Welded steel pipe also called welded pipe, the production process of the billet (steel or steel) forming method of cross-sectional shape of roll into demand for a variety of different welding methods, and then use the seamwelding process. Is the basic processes of forming and welding, welded pipe production method is according to the characteristics of the two processes of classification. The welded pipe production process simple, high production efficiency, great variety, less equipment investment, but the general strength is less than that ofseamless steel pipe. In twentieth Century 30 years, with the rapid development of high-quality strip rolling production and progress of welding and testing technology, and constantly improve the welding quality,varieties and specifications of welded steel pipe is increased, and the replacement of seamless steel pipe in more and more fields. According to the form of welded steel pipe weld is divided into longitudinal and spiral welded pipe.
Straight welded pipe production process is simple, high production efficiency, low cost, rapid development.Spiral welded pipe ERW pipe strength than high, with a narrow billet production of large diameter pipe, can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe, weld length should be increased by 30%, to 100%, low production efficiency and. Therefore, most of thesmall caliber pipe welded, large diameter welded pipe mostly using spiral welding.