What is hydrogen embrittlement in the context of H₂ gas transport?

Introduction

Hydrogen embrittlement is a term used to describe failures related to the absorption of hydrogen by metals. The specific damage mechanism relevant to hydrogen gas transportation is hydrogen stress cracking (HSC), which occurs when hydrogen molecules dissociate into atoms and diffuse into susceptible metals under tensile stress.

Answer

In the context of H₂ gas transport, hydrogen embrittlement primarily refers to hydrogen stress cracking (HSC) as the relevant damage mechanism. HSC can only occur when hydrogen molecules dissociate into atoms and penetrate susceptible metals under tensile stress. It’s important to note that absorption of hydrogen in its molecular state is not possible; only dissociated atomic hydrogen can cause HSC.