Tianjin yu xing steel tube company has been engaged in the production of cold-formed squuare and rectangular steel pipe for 8 years. With an annual production of 150.000 tons. The four production line developed by us are for the manufacuturing of super large square steel pipe(20*20-600*600), cold-formed special section pipes,opening-type steel sections, hot-rolled square pipes, and non-standard circular pipes. 1, the production line of super-large pipes(600*600*25); the pipe sqecification is 100*100-600*600, with a wall thickness of 2-25mm and a bending/distorting degree of less than 1/1000, made of straight carbon steel ,stainless steel, manganeses steel ,alloy steel and special section pipes(ellipse,lozenge,ect) 2,production line of high-accuracy cold pipe and opening-type steel section; the pipe specification is 20*20-150*150,with a wall thickness of 0.8-8mm and bending/distorting degree of 0.2/1000-0.1/1000. it could produce special-shaped steel sections(triangular,octagonal,texagonal ellipse,etc.). and can also produce all kind of opening-type steel sections.