Since the 1930s, with the rapid development of continuous rolling steel production and advancements in welding and inspection technologies, the quality of welds has continuously improved. The variety and specifications of welded steel pipes have increased, and they have been increasingly replacing seamless steel pipes in more and more fields. Welded steel pipes are categorized by the type of weld into straight seam and spiral seam pipes. By production method: process classification - arc welding pipes, resistance welding pipes, (high-frequency, low-frequency) gas welding pipes, and furnace welding pipes.

Small diameter welded pipes are usually straight seam welded, while large diameter ones are often spiral welded; they are categorized into round welded pipes and non-standard (square, rectangular, etc.) welded pipes based on the shape of the pipe ends; and they are further divided by material and application into mining fluid transmission welded steel pipes, galvanized welded steel pipes for low-pressure fluid transmission, conveyor belt roller electric welded steel pipes, and more. According to the specifications and sizes in the current national standard, they are sorted in ascending order of outer diameter multiplied by wall thickness.

Product Standards

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 Transportation): Primarily used for transporting water, gas, air, oil, heating hot water, or steam, and other general low-pressure fluids, as well as for other piping applications. The representative material is Q235A steel.

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

GB/T12770-2002 (Welded Steel Tubes for Mechanical Structures): Primarily used in machinery, automobiles, bicycles, furniture, hotel and restaurant decoration, and other mechanical components and structural parts. The representative materials include 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.

GB/T12771-1991 (Welded Steel Pipe for Fluid Transportation): Primarily used for conveying low-pressure corrosive media. Representative materials include 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, and 0017Cr17Ni14Mo2, etc.

Additionally, decorative焊接stainless steel tubes (GB/T 18705-2002), stainless steel welding tubes for building decoration (JG/T 3030-1995), and welded steel tubes for heat exchangers (YB4103-2000).