Liquefied Gas Handling Principles on Ships and in Terminals, (LGHP4) 4th Edition

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Published Date

July 2016


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Liquefied Gas Handling Principles on Ships and in Terminals, (LGHP4) 4th Edition

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This fully illustrated 500-page reference book covers every aspect of the safe handling of bulk liquid gases (LNG, LPG and chemical gases) on board ships and at the ship/shore interface at terminals. It is indispensable for personnel training for operational qualifications as well as those already engaged in liquefied gas operations.

The publication has been written primarily for serving ships’ officers and terminal staff who are responsible for cargo handling operations, but also for personnel who are about to be placed in positions of responsibility for these operations.  Its appeal extends also to many others, not directly involved in the operational aspects of the industry, who require a comprehensive and ready reference for technical aspects of their businesses. Liquefied Gas Handling Principles emphasises the importance of understanding the physical properties of gases in relation to the practical operation of gas-handling equipment on ships and at terminals.

 

In the sixteen years since this publication was last updated, the liquefied gas shipping and terminal industry has undergone considerable change. This revision reflects these changes which include, but are not limited to, vessel design, propulsion systems, size of fleet, floating regasification and reliquefaction, Arctic LNG, containment systems, efficiency increases in vessel operations, vessel capacities, technology, best practice and legislation.

Contents
Preface to the Fourth Edition
Prefaces to the Previous Editions
Figures and Tables
Definitions
Key to Symbols

CHAPTER 1 Overview of the Carriage of Liquefied Gases by Sea

 

1.1

The Liquefied Gases

 

1.1.1 LNG production

 

1.1.2 LPG production

 

1.1.3 Chemical gases production

1.2

The Principal Products

1.3

Gas Carrier Fleet

1.4

Safety Record

1.5

Regulatory Framework

 

1.5.1 Safety of Life at Sea (SOLAS)

 

1.5.2 International Convention for the Prevention of Pollution From Ships, 1973, as modified by the Protocol of 1978 (MARPOL 73/78)

 

1.5.3 International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW)

 

1.5.4 Recommendations on the Safe Transport of Dangerous Cargoes and Related Activities in Port Areas

 

1.5.5 Ship certification

 

 

CHAPTER 2 Properties of Liquefied Gases

Chapter 2 Part a) The Chemistry of Liquefied Gases

    1. Atoms, Molecules and Chemical Bonds

      1. The hydrocarbon series

      2. Chemical formulae and the IUPAC naming system

      3. Saturated and unsaturated hydrocarbons 24

    2. The Chemical Gases 28

    3. Chemical Reactivity and Compatibility 31

      1. Reactivity with construction materials 31

      2. Reactivity with other cargoes 32

    4. Self-Reaction 33

      1. Reactive properties 33

      2. Formation of polymers or dimers 33

    5. Reaction with Water – Hydrate Formation 37

    6. Reaction with Air 39

      1. Combustion 39

      2. Flammability/flammable range 40

    7. Suppression of Flammability 44

      1. Inert gas and nitrogen 45

      2. The use of inert gas 46

      3. The chemical compatibility of cargoes with inert gas or nitrogen 47

Chapter 2 Part b) The Physics of Liquefied Gases 49

    1. The Physical Properties of Liquefied Gases and their States of Matter 49

      1. Temperature, heat energy and phase change 49

      2. Specific heat, enthalpy and entropy 50

      3. Phase change – a summary 51

      4. Saturated vapour pressure (SVP) 52

      5. Liquid and vapour densities 55

      6. Liquid to vapour volume ratios 55

      7. Spillage of cargo liquid 56

      8. Viscosity of liquid cargoes 57

Chapter 2 Part c) Gas Laws, Thermodynamic Principles and Reliquefaction 59

    1. The Gas Laws and Thermodynamic Principles 59

      1. Liquefied gas mixtures, their vapour pressures and compositions 62

      2. The ‘bubble point’ and ‘dew point’ of mixtures 64

      3. The laws of thermodynamics 66

      4. Enthalpy and Mollier charts 67

      5. Thermodynamic systems – isothermal, isentropic and adiabatic processes 70

      6. Heat transfer 71

      7. Practical examples of heat transfer 72

      8. Rollover 73

    2. Reliquefaction 75

2.10.1

Indirect cycle

76

2.10.2

Direct cycle

77

2.10.3

Cascade cycle

84

2.10.4

LNG reliquefaction cycles

86

 

 

CHAPTER 3

Liquefied Gas Carrier Types

93

 

 

Chapter 3 Part a) Gas Carrier Types

 

95

 

3.1 Design Standards and Ship Types

95

 

3.1.1 The IGC Code

95

 

3.1.2 Factors affecting gas carrier design

97

 

3.2 Gas Carrier Types

98

 

3.2.1 Fully-pressurised ships

98

 

3.2.2 Semi-refrigerated ships

99

 

3.2.3 Fully-refrigerated ships

100

 

3.2.4 Ethylene/ethane ships

102

 

3.2.5 LNG carriers

103

 

3.2.6 Regasification vessels (RVs)

104

 

3.3 Gas Carrier Layout

105

 

3.4 Hazardous Zones

107

 

3.4.1 Hazardous area classification

107

 

3.4.2 IEC definitions

108

 

3.4.3 Zone determination

109

 

3.4.4 Ventilation

109

 

3.5 Survival Capability

110

 

3.6 Surveys and Certification

111

 

3.6.1 Certificate of fitness

111

 

3.6.2 Carriage of noxious liquid substances (NLS)

112

 

 

Chapter 3 Part b) Cargo Containment Systems

 

113

 

3.7 Materials of Construction and Insulation

113

 

3.7.1 Construction materials

113

 

3.7.2 Tank insulation

114

 

3.8 Cargo Containment Systems

116

 

3.8.1 Type A tanks

118

 

3.8.2 Type B tanks

121

 

3.8.3 Type C tanks (semi-refrigerated)

125

 

3.8.4 Type C tanks (fully-pressurised)

126

 

3.8.5 Membrane tanks

126

 

3.8.6 Semi-membrane containment system

134

 

3.8.7 Integral tanks

134

 

 

Chapter 3 Part c)

Propulsion System Types

135

3.9 Propulsion

System Types on LNG Carriers

135

3.9.1

Steam

137

3.9.2

Dual fuel diesel electric (DFDE)

139

3.9.3

Slow speed diesel (oil fuel)

141

3.9.4

Slow speed diesel (gas fuel)

141

 

 

