Welded Pipe Categories: General Welded Pipe, Seamless Welded Pipe, Spiral Welded Pipe

Welded steel pipes refer to seamless steel pipes that are formed by bending and deforming steel strips or plates into circular, square, or other shapes and then welded together. The raw material used for welding steel pipes is steel plates or strips.

Standard Welded Pipe

General welding pipes are used for conveying low-pressure fluids. They are manufactured from steel grades Q195A, Q215A, and Q235A. Other easily weldable soft steels can also be used. The pipes must undergo hydrostatic, bending, and flattening tests, with certain surface quality requirements. The standard delivery length is typically 4-10 meters, and it is often required to deliver pipes to a specified length (or multiple thereof). Welding pipe specifications are indicated by nominal diameter (mm or inches), which differs from the actual diameter. Welded pipes are available in two types based on wall thickness: standard and thickened. They are also classified into two types according to the pipe end form: threaded and unthreaded.

Seamless Welded Pipe

Simple production process, high efficiency, low cost, and rapid development.

Spec: Φ21.3-457.2*1.8-14

Spiral Welded Pipe

The strength is generally higher than that of seamless pipes, allowing for the production of larger diameter pipes using narrower billets. It also enables the production of pipes of different diameters with the same width billet. However, compared to pipes of the same length with a straight seam, the weld length increases by 30~100%, and the production speed is slower. Therefore, smaller diameter pipes mostly use straight seam welding, while larger diameter pipes are mostly produced using spiral welding.

Spiral-welded steel pipes are divided into two types: automatic submerged arc welding pipes and high-frequency welding pipes.

a. Spiral seam automatic submerged arc welded steel pipes are divided into two categories: Class A pipes and Class B pipes, based on the pressure levels of the conveyed medium. Class A pipes are generally made of ordinary carbon steel Q235, Q235F, and ordinary low-alloy structural steel 16Mn for welding, while Class B pipes are made of steel materials such as Q235, Q235F, and Q195 for welding, used as low-pressure fluid conveying pipes.

b. Spiral Seam High-Frequency Welded Steel Pipe - There is no unified product standard for spiral seam high-frequency welded steel pipes. They are generally manufactured using ordinary carbon steel grades such as Q235, Q235F, and others.

Spec: Φ219-2320*6-22

Standard

GB/T3091-1993 (Galvanized 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 pipe applications. The representative material is Q235A steel.

GB/T3092-1993 (Galvanized Welded Steel Pipe for Low-Pressure Fluid Transmission). Primarily used for conveying 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/T14291-1992 (Mining Fluid Conveyance Welded Steel Pipe). Primarily used for straight seam welded steel pipes in mine ventilation, drainage, and shaft gas venting. The representative material is Q235A, B-grade steel. GB/T14980-1994 (Large Diameter Electric Welded Steel Pipe for Low-Pressure Fluid Conveyance). Mainly used for conveying water, wastewater, gas, air, heating steam, and other low-pressure fluids, as well as other applications. The representative material is Q235A-grade steel.

GB/T12770-1991 (Welded Stainless Steel Tubes for Mechanical Structures). Primarily used in machinery, automobiles, bicycles, furniture, hotel and restaurant decorations, and other mechanical components and structural parts. The representative materials include 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.

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