A Review of Gas Phase Inhibition of Gaseous Hydrogen Embrittlement in Pipeline Steels

The addition of small amounts of certain gases, such as O2 , CO, and SO2 , may mitigate hydrogen embrittlement in high-pressure gas transmission pipelines that transport hydrogen. To practically implement such inhibition in gas transmission pipelines, a comprehensive understanding and quantification of this effect are essential. This review examines the impact of various added gases to hydrogen, including typical odorants, on gaseous hydrogen embrittlement of steels and evaluates their inhibition effectiveness. O2 , CO, and SO2 were found to be effective inhibitors of hydrogen embrittlement. Yet, the results in the literature have not always been consistent, partly because of the diverse range of mechanical tests and their parameters. The absence of systematic studies hinders the evaluation of the feasibility of using gas phase inhibitors for controlling gaseous hydrogen embrittlement. A method to quantify the effectiveness of gas phase inhibition is proposed using gas phase permeation studies.