CHAPTER 4 The Ship – Cargo Equipment 143

    1. Cargo Pipelines and Valves 145

      1. Cargo pipelines 145

      2. Hazards of cargo line pressure testing 146

      3. Cargo manifold reducers 147

      4. Cargo valves 149

      5. Cargo strainers 152

      6. Emergency shutdown (ESD) systems 154

      7. Effect of surge pressure should ESD activate 158

      8. Relief valves for cargo tanks and pipelines 158

      9. Types of pressure relief valves 160

    2. Cargo Pumps 164

      1. Pump performance curves 164

      2. Deepwell pumps 167

      3. Submerged motor pumps 168

      4. Booster pumps 169

      5. Ice prevention at cargo pumps 170

      6. Emergency cargo pumps 170

    3. Deck Tanks 172

    4. Cargo Heaters 173

      1. Direct cargo heaters 174

      2. Indirect cargo heaters 176

    5. Cargo Vaporisers 177

    6. Regasification Units 179

      1. Closed loop with steam heating 179

      2. Combined open/closed loop with seawater and steam heating 179

      3. Closed loop with steam heating and intermediate water/glycol loop 180

      4. Open loop with seawater heating and intermediate propane loop 180

 

 

4.7 LPG Reliquefaction Plant and Boil-Off Control

181

4.7.1 Cargo compressors and associated equipment

181

4.7.2 Reciprocating compressors

182

4.7.3 Screw compressors

183

4.7.4 Compressor suction liquid separator

184

4.7.5 Cargo compressor suction gas cooling

184

4.7.6 Purge gas condenser

185

4.8 LNG Reliquefaction Plant and Boil-off Control Systems

186

4.8.1 LNG boil-off and vapour handling systems

186

4.8.2 LNG compressors (vapour return and fuel gas)

187

4.8.3 Gas combustion units (GCU)

188

4.8.4 LNG reliquefaction

189

4.9 Inert Gas and Nitrogen Systems

192

4.9.1 Inert gas generators

193

4.9.2 Nitrogen production on ships

196

4.9.3 Pure nitrogen from the shore

197

4.10 Electrical Equipment

198

4.11 Cargo Instrumentation

200

4.11.1 Liquid level instrumentation

200

4.11.2 Magnetic level transmitters

203

4.11.3 Level alarm and automatic shutdown systems

205

4.11.4 Pressure and temperature monitoring

205

4.11.5 Gas detection systems

206

4.11.6 LNG custody transfer measurement systems (CTMS)

208

4.11.7 Integrated systems

208

4.11.8 Calibration

208

4.12 Ship/Shore Links

209

 

CHAPTER 5

 

The Terminal

 

211

 

 

Chapter 5 Part a) Onshore

 

213

 

5.1 Safe Jetty Designs

213

 

5.2 Cargo Transfer Systems

215

 

5.2.1 Hoses

216

 

5.2.2 Marine loading arms (MLAs)

217

 

5.2.3 Vapour return

223

 

5.2.4 Insulating flanges

225

 

    1. Shore Storage 226

      1. Pressurised storage at ambient temperature 227

      2. Storage in semi-pressurised spheres 232

      3. Refrigerated storage at atmospheric pressure 233

      4. Construction materials and design 239

    2. Ancillary Equipment 240

      1. Pressure relief venting 240

      2. Pipelines and valves – engineering standards and surge pressure 240

      3. Pumps, compressors and heat exchangers 246

    3. Instrumentation 252

      1. Product metering 252

      2. Pressure, temperature and level instrumentation 254

Chapter 5 Part b) Offshore 255

    1. Floating Terminals 256

    2. Facility Layout 258

      1. Engineering design considerations 260

      2. Other considerations 261

    3. Topsides Production Facilities 264

      1. Topsides production facility (LPG specific) 264

      2. Topsides production facility (LNG specific) 264

      3. Topsides production facility (regas specific) 266

    4. Product Storage and Offloading 269

      1. Cargo containment systems 269

    5. Mooring Systems 270

    6. Cargo Transfer Systems 272

      1. Side by side offloading 272

      2. Tandem offloading 273

      3. Hoses for ship to ship and offshore transfer systems 273

      4. Surge considerations for ship to ship and offshore transfer systems 274

CHAPTER 6 The Ship/Shore Interface 275

    1. Supervision and Control 277

    2. Design Considerations 278

6.2.1

Jetty operations

278

6.2.2

The terminal

279

6.2.3

The ship

279

 

 

6.3

Ship/Shore Compatibility Process (LNG)

280

 

6.3.1 Ship and terminal particulars

280

 

6.3.2 Mooring arrangements

280

 

6.3.3 Ship manifold, shore hose and marine loading arm (MLA) characteristics

 

281

 

6.3.4 Terminal gangway characteristics and ship deck landing configuration

282

 

6.3.5 Ship/shore link (SSL)

283

 

6.3.6 Other compatibility considerations

284

6.4

Ship/Shore Compatibility Process (Other Liquefied Gases)

285

6.5

Communications

286

 

6.5.1 Prior to charter

286

 

6.5.2 Prior to arrival

286

 

6.5.3 Alongside the jetty

287

 

6.5.4 Navigation, docking, mooring, meteorological and oceanographic systems

 

287

6.6

Discussions Prior to Cargo Transfer

289

6.7

Ship/Shore Safety Checklist

291

6.8

Supervision and Control During Cargo Transfer

293

 

6.8.1 Joint agreement on readiness for cargo transfer operations

293

 

6.8.2 Supervision

293

 

6.8.3 Periodic checks during cargo transfer operations

293

6.9

Operational Considerations

294

 

6.9.1 Berthing and mooring

294

 

6.9.2 Connection and disconnection of cargo hoses and MLAs

295

 

6.9.3 Cargo handling procedures

296

 

6.9.4 Cargo surveyors

297

 

6.9.5 Gangways and ship security

297

 

6.9.6 Bunkering

298

 

6.9.7 Work permits

299

 

6.9.8 Access to cargo manifold during transfer

299

6.10

Fire-Fighting and Safety

300

6.11

Linked Emergency Shutdown (ESD) Systems

302

6.12

Terminal Booklet – Information and Regulation

304

6.13

Training

305

 

CHAPTER 7 Cargo Handling Operations 307

    1. Sequence of Operations 309

    2. Initial Preparations 311

 

 

7.2.1

Tank inspection

311

7.2.2

Drying – cargo system

311

7.2.3

Drying – hold spaces and interbarrier spaces

313

7.3

Changing

Tank Atmospheres

314

 

7.3.1

Principles of atmosphere changing

315

 

7.3.2

Displacement

315

 

7.3.3

Dilution

317

7.4

Inerting –

Before Loading

319

 

7.4.1

Inerting pipelines and cargo machinery

320

 

 

7.5

7.4.2

Gassing-U

Tank preparation prior to loading ammonia

p

321

322

 

