Welded steel pipes, also called welded pipes, are steel pipes made of steel plates or strips welded after crimping, and are generally 6 meters in length. Welded steel pipes have simple production process, high production efficiency, many varieties and specifications, and low equipment investment, but their general strength is lower than seamless steel pipes.

Smaller-caliber welded pipes are welded by straight seam, while large-caliber welded pipes are mostly spiral welded; according to the shape of the end of the steel pipe, it is divided into round welded pipe and special-shaped (square, rectangular, etc.) welded pipe; according to different materials and uses, it is divided into mining fluid Conveying welded steel pipes, galvanized welded steel pipes for low-pressure fluid conveying, electric welded steel pipes for belt conveyor rollers, etc. According to the size table in the current national standard, sort by outer diameter * wall thickness from small to large.