The welded square pipe is divided into
(a) 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. (b) Divided by weld - straight welded square pipe and spiral welded square pipe.Material classification of thick walled square pipe
Square tubes are divided into ordinary carbon steel square tubes and low alloy square tubes according to material. Ordinary carbon steel is divided into: Q195, Q215, Q235, SS400, 20# steel, 45# steel, etc; Low alloy steels are divided into Q345, 16Mn, Q390, St52-3, etc.Standard classification of thick walled square pipe production
Square tubes are divided into national standard square tubes, Japanese standard square tubes, British standard square tubes, American standard square tubes, European standard square tubes and non-standard square tubes according to production standards.Section shape classification of thick walled square pipe
Square pipes are classified according to section shape: (1) Simple section square tube - square tube, thick wall rectangular tube. (2) Square pipe with complex section - flower shaped thick wall square pipe, open thick wall square pipe, corrugated thick wall square pipe and special-shaped thick wall square pipe.
Classification of surface treatment of thick walled square tubes
According to surface treatment, thick wall square pipe is divided into: thick wall hot-dip galvanized square pipe, thick wall electro galvanized square pipe, thick wall oiled square pipe and thick wall pickled square pipeThick walled square pipe is a kind of light thick walled steel pipe with hollow square section, also known as steel cold-formed profile. It is a section steel with square section shape and size, which is made of Q235 hot-rolled or cold-rolled strip or coil as the base material, cold bending and high-frequency welding. In addition to the thickening of wall thickness, the corner size and edge flatness of hot-rolled extra thick wall square pipe reach or even exceed the level of resistance welding cold formed square pipe. Thick walled square tubes are used in construction, machinery manufacturing, iron and steel construction projects, shipbuilding, solar power generation supports, steel structure engineering, power engineering, power plants, agricultural and chemical machinery, glass curtain walls, automobile chassis, airports, boiler construction, highway railings, housing construction, similar to square tubes, etc. Classification of thick walled square pipe production process According to the production process, thick wall square pipe is divided into hot-rolled thick wall square pipe, cold drawn thick wall square pipe, extruded thick wall square pipe and welded square pipe.Weight calculation formula of thick walled square pipe
Weight calculation formula of thick walled square pipe: 4 * wall thickness * (side length wall thickness) * 7.85Wall thickness classification of thick walled square pipe
Square tubes are classified by wall thickness - super thick wall square tubes, thick wall square tubes and thin wall square tubesApplication classification of thick walled square pipe
Thick walled square tubes are classified according to their uses - 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 purposesCalculation formula of rectangular tube weight
Calculation formula of rectangular pipe weight: {(perimeter ÷ 3.14) - wall thickness} * wall thickness * 0.02466Large specification
The maximum specification of the rectangular pipe production line of the process Institute is 500mm * 500mm * 19mm, which is the second in the world. The largest 26 inch square tube production line of Nippon Steel in the world is 550mm * 550mm * 22mm. At present, the largest specification of square rectangular pipe in European and American countries is 400 * 400 * 12.7mm.Application status of large square tube
In recent years, with the state's investment in capital construction, more and more major municipal and construction projects around the country have adopted the form of steel structure. Due to the advantages of beautiful appearance, reasonable stress and relatively simple node treatment, large-size thick walled square tube rectangular tube is widely used in airport terminal building Truss structure system and curtain wall support system of sports venues and Convention and exhibition centers are widely used as steel members. However, in practical application, square and rectangular steel pipes also encounter some problems that need to be solved urgently.High strength
In order to reduce self weight and improve safety performance such as earthquake resistance and impact resistance, high-strength steel has been widely used at home and abroad, and the material strength limit has reached 630mpa or even higher. The tensile strength of the base metal of the square and rectangular pipe produced by the process can reach 630mpa, ranking first in the world according to the product strength grade. The maximum strength of the products of Nippon Steel production line in Japan is only 550MPa, with a difference of nearly 15%.Product super thick
The maximum thickness of the square and rectangular tube produced by the process is 19mm. The super thickness is not only reflected in the absolute thickness, but also in the relative thickness of the product. The thickness is an important index of the difficulty of cold bending forming. The square tube is expressed by the edge thickness ratio. At present, it is generally believed at home and abroad that when the edge thickness ratio is less than 10, the product has high forming difficulty. For the square and rectangular pipe produced by the process, the edge thickness ratio of the product with small section and large wall thickness can reach 7, such as 100mm * 100mm * 14mm, 120mm * 120mm * 16mm, etc.Refractory
The cold-formed large-size thick wall square pipe made of B490RNQ hot-rolled steel fully meets and exceeds the requirements of national standard Q345B in terms of mechanical properties at room temperature, its forming and processing properties are equal to or better than Q345B, and the yield ratio meets the seismic requirements of national construction industry specifications. At the same time, its high-temperature performance is significantly better than Q345B of the same level. At 600, the yield strength of B490RNQ remains at 310mpa, which is far higher than 2 / 3 of the room temperature yield strength, while the yield strength of Q345B with a wall thickness of more than 8mm in 500 process is lower than 2 / 3 of the room temperature yield strength.