Abstract
It is indispensable for upcoming hydrogen society that the studies to improve reliability and durability of high-pressure hydrogen gas equipment are done. In this study, for a high-pressure hydrogen gas valve, the damage process and the relation between damage and leakage were investigated. In this test, a commercial valve was used to create the actual damages. Repetitive opening and closing of the valve was done in a hydrogen gas. Before and after the testing, leakage check was done. There were traces that plastic flow of surface layer and transfer occurred on the contact surfaces. Besides tribological damaging process, fatigue is also important to cause the damage, because repetitive contact created checks and eventually caused flaking. The width and depth of the damaged area increased with increase in pressing load and number of cycles. However, leakage was practically zero even a certain level of the contact damage was produced. The leakage rapidly increased when the damage was beyond certain limits which were 100μm in the width and 2μm in the depth of the damaged area. But physical meanings of these limits have not been yet understood.
