1.1    This Standard supersedes IGE/SR/22 2nd Impression (1999), Communication 1625, which is obsolete. 

1.2    This Standard has been drafted by an Institution of Gas Engineers and Managers (IGEM) Panel, appointed by IGEM’s Gas Transmission and Distribution Committee and has been approved by IGEM’s Technical Coordinating Committee on behalf of the Council of IGEM. 

1.3    This Standard provides requirements for gas transporters (GTs), gas conveyors, shippers, suppliers and information for the likes of local authorities, plant operators, utilities and emergency services on the responsibility, methods and personnel involved in dealing with a gas escape. 

1.4    The requirements detailed in this Standard are based on current practices within Great Britain (GB). 

1.5    The relevant parts of this Standard may be cited in a GT’s/gas conveyors Safety Case, but the Health and Safety Executive (HSE) will need to be satisfied that they are appropriate and have been properly applied in each case.

1.6    This Standard makes use of the terms “must”, “shall” and “should” notwithstanding Sub-Section 1.8,
•    the term “must” identifies a requirement by law in GB at the time of publication
•    the term “shall” prescribes a requirement which, it is intended, will be complied with in full and without deviation
•    the term “should” prescribes a requirement which, it is intended, will be complied with unless, after prior consideration, deviation is considered to be acceptable.

Such terms may have different meanings when used in legislation, or HSE Approved Code of Practice (ACoPs) or guidance, and reference needs to be made to such statutory legislation or official guidance for information on legal obligations.

1.7    The primary responsibility for compliance with legal duties relating to health and safety at work rests with the employer. The fact that certain employees, for example "responsible engineers", are allowed to exercise their professional judgement does not allow employers to abrogate their primary responsibilities. 
Employers are required to: 
•    have done everything to ensure, so far as is reasonably practicable, that there are no better protective measures that can be taken other than relying on the exercise of professional judgement by "responsible engineers" 
•    have done everything to ensure, so far as is reasonably practicable, that "responsible engineers" have the skills, training, experience and personal qualities necessary for the proper exercise of professional judgement 
•    have systems and procedures in place to ensure that the exercise of professional judgement by "responsible engineers" is subject to appropriate monitoring and review 

Note: The responsible engineer is a suitably qualified, competent and experienced engineer appointed to be responsible for the execution and for approval of activities designated by their employer. 

•    not require "responsible engineers" to undertake tasks which would necessitate the exercise of professional judgement that is not within their competence. There should be written procedures defining the extent to which "responsible engineers" can exercise their professional judgement. When "responsible engineers" are asked to undertake tasks which deviate from this they are to refer the matter for higher review.

1.8    Notwithstanding Sub-Section 1.6, this Standard does not attempt to make the use of any method or specification obligatory against the judgement of the responsible engineer. Where new and better techniques are developed and proved, they are to be adopted without waiting for the modification of this Standard. Amendments to this Standard will be issued when necessary and their publication will be announced in the Journal of IGEM and other publications as appropriate.

1.9    It is now widely accepted that the majority of accidents in industry generally are in some measure attributable to human as well as technical factors. People who initiated actions that caused or contributed to accidents might have acted in a more appropriate manner to prevent them.

To assist in the control of risk and proper management of these human factors, due regard is to be taken of HSG48 and HSG65.

1.10    Requests for interpretation of this Standard in relation to matters within their scope, but not precisely covered by the current text, are to be either: 

• addressed to Technical Services, IGEM, IGEM House, 26 & 28 High Street, Kegworth, Derbyshire, DE74 2DA; or 
• emailed to [email protected]. 

These will be submitted to the relevant Committee for consideration and advice, but in the context that the final responsibility is that of the engineer concerned. If any advice is given by or on behalf of IGEM, this does not imply acceptance of liability for the consequences and does not relieve the responsible engineer of any of their obligations.

1.11    This Standard was published in January 2025.
 

2.1  This Standard covers onshore purging operations for fuel gases from gas to air and from air to gas, with or without the use of inert gas. It does not cover Hydrogen.

2.2  This Standard gives guidance on purging for the commissioning or decommissioning of pipelines, mains, services, gasholders and vessels.

2.3  The purging of underground cavities and Liquefied Natural Gas (LNG) tanks are considered to be specialised operations outside the scope of these requirements.

2.4  This Standard gives detailed advice on the direct purging of Natural Gas (NG) pipelines, mains and services. They also cover the indirect purging of all plant operating with natural gas and other fuel gases in the gaseous phase.

2.5 The purging of pipelines and vessels containing Liquid Petroleum Gas (LPG) in the liquid phase is outside of the scope of this document.

2.6  Reference should be made to the Utilisation Procedures IGE/UP/1 for the purging of installation pipes in industrial and commercial premises.

2.7 Pressures quoted are gauge pressures unless otherwise stated.

2.8  Italicised text is informative and does not represent formal requirements.

2.9  Appendices are informative and do not represent formal requirements unless specifically referenced in the main sections via the prescriptive terms “must”, “shall” or “should”.