Welded pipe refers to steel pipes that are bent and shaped into circular, square, and other forms from steel strips or plates and then welded together, with seams on the surface. The raw material used in the production of welded steel pipes is steel plates or strips. With the rapid development of continuous rolling production of steel strips and the advancement of welding and inspection technologies, the quality of welds has continuously improved, and the variety and specifications of welded steel pipes have increased, replacing seamless steel pipes in more and more fields. Welded steel pipes are less expensive and more efficient in production than seamless steel pipes.

　　。

Oxygen Blowing Pipe: Used for steelmaking oxygen blowing, typically made of small-diameter welded steel pipes, available in eight sizes ranging from 3/8 inch to 2 inches. Made from steel strips of grades 08, 10, 15, 20, or Q195-Q235. Some are treated with aluminum diffusion to prevent corrosion.

Common materials for welding pipes include: Q235A, Q235C, Q235B, 16Mn, 20#, Q345, L245, L290, X42, X46, X60, X80, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.

Welded steel pipes are made from steel plates or strips, and are categorized into furnace-welded pipes, electric-welded (resistance-welded) pipes, and automatic arc-welded pipes due to their different welding processes. They are further divided into straight seam welded pipes and spiral seam welded pipes based on their welding forms. Additionally, they are classified into round welded pipes and special-shaped (square, flat, etc.) welded pipes according to their end shapes. Welded pipes are categorized into various types based on their materials and applications:

GB/T3091-2008 (Welded Steel Pipe for Low-Pressure Fluid Transmission): Primarily used for conveying water, gas, air, oil, and heating hot water or steam, as well as other general low-pressure fluids and pipes for various applications. Its representative material is Q235A steel.

GB/T14291-2006 (Mining Fluid Transmission Welded Steel Pipe): Mainly used for straight seam welded steel pipes in mining for pressure air, drainage, and shaft gas venting. The representative materials are Q235A and B-grade steel.

Welded pipes are categorized into general welded pipes, galvanized welded pipes, oxygen吹welded pipes, wire conduit, metric welded pipes, roller tubes, deep well pump pipes, automotive pipes, transformer pipes, electric welding thin-walled pipes, electric welding special-shaped pipes, scaffolding pipes, and spiral-welded pipes.