f Vintage PE Pipes & Hydrogen: H21 Project, Summary Report

Building on earlier work that created evidence on the use of contemporary polyethylene pipes for the distribution of hydrogen fuel gases at pressures below 10bar, further work has been completed. This second work stream reports on hydrogen testing with materials supplied, installed and operated in the United Kingdom since 1969, oftentimes referred as historic or vintage materials. The findings do not raise any new concerns, rather they assist in completing a portfolio of evidence validating expectations of subject experts, and of theoretical approaches, that polyethylene pipe systems are not deleteriously affected by contact with hydrogen at gas distribution pressures. In an earlier study (NIA_SGN0105), used to underpin a safety case for a new hydrogen network in Fife, much evidence was created on modern grades of polyethylene pipe, but one question remained in relation to a property known as fracture toughness. This has been satisfactorily addressed and is reported here. Furthermore, in relation to historic or vintage materials, first generation pipes have been extracted from two locations in the United Kingdom and subjected to testing in contact with hydrogen. A particular focus for vintage pipe studies has been those failure modes that real pipes are most likely to experience in wear out phases, for example slow crack growth failure linked to point loads, offset pipe welds and squeeze off locations. Attention has also been made to the matter of permeation through materials, well researched generally but here specific quantification with vintage/aged materials. The main learning outcome of interest is that permeation rates through materials are affected by temperature. As hydrogen networks can have high temperature feeds to the pipe network this is relevant, and data is provided to quantify effects with vintage materials.
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.