Tanker Safety Guide (Liquefied Gas), 4th Edition, 2023

Contents

Abbreviations

Definitions  

Chapter 1

The properties and hazards of liquefied gases

1 The properties and hazards of liquefied gases  

1.1 Introduction  

1.2 Flammability

1.3 Occupational health hazards

1.3.1 Toxicity

1.3.2 Asphyxia

1.3.3 Anaesthesia  

1.3.4 Cold burns and frostbite  

1.4 Reactivity

1.4.1 Self-reaction

1.4.2 Reaction with air

1.4.3 Reaction with other cargoes

1.4.4 Reaction with other materials  

1.5 Corrosivity

1.6 Vapour characteristics

1.7 Low temperature effects

1.7.1 Brittle fracture  

1.7.2 Spillage

1.7.3 Cooldown  

1.7.4 Ice formation

1.7.5 Rollover (LNG)

1.7.6 Rollover (LPG)

1.8 Pressure  

1.8.1 Absolute and gauge pressure  

1.8.2 High and low pressure effects

1.8.3 Pressure surge

1.8.4 Pressurised systems  

1.8.5 Reciprocating compressors

1.8.6 Cargo tank pressures

1.8.7 Liquid gas samples

1.8.8 Pressure relief valves  

1.8.9 Cargo heaters

Chapter 2

General precautions

2 General precautions  

2.1 Introduction  

2.2 Cargo information

2.3 Mooring  

2.3.1 Mooring at buoy moorings

2.4 Emergency towing-off pennants

2.5 Access to ship  

2.5.1 Means of access  

2.5.2 Lighting

2.5.3 Unauthorised access  

2.5.4 Persons smoking or intoxicated  

2.6 Warning notices

2.6.1 Permanent warning notices

2.6.2 Temporary warning notices

2.7 Craft alongside

2.8 Weather precautions  

2.8.1 Wind conditions

2.8.2 Electrical storms  

2.8.3 Cold weather  

2.8.4 Operations in ice and/or severe sub-zero temperatures

2.9 Openings in deckhouses and superstructures  

2.10 Machinery spaces

2.10.1 Funnel sources of ignition

2.10.2 Blowing boiler tubes

2.10.3 Cargo vapour  

2.11 Cargo machinery room precautions  

2.11.1 Cargo compressor/machinery rooms  

2.12 Ship’s readiness to move

2.13 Navigation and bridge procedures

2.13.1 Ship’s transmission equipment

2.14 Environmental protection

2.15 Firefighting and fire protection  

2.16 Helicopter operations

Chapter 3

Safety management

3 Safety management

3.1 Introduction

3.2 Safety culture  

3.2.1 What is a safety culture?

3.2.2 Key features of an effective safety culture

3.3 The human element

3.4 The Safety Management System (SMS)  

3.5 Safety information for shore personnel

3.6 Outside contractors  

3.7 Risk management  

3.7.1 Risk assessment process  

3.7.2 Conducting risk assessments

3.7.3 Risk assessment matrix

3.8 Safe operations

3.8.1 Leadership  

3.8.2 Stop work authority  

3.8.3 Routine operations  

3.8.4 Non-routine operations

3.9 Ship’s crewing  

3.9.1 Introduction

3.9.2 Responsibility

3.9.3 Crew resources

3.9.4 Training  

3.9.5 Familiarisation  

3.9.6 Crew communication  

3.9.7 Drills and exercises

3.9.8 Crew schedules and minimum hours of rest

3.9.9 Summary of STCW hours of rest requirements  

3.9.10 Fatigue  

3.9.11 Prevention of drug and alcohol abuse  

3.10 Personal protection and lifesaving  

3.10.1 Introduction

3.10.2 Personal protective equipment  

3.10.3 Decontamination water sprays and showers

3.10.4 Canister and filter type respirators  

3.10.5 Breathing apparatus

3.10.6 Safe haven

3.10.7 First aid

3.10.8 Resuscitation

3.10.9 Frostbite

3.11 Incident investigations

Chapter 4

Cargo handling plant and equipment

4 Cargo handling plant and equipment  

4.1 Cargo pumps  

4.1.1 Deepwell pumps  

4.1.2 Fixed submerged pumps

4.1.3 Removable (emergency) submerged pumps  

4.1.4 Booster pumps and deck mounted pumps  

4.1.5 Hold or interbarrier space pumps  

10 Tanker Safety Guide (Liquefied Gas), Fourth Edition

4.2 Compressors  

4.2.1 General

4.2.2 Reciprocating compressors  

4.2.3 Centrifugal compressors

4.2.4 Rootes-type compressors

4.2.5 Screw compressors  

4.2.6 Heat exchangers

4.3 Inert gas systems

4.3.1 General  

4.3.2 Inert gas generator  

4.3.3 Scrubbers

4.3.4 Refrigeration and condensers

4.3.5 Driers

4.3.6 Use of nitrogen as inert gas

4.4 Gas combustion units  

4.5 Pressure relief systems

4.5.1 General

4.5.2 Cargo pressure relief devices

4.5.3 Hold space relief devices  

4.6 Vacuum relief systems  

4.7 Valves  

