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

Welded steel pipes refer to seamless steel pipes that are bent and shaped into circular, square, or other forms using steel strips or plates 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 such as 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 multiples thereof). Welding pipe specifications are indicated by nominal diameter (in millimeters or inches). Nominal diameter differs from the actual diameter, with welding pipes available in two types: standard wall thickness and thickened wall thickness. Pipes are also categorized by the end type, with threaded and unthreaded options.

Seam Welded Pipe

Process simple, high production efficiency, low cost, rapid development.

Specification: Φ21.3-457.2*1.8-14

Spiral Welded Pipe

Strength is generally higher than that of straight seam welded pipes, allowing for the production of larger diameter pipes with narrower billets, as well as pipes of different diameters with the same width billets. However, compared to straight seam pipes of the same length, 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 usually employ spiral welding.

Spiral-welded steel pipes are categorized 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 of steel materials such as Q235, Q235F, and Q195, serving 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 common carbon steel grades such as Q235, Q235F, and others.

Specification: Φ219-2320*6-22

Standard

GB/T3091-1993 (Galvanized Welded Steel Pipe for Low-Pressure Fluid Transmission). Primarily used for conveying water, gas, air, oil, heating hot water, or steam, among other low-pressure fluids and for various other piping applications. The representative material is Q235A steel.

GB/T3092-1993 (Galvanized Welded Steel Pipe for Low-Pressure Fluid Transportation). Primarily used for conveying water, coal gas, air, oil, heating hot water, or steam, and other general low-pressure fluids and pipes for various other applications. The representative material is Q235A steel.

GB/T14291-1992 (Mine Fluid Conveyance Welded Steel Pipe). Primarily used for straight seam welded steel pipes in mine ventilation, drainage, and shaft gas venting. The representative materials are Q235A and B-grade steel. 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, heating steam, and other applications. The representative material is Q235A-grade steel.

GB/T12770-1991 (Welded 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. Typical materials include 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, and 0017Cr17Ni14Mo2.