Patent ID: 7223447

Claim:
A continuous method of applying an adherent protective metal coating to internal and external surfaces of a welded seam of a metal tube, comprising the following steps: applying a first protective metal coating to an external surface of a welded seam of a continuously moving metal tube; applying a second protective metal coating to an internal surface of said welded seam of said continuously moving metal tube; externally inductive heating said welded seam, first heating said first protective metal coating on said external surface of said welded scam to its melting temperature, melting said first protective metal coating over said external surface of said welded seam; applying a fluid coolant to said first protective metal coating on said external surface of said welded seam, while continuing to externally heat said welded seam, thereby freezing said first protective metal coating on said external surface of said welded seam, forming an adherent protective coating on said external surface of said metal seam; continuing externally inductive heating said welded seam, heating said second protective metal coating on said internal surface of said welded seam, melting said second protective metal coating over said internal surface of said welded seam; and quenching said metal tube.