the continuos root welding machine model crwm is built to simplify the following internal and external seam welds at longitudinal welded pipes. the crwm generally is part of a lsaw pipe mill where the pipe is formed by di......the continuos root welding machine model crwm is built to simplify the following internal and external seam welds at longitudinal welded pipes. the crwm generally is part of a lsaw pipe mill where the pipe is formed by different processes e.g. roll bending process u- forming and o- forming process progressive forming process progressive folding process the crwm can also be part of modernizing an existing pipe mill for better quality increasing the output the process is a continuous tack weld under gas shielded arc to achieve the best quality of welds. the crwm closes the edges of the open seam pipe gas during transportation through a fixed located sizing roller cage. the adjustments of the roller cage are hydro- mechanical and cnc-controlled in relation to the pipe sizes, e.g. diameter, wall thickness, material grade and length.