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Welded steel square/rectangular pipe is a steel pipe made of steel plate or strip after crimping and welding. Welded steel pipe production process is simple, high production efficiency, variety specifications.
Mainly used for pipe transportation, engineering structure, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high pressure equipment and so on
| StandardStandard | GB/T6728-2002,GB/T6725-2002,GBT3094-2000,JG 178-2005,ASTM A500 JIS G3466, EN10210 etc |
| Grade | Q195,Q235,Q345,S235JR,St37-2 |
| Diameter | 10x10mm to 600x600mm |
| Length | 5.8m,6m,9m,12m,or other length as request |
| Surface | Oiled,black painted or hot dip galvanized |
carbon square pipe tube are divided into seamless steel pipes and welded steel pipes.
seamless steel pipe is made of perforated whole round steel, and the steel pipe without weld seam on the surface is called seamless steel pipe. According to the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, and pipe jacking. According to the cross-sectional shape, the seamless steel pipe is divided into two types: round and special-shaped. The maximum diameter is 900mm and the minimum diameter is 4mm. According to different uses, there are thick-walled seamless steel pipes and thin-walled seamless steel pipes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemical industries, boiler pipes, bearing pipes and high-precision structural steel pipes for automobiles, tractors and aviation.
Welded steel pipe also known as welded pipe, is a steel pipe made of steel plate or strip after crimping and welding, generally 6 meters. Welded steel pipe production process is simple, high production efficiency, variety specifications, less investment in equipment, but the general strength is lower than seamless steel pipe.Straight seam welded pipe, steel pipe made of hot or cold rolled steel plate or steel strip coil welding, straight seam welded pipe on welding equipment are called straight seam welded pipe.
① Seamless steel pipe
1.Grade:Q195/Q215/Q235/Q345/S235JR/GRB-D/STK500
2.Size: diemeter is from 21.5 in to406.4 mm,the thickness is from 0.6mmto 20mm the length is from m to 12m
3.Standard:SY/T5037-2000.GB/T9711.1-1997,GB/T9711.2API-5L，SY/T5040 92,ASTMA53A106，DIN1626,DIN1629,DIN2448JIS G3452JIS G3454JIS G3455JIS G3456JIS G3457JIS G3461
② welded pipe
1.Grade:Q195/Q215/Q235/Q345/S235JR/GRB-D/STK500
2.Size: diemeter is from 21.5 in to406.4 mm,the thickness is from 0.6mmto 20mm ,the length is from 1m to 12m
3.Standard:SY/T5037-2000.GB/T9711.1-1997，GB/T9711.2API-5L.SY/T5040-92 ASTMA53A106.DIN1626DIN1629DIN2448.JIS G3452JIS G3454JIS G3455JIS G3456JIS G3457JIS G3461
Hot-rolled carbon steel pipes
Hot-rolled carbon steel pipes are divided into general steel pipes, low- and medium-pressure boiler steel pipes, high-pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.
Cold-rolled carbon steel pipes
Cold-rolled carbon steel pipes are divided into general steel pipes, low/high pressure boiler steel pipes, alloy steel pipes,stainless steel pipes, petroleum cracking pipes, etc., as well as carbon thin-walled steel pipes, alloy thin-walled steel pipes, etc.
The outer diameter of hot-rolled seamless pipe is generally greater than 32mm and the wall thickness is 2.5-75mm, the outer diameter of cold-rolled seamless steel pipe can be up to 6mm, the wall thickness can be up to 0.25mm, the outer diameter of thin-walled pipe can be up to 5mm, and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
Hot-rolled carbon steel pipes 
