ap-propriately overlapped or reinforcing strips must be provided.

When the quality of the laminates being produced is in doubt, GL may request that suitable test panels similar to the actual construction be manufactured and tested.

GL's previous consent is required where laminating processes other than the hand lay-up process re to be used. In such cases GL reserve the right to demand that special process test are to be performed.

3. Construction detail

Changes in laminate thickness are to be effected by a gradual taper of not less than 25 mm per 600 g/m2. Where the construction changes from sandwich lami-nate to a solid laminate, the thickness of the core ma-terials is to be reduced by a gradual type of not less than 2 : 1.

In general framing and stiffening sections are to be built up layer by layer on to the laminate while it is still in the uncured state. Where these sections inter-sect, particular attention is to be given to ensuring continuity of strength.

Discontinuities and hard points in the structure are to be avoided, and where the strength of a stiffening member is impaired by attachment of fitting, openings etc., compensation is to be provided.

Where items are prefabricated outside the mould they are to be connected by angles formed by layers of reinforcement rolled up in situ and moulded to the adjacent structure within the acceptable cure period.

Laminates may be fastened mechanically provided that the strength of the joint is not impared, that the fastenings are of a corrosion resistant metal and are spaced and positioned to meet the design require-ments. The fastenings are to be of an acceptable type

Chapter 1 Page C–2

Appendix C Design and Manufacture of GRP Constructions I - Part 5GL 1998

D

with washer plates of compatible material. The cut edges of the laminate and the fastening holes are to be sealed.

Backing and/or insert pads of adequate strength are to be fitted at the attachment of fittings. The contact area of these pads is to be suitably prepared and free from contamination.

In sandwich laminates, inserts of a material capable of resisting crushing and design loads are to be fitted at bolted connections and fittings. The insert is to be well bonded to the core material and to the laminate skins.

4. Release and curing

After completion of the lay-up the moulding is to be left in the mould for a period to allow the resin to harden before being removed. This period can vary with the type of resin and the complexity of the moulding, but is to be not less than 12 hours or that recommended by the resin manufacturer.

Large assemblies are to be adequately braced and supported for removal from the moulds and also dur-ing the fitting-out period.

Mouldings are to be stabilized in the moulding envi-ronment for at least 24 hours, or that recommended by the resin manufacturer before the application of any special cure treatment, details of which are to be sub-mitted.

E. Materials

1. Unsaturated polyester resin

1.1 The unsaturated polyester resin systems used are to be of a type that will cure without the applica-tion of local heat.

1.2 The laminating and gel coat resins, as sup-plied by the manufacturer, are to be of a type recom-mended for marine application and are to have good abrasion resistance and ageing stability Orthophatalic resins are not to be used for the gel coat of outer part.

1.3 The only additives in the gel coat resin are to be colour pigments and thixotropic agents.

1.4 The minimum characteristics of the cast lami-nating and gel coat resin are to be:

Elongation at break Minimum 2,5 % for gel coat resins 2,0 % for laminating resins

Water absorption Maximum 60 mg after 7 days

1.5 In addition to the requirements of 5.1.4 the cast laminating resin is to have a heat distortion tem-perature of not less than 53 °C.

1.6 The cast resin characteristics required by 1.4 and 1.5 are to be those obtained from tests conducted on specimens prepared using a conventional cold curing system, matured at a room temperature of not less than 18 °C for 24 hours before being post-cured at a temperature not exceeding 40 °C for a period of 16 hours. The tests are to be conducted in accordance with the relevant ISO standards.

1.7 Laminates manufactured from the above resins are to have mechanical properties in accordance with 7.2. The material manufacturer's documentary evidence of these properties is to be submitted before construction begins.

2. Catalysts and accelerators

2.1 A catalyst is a material which initiates po-lymerization of the resin.

An accelerator is a material which increases the hard-ening rate of the catalyzed resin.

2.2 The type and amount of the catalyst and ac-celerator are to be those indicated by the resin manu-facturer for the particular application, so that the resin will cure without the application of local heat.

3. Colour pigments

3.1 The pigment types are to be such that the final cure of the resin is not affected.

3.2 The pigment may be added to the resin by the manufacturer or the moulder and when added by the moulder, is to be a paste dispersal in the same of a compatible polyester resin.

