Safer high-pressure hydrogen vessel designs Infrastructure is the biggest challenge that fuel cell technology faces today. For safe hydrogen storage and transport, EU-funded researchers proposed a methodology to evaluate hydrogen enhanced fatigue when designing high-pressure metallic vessels. Industrial Technologies Energy Fundamental Research © Hramovnick, Thinkstock Hydrogen refuelling stations have been built but international standards do not properly address hydrogen enhanced fatigue effect in high-pressure hydrogen vessels. The EU-funded project MATHRYCE (Material testing and recommendations for hydrogen components under fatigue) aimed to fill this gap. The project brought together world leaders in standards development and hydrogen production and storage. The Joint Research Centre (JRC) of the European Commission also participated with government organisations from three European countries. Several components of the hydrogen supply chain such as high-pressure compressors and pressure buffers in hydrogen refuelling stations experience cyclic loading. In Europe, the local codes developed do not sufficiently account for fatigue loading under hydrogen pressure. To quantify the effect of hydrogen on fatigue life, researchers adopted a combined numerical and experimental approach. The results provided representative and currently possible conditions for a series of laboratory tests. Simultaneously, a testing campaign was set up, supporting both lab- and full-scale tests aimed at assessing the effect of hydrogen on steel. Specimen and real-sized vessels were manufactured from Cr-Mo steel with a bainite and tempered martensite microstructure. Although traditionally used to manufacture high-pressure vessels for hydrogen transport and storage, this particular steel is sensitive to hydrogen embrittlement. Under cyclic loading and high pressure hydrogen, crack initiation and growth may be accelerated. MATHRYCE partners developed test instrumentation to detect fatigue crack initiation under hydrogen pressure and measure its growth. Results of the tests under high hydrogen pressure laid the groundwork for the development of an easy-to-implement methodology to assess high-pressure hydrogen vessels. It is based on fatigue life data obtained from lab-scale tests combined with data obtained by testing full-scale cylinders under cycling loading. The design of metallic pressure vessels can now be based on solid knowledge of the influence of several parameters such as pressure and loading frequency on hydrogen enhanced fatigue. MATHRYCE results have produced recommendations for international standards bodies (ISO, CEN) and have opened the way for significant savings in the future design of hydrogen infrastructure. Keywords High-pressure hydrogen vessel, fuel cell technology, international standards, MATHRYCE, Cr-Mo steel
