Large diameter square tube production and processing technology

Large-diameter square pipe is a name for square tube, also known as square cold-formed hollow section steel, referred to as square pipe or square steel pipe. Its characteristic is that the side lengths of the pipe are equal. It is made of strip steel rolled through process treatment. Generally, the strip steel is unpacked, flattened, curled, and welded into a round tube, which is then rolled into a square tube and then cut to the required length.
1. There are two main production processes for square steel pipes: welding forming process and seamless forming process. The materials used in these two processes are mainly Q235, Q345 and 20# (Q235 can be used in the welding process, 20# can only be used in the seamless production process, while Q345 material can be used in both production processes)
2. The allowable deviation of the wall thickness of square steel pipes shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not greater than 10 mm. When the wall thickness is greater than 10 mm, it shall be plus or minus 8% of the wall thickness. Walls in the corners and weld areas Except thick.
3. The usual delivery length of square steel pipes is 4000mm-12000mm. The welding process is mostly 6000mm and 12000mm, while the seamless process is mostly 9000mm-11000mm. Large-diameter square steel pipes are allowed to be delivered in short and non-cut lengths of not less than 2000mm, and can also be delivered in the form of interface pipes, but the purchaser should cut off the interface pipes when using them. The weight of short-length and non-fixed-length products shall not exceed 5% of the total delivery volume. For square and rectangular pipes with a theoretical weight greater than 20kg/m, the weight shall not exceed 10% of the total delivery volume.
4. The curvature of square and rectangular pipes shall not be greater than 2mm per meter, and the total curvature shall not be greater than 0.2% of the total length.
5. Calculation of weight of square steel pipe and round pipe:
Circle to square conversion formula: (side length + side length) ÷ 2X1.29-thickness = outer diameter of round tube
Calculation of the weight of round pipe per meter: diameter – thickness) X thickness X 0.02466