A number of CPW manufactured HFW and SAWL pipes were tested for fracture toughness properties in high pressure 100% hydrogen environment. All tests were performed in RINA laboratory, following a developed test procedure based on code ASME B31.12 Option B (qualification of the material threshold stress intensity factor KIH). Testing involved API 5L grades of quality X60M to X70M, with a hydrogen test pressure of 80bar and varying applied stress intensity factors 110-145 MPa·√m.

Following a test exposure of 1000h, all parent material, weld and HAZ specimens presented an excellent resistance to hydrogen embrittlement showing no measurable crack propagation from the fatigue pre-crack front. Based on the results, a KIH value of 55 MPa·√m and above was established in all cases, fulfilling the minimum qualification criteria of ASME B31.12 Option B