In the UK and Ireland there is specific pressure system safety legislation which has the purpose of preventing serious injury from the hazard of stored energy (pressure) resulting from the failure of a pressure system or one of its component parts.

Mutual Energy and Gas Networks Ireland own, operate and maintain significant transmission assets in Scotland, Northern Ireland and the Republic of Ireland, and Pipeline Integrity Engineers (PIE) acts as Competent Person for these assets in accordance with the relevant pressure system safety legislation.

Over a 30-year period the approach for complying with these requirements has been developed by Operators (Users) and Competent Person’s for natural gas transportation systems, however the UK and Ireland are committed to achieving net zero by 2050 and given that hydrogen behaves differently to natural gas, there is a requirement to assess its impact on compliance with pressure systems safety legislation.

This paper discusses:

• The context of pressure system safety legislation in UK and ROI, its background and what it is trying to achieve.
• How pipeline operator compliance for natural gas systems is achieved, by schemes of examination and definitions of safe operating limits, and the role of the Competent Person.
• How the current compliance approach will be impacted by a repurposed (blended) hydrogen system, e.g. will different examination tools and techniques be required and at what frequencies, and how will existing and future modifications and repairs be assessed for hydrogen service?
• Will there be different safe operating limits for repurposed (blended) hydrogen systems?