LNG Shipping Knowledge, 3rd Edition

This publication details the underpinning knowledge required for ship’s officers serving on LNG carriers, as set out in SIGTTO’s ‘LNG Shipping Competency Standards’.

Published July 2020

ISBN 9781856099035


Now in its 3rd edition (2020), this publication has been updated to reflect the substantial technical and operational advances on LNG carriers that have occurred since it was first prepared across 2006- 2008.


To put this level of advance in context, in 2006, the world fleet of LNG carriers was over 200 ships. At the beginning of 2020 there were 540 LNG carriers in service, with over 130 LNG carriers on order. In 2019 alone, LNG carriers carried out 5,701 trade voyages.


At almost 500 pages, this publication details all areas of LNG carriage and care by sea



1 LNG Fundamental Knowledge and Understanding
1.1 Physics and Chemistry
1.2 Principles of Design
1.3 Regulations and Guidance
1.4 Principles of Tank Atmospheres
1.5 Properties of Materials
1.6 Hazards of LNG and Relevant Gases
1.7 Environmental Impact
1.8 Risk Assessment
1.9 Individual Responsibilities
1.10 Contingency Plans
1.11 Record Keeping
1.12 Planning

2 LNG Equipment
2.1 Cargo System – Tank Construction
2.2 Air and Inert Gas Driers
2.3 Inert Gas Generator
2.4 Nitrogen Systems
2.5 LNG Vaporiser
2.6 High Duty Compressor(s)
2.7 Low Duty Compressor(s)
2.8 Gas Heaters
2.9 Forcing Vaporiser
2.10 Cargo Pumps
2.11 Spray Pumps
2.12 Cargo Tank Protection Devices
2.13 Cargo Line Protection Devices
2.14 Cargo Space Protection Devices
2.15 Cargo Liquid and Vapour Valves
2.16 Cargo Tank Protection System
2.17 Reliquefaction Plant (if fitted)
2.18 Gas Combustion Unit (Oxidiser)
2.19 Regasification Plant
2.20 Cargo Related Spaces

3 LNG Support Systems
3.1 Nitrogen Pressurisation and Purge
3.2 Cofferdam Heating System
3.3 Fixed Gas Detection
3.4 Portable Gas Detection Equipment
3.5 Emergency Shutdown System (ESDS)
3.6 Emergency Mooring Release
3.7 Water Curtain
3.8 Drenching System
3.9 Fixed Dry Powder Installations
3.10 Level Gauging Systems
3.11 Custody Transfer Measurement System (CTMS)
3.12 Certified Safe Electrical Equipment
3.13 High Voltage Systems
3.14 IAS System
3.15 Turbo Alternator Control Systems
3.16 Propulsion Types
3.16.1 Current situation
3.16.2 Steam turbines
3.16.3 Slow-speed diesel (SSD)
3.16.4 Dual-fuel diesel electric/tri-fuel diesel electric (DFDE/TFDE)
3.16.5 M-type electronically controlled gas injection (ME-GI)
3.16.6 Gas and diesel low-pressure two-stroke engine (X-DF)
3.16.7 Ultra steam turbine (UST)
3.16.8 Gas turbines
3.16.9 Steam turbine and gas engine (STaGE)
3.16.10 COGES
3.16.11 Further considerations for LNGC propulsion systems
3.17 Gas Combustion Systems

4 LNG Standard Operations
4.1 Cargo Tank Cleaning
4.2 Hold Space and Cargo Tank Drying
4.2.1 Drying hold spaces on Moss type LNG carriers
4.2.2 Drying insulation spaces on membrane type LNG carriers (Mark III and NO96)
4.2.3 Drying the insulation spaces of NO96 cargo containment system
4.2.4 Drying of cargo tanks
4.3 Nitrogen Purging of Containment System
4.3.1 Drying and inerting of tank insulation and annular space (Moss spherical type)
4.3.2 Nitrogen purging the interbarrier and insulation spaces (membrane type – GTT Mark III only)
4.3.3 Nitrogen purging the interbarrier and insulation spaces (membrane type – NO96)
4.3.4 Other considerations when purging the interbarrier and insulation spaces for membrane type LNG carriers
4.4 Inerting of Cargo System
4.5 Ship and Shore Preparation and Manifold Connection
4.6 Gassing Up (Purging) of Cargo System
4.7 Cooldown of Cargo System
4.8 Loading
4.9 Loaded and Ballast Passage
4.10 Discharging
4.11 Warm-Up
4.12 Gas Freeing
4.13 Aeration
4.14 Ship to Ship (STS) Preparation and Manifold Connection
4.15 Ship to Ship Transfer of Cargo

5 LNG Non-Standard and Emergency Operations
5.1 Types of Non-Standard and Emergency Operations
5.2 Multiple Cargo Pump Failure in One Tank
5.3 Gas Freeing a Single Tank
5.4 Part Load and Discharge
5.5 Non-Availability of Key Equipment
5.6 Loss of Gas Handling Capability
5.7 Prolonged Loss of Power to Cargo and Ancillary Systems
5.8 Loss of Primary Containment
5.9 Ballast Tank Leakage into Containment Space
5.10 Nitrogen Supply Failure
5.11 Jettison of Cargo
5.12 Overfilling of a Cargo Tank
5.13 Loss of Cargo Pipeline Containment
5.14 Failure of Integrated Automation System
5.15 Uncontrolled Release of Cargo

6 LNG Commercial Considerations
6.1 Terms and Conditions in Use 446
6.1.1 Have an awareness of the following terms and their relevance
6.1.2 Have an awareness of the principles of LNG measurement
6.1.3 Have an awareness of the basic types of time charters
6.1.4 Have an awareness of basic LNG time charter performance clauses
6.1.5 Have an awareness of the economic Implications of boil-off/heel management
6.1.6 Have an awareness of the relevant industry international organisations and bodies
6.2 Vetting and Inspection Processes
6.3 Ship/Shore Compatibility Assessment

Annex – I Reference Documents
Annex – II Definitions 469

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