Pressurized gaseous hydrogen permeation experiments on pipeline steel: the impact of trace O2 and H2S impurities

Safety issues linked to the compatibility of existing pipeline and storage ferritic steels with pressurized hydrogen gas are a central concern. It is well known that hydrogen diffuses into steel, weakens it mechanical properties, and leads to hydrogen embrittlement. A second risk facing high pressure installations arises from hydrogen permeation across the through thickness – resulting in permanent leaks. Although quite well understood in aqueous media, the labile kinetics of hydrogen absorption in steels are relatively less known under high pressure hydrogen gas at near-ambient temperatures. Furthermore, the presence of trace impurities such as water, oxygen and H₂S in the transported/stored high pressure hydrogen, may impact the surface state and uptake of hydrogen to varying extents. 

Here, we present our hydrogen permeation results across ferritic pipeline steel that has been employed for studies under dry gaseous pressure. Strategies to overcome the impressive natural iron oxide barrier resistance towards generalized hydrogen uptake in pipeline steel are initially shared, along with insight on the care needed to successfully conduct such experiments under high pressure. Subsequently, we demonstrate the impact of co-mingling O₂ and H₂S with the pressurized hydrogen, known contaminants in real-world gas transport, could have on the generalized hydrogen uptake kinetics with the support of permeation transients and surface characterization tools.