What are the categories of thin-walled welded steel pipes?
Date:
03 Apr,2023
The wall thickness of seamless steel pipe is relatively thick, and the diameter thickness is relatively small.However, the diameter of the pipe is limited, its application is also limited, and the production cost, especially the production cost of large-caliber seamless steel pipes, is relatively high.
1. The wall thickness of seamless steel pipe is relatively thick, and the diameter thickness is relatively small.However, the diameter of the pipe is limited, its application is also limited, and the production cost, especially the production cost of large-caliber seamless steel pipes, is relatively high.
2. The high-frequency welded pipe has a good shape and uniform wall thickness. The internal and external burrs generated by the welding are scraped flat by the corresponding tools, and the quality of the welds is strictly controlled through non-destructive testing online. The degree of automation is high and the production cost is low.However, the wall thickness is relatively thin and the pipe diameter is relatively small. The wall thickness generally does not exceed 12mm and the pipe diameter generally does not exceed 610mm. The steel structure is particularly suitable for making pipe frame structures.
3. Straight seam submerged arc welded pipe adopts double-sided submerged arc welding welding process, which is welded under static conditions. The quality of the welds is high, the welds are short, and the chance of defects is very small.The steel pipe is expanded through the full length, the pipe shape is good, the size is accurate, the steel pipe wall thickness range and the pipe diameter range are wide, the pipe diameter range can reach 406-1829mm, the wall thickness range can reach 6.0-60mm, the degree of automation is high, compared with seamless steel pipe, the production cost is low, suitable for buildings, bridges, embankments, marine platforms and other steel structures carrying columns, large-span building structures, and power poles and masts that require wind and seismic resistance.
4. The welds of spiral submerged arc welded pipe are distributed in a spiral line, and the welds are long, especially when welding under dynamic conditions, the welds leave the forming point before they can cool down, which can easily produce welding thermal cracks.The direction of the crack is parallel to the weld and at an angle to the axis of the steel pipe, generally between 30-70°.This angle is just in line with the shear failure angle, so its bending, tensile, compressive and torsional resistance is far inferior to that of straight-seam submerged arc welded pipe. At the same time, due to the limitations of the welding position, the saddle-shaped and fish-ridge-shaped welds produced affect the aesthetics.In addition, during the construction process, the intersecting wire welds at the nodes of the spiral welded female pipe split the spiral joints, resulting in greater welding stress, which greatly weakens the safety performance of the components. Therefore, the non-destructive testing of the welds of the spiral welded pipe should be strengthened to ensure the welding quality. Otherwise, spiral submerged arc welded pipes should not be used in important steel structure occasions.
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