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HSE launch consultation on changes to GSMR 1996

The HSE’s latest consultation relates to the review of the Gas Safety (Management) Regulations 1996 (GSMR). These regulations apply to the conveyance of natural gas and biomethane through pipes to domestic and other consumers.

This GSMR review emanated from the ‘Opening up the Gas Market’ report (OGM), commonly known as the Oban Project, after its demonstration of higher Wobbe Number (WN) gas in the community in Oban, Scotland. The scope of the review was later widened to assess the inclusion of gas with a lower WN than currently permitted and consideration of alternatives to the control of gas content and characteristics which are currently prescribed in Schedule 3 of GSMR.

This consultation seeks views on HSE’s assessment of these proposals and its plans to implement them.

Having assessed the current body of safety evidence, HSE has concluded that there are still outstanding safety and practicality questions for some proposals which need to be addressed before making legislative changes. At this stage, HSE is therefore seeking views on the below set of changes:

  1. A new lower Wobbe number (WN) limit (reducing from ≥47.2 MJ/m³ to ≥46.5 MJ/m³ (the existing lower emergency limit))
  2. To remove the Incomplete Combustion Factor (ICF) and the Soot Index (SI) limits in Schedule 3 and introduce a relative density of ≤0.700
  3. To incorporate the HSE class exemption limit of ≤1 mol% for oxygen in gases conveyed at pressures up to 38 barg
  4. Clarity that biomethane pipelines are to be considered to be part of the gas network

These changes intend to bring the regulations up to date and facilitate the conveyance of gas from different sources more easily, including biomethane. It is hoped this will make injection of biomethane easier, however the limiting factor for most biomethane plants is the flow weighted average calorific value (FWACV). These CV targets come from The Gas (Calculation of Thermal Energy Regulations) 1996 and not GSMR so it is unclear how much impact a lower WN will have. There is, however, separate work being done to change the billing methodology of customers so that CV targets can be lowered and there isn’t a need for propane.

For more information on the context, rationale and proposed changes can be found here. It also contains two supporting documents (appendix 1+2) and the HSE survey for feedback.

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