MANUFACTURE OF WELDED STEEL PIPE FORMED BY STICKING TIGHTLY STAINLESS STEEL ON BOTH INSIDE AND OUTSIDE SURFACES

摘要

PURPOSE:To prevent a steel base material from being exposed to a joint by forming a strip whose both surfaces are covered with stainless steel, to a tubular body by holding a prescribed gap, packing a stainless steel made filler material into this gap, and welding the joint from the outside surface. CONSTITUTION:A strip 3 formed by sticking tightly a stainless steel covering 2 to both surfaces of a steel base material 1 is fed continuously to a forming roll device 9 from an uncoiler 8, curved and formed gradually in a shape of a pipe, and formed to a tubular body 10 provided with a prescribed gap A in its joint 11. Subsequently, a filler material 13 of a stainless steel made wire rod of a section T shape consisting of a head part 14 and a leg part 15 is fed continuously along the joint 11 of the tubular body 10 from an uncoiler 12, and the leg part 15 is packed in the gap A. Next, the tubular body 10 is fed to an argon arc welding machine 16, gaseous argon is used an inner gas, and the joint 11 is welded continuously from the outside surface by a tungsten electrode 18. In this way, the joint 11 is covered completely with stainless steel, and there is no possibility that the steel base material is exposed.