1.1 This Standard supersedes Edition 2 Communication 1762 published in 2012 and Edition 1 Communication 1712 which was published in 2006. It has been drafted by a Panel appointed by the Institution of Gas Engineers and Managers’ (IGEM’s) Technical Co-ordinating Committee, subsequently approved by that Committee; the Gas Utilisation Committee, the Gas Measurement Committee, the Gas Transmission and Distribution Committee, and published by the authority of the Council of IGEM. 

1.2 This Standard summarises best practice for the design, installation, operation, inspection and maintenance of gas installations for multi-occupancy buildings (see Sub-Section 2.1). It combines well established practices with new advice on aspects of design and construction of such installations. The Standard consolidates best practice and guidance from Legislation, and existing gas industry standards and procedures, with the aim of helping to achieve safe designs, installations and continuing operation for gas in the buildings concerned throughout the lifetime of the asset. 

1.3 This Standard is primarily for an informed and experienced audience such as Gas Engineering professionals, Architects, Mechanical and Electrical Engineering Consultants, Building Facilities and Maintenance Managers and the Responsible Person for the building. It is assumed that readers of this standard are familiar with and understand the roles specified in the Construction (Design and Management) Regulations (CDM).   

1.4     Compliance with this Standard cannot confer immunity from statutory legal obligations. 

1.5     Significant amendments have been made compared to the second edition. These include: 

• reviewed risk hierarchy for timber and traditionally constructed buildings
• revision of figures and the addition of new figures
• reviewed responsibilities associated with new work, replacement work and ongoing operation inspection and maintenance
• updated requirements for inspection of network pipelines
• updated references to materials standards
• reviewed competence requirements
• reviewed record keeping and information to be presented to the Responsible Person for the Building
• decommissioning.

1.6 This Standard makes use of the terms “must”, “shall” and “should”, when prescribing particular requirements. Notwithstanding Sub-Section 1.10:  

• the term “must” identifies a requirement by law in the 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.

Note: The phrase “prior consideration” means that a suitable and sufficient risk assessment will be completed and documented to show that the alternative method delivers the same, or better level of protection.
Such terms may have different meanings when used in Legislation, or Health and Safety Executive (HSE) Approved Codes 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    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 should be taken of HSG48 and HSG65. 

1.8    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 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 that deviate from this, they should refer the matter for higher review.

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 in the sense that actions by people initiated or contributed to the accidents, or people might have acted better to avert them. 
It is, therefore, necessary to give proper consideration to the management of these human factors and the control of risk. To assist in this, it is recommended that due cognisance be taken of the HSG48 and HSG65. 

1.10    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 modification to this Standard. Amendments to this Standard will be issued when necessary and their publication will be announced in IGEM’s Journal and other publications as appropriate. 

1.11    Requests for interpretation of this Standard in relation to matters within its scope, but not precisely covered by the current text, should be addressed either to:

• Technical Services, IGEM, IGEM House, 26 & 28 High Street, Kegworth, Derbyshire, DE74 2DA, or
• by e-mail 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 relieve the “responsible engineer” of any of his or her obligations. 
1.12     This Standard was published in February 2022. 

2.1 This Standard covers gas infrastructure to and within multi-occupancy buildings including those designated as high risk buildings and the individual dwellings and commercial units within such buildings. The principles underpinning this Standard apply to all building situations whether typical or more complex ones (see Appendix 1). 
 
Note: Properties deemed separate buildings, each comprising an individual single dwelling, such as detached, semi-detached or terraced houses/bungalows, are not covered by this Standard. 
 
2.2 This Standard covers new, replacement and like for like component replacement of gas network pipelines, meter installations, installation pipework (including secondary meters), appliances and chimneys.  
 
This Standard also covers inspection, maintenance, monitoring, repair, alteration and decommissioning processes. 
 
    Note 1:     In this context, “new and replacement” embraces: 

• any first time gas supply or replacement of any of the above mentioned sections of the gas supply system 
• any new extension to an existing section of the gas supply system 
• significant partial replacement of/alteration to any of the sections of the gas supply system. For example, the replacement of a riser system having one or more laterals connected would likely be deemed ‘significant partial replacement’. 

