Ship/Shore Interface for LPG/Chemical Gas Carriers and Terminals

Number of Pages:
Book Height:
297 mm
Book Width:
210 mm
1 kg
Published Date:
July 2018
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This publication identifies potential hazards at the LPG/chemical gas ship/shore interface. Referencing industry regulations and guidance, it suggests best working practices for the terminal and the ship to minimise the risk of incident and to help raise overall safety awareness.

This publication describes risk assessment and hazard identification techniques that can be applied by LPG/chemical gas shipping staff and terminal operators. It identifies the principal risks at the ship/shore interface, including vessel arrival and departure, loading and discharge operations, gas detection and exposure to hazardous products. Diagrams support the text and effectively illustrate how to mitigate ‘top event’ hazards to cargo containment.

Since the beginning of LPG shipping in the mid 1930s, through to the present day, the industry has built up an impressive safety record.

This safety record is due to reasons that include, but are not limited to:

  • A strong, overarching safety philosophy
  • robust design of equipment and systems
  • good operational and maintenance procedures
  • operations in excess of the minimum requirements
  • high standards of training coupled with competency verification
  • the fact that the IGC Code was developed based on actual experience of the early days of liquefied gas transportation at sea
  • an ability to share lessons learnt and to develop best practices as an industry through the industry body, SIGTTO.

LPG carriers range from small pressurised ships of 500–12,000 m3 capacity, used for the shipment of propane, butane and chemical gases at ambient temperature, to the fully refrigerated and semi-refrigerated LPG carriers of very large gas carriers (VLGCs) of 70,000–95,000 m3 capacity, which are used for the transport of LPGs and ethane.

Between these distinct types is a third ship type, the semi-refrigerated LPG carrier. Semi-refrigerated LPG carriers are very flexible ships able to carry many cargoes in a fully refrigerated condition at near atmospheric pressure, or at temperatures corresponding to carriage pressures of 4–9 bar.

Because of the simplicity of the design and the range of worldwide trading opportunities, more fully pressurised LPG carriers have been built than any other type of LPG carrier. The fully pressurised fleet is engaged in the distribution of liquefied gases to virtually every country with a coastline. Fully pressurised ships are among the smallest of the LPG carriers and tend to serve regional trades.

There is a considerable variation in the design, construction and operation of LPG carriers in general, due to the differences in the cargoes carried and the number of cargo containment systems utilised.

In comparison to most other ship types, LPG carriers have a better safety record. However, casualty statistics involving LPG carriers demonstrate that risk is potentially greater when the ship is in port than when at sea. For this reason, it is appropriate that the attention of this publication will, in large part, concentrate on the port facilities and the activities of ship and shore personnel involved in cargo operations.

The ship/shore interface is the area where the activities of personnel on the ship and shore overlap. It is prudent to be aware that actions on one side of the interface will affect the other party.

Liquefied gas cargo handling procedures can be complex and the cargo itself is potentially hazardous. For these reasons, personnel operating LPG carriers and terminals require a thorough understanding of ship and shore equipment and cargo properties. It is essential for them to have good operating procedures available to avoid incidents and for emergency plans to be in place in case an incident does occur.

Raising safety awareness in the LPG/chemical gas shipping and terminal industries should help to reduce the occurrence of LPG ship/shore interface related incidents in the future.

1. Hazards and Risk Management

1.1 Introduction

1.2 The ‘Bowtie Method’ of Risk Assessment and Management

1.3 Hazards, Threats and Barriers Identified

2. Operational Readiness

2.1 The Terminal

2.2 The Ship

3. Pre-Arrival

4. Arrival Alongside Prior to Cargo Operations Commencing

4.1 Pre-Cargo Operations Meeting

4.2 Safe Access

4.3 Emergency Procedures

4.4 Mooring

4.5 Simultaneous Operations (‘SimOps’)

5. Cargo Operations (General)

5.1 Cargo Emergency Shutdown (ESD) System and Ship/Shore Link (SSL)

5.2 Communications

5.3 Manifolds and Transfer Systems

5.4 Awareness of Surge Pressures

5.5 Gas Detection On Board an LPG Carrier

5.6 Gas Detection at the Terminal

5.7 Cargo Sampling

5.8 Cargo Monitoring Instruments – Checks Prior to and During Cargo Transfers

5.9 Warm Cargoes

5.10 Reliquefaction and Tank Pressure Management

5.11 Hydrates

5.12 Incondensibles

5.13 Cargo Equipment Temperature, Flow and Pressure Limitations

5.14 Manifold Connection

5.15 Insulating against Static Electricity

5.16 Vapour Return

6. Cargo Loading

6.1 Gassing-Up

6.2 Cooldown

6.3 Preliminary Procedures before Loading

6.4 Management of Tank Pressure During Loading

6.5 Commencement of Loading

6.6 The use of Automatic Shutdown during Topping Off

6.7 Operation of the Reliquefaction Plant during Bulk Loading of LPG

6.8 Cargo Tank Loading Limits

6.9 Odorisation of LPG

6.10 Inhibition

7. Cargo Discharge

7.1 Discharge Temperature and Pressure

7.2 Blending at the Terminal

8. LPG Carrier Departure

8.1 Manifold Draining, Purging and Disconnection Procedure

8.2 Disconnection

8.3 Preparation Prior to Unmooring

9. Release of Vapour

10. Cold Spill

11. Asphyxiation and Toxicity

Annexes and Back Up Data

Annex A – Competencies & Training

Annex B – Properties of Chemical and Liquefied Petroleum Gases

Annex C – LPG/Chemical Ship Types

Annex D – Bowtie Diagrams


The Society of International Gas Tanker and Terminal Operators (SIGTTO) is an international body established for the exchange of technical information and experience, between members of the industry, to enhance the safety and operational reliability of gas tankers and terminals.

Number of Pages:
Binding Format:
Book Height:
297 mm
Book Width:
210 mm
1 kg


Published Date:
July 2018