7.5.1

Gassing-up at sea using liquid from tanks

323

 

7.5.2

Gassing-up alongside

324

7.6

Cool-down

328

 

7.6.1

Refrigerated LPG cargoes

329

 

7.6.2

LNG

330

 

7.6.3

Semi-pressurised/semi-refrigerated ships

331

7.7

Loading

 

332

 

7.7.1

Preliminary procedures

332

 

7.7.2

Trim, stability and stress

333

 

7.7.3

Sloshing

333

 

7.7.4

Management of tank pressure during loading

334

 

7.7.5

Commencement of loading

338

 

7.7.6

Operation of the reliquefaction plant during bulk loading of LPG

340

 

7.7.7

Operation of the reliquefaction plant during bulk loading of LNG

341

 

7.7.8

Cargo tank loading limits

341

7.8 The Loaded Voyage 345

7.8.1

Cargo temperature and pressure control

345

7.8.2

Operation of the reliquefaction plant on refrigerated LPG carriers

346

7.8.3

Operation of the reliquefaction plant on LNG carriers

348

7.8.4

LNG carriers – gas combustion unit (GCU)

350

7.8.5

LNG boil-off gas (BOG) as fuel

351

7.8.6

Other boil-off gas (BOG) as fuel

352

 

    1. Discharging 353

      1. Discharge by pressurising the vapour space 353

      2. Discharge by cargo pump 353

      3. Discharge via booster pump and cargo heater 357

      4. Tank pressure management 357

      5. Operation of the reliquefaction plant during discharge 361

      6. Completion of discharge 361

      7. Draining of tanks and pipelines 362

    2. The Ballast Voyage 364

      1. LPG carriers 364

      2. LNG carriers 364

    3. LNG Carrier – Ballast Voyage on Ships Fitted with a Combination

of a Reliquefaction Plant/GCU 365

      1. Warm ballast voyage (use of GCU) 365

      2. Cold ballast voyage (use of reliquefaction plant) 365

    1. Gas-Freeing 366

      3

      1. LPG/NH carriers 366

      2. LNG carriers 372

    2. Ship to Ship Transfer (STS) 377

CHAPTER 8 Cargo Measurement and Calculation 379

 

8.1

Principles

for Liquefied Gases

381

 

8.1.1

Special practices for gas cargoes

381

 

8.1.2

General – density in air and density in a vacuum

382

 

8.1.3

Gas-up and cool-down quantity calculation

386

 

8.1.4

Shore terminal considerations

387

    1. Taking Samples of Liquefied Gas Cargoes 389

      1. Why cargo samples are taken 389

      2. Sampling systems – ‘open loop’ or ‘closed loop’ systems 390

      3. The procedures involved in taking samples 393

    2. Measurement of Cargo Tank Volumes 396

      1. Trim correction 397

      2. List correction 398

      3. Tape correction 398

      4. Float correction 398

      5. Tank shell contraction and expansion 398

    3. Measurement of Density 399

      1. Density measurement methods 399

 

8.5

Ship/Shore Calculation Procedures

401

 

8.5.1 Outline of weight in air calculation

401

 

8.5.2 Procedures using standard temperature

401

8.6

Example – LPG Cargo Calculation

403

8.7

Other Calculation Procedures and Measurement Units

404

8.8

LNG Quantification

405

 

8.8.1 Example of contractual requirements for the measurement of the energy transferred at an LNG unloading terminal

 

410

8.9

Cargo Documentation

415

 

 

CHAPTER 9 Health, Environment and Safety Management 417

Chapter 9 Part a) Safety Management 419

    1. Safety Management Systems (SMS) 419

    2. Security 421

    3. Safety Organisation 422

      1. Terminal organisational structure 422

      2. Shipboard safety organisation 422

      3. Training, competency and experience 424

Chapter 9 Part b) Hazards and Emergency Procedures 425

    1. Principal Hazards 425

      1. Flammability 426

      2. Jet fires 427

      3. Liquid (pool) fires 427

      4. Vapour cloud explosion 429

      5. BLEVE 429

      6. Vaporisation of spilled liquid 430

      7. Rapid phase transitions (RPT) 430

      8. Uncontrolled release of vapour 431

      9. Vapour exposure 431

      10. Asphyxia (suffocation) 434

      11. Medical treatment for asphyxia or the effects of toxic materials 436

      12. Giving oxygen to a casualty 438

      13. Frostbite 440

      14. Chemical burns 442

      15. Other hazards of liquefied gases 442

    2. Emergency Planning 443

      1. The emergency plan 443

      2. Ship emergency procedures 443

      3. Terminal emergency procedures 444

    3. Removal of Ship from Berth 446

    4. Ship to Ship Cargo Transfer 447

    5. Hazards with the Use of Hoses and Marine Loading Arms (MLAs) 448

    6. Sources of Ignition 450

    7. Fire and Fire-Fighting Management 451

    8. Extinguishing Mediums 452

      1. Water 452

      2. Foam 453

      3. Dry chemical powders 453

      4. Carbon dioxide (CO2) systems 454

      5. Alarm procedures 455

      6. Training 456

Chapter 9 Part c) Process Safety 457

    1. Risk Assessment 460

      1. Principles of risk assessment 460

      2. Qualitative versus quantitative 461

      3. Inherent risk versus residual risk 461

      4. Risk assessments in practice 462

    2. Procedures 463

    3. Standards 464

    4. Management of Change (MoC) 465

    5. Inspection and Maintenance 467

    6. Permit to Work Systems (PTW) 469

      1. Types of permit to work 472

      2. Lock-out and tag-out 476

    7. Incident Investigation and Reporting 478

      1. Incident reporting 478

      2. Root cause analysis (RCA) and risk assessments 479

    8. Process Safety Information 480

Chapter 9 Part d) Personal Health & Safety 481

    1. Hazardous Atmospheres 481

    2. Personal Protection 482

      1. Induction 482

    3. Entry into Enclosed Spaces 484

      1. Precautions for tank entry 484

      2. Procedures for tank entry 485

      3. Rescue from enclosed spaces 485

      4. Mandatory enclosed space entry and rescue drills 486

    4. Personal Protective Equipment (PPE) 487

    5. General Safety Precautions 488

      1. Breathing apparatus 490

      2. Protective clothing 492

    6. Safety Data Sheets (SDS) 493

Chapter 9 Part e) Environmental Stewardship 495

    1. Air Emissions 496

    2. Energy Efficiency Design Index (EEDI) 497

    3. Effect of Non-Core Ship/Shore Services 498

Appendix 499

Index 505

Other SIGTTO Publications You May be Interested in 521

Reference Tables and Diagrams

Figures and Tables

Inside front and back covers — LPG, LEC and LNG carriers (to scale)

 

Figure No.

