Does hydrogen gas affect the fatigue strength of materials in hydrogen gas transport systems?

Introduction

This FAQ examines the impact of hydrogen gas on the fatigue strength of materials used in hydrogen gas transport systems. It addresses concerns related to fatigue resistance in the presence of hydrogen and its effects on machinery subjected to cyclic loads.

Answer

Studies have shown that the fatigue strength of certain steels may be reduced even in low-pressure hydrogen (H2) environments. While hydrogen absorption may not necessarily lead to hydrogen-enhanced cracks, it can cause changes in the mechanical properties of the metal under study. The presence of hydrogen gas, even at low pressure, can lower fatigue resistance, which can be detrimental to machinery exposed to cyclic loads.

However, in the case of valves, especially large bore gas transportation valves, they are infrequently actuated, and the loads experienced during actuation do not exceed their fatigue strength. Therefore, fatigue-related failures are unlikely to occur in most cases.