Use/classification/definition/marking method of square tube:

Square pipe is a kind of pipe that can be seen frequently both in building materials and decorative structures. However, it is still difficult to understand what square tubes are, how they are rolled, how their specifications are expressed, what their main performance requirements are, where they are commonly used or some friends who are new to the steel industry. In this chapter, we will sort out some common knowledge of square tubes for you to help beginners systematically understand square tubes.

Common use of square tubes: square tubes can be used in construction, machinery manufacturing, steel erection and other projects, with detailed applications such as shipbuilding, solar power generation support, steel construction engineering, power engineering, power plant, agricultural and chemical machinery, glass curtain wall, automobile chassis, airport, boiler construction, highway railing, housing construction, pressure vessels, oil tanks, bridges, power plant equipment, Lifting and transportation machinery and other welded structural parts with high load.

Square tube is a kind of light thin-walled steel tube with hollow square section, also known as steel cold-formed section. From the perspective of rolling method, it is a section steel with square section and overall dimension made of Q235 and other steel materials, hot rolled or cold rolled strip or coil as the base material, after cold bending and forming, and then high-frequency welding.

Main mechanical properties: square tube has good comprehensive mechanical properties, good weldability, cold and hot workability, corrosion resistance, and good low-temperature toughness.

Square tubes are made of ordinary carbon steel and alloy steel, so there are ordinary carbon steel square tubes and low-alloy square tubes. Ordinary carbon steel includes Q195, Q215, Q235, SS400, 20 # steel, 45 # steel, etc; Low alloy steels include Q345, 16Mn, Q390, ST52-3, etc.

Classification of square tubes: square tubes can be divided from the aspects of consumption technology, consumption specifications, appearance disposal, section appearance, etc.

Consumption process can be divided into hot rolling Seamless square tube , cold drawn seamless square tube, extruded seamless square tube, welded square tube and other varieties, which can be divided into electric arc welding and resistance welding according to the welding process, and straight seam welding and spiral welding square tube according to the weld seam. According to the consumption specifications, there are different classifications. According to the section shape, it can be divided into flower shaped square tubes, tooth shaped square tubes, corrugated square tubes, and special-shaped square tubes. According to the surface treatment, it can also be divided into hot-dip galvanized, electro galvanized, oiled, and pickled square tubes. In addition, the classification of square tubes also includes the classification of tube wall thickness and usefulness. We will not introduce them one by one here. Interested friends can deepen their understanding.

Let's look at the specification marking method of square pipes: mainly expressed by side width * side width * pipe wall thickness. E.g. 16 × sixteen × 0.4~1.5 indicates that the edge width is 16mm and the pipe wall thickness is 0.4-1.5mm.

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