Square pipe is a name for square pipe and rectangular pipe, that is, steel pipe with equal and unequal side lengths. It is made of rolled strip steel after process treatment. Generally, the strip steel is unpacked, leveled, crimped and welded to form a round pipe, then rolled into a square pipe from the round pipe, and then cut into the required length.

1. The allowable deviation of the wall thickness of square pipe shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is no more than 10mm, plus or minus 8% of the wall thickness when the wall thickness is more than 10mm, except for the wall thickness of corners and weld areas.

2. The usual delivery length of square rectangular pipe is 4000mm-12000mm, mostly 6000mm and 12000mm. The rectangular tube is allowed to deliver short and non fixed length products not less than 2000mm, and can also be delivered in the form of interface tube, but the Demander shall cut off the interface tube when using it. The weight of short gauge and non fixed gauge products shall not exceed 5% of the total delivery volume. For square moment tubes with theoretical weight greater than 20kg / m, it shall not exceed 10% of the total delivery volume

3. The bending degree of square rectangular pipe shall not be greater than 2mm per meter, and the total bending degree shall not be greater than 0.2% of the total length

According to the production process, square tubes are divided into hot-rolled seamless square tubes, cold drawn seamless square tubes, extruded seamless square tubes and welded square tubes.

The welded square pipe is divided into

1. According to the process – arc welding square tube, resistance welding square tube (high frequency and low frequency), gas welding square tube and furnace welding square tube

2. According to the weld – straight welded square pipe and spiral welded square pipe.

Material classification

Square tubes are divided into ordinary carbon steel square tubes and low alloy square tubes according to material.

1. Ordinary carbon steel is divided into Q195, Q215, Q235, SS400, 20# steel, 45# steel, etc.

2. Low alloy steel is divided into Q345, 16Mn, Q390, St52-3, etc.

Production standard classification

Square tube is divided into national standard square tube, Japanese standard square tube, British standard square tube, American standard square tube, European standard square tube and non-standard square tube according to production standards.

Section shape classification

Square pipes are classified according to section shape:

1. Simple section square tube: square tube, rectangular tube.

2. Square tube with complex section: flower shaped square tube, open square tube, corrugated square tube and special-shaped square tube.

Surface treatment classification

Square pipes are divided into hot-dip galvanized square pipes, electro galvanized square pipes, oiled square pipes and pickled square pipes according to surface treatment.

Use classification

Square tubes are classified by use: square tubes for decoration, square tubes for machine tool equipment, square tubes for mechanical industry, square tubes for chemical industry, square tubes for steel structure, square tubes for shipbuilding, square tubes for automobile, square tubes for steel beams and columns, and square tubes for special purposes.

Wall thickness classification

Rectangular tubes are classified according to wall thickness: extra thick walled rectangular tubes, thick walled rectangular tubes and thin-walled rectangular tubes. Our factory has the production technology on the market, and is very skilled. Welcome international friends to consult. We will try our best to meet your various needs.