Welded Line Pipe is not commonly manufactured by the Electric Resistance weld ERW process. The manufacture of welded line pipe by the ERW process begins with coils of hot rolled sheet steel which are cut by a slitting machine into stripes of precise width needed to produce a desired diameter of pipe. The slit coils are fed into the pipe/tube  mills which cold -from the flat ribbon of steel into a tubular clynder by a series of tapered forming rolls. The product is then welded along the joint axis through ERW.The welded tubes then passes under a tool  that remove the outside flash reasulting from the pressure during welding. Inside flash may also be remove likewise by cutting tools. The pipe is then subjected to such post weld heat treatment of the welded seam only or treatment of the full cross-section of the pipe to accurate diameter tolerance. The product is cooled and then cut at the end of the pipe mill by a flying shear or  saw.