FLUX-CORED WIRE FOR WELDING AND ITS PRODUCTION

摘要

PURPOSE:To obtain a good welded state in a flux-cored wire for welding for which a long-sized pipe welded and joined at a seam is used by regulating the shapes of weld beads formed on the inside surface of the pipe. CONSTITUTION:A covered pipe 2 has weld beads 4 formed in the production stage of pipe by welding of an electric welded pipe in the longitudinal direction on the inside surface thereof. If a flux-cored wire for welding having the section wherein the ratio h/t between the height (h) of the beads 4 on the inside surface of the pipe and the inside thickness (t) of the pipe is <=0.5 and that the ratio a/A between the sectional area (a) of the beads on the inside surface of the pipe and the sectional area of the pipe inside is <=0.04 is produced, a good welded state is provided. Said wire is produced by packing a flux in the electric welded pipe having a section where the relation h'/t'=0.04-0.4 between the height h' of the beads on the inside surface of the pipe and the wall thickness t' of the pipe and the relation a'/A'=0.001-0.03 between the sectional area a' of the beads on the inside surface of the pipe and the sectional area A' of the pipe inside. Thus, the wire is drawn.