4.8 Filters and strainers  

4.9 Expansion bellows  

4.10 Vent and purge masts  

4.11 Pipeline supports  

4.12 Insulation

Chapter 5

Cargo system instrumentation

5 Cargo system instrumentation  

5.1 Liquid level gauges

5.1.1 General  

5.1.2 Radar gauges

5.1.3 Ultrasonic gauges  

5.1.4 Float gauges

5.1.5 Capacitance probes

5.1.6 Slip-tube and fixed tube gauges  

5.2 Level alarms, automatic shutdown and emergency shutdown  

5.2.1 High level alarms

5.2.2 Low level alarms  

5.2.3 Automatic shutdown systems  

5.2.4 Emergency shutdown (ESD) systems  

5.3 Pressure indicating devices

5.4 Temperature monitoring equipment

5.5 Gas detection equipment  

5.5.1 General precautions

5.5.2 Infra-red detectors  

5.5.3 Thermal conductivity meters  

5.5.4 Combustible gas detectors

5.5.5 Chemical absorption detector tubes

5.5.6 Oxygen analysers

5.5.7 PID detectors

5.5.8 FID detectors

5.5.9 Personal gas monitors  

5.5.10 Multi-gas instruments

5.6 Equipment alarm and shutdown circuits  

5.7 Instrument and control air supplies

Chapter 6

Transportation of liquefied gas

6 Transportation of liquefied gas

6.1 Introduction  

6.2 Basic cargo system design considerations

6.2.1 General  

6.2.2 Pressurised carriage  

6.2.3 Refrigerated carriage  

6.2.4 Cargoes carried

6.3 The IGC Code

6.3.1 Gas carrier design standards  

6.4 Cargo containment systems  

6.4.1 General

6.4.2 Pressure vessel systems  

6.4.3 Low pressure systems

6.4.4 Hull and insulation arrangements  

6.4.5 Refrigeration systems

6.4.6 Cargo tank types  

6.5 Gas carrier types and arrangements  

6.5.1 Fully-pressurised gas carriers

6.5.2 Semi-pressurised gas carriers

6.5.3 Ethylene carriers  

6.5.4 Ethane carriers  

6.5.5 LPG carriers  

6.5.6 Methane/LNG carriers

6.6 Carriage of noxious liquid substances  

6.7 MARPOL

6.8 IMO Ballast Water Management Convention  

12 Tanker Safety Guide (Liquefied Gas), Fourth Edition

Chapter 7

Fire hazards and precautions

7 Fire hazards and precautions

7.1 Introduction  

7.2 Flammability of liquefied gases

7.3.1 Loading  

7.3.2 Carriage

7.3.3 Disposal

7.4 Atmosphere control

7.4.1 General  

7.4.2 Cargo tanks and piping systems

7.4.3 Hold and interbarrier spaces  

7.4.4 Inert gas quality

7.4.5 Inert gas hazards and precautions

7.5 Static electricity

7.5.1 Electrostatic generation

7.5.2 Steam  

7.5.3 Carbon dioxide

7.5.4 Ship/shore insulating, earthing and bonding

7.6 Precautions against sources of ignition  

7.6.1 Smoking

7.6.2 Electrical installations

7.6.3 Portable electrical equipment

7.6.4 Ship’s communications equipment  

7.6.5 Electrical maintenance and repairs

7.6.6 Personal electronic items  

7.6.7 Aluminium equipment

7.6.8 Auto-ignition

7.6.9 Spontaneous combustion  

7.7 Hot work  

7.7.1 General  

7.7.2 Assessment of hot work

7.7.3 Hot work permit  

7.7.4 Preparations for hot work  

7.7.5 Checks by officer responsible for safety during hot work  

7.7.6 Actions on completion of hot work  

7.7.7 Hot work flow chart

7.8 Cold work

7.8.1 Mechanically powered tools

7.8.2 Hand tools  

7.9 Firefighting and fire protection equipment

7.9.1 Firefighting equipment  

7.9.2 Vent mast protection screens and flame screens  

Chapter 8

Cargo operations

8 Cargo operations  

8.1 Introduction

8.2 Responsibility

8.3 Commissioning the cargo system

8.4 General cycle of operations  

8.5 Preparation for cargo transfer

8.5.1 General  

8.5.2 Pressure surge

8.6 Inerting and gassing-up  

8.6.1 General  

8.6.2 Inerting

8.6.3 Gassing-up

8.6.4 Methods of inerting and gassing-up

8.7 Preparations for loading  

8.7.1 General  

8.7.2 Cooldown of tanks and pipelines

8.7.3 Ice or hydrate formation

8.7.4 Minimum cargo tank temperature  

8.7.5 Rollover precautions  

8.8 Cargo loading

8.9 Cargo conditioning

8.9.1 General  

8.9.2 Reliquefaction and boil-off control  

8.9.3 Sloshing

8.9.4 Use of cargo as fuel

8.10 Cargo discharge

8.11 Ship-to-ship transfer  

8.12 Ballasting and de-ballasting  

8.13 Simultaneous operations  

8.13.1 LNG bunkering simultaneous operations

8.14 Separation of cargoes  

8.15 Commingling of LPG cargoes in port  