 

Figure 1.1

Title

 

Constituents of natural gas

 

 

4

Figure 1.2

Flow diagram for a typical gas liquefaction plant (known as a ‘train’)

5

Figure 1.3

The production, transport and use of LPGs

6

Figure 1.4

Production of chemical gases (simplified)

7

Figure 2.1

Atoms consist of electrons, protons and neutrons

19

Figure 2.2

Methane CH4

21

Figure 2.3

Ethane C2H6

21

Figure 2.4

Propane C3H8

22

Figure 2.5

Normal butane C4H10

22

Figure 2.6

Iso-butane

22

Figure 2.7

Saturated hydrocarbon (ethane (C2H6))

24

Figure 2.8

Unsaturated hydrocarbons (ethylene (C2H4) and acetylene (C2H2))

25

Figure 2.9

Butadiene structures

25

Figure 2.10

Vinyl chloride (C2H3CI)

29

Figure 2.11

Ethylene oxide (C2H4O) and propylene oxide (C3H6O)

30

Figure 2.12

The dimerisation and polymerisation of VCM (C2H3Cl)

34

Figure 2.13

Cargo pump, spool piece and strainer showing polymerisation

34

Figure 2.14

Inhibitor information form

35

Figure 2.15

Dimerisation of butadiene

36

Figure 2.16

Hydrate plug in the pump sump of a semi-refrigerated LPG carrier after a cargo of ‘wet’ butane

 

37

Figure 2.17

Hydrate at the cargo manifold after the discharge of a ‘wet’ butane cargo

37

Figure 2.18

Solubility of water in butadiene

38

Figure 2.19

Flammable ranges of butane, ethylene and methane (percent in air)

40

Figure 2.20

Likely flammable vapour zones in the event of a liquefied gas spill

43

Figure 2.21

Flammable range diagram

44

Figure 2.22

Changes of state

51

Figure 2.23

Barometric method for measuring saturated vapour pressure

52

Figure 2.24

Pressure vs temperature – liquefied gases

53

Figure 2.25

Properties of propane liquid and vapour

55

Figure 2.26a

Boyle’s Law for gas at constant temperature

59

Figure 2.26b

Charles’ Law for gas at constant pressure

59

Figure 2.26c

The Pressure Law for gas at constant volume

59

Figure 2.27

Illustration of ‘absolute temperature’

60

Figure 2.28

Equilibrium diagram for propane/butane mixtures at atmospheric pressure

65

Figure 2.29

Natural boil-off, weathering or flash vaporisation

66

Figure 2.30

Schematic Mollier diagram

68

Figure 2.31

Relationship between adiabatic and isothermal compression

70

Figure 2.32

Comparative heat transfer rates for various materials

72

 

 

Figure 2.33

Heat transfer within a cargo tank

72

Figure 2.34

LNG tank with normal non-stratified convection heat transfer

73

Figure 2.35

Conditions in an LNG tank where stable stratification has been caused by filling with liquids of different densities

 

73

Figure 2.36

Rollover

74

Figure 2.37

Indirect cooling cycles

76

Figure 2.38

Single stage, direct cargo reliquefaction cycle

78

Figure 2.39

Mollier chart: Single stage direct reliquefaction cycle

80

Figure 2.40

Propane – ethane equilibrium diagram

81

Figure 2.41

Schematic Mollier chart: 2-stage direct compression cycle

81

Figure 2.42

2-stage direct reliquefaction cycle

82

Figure 2.43

Refrigerant type reliquefaction plant (cascade cycle)

84

Figure 2.44

Schematic Mollier chart – cascade cycle

86

Figure 2.45

Simplified cascade refrigeration cycle for LNG

87

Figure 2.46

Cooling curve for multi-stage cascade refrigeration cycle for LNG

88

Figure 2.47

Simplified precooled MR reliquefaction process

89

Figure 2.48

Comparative cooling curves for the cascade, precooled MR and dual MR liquefaction processes

 

90

Figure 2.49

Brayton refrigeration cycle and temperature-entropy diagram

91

Figure 2.50a

Nitrogen expander cycle

91

Figure 2.50b

3-stage nitrogen expander cycle

91

Figure 3.1

Selection of containment system

97

Figure 3.2

Fully-pressurised gas carrier

98

Figure 3.3

Semi-refrigerated gas carrier

99

Figure 3.4

Fully-refrigerated LPG carrier (85,000 m3)

101

Figure 3.5

Ethylene carrier

102

Figure 3.6

Ethane carrier

102

Figure 3.7a

Membrane type LNG carrier

103

Figure 3.7b

Moss type LNG carrier

103

Figure 3.8

The LNG fuelling vessel Seagas refuels the ferry Viking Grace

103

Figure 3.9

Regasification vessel connected to a submerged turret loading system (STL)

104

Figure 3.10

Typical compressor room/electric motor room on a fully-refrigerated LPG carrier

105

Figure 3.11

Cargo compressor room on a 37,000 m3 LPG carrier

105

Figure 3.12

Fixed dry powder monitor on semi-refrigerated LPG carrier

106

Figure 3.13

Fixed water protection for the front of the accommodation block

106

Figure 3.14

Diagram showing hazardous area on an LPG carrier

107

Figure 3.15

Diagram showing hazardous area on an LNG storage tank

107

Figure 3.16

View of a Type A tank as found on a fully-refrigerated LPG carrier

118

Figure 3.17

Prismatic Type A tank

120

Figure 3.18

Self-supporting spherical Type B – LNG carrier

121

Figure 3.19

Self-supporting prismatic Type B tank

122

Figure 3.20

Self-supporting spherical Type B – LNG carrier

122

Figure 3.21

Moss (Type B) tank under construction, showing the equatorial ring

(To increase the volume without increasing hull dimensions, the Moss tank

can be constructed in a ‘stretched version’ where a cylindrical section is inserted in the equatorial area)

 

 

 

123

 

 

Figure 3.22

Moss (Type B) tank under construction and showing the central pipe tower arrangement

124

Figure 3.23

Type C tank (semi-refrigerated)

125

Figure 3.24

Type C tanks – fully-pressurised gas carrier

126

Figure 3.25

Type C tanks mounted in a barge to be used in a floating LNG project

126

Figure 3.26

Principles of membrane containment system

127

Figure 3.27

Membrane containment system

127

Figure 3.28

GTT NO 96 containment system

128

Figure 3.29

Construction of the Gaztransport membrane system (NO 96)

