Inhibiting effect of carbon monoxide on gaseous hydrogen embrittlement of pipelines transporting hydrogen

Hydrogen embrittlement (HE) potentially occurs on pipe steels in hydrogen-blended natural gas environments, compromising integrity of the pipelines. The mechanistic aspect about the role of CO in hydrogen dissociative adsorption and steel has remained unknown. In this work, in-situ high-pressure gaseous hydrogen-charging and tensile experiments were conducted to investigate hydrogen atom entry and the resulting mechanical responses of an X52 pipe steel in the presence of CO. The density functional theory and first-principle molecular dynamics were used to reveal the effect of CO on hydrogen dissociative adsorption. A feasible solution to address the HE risk was proposed.