Development of a Hydrogen Supplement for use with IGEM/SR/25

In response to the UK Government’s commitment to achieve net-zero carbon emissions by 2050, a range of research and demonstration projects are underway to investigate the feasibility of using hydrogen in place of natural gas within the national transmission and distribution system. In order for these projects to achieve their full scope of work, a mechanism for performing hazardous area classification for hydrogen installations is required. At present, IGEM/SR/25 is used to undertake such assessments for natural gas installations, but the standard is not currently applicable to hydrogen or hydrogen/natural gas blends.
This report presents updated data and a summary of the recommended methodologies for hazardous area classification of installations using hydrogen or blends of up to 20% hydrogen in natural gas. The contents of this report are intended to provide a technical commentary and the data for a hydrogen-specific supplement to IGEM/SR/25. The supplement will specifically cover 100% hydrogen and a 20/80% by volume blend of hydrogen/natural gas. Reference to intermediate blends is included in this report, where appropriate, to cover the anticipated step-wise introduction of hydrogen into the natural gas network.
This report is divided into a series of appendices, each of which covers a specific area of the IGEM standard. Each appendix includes a summary of specific recommendations made to enable IGEM/SR/25 to be applied to hydrogen and blends of up to 20% hydrogen in natural gas. The reader is encouraged to review the individual appendices for specific conclusions associated with the topic areas addressed in this report.
In general, the existing methodologies and approaches used for area classification in IGEM/SR/25 have been deemed appropriate for installations using either hydrogen or blends of up to 20% hydrogen in natural gas. Where necessary, revised versions of the equations and zoning distances used in the standard are presented, which account for the influence of material property differences between natural gas and the two alternative fuels considered in this work.