130

Figure 3.30

GTT NO 96 containment system

130

Figure 3.31

GTT NO 96 containment system

131

Figure 3.32

Technigaz MK III containment system

131

Figure 3.33

Technigaz waffle

132

Figure 3.34

Technigaz reinforcement

132

Figure 3.35

Construction of the Technigaz membrane – MK lll

133

Figure 3.36

BOG, BOR and their relationship to vessel speed

136

Figure 3.37

Simplified steam turbine propulsion plant overview

137

Figure 3.38

Simplified schematic of steam turbine propulsion system with reheat

138

Figure 3.39

Simplified dual fuel propulsion plant overview

139

Figure 3.40

Otto cycle

139

Figure 3.41

Major components of a diesel-electric propulsion plant

140

Figure 3.42

Typical diesel-electric drive train efficiency

140

Figure 3.43

Simplified slow speed diesel propulsion plant

141

Figure 3.44

Simplified representative ME-GI propulsion plant

(with high pressure pump/vaporiser) and DF auxiliary diesel generators

 

142

Figure 3.45

Combustion process in gas injection diesel engine

142

Figure 4.1

Liquid and vapour manifold arrangement on a fully-pressurised gas carrier

145

Figure 4.2

Piping arrangement on the tank dome adjacent to a deck tank on a fully-refrigerated LPG carrier

 

145

Figure 4.3

Cargo manifold reducers

147

Figure 4.4

Cargo manifold with reducer fitted

147

Figure 4.5

Orientation of presentation flange bolt holes

148

Figure 4.6

Pneumatic and manually operated valves on a fully-refrigerated LPG carrier

149

Figure 4.7

Piping system on a Type C cargo tank dome, including the valve arrangement. This particular drawing is typical for a semi-pressurised ship

 

150

Figure 4.8

Example placement of manifold strainer

152

Figure 4.9

Hydrates in a manifold strainer from a cargo of butane

153

Figure 4.10

Cargo manifold strainer on an LNG carrier

153

Figure 4.11

ESDs on semi-refrigerated LPG carriers

154

Figure 4.12

Initiation of ESD2

156

Figure 4.13

ESD2 closes ERS valves and uncouples MLAs

156

Figure 4.14

MLAs disconnect and retract with minimum spillage

156

Figure 4.15

ESD systems

157

Figure 4.16

Pilot operated relief valve, diaphragm type (interbarrier space)

158

Figure 4.17

Maximum allowable relief valve setting (MARVS) of 18 kg/cm2 on a Type C tank

159

Figure 4.18a

Pilot operated pressure relief valve (piston type)

160

 

 

Figure 4.18b

Pilot operated pressure relief valve (diaphragm type)

161

Figure 4.18c

Working principles of a pilot operated pressure relief valve (piston type)

161

Figure 4.19

Conventional spring loaded pressure relief valve

162

Figure 4.20

Characteristics of main types of pressure relief valves

163

Figure 4.21

Cargo pump dome on an LPG carrier

164

Figure 4.22

Pump performance curves – a deepwell pump

165

Figure 4.23

Centrifugal pumps in parallel – combined characteristics

166

Figure 4.24

Centrifugal pumps in series – combined characteristics

166

Figure 4.25

Typical deepwell pump

167

Figure 4.26

Deepwell pump assembly being removed during refit

167

Figure 4.27

Typical LNG submerged motor pump assembly

168

Figure 4.28

Submerged motor pump being removed during refit of an ammonia carrier

169

Figure 4.29

Horizontal booster pump

169

Figure 4.30

Horizontal booster pump

169

Figure 4.31

Fitting of an emergency cargo pump on an LNG carrier

171

Figure 4.32

Type C deck tank on a fully-refrigerated LPG carrier

172

Figure 4.33

Cargo heater on a fully-pressurised LPG carrier

173

Figure 4.34

Cargo heater on a fully-refrigerated LPG carrier

173

Figure 4.35

Direct cargo heater

175

Figure 4.36

An indirect cargo heater using an intermediate fluid

176

Figure 4.37

Steam heated cargo vaporiser

177

Figure 4.38

Typical LNG vaporiser

178

Figure 4.39

LNG regasification system – closed loop with steam heating

179

Figure 4.40

LNG regasification system – combined open/closed loop with seawater and steam heating

 

179

Figure 4.41

LNG regasification system – closed loop with steam heating and intermediate water/glycol loop

 

180

Figure 4.42

LNG regasification system – open loop with seawater heating and intermediate propane loop

 

180

Figure 4.43

LPG cargo compressor and motor arrangement

181

Figure 4.44

LPG cargo compressor

181

Figure 4.45

Burckhardt oil-free compressor

182

Figure 4.46

Typical rotor for an oil-free screw compressor

184

Figure 4.47

Typical purge gas condenser system

185

Figure 4.48

Gas heater (with steam as heating medium)

186

Figure 4.49

2-stage LD compressor: equipped with precoolers to achieve full pressure under conditions of warm BOG

 

186

Figure 4.50

4-stage LD compressor: typical DFDE propulsion plant

187

Figure 4.51

HD compressor

188

Figure 4.52

LD compressors

188

Figure 4.53

LNG gas combustion unit

188

Figure 4.54

Process flow diagram for the Hamworthy MK I reliquefaction system

190

Figure 4.55

Process flow diagram for the Cryostar EcoRel reliquefaction system

191

Figure 4.56

Inert gas generator

192

Figure 4.57

Flow diagram of an inert gas generator

194

 

 

Figure 4.58

Saturated water content of inert gas

195

Figure 4.59

Drying inert gas (adsorption drier)

195

Figure 4.60

The membrane system for producing nitrogen (N2)

196

Figure 4.61

Nitrogen system, filling air compressors and storage tank

196

Figure 4.62

The pressure swing adsorption process for producing nitrogen (N2)

197

Figure 4.63a

Float level gauge

200

Figure 4.63b

Float level gauge

201

Figure 4.64

Diagram of a float gauge installed in a tubular well

201

Figure 4.65

Float gauge on an LNG carrier with MK III containment system

201

Figure 4.66a

Radar tank level gauge

201

Figure 4.66b

Radar tank level gauge

202

Figure 4.67

Slip-tube

203

Figure 4.68

Direct insertion magnetic gauge

204

Figure 4.69

Externally mounted

204

Figure 4.70

High level alarms on a fully-pressurised LPG carrier

205

Figure 5.1

Cargo transfer piping arrangement from jetty to LNGC

215

Figure 5.2

Marine loading arms

217

Figure 5.3

LPG marine loading arm

218

Figure 5.4

LNG marine loading arms

218

Figure 5.5

Representative marine loading arm operating envelopes

219

Figure 5.6

Typical gas carrier marine loading arm

219

Figure 5.7

MLA presentation flange

220

Figure 5.8a

Quick connect/disconnect coupling (QC/DC) – Hydraulic

221

Figure 5.8b

QC/DC plan view diagram

221

Figure 5.9

Powered emergency release coupling (ERC)

