Seamless steel pipe and welded pipe are divided according to different production processes. Seamless steel pipes include hot rolling, cold rolling, cold drawing and other process such as cold extrusion. Welded pipe is made of steel plate by crimp welding. Small pipe is usually welded by straight seam welding and large pipe is generally welded by spiral welding.
Because the welded pipe has welds and its mechanical properties are poor, its application scope is limited, but its price is cheaper. The remarkable difference between seamless steel pipe and welded pipe is that there are welds in welded pipe and no in seamless steel pipe. But if the welded pipe is handled well, it is not easy for laymen to see the difference.