Welded steel pipe standards and materials

Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or strip steel after crimping and welding. Welded steel pipe has simple production process, high production efficiency, many varieties and specifications, and less equipment investment, but its general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has continued to improve, and the variety and specifications of welded steel pipes have increased day by day. Seam steel pipe. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of the weld seam.

The blanks used for welded steel pipes are steel plates or strip steel, which are divided into furnace welded pipes, electric welding (resistance welding) pipes and automatic arc welded pipes due to their different welding processes. Because of its different welding forms, it is divided into two types: straight seam welded pipe and spiral welded pipe. Because of its end shape, it is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Due to their different materials and uses, welded pipes are divided into the following varieties:

GB/T3091-1993 (galvanized welded steel pipe for low-pressure fluid transmission). Mainly used for conveying water, gas, air, oil and heating hot water or steam and other general lower pressure fluids and other purposes. Its representative material is Q235A grade steel.

GB/T3092-1993 (galvanized welded steel pipe for low-pressure fluid transmission). Mainly used for conveying water, gas, air, oil and heating hot water or steam and other general lower pressure fluids and other purposes. Its representative material is: Q235A grade steel.

GB/T14291-1992 (welded steel pipes for mine fluid conveyance). It is mainly used for straight seam welded steel pipes for mine compressed air, drainage, and shaft discharge gas. Its representative material is Q235A and B grade steel.
GB/T14980-1994 (large-diameter electric-welded steel pipes for low-pressure fluid transmission). Mainly used for conveying water, sewage, gas, air, heating steam and other low-pressure fluids and other purposes. Its representative material is Q235A grade steel.

GB/T12770-1991 (stainless steel welded steel pipes for mechanical structures). Mainly used in machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.

GB/T12771-1991 (stainless steel welded steel pipes for fluid transportation). It is mainly used for conveying low-pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.

The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe, and the welded pipe with a larger diameter can be produced with a narrower billet, and welded pipes with different diameters can be produced with the same width billet. But compared with the straight seam pipe of the same length, the weld length is increased by 30~100%, and the production speed is lower. Therefore, most of the welded pipes with smaller diameters adopt straight seam welding, and most of the large diameter welded pipes adopt spiral welding.