222

Figure 5.10

Emergency release coupling (dry-break coupling)

222

Figure 5.11

BOG compressor station at an LNG loading terminal

223

Figure 5.12

A typical shore-based blower, used for removing LPG vapours from a ship's tanks and returning them to shore

 

224

Figure 5.13

LPG loading terminal arrangement. This is a typical arrangement, with vapour return capability using a shore based in-line blower

 

224

Figure 5.14

Insulation flange arrangement and components

225

Figure 5.15

LNG storage tanks

226

Figure 5.16

Fully-pressurised storage in a horizontal cylindrical tank above ground

228

Figure 5.17

Fully-pressurised storage in a mounded horizontal cylindrical tank

229

Figure 5.18

Mined rock cavern suitable for LPG storage

230

Figure 5.19

Salt cavern LPG storage

231

Figure 5.20

Semi-pressurised storage in spheres

232

Figure 5.21

Semi-pressurised storage tank

232

Figure 5.22

Typical single wall tank – LPG storage

234

Figure 5.23

Double wall LNG tank – concrete bund

235

Figure 5.24

LNG tank – double wall

236

Figure 5.25

Double wall tank for LNG

236

Figure 5.26

Double containment steel tank for LPG

237

Figure 5.27

LPG tank with earth berm

238

 

 

Figure 5.28

In-ground tank for LNG

238

Figure 5.29

In-ground tank for LNG

239

Figure 5.30

Pneumatically controlled valves in shore line

241

Figure 5.31

Shore pipeline to semi-pressurised sphere tanks

242

Figure 5.32

Aerial view showing expansion loops on the jetty

244

Figure 5.33

Bursting disk and surge drum arrangement for surge pressure relief

245

Figure 5.34

Simplified pipeline arrangement within an LPG terminal

248

Figure 5.35

Simplified arrangement of an LNG receiving terminal

250

Figure 5.36

A positive displacement meter

252

Figure 5.37

A turbine meter

253

Figure 5.38

A prover loop

254

Figure 5.39

Escravos LPG FSO with export LPG carrier Berge Spirit in tandem

256

Figure 5.40

Sanha LPG FPSO

256

Figure 5.41

LNG FPSO concept diagram

257

Figure 5.42

Large scale FLNG facility

258

Figure 5.43

The Shell Prelude FLNG facility

259

Figure 5.44

Typical system boundaries for FLNG

264

Figure 5.45

LNG carrier discharging to an RV

266

Figure 5.46

LNG regasification process for an open-loop/closed-loop solution with propane as the intermediary heat transfer medium

 

266

Figure 5.47

The internal turret mooring system

270

Figure 5.48

An external turret mooring system

271

Figure 5.49

Spread mooring systems

271

Figure 5.50

Tower mooring systems

271

Figure 5.51

Articulated tandem offloading

273

Figure 6.1

Cargo manifold on an LNG carrier

281

Figure 6.2

Telescopic shore gangway landed on an LNGC's deck

282

Figure 6.3

Ship/shore link (SSL) storage bins on jetty

(Left: fibre optic, middle: pneumatic and right: electric)

 

283

Figure 6.4

Ship/shore compatibility process should consider all items directly relevant to the gas carrier berthed alongside, such as whether the ship’s refrigeration plant seawater cooling outlet would be obstructed by the terminal fenders

 

 

285

Figure 6.5

Mooring tension monitoring display

287

Figure 6.6

When a ship is alongside, no cargo operations or inerting should commence until the ISGOTT (Reference 2.4) ship/shore safety checklist has been completed by the ship and the terminal and it has been confirmed that operations can be safely carried out. It is normal practice that this checklist is presented to

the ship by the terminal

 

 

 

 

291

Figure 6.7

OOW communicating with the deck watch

293

Figure 6.8

LNG carrier forward mooring area

294

Figure 6.9

Example connection and disconnection of cargo hoses and MLAs

295

Figure 6.10

Smaller gas carriers will often have to use their own gangway in port. It will usually be positioned as close to the accommodation as possible, with a strong safety net beneath, and be properly illuminated at night

 

 

297

Figure 6.11

Telescopic gangway on LNGC, viewed from the jetty

298

Figure 6.12

Dry powder monitors positioned and ready for immediate use

300

 

 

Figure 6.13

Deck water spray system on an LNG carrier

301

Figure 7.1

LNG sequence of operations

309

Figure 7.2

LPG sequence of operations

310

Figure 7.3

Air drying – operational cycle

312

Figure 7.4

Access to hold spaces on a fully-refrigerated LPG carrier

(Note: The hold spaces on LPG carriers fitted with independent Type A tanks must be inerted when carrying flammable cargoes, as is required by the IGC Code)

 

 

313

Figure 7.5

Inerting cargo tanks by the displacement method

314

Figure 7.6

Air/inert gas interface

315

Figure 7.7

All tanks being inerted in parallel

316

Figure 7.8

Displacement in series (‘cascading’), used in conjunction with cargo scavenging

316

Figure 7.9

Inerting by continuous dilution under vacuum

317

Figure 7.10

Forward vent mast on a fully-refrigerated LPG carrier

319

Figure 7.11

Gassing-up LPG cargo tanks using liquid from shore

322

Figure 7.12

Gassing-up LPG cargo tanks using vapour from shore

326

Figure 7.13

LPG cargo tank cool-down using liquid from shore: vapour returned to shore

328

Figure 7.14a

Spray piping connections on a Moss tank dome

330

Figure 7.14b

Spray piping in tower in a Moss tank dome

330

Figure 7.15

Spray rails on a membrane vessel

330

Figure 7.16

Gas carriers should calculate the trim and stability (SF, BM & GM) for each stage of the cargo operation

 

333

Figure 7.17

Sloshing action within a membrane tank

333

Figure 7.18

Loading with vapour return

336

Figure 7.19

Loading without vapour return

337

Figure 7.20

Type C tank that is operated between 0°C and 45°C

342

Figure 7.21

LNG carrier on loaded voyage

345

Figure 7.22

Cargo refrigeration at sea

347

Figure 7.23

BOG compressor

349

Figure 7.24

Precooler and cold box

349

Figure 7.25

BOG compressor

349

Figure 7.26

Cold box

350

Figure 7.27

Compander unit (with electric motor drives)

350

Figure 7.28

LNG cargo BOG vapour header

351

Figure 7.29

Forcing vaporiser

352

Figure 7.30

Centrifugal cargo pumps should always be started against a closed or partially open valve

 

