Steel pipe and a method for welding thereof and pipeline resistant to

Abstract

A pipeline and steel pipe having superior resistance to carbon dioxide corrosion and suitable for transporting crude oil, natural gas and the like containing carbon dioxide. The pipeline includes in combination, pipe sections including a base metal having a composition containing not more than 0.25 wt % of C, from 0.01 to 0.50 wt % of Si; from 0.1 to 2.0 wt % of Mn; not more than 0.03 wt % of P; not more than 0.01 wt % of S; from 0.25 to 1.0 wt % of Cr; from 0.01 to 0.10 wt % of Al, and the balance substantially Fe and inevitable impurities, and a weld metal connecting the pipe sections together having a Cr content ranging from a value which is 0.2 wt % smaller than the Cr content of the base metal and a value which is 1.0 wt % greater than the Cr content of the base metal. The method of the invention includes circumferential welding for connecting steel pipes together by gas-metal arc welding using a welding wire containing Cr and Ti in such amounts as to meet the condition of: Cr wt % +3.times.Ti wt % .ltoreq.2.4 wt % wherein , Cr wt % and Ti wt % respectively represent the contents of Cr and Ti of the welding wire in wt %.