Classification and various uses of welded steel pipes

Welded pipes, also known as welded steel pipes, are basically steel pipes made by welding steel plates or strips after curling and forming. Welded steel pipes have simple production processes, high production efficiency, many varieties and specifications, and low equipment investment, but their general strength is lower than that of seamless steel pipes. Since the 1930s, with the rapid development of high-quality strip steel continuous rolling production and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the varieties and specifications of welded steel pipes have increased day by day, and they have replaced seamless steel pipes in more and more fields. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of welds.

First, the classification of welded pipes

Welded pipes are classified by use: according to their use, they are divided into general welded pipes, galvanized welded pipes, oxygen-blown welded pipes, wire casings, metric welded pipes, roller pipes, deep well pump pipes, automobile pipes, transformer pipes, electric welded thin-walled pipes, electric welded special-shaped pipes and spiral welded pipes.

Second, the application scope of welded pipes

Welded pipe products are widely used in boilers, automobiles, ships, doors, and windows steel for light structures of buildings, furniture, various agricultural machinery, scaffolding, wire threading pipes, high-rise shelves, containers, etc. All can meet customer requirements, and special specifications of welded pipes can be processed according to user requirements.

Third, the theoretical calculation method of welded pipe weight

The theoretical calculation method of welded pipe weight has a formula to follow;

Theoretical weight of steel pipe per meter (the density of steel is 7.85kg/dm3)

Calculation formula: W=0.02466 (D-S) S

Where: W--theoretical weight of steel pipe per meter, kg/m;

D--nominal outer diameter of steel pipe, mm;

S--nominal wall thickness of steel pipe, mm.

Fourth, the official definition and industrial use of welded pipes

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

1. GB/T3091-1993 (galvanized welded steel pipe for low-pressure fluid transportation). It is mainly used for conveying water, gas, air, oil, heating hot water or steam, and other generally low-pressure fluids and other pipes. Its representative material is Q235A grade steel.

2. GB/T3092-1993 (galvanized welded steel pipe for low-pressure fluid transportation). It is mainly used for conveying water, gas, air, oil, heating hot water or steam, and other generally low-pressure fluids and other pipes. Its representative material is: Q235A grade steel.

3. GB/T14291-1992 (welded steel pipe for fluid transportation in mines). It is mainly used for straight seam welded steel pipes for mine compressed air, drainage, and axial gas discharge. Its representative materials are Q235A and B-grade steel. GB/T14980-1994 (Large diameter electric welded steel pipe for low-pressure fluid transportation). Mainly used for conveying low-pressure fluids such as water, sewage, gas, air, heating steam, and other purposes. Its representative material is Q235A grade steel.

4. GB/T12770-1991 (Stainless steel welded steel pipe for mechanical structure). Mainly used for 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.

5. GB/T12771-1991 (Stainless steel welded steel pipe for fluid transportation). Mainly used for conveying low-pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.