Welded steel pipe, also known as welded pipe, is the steel pipe that made of steel plate or steel strip after crimped and welded. The production process of welded steel pipe is simple, production efficiency is high, variety specifications are many, the investment of equipment is little, but its general strength is lower than the seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip continuous rolling line and the improvement of welding and inspection technology, the quality of welding line has been increasing continuously, and the specifications of welded steel pipes have been increasing. And welded pipe have replaced the seamless steel pipe in more and more field. Sewing steel pipe. The welded steel pipe is divided into straight seam welded pipe(also called LSAW steel pipe) and spiral welded pipe(also called SSAW steel pipe) according to the form of welding line.
Production process of LSAW steel pipe is simple, production efficiency is high, cost is low, and it develops rapidly. The strength of the SSAW steel pipe is generally higher than that of the LSAW steel pipe, and the SSAW steel pipe with larger diameter can be produced with the narrow billet. And it also can use the billet with the same width to produce t SSAW steel pipe with different diameter. However, compared with the straight seam welded pipe in identical length, the length of welding line increased by 30 to 100%, and the production rate was low.
Therefore, pipe manufacturers usually use straight seam welding to produce the smaller diameter of the pipe, use spiral welding to produce large diameter welded pipe.
