Development Process of Small Diameter Welded Pipe Production Lines

There are numerous forming methods for small diameter welded pipe production lines (lines with diameters below 8 inches). The earliest methods included the guide plate forming method and the opposed roller forming method (including edge bending, center bending, and circumferential bending). The row roller forming method was introduced at the end of the 1970s. Entering the 1980s, in order to improve product quality and expand the range of product specifications, numerous new forming methods were successively developed. These primarily included: the vertical roller forming method (VRF) and linear row roller forming method for producing thin-walled pipes; the assembled forming method with edge forming machines for producing thick-walled pipes; the composite forming method for producing extremely thick-walled pipes; the W-bend roller forming method and flexible forming method (FF method) capable of producing both thin-walled and thick-walled pipes; the roller-less natural forming method for producing ultra-thin-walled pipes; and the convexity-free bending roller forming method (CBR method), among others. In recent years, in addition to the guide plate forming method, all other forming methods have been adopted. The thinnest pipe produced has a t/D ratio of 0.3%, while the thickest welded pipe has a t/D ratio of 26%. The production steel grades include carbon steel, alloy steel, and stainless steel.