CIRCUMFERENTIAL WELDED JOINT OF LINE PIPE, METHOD OF FORMING CIRCUMFERENTIAL WELDED JOINT OF LINE PIPE, AND LINE PIPE

摘要

This circumferential weld joint for line pipes that is formed by abutting the ends of steel pipes having yield strengths (API Spec 5L Specification) of 555 N/mm2 or more and welding the abutment section in the circumferential direction is characterized in that the joint strength ratio smatch = (TS-w/TS-b)·(YS-w/YS-b), which is represented by the product of the ratio (TS-w/TS-b) of the tensile strength of the weld metal (TS-w) to the tensile strength of the base metal (TS-b) and the ratio (YS-w/YS-b) of the yield strength of the weld metal (YS-w) to the yield strength of the base metal (YS-b), and the ductile crack generation critical equivalent plastic strain ep-cri (%) of the heat-affected section of the base metal satisfy Equation (1), and the yield strength of the weld metal (YS-w) and the yield strength of the base metal (YS-b) satisfy Equation (2). smatch > 4.85 ep-cri -0.31 --- (1) YS-w/YS-b = 1.0 --- (2)