353

Figure 7.31

Combined ship and shore cargo pumping characteristics – single pump

354

Figure 7.32

Illustrations of static head and friction head

355

Figure 7.33

Combined ship and shore cargo pumping characteristics – parallel pumps

355

Figure 7.34

Pipeline diagram of a cargo booster pump and heater

358

Figure 7.35

Discharge without vapour return (Vapour returned to the cargo tank during discharge from the cargo vaporiser)

 

359

Figure 7.36

Discharge with vapour return (Vapour returned to the cargo tank during discharge from the shore via the ship’s vapour return line)

 

360

Figure 7.37

Excess cargo vapour from a cargo tank, passing via the tank’s vapour line to the ship’s cargo compressor, while discharging cargo on a semi-refrigerated LPG carrier

 

361

 

 

Figure 7.38

Q-Flex LNG carrier fitted with LNG reliquefaction plant and GCU

365

Figure 7.39

Removal of cargo liquid residue by pressurisation in a Type C tank

367

Figure 7.40

Inerting of cargo tanks to remove cargo vapour

369

Figure 7.41

Aeration of cargo tanks

370

Figure 7.42

Removal of residual liquid in an LNG carrier’s tank prior to gas-freeing

374

Figure 7.43

Aerating of cargo tanks with dry air, venting inert gas

376

Figure 7.44

LNG ship to ship transfer

377

Figure 8.1

Weight in air conversion

382

Figure 8.2

Loading terminal general arrangement

387

Figure 8.3

Sampling presentation connection arrangement showing top/middle/bottom sampling connections (Note that the second valve is not shown)

 

390

Figure 8.4

Release of a small amount of cargo vapour while creating an ullage in a liquid sample container

 

390

Figure 8.5

Semi-refrigerated LPG carrier closed loop sampling connection

391

Figure 8.6

Fully-refrigerated LPG carrier closed loop sampling connection

391

Figure 8.7

Semi-refrigerated cargo system showing alternative sampling connections

392

Figure 8.8

Cargo sampling point

393

Figure 8.9

Cargo calculations – correction for trim

397

Figure 8.10

Effect of vessel trim on tank levels

397

Figure 8.11

Cargo calculations – correction for list

(As viewed from astern. Note the centreline bulkhead valve is closed)

 

398

Figure 8.12

Custody transfer measurement system (CTMS)

405

Figure 8.13

Flow diagram for calculating the energy of LNG transferred

409

Figure 8.14

Example of a certificate of discharge from custody transfer measurement system (CTMS)

412

Figure 8.15

Example of a certificate of analysis

413

Figure 8.16

Example of the energy calculation of LNG transferred at a discharge port on the basis of the certificate of discharge

 

414

Figure 9.1

On LNG ships, a water curtain is fitted to provide a warming flow of water down

the ship’s side adjacent to the cargo manifold. This is to limit the possibility of any brittle fracture in the event of any spillage of LNG

 

 

427

Figure 9.2

Pool fire configurations

428

Figure 9.3a

Open the airway with a head tilt-chin lift manoeuvre

436

Figure 9.3b

Look, listen and feel for signs of breathing. Where there are no signs of meaningful breathing – chest compressions will normally need to be started

 

436

Figure 9.4

Placing a casualty in the recovery position

437

Figure 9.5

High sitting up position for a casualty

438

Figure 9.6

Emergency decontamination shower

442

Figure 9.7

LNG STS

447

Figure 9.8

Deck spray line

452

Figure 9.9

Deck and accommodation deluge systems

452

Figure 9.10

Dry powder hose and gun

454

Figure 9.11

The Swiss Cheese Model, including progression of a process safety incident

458

Figure 9.12

The ALARP triangle

461

Figure 9.13

A toolbox talk briefs everyone on the work before the work is commenced

471

Figure 9.14

Example of an Enclosed Space Entry Permit (IMO)

475

 

 

Figure 9.15

The effectiveness of any isolation will usually need be confirmed prior to issuing the permit

 

476

Figure 9.16

A safety induction, including details of muster stations and roles in the event

 

 

of an emergency, will be conducted as soon as possible after joining

482

Figure 9.17

Representative air flow over an accommodation block

489

Figure 9.18

EEBD set that will provide an air supply for 15 minutes

490

Figure 9.19

Self-contained breathing apparatus (SCBA)

490

Figure 9.20

Crew member wearing a splash suit and SCBA

491

Figure 9.21

Respirator mask (gas mask) fitted with an NH3 cartridge. These cartridges are colour coded to help you select the right one. Green is the cartridge colour

 

 

code for ammonia/NH3

492

Figure 9.22

General environmental challenges for ships

495

 

Table No.

 

Title

 

Table 1.1

Atmospheric boiling point of certain liquefied gases

3

Table 2.1

Common elements

20

Table 2.2

IUPAC names and synonyms

27

Table 2.3

Reactive properties of liquefied gas cargoes with construction materials

31

Table 2.4

Chemical incompatibilities of liquefied gases

32

Table 2.5

Reactive properties of liquefied gas cargoes

33

Table 2.6

Ignition properties for liquefied gases

41

Table 2.7

Flammability range in air and oxygen for some liquefied gases

44

Table 2.8

Typical compositions of inert gas produced on board gas carriers

45

Table 2.9

Conversion factors for units of pressure

54

Table 2.10

Physical properties of gases

56

Table 2.11

Viscosity comparison of liquid cargoes

57

Table 2.12

Raoult’s Law

63

Table 2.13

Calculation for molecular mass of a natural gas mixture

64

Table 3.1

Typical insulation material conductivities at 20°C

114

Table 3.2

Main cargo containment systems comparison

117

Table 3.3

IGC Code requirements for secondary barriers in relation to cargo

 

 

containment tank types

117

Table 3.4

General propulsion plant thermal efficiencies

136

Table 4.1

Classification of explosion proof equipment

199

Table 6.1

Emergencies that may initiate the ESD

303

Table 6.2

Actions that are usually initiated by the ESD

303

Table 8.1

Extract based on ASTM D1250-08 Density/ Weight/ Volume Intraconversion Part 3

 

 

‘Conversions for Absolute Density at 15 degrees C’

 

 

(This is similar to the old ASTM Table 56 1980)

385

Table 9.1

Toxicity classifications

431

Table 9.2

Main liquefied gases, including their flammable and toxic hazards

433

Table 9.3

Health data – cargo inhibitors

434

Table 9.4

Health data – liquids

440

Table 9.5

Enclosed spaces on gas carriers

484

Title: Liquefied Gas Handling Principles on Ships and in Terminals, (LGHP4) 4th Edition
Edition: Fourth
Number of Pages: 568
Product Code: WS1454K
ISBN: ISBN 13: 978-1-85609-714-7 (9781856097147), ISBN 10: 1-85609-714-5 (1856097145)
Published Date: July 2016
Binding Format: Hardback
Weight: 2.50 kg
Author: SIGTTO

Customer Reviews

Everything you need to know about handling liquefied gas cargoes on board ship and at the terminal ship-shore interface Review by LNG World Shipping 1st September 2016
SIGTTO Updates LNG/LPG guide
Everything you need to know about handling liquefied gas cargoes on board ship and at the terminal ship-shore interface can be found between the covers of the updated fourth edition of Liquefied Gas Handling Principles, flagship publication of the Society of International Gas Tanker and Terminal Operators (SIGTTO).