3.3 The amount of pigment added is not to ex-ceed that indicated by the resin manufacturer for a satisfactory depth of colour, and in no case is to ex-ceed 5 % by weight of the resin in the system.

3.4 No pigments are to be used in the laminating resins forming the internal surface of fuel and water tanks.

4. Fillers

4.1 Fillers are not to prejudice the characteristics of the resins.

4.2 The type and amount of filler which may be added to a resin are not to alter significantly the vis-cosity of the resin, and the amount is not to exceed 13 % (including 3 % thixotropic filler) by weight of the resin or the proportion recommended by the manu-facturer, whichever is less.

4.3 Fillers are not to be used in the structural laminates of oil fuel and water tanks.

I - Part 5 GL 1998


E

4.4 Fillers are to be uniformly dispersed in the resin mix.

4.5 Fillers of calcium carbonate or similar alka-line type are not to be used in fire retardant laminates.

5. Fire retardants

Where fire retardant laminates are obtained by incor-porating additives in the resin system the type and quantity of the additives are to be those recommended by the manufacturer and are not to alter significantly the viscosity of the resin or the mechanical properties of the laminates produced.

6. Glass fibre reinforcements

6.1 Glass fibre reinforcements are to be manu-factured from low-alkaline borosilicate "E" glass with an alkali content of not more than 1 % expressed as Na2O.

6.2 Glass fibre reinforcements are to have been treated with a sized, finish and binder as appropriate and are to be suitable for use with polyester resin and to be of a type that will provide good wet strength and ageing properties when the reinforcements are incor-porated in a laminate.

6.3 Glass reinforcements are to be of the above type and grade and may consist of:

– Chopped strand or continuous filament mat

– Woven rovings

– Unidirectional rovings

– Cloth fabrics

– Composite reinforcements.

6.4 The materials are to be sufficiently free from imperfections, discolorations, foreign matter, moisture and other defects as not to affect the quality of the laminates produced.

6.5 The reinforcements when moulded into a laminate are to have mechanical properties in accor-dance with 7.2. The material manufacturer's docu-mentary evidence of these properties is to be submit-ted before construction begins.

7. Laminate material properties

7.1 The mechanical properties of laminates, con-structed with the unsaturated polyester resin systems and glass fibre reinforcements indicated in 1. to 6. can vary considerably depending upon the actual types of material, methods and conditions under which they are manufactured. When selecting the resin system, con-sideration should be given by the builder to the com-patibility of the elongation at break of the gel coat and

laminating resins and the heat distortion temperature of the laminating resin.

7.2 The laminates manufactured from the resins and reinforcements indicated in 1. and 6. are to have a minimum glass content by weight of 0,30 and me-chanical properties not less than the following:

Ultimate tensile strength 85 N/mm2

Tensile modulus 6350 N/mm2

Ultimate flexural strength 152 N/mm2

Flexural modulus 5206 N/mm2

Ultimate compressive strength 117 N/mm2

Compressive modulus 6000 N/mm2

Ultimate shear strength 62 N/mm2

Shear modulus 2750 N/mm2

Interlaminar shear strength 17,25 N/mm2

7.3 Where the glass reinforcement content by weight in a laminate is other than 0,30, it is to be as-sumed for scantling calculations that the basic me-chanical properties are as determined the following formulae:

Ultimate tensile strength

2c c1278G 510G 123− + N/mm2

Tensile modulus

( ) 3c37,0G 4,75 10− N/mm2

Ultimate flexural strength

2c502G 106,8+ N/mm2

Ultimate compressive strength

( )2 3c33,4G 2,2 10+ N/mm2

Ultimate compressive strength c150G 72+ N/mm2

Compressive modulus

( )2 3c40,0G 6,0 10+ N/mm2

Ultimate shear strength c80G 38+ N/mm2

Shear modulus

( ) 3c17G 2,24 10+ N/mm2

Interlaminar shear strength 22,5 17,5G− N/mm2

For unidirectional rovings the tensile properties are to be determined by applying the following formulae:

Ultimate tensile strength (UDR)

2c c1900G 1500G 560− + N/mm2



E

Tensile modulus (UDR)

( )2 3c143G 42,7 10− N/mm2

where

Gc glass content of laminate by weight (exlcuding gel coat) determined by formula:

c 3072TW

2,56G

1,36=

+

where

T [mm] nominal laminate thickness determined in accordance with 7.4

W [g/m2] total weight of glass reinforcement in laminate.

