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

Welded steel pipes refer to pipes that are formed by bending and deforming steel strips or plates into shapes such as circular or square, and then welded together, with a seam on the surface. The raw material used for welding steel pipes is steel plates or strips.

General Welded Pipe

General welding pipes are used for transporting 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 hydraulic pressure, bending, and flattening tests, with certain surface quality requirements. The standard delivery length is typically 4-10 meters, often requiring fixed or multiple fixed lengths. Welding pipe specifications are indicated by nominal diameter (in millimeters or inches). The nominal diameter differs from the actual size, with two types of pipes available according to the wall thickness: standard and heavy-duty. Pipes are also categorized by their end forms into threaded and unthreaded types.

Seamless Welded Pipe

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

Specification: Φ21.3-457.2*1.8-14

Spiral Welded Pipe

Strength is generally higher than that of seamless pipes, allowing larger diameter pipes to be produced from narrower billets, and different diameter pipes can be made from the same width billets as well. However, compared to pipes of the same length with a straight seam, the weld length increases by 30~100%, and production speed is slower. Therefore, smaller diameter pipes mostly use straight seam welding, while larger diameter pipes usually opt for 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 of the conveyed medium. Class A pipes are generally made of ordinary carbon steel Q235, Q235F, and ordinary low-alloy structural steel 16Mn, while Class B pipes are made from steel grades such as Q235, Q235F, and Q195, used as low-pressure fluid conveyance pipes.

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

Specification: Φ219-2320*6-22

Standard

GB/T3091-1993 (Galvanized Welded Steel Pipe for Low-Pressure Fluid Transportation). 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/T3092-1993 (Galvanized Welded Steel Pipe for Low-Pressure Fluid Transmission). Primarily used for conveying water, gas, air, oil, heating hot water, or steam, among other lower-pressure fluids and for various other pipeline 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 mining for pressure air, drainage, and shaft gas venting. The representative material grades are Q235A and B. GB/T14980-1994 (Large Diameter Electric Welded Steel Pipe for Low-Pressure Fluid Conveyance). Mainly used for conveying low-pressure fluids such as water, wastewater, gas, air, and heating steam, as well as other applications. The representative material grade is Q235A.

GB/T12770-1991 (Welded Steel Pipes 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 Steel Pipe for Fluid Transportation). Primarily used for conveying low-pressure corrosive media. Representative materials include 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, and more.