Pipelines for hydrogen transport : a review of integrity and safety challenges

The European Commission highlights hydrogen as an important energy carrier and chemical feedstock that could help decarbonise sectors otherwise deemed hard-to-abate. Europe's existing natural gas grid is seen as a promising asset to repurpose for the transportation of hydrogen. This technical report provides a literature review of hydrogen's impact on pipeline materials, particularly steel and polymers. Hydrogen is known to reduce the ductility, fracture toughness, and the fatigue crack growth resistance of steel materials commonly found in transmission pipelines. It is also known to permeate through polymeric materials that are often used in the distribution grid. The possible implications for pipeline integrity and safety are reviewed. This report emphasises the need for further experimental research and practical experience combining material science and safety engineering disciplines. Key areas lacking knowledge include the full- or large-scale validation on pipeline sections of small-scale laboratory results, the behaviour of typical pipeline defects, and the long-term performance of polymeric pipeline materials, all under the influence of gaseous hydrogen. The report highlights the essential role of testing facilities such as the High-Pressure Gas Testing Facility (GasTeF) of the European Commission's Joint Research Centre in addressing these gaps.