Hydrogen related mechanisms influencing the galling behaviour of austenitic stainless steels in threaded components

Threaded stainless steel connections are critical to ensuring safety and leak‑tightness in Underground Hydrogen Storage (UHS). While galling is a well‑known failure mechanism in threaded connections used in conventional energy infrastructures, the influence of hydrogen on galling behaviour remains insufficiently understood. This knowledge gap complicates the direct transfer of materials and design approaches from oil and gas to hydrogen related applications. This study examines the tribological behaviour of an austenitic stainless steel widely used in threaded connections, comparing its response in the virgin condition and after controlled hydrogen uptake. Dry sliding tests representative of tightening operations were combined with surface analyses to understand frictional and wear mechanisms. Results show that hydrogen does not intensify galling damage and instead leads to a reduction in friction, supporting the use of conventional stainless steels in hydrogen‑rich underground storage environments.