Applications of fracture mechanics in assessing integrity of hydrogen storage systems

This paper addresses the challenges in designing high pressure, durable, safe, and cost-effective vessels for storage of gaseous hydrogen and the role of fracture mechanics in meeting those challenges. The design life limiting material property for vessels made from tempered martensitic steel is the environment assisted fatigue crack growth rate (FCGR) that depends on ΔK, the load ratio, loading frequency, and the H2 pressure. The effects of these variables individually and synergistically are explored in this paper. FCGR behavior at negative load ratios, R, of −1.0 and −0.5 were found to be comparable to those at load ratios of 0.1 and 0.2; the effects of load ratio appear to become stronger for R > 0.2. The effect of decreasing loading frequency, ν, on the FCGR behavior in H2 gaseous environment is small for frequencies less than 1 Hz. FCGR behavior is shown to increase with gas pressure and the effect appeared to be highest in going from air environment to 10 MPa H2 pressure and then it saturated at 45 MPa. The impact of these variables and others such as autofrettage, on the design life of H2 storage vessels are explored.