Micro hardness tests may be conducted to ensure that welding does not affect the toughness of the hydrogen pipe materials. These tests can be part of the welding procedure and operator qualification process, and they can also be performed on samples from

Micro hardness tests can be performed to verify that welding does not compromise the toughness of hydrogen pipe materials. These tests can be incorporated into the welding procedure and operator qualification process, and can also be conducted on samples from welds produced during manufacturing. Hardness testing is mandated for welding procedure qualification tests on materials that have acceptance criteria specified in ASME B31.12, as detailed in the table below. Update (2024-09-18): Micro hardness tests can be employed to verify that welding processes do not compromise the toughness of hydrogen pipe materials. These tests can be included in the qualification procedure for both welding techniques and operator skills, and can also be carried out on samples taken from production welds. For certain materials outlined in ASME B31.12, hardness testing is a necessary component of welding procedure qualification tests, as specified in the table below.