Development of Screening Technology for Hydrogen Embrittlement Compatibility of Pipeline Steels and Welds Using Simple In-Situ Tests in High-Pressure Environments

Simple screening technology for hydrogen embrittlement (HE) of steels for hydrogen energy facilities using the in-situ small punch (SP) test method has been established. The HE behaviors of API X70 steel base metal and welds for pipelines were investigated using the relative reduction of thickness (RRT) obtained by the in-situ SP test. As a result, it was found that API X70 steel exhibited similar HE sensitivity regardless of test conditions and weld regions. In this study, to give data application reliability to the RRT obtained by the in-situ SP test of ferritic steels, a simple in-situ slow strain-rate tensile (SSRT) test method using a hollow-type specimen was devised. It was used to evaluate the HE sensitivity of the API X70 steel and welds at various temperatures, and the obtained relative reduction of area (RRA) was used to compare to the RRT by in-situ SP test. As a result, it can be found that RRT by in-situ SP test showed a generally good relationship with RRA by the SSRT, even though some variation existed depending on the test temperature, confirming that the in-situ SP test can be effectively applied to the HE sensitivity screening of pipeline steels and welds in high-pressure hydrogen environments.