This review paper introduces a research project that seeks to quantify oxygen inhibition of gaseous hydrogen embrittlement with possible application for gas transmission pipelines transporting hydrogen. And it summarizes the compelling laboratory evidence that oxygen may inhibit gaseous hydrogen embrittlement. Quantification of oxygen inhibition of gaseous hydrogen embrittlement is needed to allow evaluation of this approach to the inhibition of hydrogen embrittlement in gas transmission pipelines. The experimental approach is explained as the quantification of the amount of hydrogen entering the steel from gas mixtures containing hydrogen using a purpose-built gas phase permeation cell.

Hydrogen transport by blending hydrogen into natural gas transmission pipelines and by pure-hydrogen pipelines is a prospective mode of energy transmission during the transition to renewables. The risk of hydrogen embrittlement (HE) in pipeline steels must first be quantified to ensure safe pipeline operation. This review provides an overview of HE in pipeline steels. Most pipeline steels have reduced ductility when exposed to hydrogen partial pressures of 100 bar and above. Higher-strength pipeline steels (X80 and X100) have been found to undergo HE at ∼50 bar hydrogen. Hydrogen-induced subcritical crack growth in pipeline steels has not been reported in the literature. There are few articles on HE in pipeline welds, with some indications that the weld is more susceptible to HE, and some indications that it is less. The relationship between hydrogen pressure and absorbed hydrogen concentration has not been evaluated. Gaps in knowledge are identified in the conclusions.