1.1 This Guidance provides advice for Large Gas users of the actions they should take during a natural gas supply emergency. It provides an insight into the potential reasons for the cessation of gas supplies to Large Gas users, in particular industrial gas users and the actions necessary to be taken in an emergency, how to plan for such an event, and how the impacts can be minimised. 
 
1.2     A natural gas "supply emergency" is defined by Regulation 2(1) of the Gas Safety (Management) Regulations 1996 (GS(M)R) as “an emergency endangering persons and arising from a loss of pressure in the network or any part thereof”. A supply emergency therefore describes a state where a dangerous situation exists. 
 
A natural gas supply emergency is any situation which has resulted in, or could result in, a loss of pressure to consumers. 
 
A Network Gas Supply Emergency (NGSE) occurs where there is an imbalance of supply and demand for gas in National Grid’s National Transmission System (NTS) (the Primary System). This can be caused by insufficient gas being available to meet demand, or, by equipment damage or failure on the NTS. 
 
A Local Gas Supply Emergency (LGSE) occurs where there is an imbalance of supply and demand for gas on a GDN’s network (the Secondary System). This is typically caused by damage or failure to part of the GDN’s network. 
 
1.3 If a natural gas supply emergency occurs or is likely to occur then the local gas distribution network operator has a duty under their GS(M)R Safety Case to manage the network to ensure the risks from the dangerous situation are minimised.  
 
1.4 The gas distribution network operators have Gas Supply Emergency Procedures in place that describe the arrangements and processes to prevent a dangerous occurrence, these include instructions for Large Gas users to stop using gas immediately to safeguard the network and to limit disruption to smaller consumers, for whom turning off the gas supply would be potentially dangerous. 
 
1.5 IGEM/GL/9 aims to give simple advice to large natural gas consumers on how they should plan and take action safely to ensure their gas supplies are shut down safely and quickly, when directed to do so.  
 
The IGEM/GL/9 document has been prepared in conjunction with the Health and Safety Executive, the gas network operators and industry experts including large gas consumers, and in conjunction with the Department for Business, Energy and Industrial Strategy (BEIS), Office of Gas and Electricity Markets (Ofgem), the Energy Emergency Executive Committee (E3C) and the Network Emergency Coordinator (NEC). 
 
1.6  Minimising the impacts of potential natural gas supply emergencies requires the co-operation of everyone in the industry. Through working together, detailed planning and the provision of up-to-date quality contact information and communication channels, and the relevant employees having the competence and authority to act, gas supply network emergencies can be managed and their impacts minimised. This is a vital part of the industry emergency process for reducing demand on the gas network quickly and safely. 
 
With appropriate contingency planning, gas consumers may avoid being exposed to greater costs and commercial risks than would otherwise be expected. 
 
1.7  Site occupiers will also have safety responsibilities under other safety legislation such as the Health and Safety at Work Act and the Provision and Use of Work Equipment Regulations. This publication does not cover all the safety issues arising from such legislation. However, the need for competent persons, planning and safe procedures is of paramount importance. 
 
1.8  When a direction to cease consumption is received then the user should act quickly and safely. The Large Gas user will be contacted by the gas transporter as soon as there is a requirement for gas use to be stopped. It is a criminal offence for the person receiving the direction to knowingly fail to comply with such a direction. The direction to stop using gas may be sent by email, phone, fax, or in person on site. 
 
1.9 This Standard makes use of the terms “must”, “shall” and “should” when prescribing particular requirements. Notwithstanding Sub-Section 1.9: 

• the terms “must” identifies a requirement by law in Great Britain (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. 

 
1.10 The primary responsibility for compliance with legal duties 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 must: 

• 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 
• not require “responsible engineers” to undertake tasks which would necessitate the exercise of professional judgement that is beyond 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 should refer the matter for higher review. 

 
1.11    Notwithstanding Sub-Section 1.7, 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 should be adopted without waiting for 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. 
 
1.12    Requests for interpretation of this Standard in relation to matters within its scope, but not precisely covered by the current text, may be addressed to Technical Services, IGEM, IGEM House, High Street, Kegworth, Derbyshire, DE74 2DA, and 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 any liability for the consequences and does not relieve the responsible engineer of any of his or her obligations. 
 
1.13    This Standard was published in January 2018. 
 
       

2.1  This Guidance provides advice for those Large Gas users of natural gas who may be directed to cease the use of Natural Gas in the event of a gas supply emergency, and therefore should know their responsibilities and actions to be taken should the eventuality arise.  
 
2.2  This Guidance does not address any supply cessation issues that are associated with any contractual arrangements (between users and their gas shipper/supplier) for an interruptible supply except that some or all of the technical guidance will be applicable.  
       
This Guidance is provided to ensure Large Gas users understand their responsibilities and to enable them to prepare company and local site specific plans to act quickly.  
 
2.3 For the gas industry participants and the UK gas supply chain overview (see Appendix 3).