Patent ID: 6103027
Filing Date: 2000-08-15
Classification: B21C,C21D

Abstract:
The method of fabricating metal pipe from weldable and ductile metals comprising the steps of:utilizing a tubular pipe stock of a preselected length formed into a cylindrical shape from flat plate stock and having a weld seam formed from the parent material of the plate stock for joining the confronting ends of the cylindrically formed plate stock,cutting said pipe stock to form pipe blanks of a desired length,substantially full annealing said pipe blanks followed by rapid cooling and removing excess weldment from the outer surface of said pipe blank,roll extruding said pipe blanks to form rolled pipe blanks of an increased length while reducing the wall thickness by at least around 30%, andsubstantially full annealing said rolled pipe blanks followed by rapid cooling to remove mechanical strain resulting from the roll extrusion and to reform the grain structure of the weldment to be comparable to the metal microstructure of the parent non-welded material whereby the rolled pipe blanks are finished seam free pipe.