scope:

This Standard contains guidance on carrying out onshore purging operations (replacement of a gas in a pipeline, vessel or gasholder), designed to prevent the formation of flammable gas mixtures.

These recommendations are intended to provide guidance to those involved in purging operations in the gas industry. They cover onshore purging operations for fuel gases from gas to air and from air to gas, with or without the use of inert gas, designed to prevent flammable gas mixtures being produced. Specifically, this document contains guidance on purging for the commissioning or decommissioning of pipelines, mains, services, gasholders and vessels, along with the indirect purging of all plants operating with natural gas and other fuel gases. It does not cover the purging of underground cavities and LNG tanks. It contains details of:

• the general principles and methods of purging,

• planning of purging operations,

• isolation methods,

• purging of distribution mains and services,

• purging of transmission pipelines,

• purging of low pressure gasholders,

• purging of vessels (including high pressure gas storage)