f H21 Phase 2: Purging of Hydrogen Distribution Pipelines

Over the last two years, a significant programme of work has been undertaken as part of the H21 Phase 2 project to investigate purging of hydrogen distribution pipelines. The aim has been to undertake the underpinning science to support the development of safe and efficient purging procedures for hydrogen distribution pipelines. This report documents that scientific evidence-gathering process.
The report starts with a review of the existing pipeline purging practice and standards. Previous scientific work supporting the purging of town gas and natural gas distribution pipelines is reviewed. The properties of hydrogen are examined and previous work on hydrogen ignition potential and Deflagration to Detonation Transition (DDT) in pipes is assessed. The findings of the literature review are discussed and the decision to proceed with indirect (as opposed to direct) purging is explained.
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.