Welded pipe is the abbreviation for welded steel pipes , which is a type of steel pipe.
Steel pipes, as an important component of steel products, are classified as welded steel due to their different manufacturing processes and the shapes of the billets used
There are two main categories: pipe (plate, strip blank) and seamless steel pipe (round blank).
Seamless steel pipes are rarely used in engineering construction departments, and most of them are welded steel pipes made of steel plates and strips, abbreviated as welded steel pipes .
Scaffolding steel pipes are a type of straightwelded steel pipes .
(1) Welded steel pipes
The billets used for welding steel pipes are steel plates or strips, which are divided into furnace welded pipes and electric welding (resistance welding) due to their different welding processes
Pipe and automatic arc welded pipe. Due to their different welding forms, they are divided into two types: straight seam welded pipes and spiral welded pipes. Due to its end shape
It is divided into circular welded pipes and irregular (square, flat, etc.) welded pipes. Welded pipes are divided into several types due to their different materials and uses:
GB/T3091-1993 (Galvanized Welded Steel Pipe for Low Pressure Fluid Transportation). Mainly used for conveying water, gas, air
Pipes for low pressure fluids and other purposes such as oil and heating hot water or steam. Its representative material is Q235A grade steel.
GB/T3092-1993 (Galvanized Welded Steel Pipe for Low Pressure Fluid Transportation)% is mainly used for conveying water, gas, air
Pipes for low pressure fluids and other purposes such as oil and heating hot water or steam. Its representative material is Q235A grade steel.
GB/T14291-1992 (Welded steel pipes for mining fluid transportation) mainly used for mine air pressure, drainage, and shaft gas discharge
Straight seam welded steel pipe. Its representative material is Q235A and B grade steel. GB/T14980-1994 (Large straight pipes for low-pressure fluid transportation)
The diameter welded steel pipe is mainly used for conveying low-pressure fluids such as water, sewage, gas, air, heating steam, and other purposes. his
The representative material is Q235A grade steel.
GB/T12770-1991 (Stainless steel welded steel pipes for mechanical structures) are mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration, and other mechanical components and structural components. Their representative materials are 0Cr13 and 1Cr17 00Cr19Ni11、
1Cr18Ni9, 0Cr18Ni11Nb, etc.
(2) Seamless steel pipe
Due to their different manufacturing processes, they are further divided into two types: hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes. Cold drawing
(Rolling) pipes are divided into two types: circular pipes and irregular pipes.
a. Overview of process flow
Hot rolling (extruded seamless steel pipe): round tube billet – heating – → piercing -+three roll oblique rolling, continuous rolling or extrusion – tube detachment -+sizing (or
Reducing) → Cooling -+Blank Tube -+Straightening -+Hydrostatic Testing (or Flaw Detection) – Marking -+Storage.
Cold drawn (rolled) seamless steel pipe: round tube blank – → heating – perforation and punching – annealing – → acid washing – oil coating (copper plating) – →
Multi pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → hydraulic test (flaw detection) → marking → storage.
B. Seamless steel pipes are divided into the following varieties due to their different uses:
GB/T8162-1999 (Seamless Steel Pipe for Structural Purposes). Mainly used for general and mechanical structures. Its representative material (brand)
No. 20 and No. 45 carbon steel; Alloy steel Q345.20Cr. 40Cr 20CrMo、30-35CrMo. 42CrMo
Etc.
