Abstract Transporting high-pressure gaseous hydrogen through the existing pipeline network – both subsea and onshore – is a promising strategy for cost-effectively expanding the hydrogen infrastructure, supporting the transition to sustainable fuels. However, repurposing pipelines to transport high-purity hydrogen poses challenges to material integrity, as hydrogen can accelerate fatigue crack growth in pipeline steels, especially under their typical operating conditions characterized by cyclic loading due to daily pressure fluctuations. Additionally, loading peaks, such as those from pressure testing, may further influence crack propagation. Despite these concerns, the effect of hydrogen on overload-affected fatigue behavior remains underexplored. This study examines the impact of hydrogen on fatigue crack acceleration in a vintage Norwegian X65 pipeline steel (originally installed in 1982), focusing on how overload (OL) conditions modify crack growth in three scenarios: (a) overload in air followed by FCG in air, (b) overload in high-pressure hydrogen followed by FCG in the same environment, and (c) overload in air at atmospheric pressure followed by FCG in high-pressure hydrogen. Preliminary results show that hydrogen significantly impacts the sudden acceleration in the FCG typically induced by the overload, but it does not seem to affect the overload-induced delayed retardation in the FCG. In any case, hydrogen leads to accelerated crack propagation and can potentially jeopardize material integrity. In cases where overloading occurs in air and is followed by FCG in hydrogen – a scenario potentially similar to pressure testing before hydrogen injection in pipelines – a specific behavior in the hydrogen-induced crack acceleration was observed, underscoring the need for thorough safety considerations in pipeline repurposing.
Giannini et al. (Sun,) studied this question.