| 摘要 |
PURPOSE:To omit tack welding and to perform welding without welding defects by welding a steel pipe while the root faces in the butt weld zones of a straight seam have wedge-like clearances opened at specific angles toward the groove on the opposite side of welding. CONSTITUTION:In butt weld zones 2 of the straight seam of an O pipe 1, said pipe is beforehand worked piror to forming to the O pipe 1 by inclining root faces 5 to each other so as to make point contact, making the contact point coincident with the meeting point of the deepest groove on the outside surface side, opening both faces 5 at 3-20 deg. angle toward the groove on the inside surface side on the opposite side with the said point as a starting point and forming a wedge-like clearance until said faces intersect with the groove on the opposite side. In welding, the outside surfaces are subjected to regular welding without tack welding, then the inside surfaces are subjected to regular welding. Thus, the entry of air from the faces 5 into molten metal is prevented. |
