Internal Corrosion Considerations for Hydrogen Embrittlement Inhibitors

Abstract Converting natural gas pipelines to transport pure hydrogen or blends with natural is currently being implemented as part of the energy transition strategy to achieve net zero emissions. Addition of hydrogen to existing natural gas pipelines increases the risk of hydrogen embrittlement and poses potential integrity issues such as cracking to the pipelines. Prior work has demonstrated that the use of inhibitors such as oxygen, carbon monoxide, and others can inhibit a material’s adsorption of atomic hydrogen and have been proposed to reduce the risk of hydrogen embrittlement. While these inhibitors may potentially reduce the risk of hydrogen embrittlement, there may be unintended consequences if the impact of these inhibitors on internal corrosion is not carefully evaluated. For example, the use of oxygen in the inhibitors can increase the potential for oxygen corrosion. This paper covers the methodology to evaluate the impact of internal corrosion on pipelines for any inhibitors used to prevent hydrogen embrittlement before they are applied. The recommendations for internal corrosion control when using oxygen-based inhibitors are discussed. Additionally, a comprehensive review of the proposed inhibitors for hydrogen embrittlement along with a discussion on their mode of action to prevent or mitigate hydrogen embrittlement is presented.