METHOD AND APPARATUS FOR THE PRODUCTION AND/OR TESTING OF WELDED HELICAL SEAM PIPE

摘要

A method of producing welded helical seam pipe, made from steel sheet or strip which is wound into pipe formation, is disclosed. Prior to the welding of the wound steel sheet, an optically scannable reference line is applied to the steel sheet which extends parallel to and adjacent one of the edges of the sheet. The welding is effected by applying a first welding seam with a first welding head located within the pipe interior and a second welding seam with a second welding head located outside the pipe. In accordance with the invention, the optically scannable reference line is applied to that face of the sheet which forms the inner surface of the welded pipe. The thus interiorly located reference line is optically scanned so as to obtain scanning information which, through operative connection to control means, controls the welding movements or operation of both the first and the second welding heads. The inventive method is particularly suitable in the production of pipe which is tack-welded prior to finish welding.