Evaluation of lifetime predictions for future hydrogen pipelines by different fracture mechanics‐based design codes

The realization of a hydrogen transport network requires the requalification of existing high‐pressure natural gas pipelines and the design and construction of new hydrogen pipelines. Therefore, appropriate design codes are needed, which consider the detrimental effects of gaseous hydrogen on the mechanical properties and ensure a robust, but not too conservative, lifetime concept. For the assessment of hydrogen pipelines, the ASME B31.12 is understood as a benchmark standard. Recently, the technical rule DVGW G 464 (2023) was published in Germany. Both standards consider a fracture mechanics‐based concept, where the pipeline design lifetime is assessed by the hydrogen‐assisted fatigue crack growth of a pre‐existing defect until a defined lifetime criterion is reached. This article compares both concepts within a use case study, where influencing factors on the lifetime predictions are identified and discussed. Relatively similar results are obtained for typical loading scenarios, whereby the ASME B31.12 predicts more allowable cycles compared to the DVGW G 464 mostly arising from a different assumed crack length. To reduce the conservatism, the focus in the design and assessment of hydrogen pipelines should be placed on a detectable small initial crack size and the measurement of material‐specific crack growth curves resulting in pronounced lifetime enhancements.