Method of making butt welded tubes
AssigneeNippon Kokan Kabushiki Kaisha
InventorsTakao Nakamura, Itsuo Hirose, Rokuro Misawa, Hidenori Horii, Akira Hagio, Tetsuo Sada
Life of this patent
Estimating the term…
Abstract
A butt welded tube is provided having excellent properties by the steps of forming a skelp onto a round shape, butt welding the edges thereof with butt welding rolls, blowing oxygen or air into the weld zone, so that said zone is brought to a melted condition with oxidizing heat based on said blowing and some notches which are formed are blown off with said blowing, and then said tube is passed through a train of reducing rolls to obtain a smooth surface and the required dimension of said tube.
Claims5
In a method of making butt welded tubes of oxidizable material comprising heating a skelp to a temperature suitable for butt welding of the material, passing the heated skelp between forming rolls to form it into a tube having longitudinal edge positions bounding an open seam, and passing said open-seam tube between butt-welding rolls to cause said longitudinal edge portions to become butt welded, the improvement of blowing oxygen under pressure onto said butt welded edge portions, whilst they are at a temperature at which oxidation will occur, thereby to cause increase of temperature of said edge portions and result in removal by oxidation and blowing away of protrusions formed during the butt welding, and whilst said butt welded edge portions are at increased temperature passing said tube through reducing rolls to produce a substantially seamless tube.
Dependencies are inferred from the claim text.