Observation of Surface Damage in a Valve for Hydrogen Gas and Leakage Conditions

Abstract

A basic study to upgrade long-term reliability and durability of a high-pressure hydrogen gas valve was carried out in anticipation of increase of the use of hydrogen utilization machines and infrastructures. The morphology of the surface damage in the sealing components, the damaging mechanism and the relation between development of the damage and leakage were investigated. The surface damage in hydrogen gas was caused by surface plastic flow and transfer of material. In addition, fatigue crack and following delamination were caused by repetitive contact. Small amount of the surface damage didn’t cause leakage. When the surface damage reached a certain amount of depth or width, steep increase of the leakage was caused. Although the meaning of the limitation of the depth or width of the surface damage to cause the rapid increase of leakage is not fully understood, it was recognized that holistic studies to minimalize surface damage including contact conditions, shape of the sealing components and material are required in terms of wear but also in terms of fatigue.