PIPELINE AND MANUFACTURING METHOD THEREOF

摘要

A pipeline is a pipeline having plural weld zones in which ends of plural steel pipes are joined by welding, the plural steel pipes are produced from plural charges of molten steel having one or more steel compositions; yield point elongation is not present on a stress-strain curve obtained when stress is applied in a longitudinal direction of each of the steel pipes; a thickness of each of the steel pipes t (mm) and an average pipe outside-diameter D (mm) satisfy t/D×100‰¤6; and in the plurality of the weld zones, ”YS which is a yield strength difference between one steel pipe and the other steel pipe that are welded to each other (MPa), and YR representing a yield ratio that is a ratio of the yield strength to tensile strength of a pipe having a lower yield strength out of the one steel pipe and the other steel pipe, satisfy ”YS‰¤-1.75×YR+230.