8.16 Changing cargoes

8.16.1 Cargo stripping  

8.16.2 Change of cargo

8.16.3 Displacing atmosphere with nitrogen/inert gas (inerting)

8.16.4 Gassing-up with vapour of the next cargo  

8.16.5 Water washing after ammonia cargoes

8.17 Gas-freeing and aeration  

8.18 Venting at sea  

8.19 Deck storage tanks  

8.20 Sampling

8.20.1 Sampling systems

8.20.2 Liquid samples

8.20.3 Vapour samples  

8.21 Custody transfer measurement systems

8.22 Drydocking and repair periods

Chapter 9

Cargo equipment

9 Cargo equipment

9.1 Introduction  

9.2 Plant and equipment precautions  

9.2.1 Pumps

9.2.2 Compressors  

9.2.3 Heat exchangers  

9.2.4 Electrical equipment  

9.2.5 Control and alarm systems

9.2.6 Instrumentation

9.2.7 Valves  

9.2.8 Cargo vent systems  

9.2.9 Expansion/contraction fittings  

9.2.10 Cargo pipelines

9.2.11 Ship’s cargo hoses

9.2.12 Manifold connections using emergency release couplings  

9.2.13 Inert gas systems

9.2.14 Dry air supply  

9.2.15 Ventilation equipment

9.3 Equipment maintenance  

9.3.1 Maintenance  

9.3.2 Maintenance of electrical equipment  

Chapter 10

Reliquefaction and boil-off control

10 Reliquefaction and boil-off control  

10.1 The types of reliquefication systems  

10.2 Types of refrigerated gas carriers

10.2.1 LPG carriers

10.2.2 LNG carriers  

10.3 Reliquefaction systems

10.3.1 Plant requirements

10.3.2 Plant duties

10.3.3 Plant auxiliary functions

10.3.4 Refrigerant system auxiliary functions  

10.3.5 Reliquefaction cycles

10.4 Reliquefaction plant operations (for LPG carriers)

10.4.1 General

10.4.2 Preliminary precautions

10.4.3 Cargo reliquefaction plant operations

10.4.4 Refrigerant system operations  

10.4.5 Completion of reliquefaction operations  

10.4.6 Glycol systems  

10.4.7 Anti-freeze injection  

10.4.8 Hydrate formation  

10.4.9 Incondensable gases

Chapter 11

Bunkering 

11 Bunkering  

Chapter 12

Pressure surge effects

12 Pressure surge effects

12.1 Introduction

12.2 Generation of pressure surge  

12.3 Other surge pressure effects

Chapter 13

Enclosed spaces

13 Enclosed spaces

13.1 General

13.1.1 Hazards of enclosed spaces  

13.1.2 Oxygen deficiency  

13.1.3 Toxic and/or flammable gases

13.1.4 The presence of inert gas

13.1.5 Oxygen enrichment

13.2 Atmosphere in enclosed spaces

13.3 Requirements for enclosed space entry

13.3.1 Planning  

13.3.2 Entry permit

13.4 Testing before entry

13.4.1 Testing for entry in shipyards  

13.5 Entry into enclosed spaces  

13.5.1 Entry into cargo tanks  

13.5.2 Entry into enclosed spaces other than cargo tanks  

13.5.3 Cargo control rooms

13.5.4 Cargo pump or compressor rooms, motor rooms and airlocks

13.5.5 Engine or boiler rooms

13.6 Work in enclosed spaces

13.7 Enclosed space entry permit  

13.8 Rescue from enclosed spaces

13.8.1 General

13.8.2 Preventing enclosed space accidents

13.8.3 Rescue and recovery organisation  

13.8.4 The rescue operation

13.8.5 Rescue and recovery equipment

Chapter 14

Emergencies

14 Emergencies

14.1 Water leakage into hold or interbarrier space

14.2 Hose burst, pipework fracture or cargo spillage

14.3 Dispersion of liquid spill and vapour emissions by water spray

14.4 Tank leakage

14.5 Emergency discharge of cargo at sea (jettison)  

14.6 Safety incidents involving personnel

14.7 Reporting

Chapter 15

Firefighting

15 Firefighting  

15.1 Introduction

15.2 Firefighting organisation

15.3 Special considerations for fighting liquefied gas fires

15.3.1 Isolating the source  

15.3.2 Use of water

15.3.3 Use of dry powder

15.4 Vent mast fires

15.5 Fires near to the ship

15.6 Boiling liquid/expanding vapour explosion (BLEVE)

Chapter 16

Drydocking and repair periods

16 Drydocking and repair periods

16.1 Special considerations  

16.1.1 Cargo tanks and hold or interbarrier spaces

16.1.2 Instruments  

16.1.3 Hot work during repair periods  

16.1.4 Deck storage tanks  

16.2 Recommissioning

Appendices

Appendix A Ship/shore safety checklist  

Appendix B Conversion tables

Appendix C Example hot work permit

Appendix D Example enclosed space entry permit

References