LNG Operational Practice, 3rd Edition 2026

The book covers the operations undertaken throughout a typical trading cycle for an LNG carrier, including post-dry dock operations; drying of cargo tanks; inerting of cargo tanks; gassing-up; initial cooldown; cargo loading; departure from the load port and the laden voyage; cargo discharge; ramp-down and post-discharge operations; the ballast voyage; ship-to-ship transfer; and preparations for dry dock, including warming-up, inerting and aeration of cargo tanks. Expanded guidance on post-discharge operations and planning considerations for future voyages is also included.

Operational 3D models have been revised and annotated, with colour-coded arrows showing the direction of flow to provide greater clarity of the processes involved, particularly during drying, inerting and gassing-up.

Introduction

This third edition discusses emerging technologies, refinements in onboard practices and up-to-date operational experience, helping to evolve this title into a must-have for ships’ officers working on board LNGCs, or for officers looking to transition onto LNGCs.

Emil Karlovic
Master,
MOL LNG Transport (Europe)

Contents Listing

Acknowledgements

Section 1: General Information

1 Physical Properties, Composition and Characteristics of LNG

1.1 Overview

1.2 Flammability of LNG

1.3 Saturated Vapour Pressure (SVP)

1.4 Vapour Density

1.5 Safety Precautions in LNG Handling

2 Normal Trading Cycle of an LNGC

3 Cargo Containment Systems

3.1 Overview

3.2 Moss Rosenberg (Moss)

3.3 Mark III (GTT

3.4 NO96 (GTT)

4 Cargo Handling Equipment

4.1 Cargo Pump

4.2 Spray/Stripping Pump

4.3 High Duty Compressor

4.4 Low Duty Compressor

4.5 Gas Heater

4.6 Vaporiser

4.7 Reliquefaction Plant

4.8 Gas Combustion Unit (GCU)

5 Auxiliary Equipment

5.1 The Cargo Valves Remote Control System

5.2 Ship/Shore Link and ESD System

5.3 N2 Generator

5.4 IG Plant

5.5 Custody Transfer and Measurement System (CTMS)

5.6 Cargo Tank Gauging System

5.7 Gas Detection Equipment

5.8 Cofferdam Heating System

5.9 Vacuum Pumps

5.10 Tank Overflow Protection

Section 2: Post Dry-dock Operations

6 Operations Related to Auxiliary Systems

6.1 Moss Type LNG Carriers

6.2 Membrane Type LNG Carriers (Mark III and NO96)

7 Cargo Tank Operations

7.1 Drying of Cargo Tanks

7.2 Inerting of Cargo Tanks

7.3 Gassing-up the Cargo Tanks

7.4 Initial Cooldown of Cargo Tanks

Section 3: In-service Operations

8 Loading Operations

8.1 Overview

8.2 Preparation for Loading

8.3 Pre-loading Operations

8.4 Cooldown for Loading

8.5 Ramp-up to Bulk Rate

8.6 Bulk Rate Loading

8.7 Ramp-down

8.8 Post-loading Operations

8.9 Departure from Load Port

9 Laden Voyage

9.1 Overview

9.2 Laden Voyage of LNG Carriers with Gas Burning Propulsion System

9.3 Laden Voyage of LNG Carriers with Reliquefication Plant

9.4 Further Considerations on Laden Voyage

10 Discharge Operations

10.1 Overview

10.2 Preparation for Discharge

10.3 Pre-discharge Operations

10.4 Ramp-up to Bulk Rate

10.5 Operational Description – Bulk Rate Discharge

10.6 Ramp-down

10.7 Post-discharge Operations

10.8 Departure from Discharge Port

10.9 Further Considerations During Discharge

11 Ballast Voyage

11.1 Overview

11.2 Heel Management

11.3 Further Considerations on Ballast Voyage

12 Ship to Ship Transfer Operations

12.1 Pre-arrival Stage

12.2 Approach and Mooring Stage

12.3 Cargo Transfer Stage

12.4 Post-transfer Procedure

Section 4: Pre Dry-dock Preparations

13 Cargo Tank Operations

13.1 Warming up Cargo Tanks

13.2 Inerting of Cargo Tanks

13.3 Aeration of Cargo Tanks

Glossary

About the Author

Witherbys titles are developed using scripts developed by technical experts that are peer reviewed within work groups. Typically, they seek to improve understanding of the regulations, recommendations and guidelines issued by Industry.

Witherbys staff have significant expertise in the fields of navigation and hazardous cargoes as well as in the presentation of complex subjects in a graphic and easy to understand manner.