 
Regarding replacement/alteration, it is important to comply with legal obligations, for example, the checks required by Gas Safety (Installation & Use) Regulations (GS(I&U)R) following work on any part of a gas supply system. 
 
Note 2: A network pipeline supplying a primary meter installation will be a “service” or a “distribution main”. The difference, for the purposes of this Standard, is insignificant except when cross referring to other Standards, for example IGEM/TD/3 and IGEM/TD/4. This Standard uses either or both of the terms “network” or “pipeline” throughout.  
 
Note 3: IGEM/TD/3 does not address pipes in buildings. IGEM/TD/4 references IGEM/G/5 with respect to gas in multi-occupancy buildings. 
 
2.3 This Standard defines requirements covering the core areas of safety for gas in multi-occupancy buildings, such as: 

• planning, risk assessment and minimising risk  
• meter installations and location of gas meters with respect to escape routes and the GS(I&U)R and Building Regulations  

 
Note: This affects many other aspects of the installation significantly, for example ventilation, consumer access for meter reading and isolation, and escape routes.  

• network pipelines, types of building entry, risers, laterals and isolation valves  
• ventilation of network pipelines, meter installations and installation pipework 
• access for inspection and maintenance to network pipelines, meters, installation pipework and appliance chimneys  
• modifications, repairs, testing, re-commissioning and decommissioning of existing network pipelines 
• energy centres and their associated risks   
• installation pipework, gas appliances and chimneys 
• materials  
• location of valves 
• inspection, maintenance and decommissioning
• electrical safety and equipotential bonding. 

 
Note: The text on this subject has been drawn up with the assistance of the Institution of Engineering Technology (IET) and the Energy Networks Association (ENA). 

• roles, responsibilities and competence. 

 
Note: This Standard includes requirements that are either additional to or vary existing requirements contained in other standards where the requirements of those other standards may not be sufficient for gas installations in multi-occupancy buildings. However, those existing Standards are referenced and the majority of their requirements will still apply where relevant. These standards include: 

• IGEM/TD/3 and IGEM/TD/4 for network pipelines 
• IGEM/TD/13 for pressure regulating installations (PRIs) 
• BS 6400 for domestic-sized meter installations 
• IGEM/GM/6 and IGEM/GM/8 for larger meter installations 
• IGEM/GM/7A and IGEM/GM/7B for electrical connections to, and hazardous area classification of, meter installations 
• BS 6891 for domestic-sized installation pipework 
• IGEM/UP/2 for larger installation pipework 
• IGE/UP/7 for timber and light steel framed buildings 
• BS 5440-1 and 2 for the supply of chimneys and ventilation • IGEM/UP/17 for dealing with shared chimney and flue systems 
• BS 8313 Building Services in Ducts.  

2.4    This Standard addresses requirements for the risk assessment of gas installations within any multi-occupancy building and the individual dwelling(s)/unit(s) within such a building. 
 
2.5    This Standard generally addresses appliances within domestic dwellings or commercial units which have been UKCA or previously CE marked or designed to a relevant Standard. 
 
This Standard covers all types of open flue chimney or room sealed chimney systems (that comply with appropriate construction standards) for gas appliances, whether they are separate from, or integral with, the appliances. 
 
2.6    This Standard addresses gas installations intended to contain odorised Natural Gas (NG).  
 
Note 1: This Standard assumes a gas supply layout as given in IGEM/G/1 for “Standard gas supply arrangements”. Where a “bulk meter” serves secondary meters, via installation pipework, the principles of IGEM/UP/2 also may be applicable. 
 
 Note 2:     For energy centre installations, see Section 11. 
 
2.7    The term “meter” means “gas meter installation” unless otherwise stated. 
 
2.8    The term Gas Transporter (GT) is deemed to include a “Gas Conveyor” conveying gas in a network pipeline.  
 
Note 1:     The definition of “Gas Conveyor” is given in IGEM/G/1 and IGEM/G/4. 
 
Note 2: An alternative description taken from The Gas (Exemptions) Order 2011 is “Licence Exempt Gas Transporter”.  

2.9    All pressures quoted are gauge pressures, unless otherwise stated. 
 
2.10    Italicised text is informative and does not represent formal requirements. 
 
2.11    Appendices are informative and do not represent formal requirements unless specifically referenced in the main sections via the prescriptive terms “must”, “shall” or “should”.