Liquefied Petroleum Gas Sampling Procedures

This publication is a comprehensive guide to liquefied petroleum gas sampling. It covers the entirety of the process from beginning to end and looks at:

• The basic reasons for taking cargo samples
• Sampling connections, eg open and closed loop systems
• Types of sample containers
• Recommended standard sample connections
• Safe procedures for taking samples.

It has been fully updated by a working group made up of several industry experts and coordinated by SIGTTO.

In the liquefied gas shipping industry, cargo sampling is a common requirement as part of routine quality control and custody transfer procedures.

Provided that proper procedures established on both ship and shore are carried out by trained personnel familiar with the operation, and that they use fully compatible equipment that is suitable for the task, the risks associated with taking liquefied gas samples should be minimal. However, should these requirements not be met experience has shown that the possibility of an incident will increase significantly. The most typical example of this situation is a requirement for shore representatives to draw samples from ship tanks

In November 1988, SIGTTO published ‘Report of a Working Group on Liquefied Gas Sampling Procedures’, and subsequently, the recommendations of this report were widely adopted by the industry. However, following two separate incidents onboard gas carriers within UK ports, where in the first case there was a release of VCM from the ship’s vent mast due to inadvertent cargo transfer during sampling and, in the second, an unapproved sample valve unscrewed when attempting to connect a sample container, resulting in a release of propane, the UK Marine Accident Investigation Branch (MAIB) issued Recommendation No. 2007/149. One of the recommendations of this MAIB document urged SIGTTO to "review and revise guidance provided to the industry on sampling arrangements", which resulted in the publication of this guidance document.

This document discusses and advises on the following aspects of sampling:

• Basic reasons why cargo samples are taken
• sampling systems- ‘Open’ and ‘Closed’ loop systems
• types of sample containers
• recommended standard sampling connections
• safe procedures for taking samples.

Taking Samples of Liquefied Gas Cargoes

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Summary

1. The Basic Reasons why Cargo Samples are Taken

2. Sampling Systems – ‘Open Loop’ or ‘Closed Loop’ Systems

3. The Standard Type of Containers Used to Obtain and Transport Systems

4. Standard for Sampling Connection Fittings

5. The Procedures Involved in Taking Samples

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Bibliography

SIGTTO

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. Learn more: https://www.sigtto.org/about-us/