Classification of square steel pipe

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 strip steel by processing and rolling. Generally, the strip is unpacked, flattened, crimped, welded to form a round tube, and then rolled from the round tube into a square tube and then cut to the required length.Also known as square and rectangular cold bending hollow steel, short for square tube and moment tube, code for F and J, respectively

1. The allowable deviation of the wall thickness of the rectangular pipe shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not more than 10mm, and plus or minus 8% of the wall thickness when the wall thickness is greater than 10mm, except for the wall thickness of the bend and weld area.
2. The usual delivery length of square tube is 4000mm-12000mm, with 6000mm and 12000mm in the majority. Square tube is allowed to deliver not less than 2000mm short ruler and non-size products, can also be delivered in the form of interface tube, but the customer should cut out the interface tube when using. The weight of short and non-fixed size products shall not exceed 5% of the total delivery volume, and for square tube with theoretical weight greater than 20kg/m, it shall not exceed 10% of the total delivery volume
3. The bending degree of square tube shall not be greater than 2mm per meter, and the total bending degree shall not be greater than 0.2% of the total length

Process classification

Square tube according to the production process: hot rolled seamless square tube, cold drawn seamless square tube, extruded seamless square tube, welded square tube.

The welded square pipe is divided into:

1. According to the process – arc welding square pipe, resistance welding square pipe (high frequency, low frequency), gas welding square pipe, furnace welding square pipe
2. According to the weld, it is divided into straight seam welded square pipe and spiral welded square pipe.

The material classification
Square pipe according to material: general carbon steel square pipe, low alloy square pipe.

1. general carbon steel is divided into :Q195, Q215, Q235, SS400, 20# steel, 45# steel and so on.
2. low alloy steel is divided into :Q345, 16Mn, Q390, ST52-3 and so on.

Classification of production standards

According to the production standard, the square tube is divided into: national standard square tube, Japanese standard square tube, British system square tube, American standard square tube, European standard square tube, non-standard square tube.

Square pipes are classified by section shape:

1. simple section square tube: square tube, rectangular square tube.
2. complex section square tube: flower shaped square tube, open shaped square tube, corrugated square tube, special shaped square tube.

Surface treatment classification
Square pipe according to surface treatment: hot dip galvanized square pipe, electric galvanized square pipe, oil coated square pipe, pickling square pipe.

Use classification

The square pipes are classified by use: decorative square pipes, machine tool and equipment square pipes, machinery industry square pipes, chemical square pipes, steel structure square pipes, shipbuilding square pipes, automobile square pipes, steel beam and column square pipes, special purpose square pipes.

Classification of wall thickness

Square rectangular tube according to the wall thickness classification: super thick wall square rectangular tube, thick wall square rectangular tube and thin wall square rectangular tube.

Application: Widely used in machinery manufacturing, construction, metallurgical industry, agricultural vehicles, agricultural greenhouses, automobile industry, railway, highway guardrail, container skeleton, furniture, decoration and steel structure fields.

Used in engineering building decoration, glass curtain wall, doors and Windows, steel structure, guardrail, machinery manufacturing, automobile manufacturing, electrical home appliances manufacturing, shipbuilding, container manufacturing, electricity, agricultural construction, agricultural greenhouse, bike rack, motorcycle frame, shelves, fitness equipment, leisure and tourism supplies, steel furniture, all kinds of specifications of the oil casing, tubing and line pipe, water, gas, water, air, mining Warm and other fluid transport, fire protection and support, construction, etc.

Hardness testing

Hardness is a pointer to measure the degree of hardness of metal materials. The most commonly used method to determine the hardness of square rectangular tube in production is the pressure hardness method. It is used to press into the surface of the metal material under a certain load with a certain geometric shape of the indenter, and test its hardness value according to the degree of pressure.