The guide has come a long way since its 160-page first edition launched in 1986 and the previous, 275-page third edition, published in 2000. The latest edition of the book, nicknamed LGHP4 by the SIGTTO community, has been revised to accommodate the many advances taking place in gas shipping and terminal technology and now weighs in at 530 pages and 2.5kg.

Liquefied Gas Handling Principles deals with handling liquefied gases carried in bulk, including LNG, LPG and chemical gases, and is a valuable reference work for everyone involved in design, construction and operation of gas carriers and terminals.

Like previous publications in the series, however, the new edition has been written primarily for serving ships’ officers and terminal staff responsible for cargo-handling operations, and for those who oversee these operations.

SIGTTO now has 139 full members, 48 associates and 27 non-contributory members. It drew on this broad resource base to compile LGHP4. The job of editing and structuring that input into the latest revisions fell to SIGTTO technical adviser Rick Boudiette, who submitted the final draft for peer review and endorsement by members of SIGTTO’s General Purposes Committee and several subject-matter experts.

The guide stresses the importance of understanding the physical properties of liquefied gas cargoes in relation to the operation of gas-handling equipment and systems on the ship and at loading and discharge jetties. Operators need to know how and why each gas behaves the way it does, and the associated hazards, across a range of operating scenarios, to appreciate the role of the shipboard and terminal equipment they are controlling.

LGHP4 features a revised and extended section on liquefied gas properties. Chapter two has been divided into three major subsections; the chemistry of liquefied gases, the physics of liquefied gases and gas laws, thermodynamic principles and reliquefaction.

For a newcomer there is much vital information to assimilate. A modern multigas carrier is constructed to carry upwards of 15 different cargoes, each with its own flash point, flammability range, auto-ignition temperature, boiling point, critical pressure, reactivity characteristics, density, viscosity and chemical compatibility with inert gas.

Once these properties are assimilated, it is necessary to understand the concepts of specific heat, enthalpy, entropy, phase change and saturated vapour pressure, and the basic laws of thermodynamics.

Safe and efficient handling of cargoes – and adhering to procedures that mitigate against the risks posed by their carriage in bulk – requires a basic appreciation of these liquefied gas properties and principles of gas behaviour.



Reader-friendly

LGHP4 may weigh heavily on the scales, but it brings a light touch to the complexities of handling liquefied gases and is above all a reader-friendly publication. The running commentary, with its straightforward explanations and numerous section breaks, incorporates colour-coded blocks of text.

Blue-shaded boxes contain information of an operational nature that offers useful hints for planning purposes. Yellow-shaded boxes contain cautionary information regarding operations. Grey-shaded boxes with a red border denote information considered to be of particular importance. These cautions are relatively rare and merit special attention.

One blue-tinted box contains LGHP4’s statement that certain chemical gases such as diethyl ether, propylene oxide and isoprene, which are not strictly liquefied gases, are carried under high vapour pressures. This fact, coupled with the health and flammability hazards, has led to these and similar compounds being listed in both the International Gas Carrier (IGC) and International Bulk Chemical (IBC) Codes.

These cargoes are most often shipped in gas carriers but when carried on chemical tankers, such cargoes will often be required to be stowed in independent tanks. They are also subject to many of the handling principles covered in LGHP4.

Readers will find the visual material in LGHP4 invaluable. Most of the book’s 325-plus figures are new or are updated versions of earlier visuals. Rick Boudiette and staff at Witherby developed the figures that required amendment or configuration from scratch.

The figures range from flow, equilibrium, schematic and process diagrams and depictions of refrigeration and reliquefaction cycles to photos of gas ship types, cutaways of containment systems and key cargo-handling equipment, propulsion system overviews and pictures of ship and terminal safety systems and damage that can be caused by unwanted reactions such as polymerisation and hydrate formation.

The figures are augmented by detailed tables, including those that encapsulate the key physical and chemical property data of the many gas carrier cargoes.



Technical advances

Notwithstanding the expanded coverage of liquefied gas physical and chemical properties, the increased LGHP4 page count reflects technological advances during the 16 years since the third edition appeared. And so offshore operations, a range of new propulsion systems and environmental stewardship get the LGHP treatment for the first time.

Ship-to-ship (STS) cargo transfers have become a routine commercial operation over the past decade, thanks to the rising popularity of floating storage and regasification units
(FSRUs) as LNG-receiving terminals. And as the first floating LNG production (FLNG) vessels come into service, similar transfers will become part of the operating scenario at offshore loading facilities, prompting LGHP to review the various STS systems available.

Considerations of propulsion systems and environmental stewardship cross over, as the need to meet new, mandated standards of higher energy efficiency benefits from the introduction of dual-fuel, gas-burning engines. Two-stroke engines offer the highest propulsive efficiencies of marine power plants and manufacturers have succeeded in developing dual-fuel versions of these units and, over the past 18 months, in winning the majority of LNG carrier newbuilding propulsion system orders.

Technical innovation has also manifested itself in other, more subtle ways across the gas cargo-handling spectrum. New two and four-stroke dual-fuel engines have required new types of equipment to be fitted on board LNG carriers, including gas combustion units (GCUs), reliquefaction plants and other systems for controlling boil-off gas (BOG).

LGHP4 also considers the differences between warm and cold ballast voyages, highlighting the key role of GCUs for the former and reliquefaction plants for the latter.

In the cargo containment-system section the new edition reviews the refinements that Gaztransport & Technigaz (GTT) has introduced in recent years with its No 96 and Mark III membranes, spurred by the drive to reduce cargo BOG rates and to enhance membranes’ ability to withstand sloshing loads.

For the Mark III membrane these goals have been achieved through the development of Mark III Flex. In the case of the No 96 design, using different insulating materials provides lower BOG rates and strengthened insulation boxes increase the ability to sustain higher sloshing loads without system damage.


The fourth edition of Liquefied Gas Handling Principles is available from Witherby Publishing; www.witherbys.com, priced £275
(Posted on 09/09/2016)

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