METHODS AND APPARATUS FOR COATING THE SEAMS OF WELDED TUBES

摘要

A method of coating the welded seam of a metal tube (20) comprising heating the weld area only of the metal tube to a first temperature which is less than the melting temperature of a protective metal coating, applying the protective metal coating over the seam and heating the entire tube, preferably with a full body induction coil (78), to a second temperature which is at least equal to the difference between the first temperature and the melting temperature of the metal coating, such that the temperature of the seam area is heated to a temperature equal to or greater than the melting temperature of the metal coating, whereby the metal coating firmly adheres to the welded seam. In applying a coating over the exterior surface of the seam, the coating is preferably applied by thermally spraying (70) molten metal coating material over the seam.