The required values shall be the minimum values, in both the 0° ad 90° orientations for bidirectional and random in place reinforcements and 0° for unidirec-tional reinforcements.

7.4 The nominal laminate thickness T (excluding the gel coat) for an assumed specific gravity of glass and resin of 2,56 and 1,2 respectively, is the aggregate of the thickness t of each layer of reinforcement in the laminate calculated as follows:

c

w 2,56t 1,36mm

3072 g= ⋅ −

where

w [g/m2] weight of reinforcement layer

gc glass content of layer by weight.

7.5 Reinforcements are to be thoroughly impreg-nated with resin and consolidated so that the glass content by weight of the various reinforcements gener-ally does not exceed the following:

Chopped strand mat or sprayed fibres 0,34

Woven rovings 0,50

Unidirectional rovings 0,54

Cloth fabrics 0,50

7.6 The laminate mechanical properties, the nominal thickness and the weight, type and glass con-tent of the individual reinforcements to be used are to be indicated on the construction drawings.

7.7 If the mechanical properties of proposed laminates differ from those determined in accordance with 7.3 the properties and glass content will be sub-jected to compulsory confirmation by testing.

The test specimens are to be cut from laminates ma-tured at a room temperature of between 16 °C to 20 °C for 24 hours before being post-cured at a temperature

not exceeding 40 °C for a period of 16 hours. When the flexual properties are determined, the moulded surface is to be in tension. The tests are to be con-ducted in accordance with ISO standards.

7.8 In composite laminates, woven reinforcement provided that the interlaminar shear strength is not less than that required for the particular laminate (see 7.3).

7.9 The tests are to be carried out on specimens cut from laminates manufactured by the builder from the same materials and construction sequences as are proposed for the construction proper.

8. Core materials for sandwich construction

8.1 Rigid expanded plastics are to satisfy the following requirements. They shall

a) be of closed-cell type and impervious to water, fuel and oil with good ageing stability,

b) have low water absorption,

c) be compatible with the polyester resin,

d) have good strength retention at 60 °C,

c) have characteristics and mechanical properties not less than those indicated in Table 1.

8.2 End-grain balsa is to satisfy the following requirements. It shall

a) have been chemically treated against fungal and insect attack and kiln dried shortly after felling,

b) have been sterilized,

c) have been homogenized,

d) have an average moisture content of 12 %,

e) if manufactured into formable sheets of small blocks, the open weave backing material and ad-hesive are to be respectively compatible and soluble with the polyester laminating resin,

f) have characteristics and mechanical properties not less than those indicated in Table 2.

8.3 Other core materials will be individually considered by reference to their characteristics and intended applications.

9. Materials for integrated structural mem-bers

Metals such as steel or aluminium alloys used in the construction are to be of a quality suitable for the pur-pose intended. Where structural members or compo-nents manufactured from these materials are to be encapsulated or structurally bonded to laminates, the material shall not adversely affect the cure of the resin system, and the surface area of the component that will be in contact with the resin is to be thoroughly cleaned, degreased and, where practicable, either shot blasted or abraded to provided a key.

I - Part 5 GL 1998


E

Table 1

Material

Strength values [N/mm2]

Modulus of elasticity [N/mm2]

Apparent density

[kg/m3] Tensile Compressive Shear Compressive Shear

Polyurethane (PU) 96

Polyvinylchloride (PVC) 60 0,85 0,60 0,50 17,2 8,5

Table 2 Minimum characteristics and mechanical properties of end-grain balsa

Strength values [N/mm2]

Apparent density

Compressive Tensile

Compressive modulus of elasticity

[N/mm2]

Shear modulus of elasti-

city

Direction of stress Shear Direction of stress

[kg/m3] Parallel to grain

Perpendicu-lar to grain

Parallel to grain

Perpendicu-lar to grain

Parallel to grain

Perpen-dicular to grain

[N/mm2]

96 5,00 0,35 9,0 0,44 1,10 2,275 35,2 105



E