As the demand for hydrogen (H₂) as an alternative energy source grows within the industry, pipeline transportation will play a pivotal role in connecting H₂ production and storage sites as well as in distributing to end users. The repurposing of existing pipelines to transport H₂ requires a comprehensive understanding of their current condition and how it may be impacted by the introduction of H₂.

Hydrogen embrittlement affects pipeline steels in several ways: Ductility and fatigue performance are reduced, and some tests have indicated small reductions in material strength. These material changes have a direct impact on the performance of pipelines that contain existing anomalies such as mechanical damage and metal loss. The applicability of commonly applied anomaly assessment and acceptance criteria must be understood before they can be applied to H₂ pipelines. This is the case particularly where the criteria adopt limits that have been established through empirical validation approaches involving testing of pipelines in air and/or natural gas.

As part of the SafeH2Pipe project, research into defect performance in a hydrogen environment is being conducted, consisting of both finite-element analysis and full-scale testing. This paper reviews the assessment criteria that are currently applied to mechanical damage and metal loss anomalies and discusses the potential impact of hydrogen embrittlement. It focusses on how finite element analysis can be used before performing full-scale testing to model the elastic and plastic response of anomalies, considering modified material properties. The results of these analyses can inform the design of the full-scale test setup, which will be the next phase of the SafeH2Pipe project.