Enhanced hydrogen entry into carbon steel under combined condition of high-pressure hydrogen and presence of water

Abstract

Assessing hydrogen uptake in steel is essential for evaluating the risk of hydrogen embrittlement and the feasibility of repurposing underground gas storage facilities for hydrogen storage. However, the impact of diverse environmental conditions in these facilities on hydrogen entry remains insufficiently studied. To identify critical conditions and the underlying mechanisms of hydrogen entry, we investigated hydrogen uptake in carbon steel under near-field exposure scenarios. Steel samples were exposed to controlled environments, including immersion tests, high-pressure hydrogen exposures (0–80 bar H₂, 0–100 °C) in an autoclave, and their combination. Hydrogen uptake was quantified using thermal desorption analysis, while corrosion rates were determined through mass loss measurements. Deuterium oxide was used to distinguish hydrogen originating from corrosion and high-pressure hydrogen gas. Hydrogen uptake was low in dry gaseous hydrogen up to 80 bar and 50 °C but increased in humid hydrogen above 30 bar pressure and further in presence of bulk water solution. It was proved experimentally that the atomic hydrogen in steel originated from the gaseous phase. The water-enhanced high-pressure hydrogen uptake was controlled by hydrogen pressure and was little affected by temperature and environmental corrosivity. Corrosion-induced hydrogen uptake was generally low. The practical implications of these findings for the risk of steel embrittlement in gas infrastructure are discussed.