Welded structure having improved resistance to stress corrosion cracking

摘要

This invention relates to a welded line pipe structure for transporting corrosive petroleum or natural gas. It is constituted by martensitic stainless steel pipes containing 8 - 16% Cr and at most 0.05% C. By suitably controlling the welding conditions at the time of girth welding of the steel pipes so as to ensure that the Cr concentration in grain boundary Cr-depleted portions existing immediately beneath a weld oxide scale is at least 5%, the occurrence of SCC in a high temperature CO 2 environment can be prevented.