論文
高圧水素施設で水素漏洩を起こした高圧配管用T型ジョイントの破壊力学解析
2020 年 69 巻 5 号 p. 401-407
詳細
2020 年 69 巻 5 号 p. 401-407
This paper deals with the fracture mechanics-based analysis of T-type joint for piping that caused hydrogen leakage in a high pressure hydrogen facility (Service pressure: 99 MPa). T-type joint is made of precipitation hardening martensitic 17-4PH stainless steel (corresponds to JIS-SUS630). The design fracture pressure of T-type joint is as high as 1050 MPa. Nevertheless, T-type joint caused hydrogen leakage in 150 MPa hydrogen gas whose pressure was 14 % of the design fracture pressure. According to fracture toughness tests of JIS-SUS630, fracture toughness, KIc, in air at the displacement velocity of V = 5.9×10–3 mm/s was 83.2 MPa・m1/2 and hydrogen-induced crack growth threshold, KI,H, in 115 MPa hydrogen gas at V = 2.0×10–5 mm/s was 7.4 MPa・m1/2 which was 9 % of KIc. Fracture surface in hydrogen gas was covered with quasi-cleavage. Fracture mechanics-based analysis using KI,H showed that hydrogen-leakage of T-type joint was caused by hydrogen-induced crack growth from peel-like defect in 150 MPa hydrogen gas.
