Black square tube is a commonly used steel pipe material, also known as black rectangular steel pipe or square welded pipe. Its cross-sectional shape is rectangular or square, with high strength and compressive resistance. Black square tube is mainly made by welding process, and common finished product sizes are 30*20mm, 40*20mm, 50*25mm, etc., which can also be customized according to customer needs.
Black square tube is widely used in the field of construction engineering. Due to the unique characteristics of the cross-sectional shape of black square tube, it plays an important role in the frame and supporting structure of the building. It can be used to make various building components such as steel structure columns, beams, crossbeams, stair handrails, etc., to provide stable structural support for the building. The inside and outside of the black square tube are not galvanized. Therefore, when using black square tube, it is necessary to pay attention to its anti-rust treatment to prevent it from rusting in a humid environment. During storage and transportation, the black square tube should be kept dry and ventilated to avoid direct contact with moisture and chemicals.
Black square tube refers to a square steel tube with black oxide skin or black anti-rust treatment on the surface, which is widely used in building structure, machinery manufacturing, furniture manufacturing and other fields. Its manufacturing process is mainly divided into two categories: seamless black square tube and welded black square tube, and the process flow of the two is different.
Welded black square tube is the most common type of black square tube on the market, and its manufacturing process includes multiple steps. First, high-quality low-carbon steel or low-alloy steel strip is selected as the raw material, and the thickness and width of the steel strip are determined according to the pipe specifications. The steel coil is unrolled by the unwinder and corrected by the leveling machine to ensure that the steel strip is flat and wave-free, and then it is longitudinally cut into strip steel of appropriate width according to the specifications. Then, the strip steel is gradually bent into a circle by the forming machine, and then pressed into a square or rectangular section by the forming roller. Subsequently, the pipe seam is welded by high-speed electric resistance welding (ERW) or submerged arc welding (SAW) technology to ensure that the weld is firm and flat, and the weld surface is ground or polished to ensure that the surface of the pipe body is smooth. Some high-end products will also be annealed or heat treated to release internal stress and improve mechanical properties. The pipe is cut to length according to customer needs, and the surface is kept in natural black oxide scale or sprayed with black anti-rust paint. Finally, the size, weld and appearance are inspected, and the qualified ones are packaged and shipped.
Welded black square pipe process
1.Raw material preparation: Select high-quality steel strip.
2.Uncoiling and leveling: Unroll and level the steel strip.
3.Forming: Bend into a square shape by a forming machine.
4.Welding: Use resistance welding or submerged arc welding to weld the pipe seam.
5.Weld seam treatment: Grind the weld seam to ensure the surface is flat.
6.Cutting and surface treatment: Cut to length, keep black oxide scale on the surface or spray black paint for rust prevention.
7.Inspection and packaging: Check the size and weld quality before packaging.
Seamless black square pipe process
2.Cold bending into a square tube shape.
3.Straightening and cutting, surface treatment before delivery.
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