What Is a Steel Tube?

Steel tubes can be classified according to rolling methods, whether there are seams and cross-sectional shapes. According to the rolling process classification, steel tubes can be divided into hot-rolled steel tubes and cold-rolled steel tubes; according to whether there are seams in steel tubes, steel tubes are divided into seamless steel tubes and welded steel tubes. Among them, the commonly used welded steel tubes can be divided into high-frequency welded tubes according to the type of weld. 3, straight seam submerged arc welded pipe, spiral submerged arc welded pipe, etc.

Classification

The thickness of the seamless steel pipe is relatively thick, and the diameter is relatively small. But the pipe diameter is limited, its application is also limited, and the production cost, especially

The spiral submerged arc welded pipe has a spiral distribution, and the weld is long, especially when it is welded under dynamic conditions. The weld leaves the forming point before it has time to cool, and it is very easy to generate welding thermal cracks. The direction of the crack is parallel to the weld and forms a certain angle with the axis of the steel pipe, generally between 30-70 °. This angle is just consistent with the shear failure angle, so its bending, tensile, compression and torsion resistance is far inferior to that of a straight seam submerged arc welded pipe. At the same time, due to the limitation of the welding position, the saddle-shaped and ridge-shaped welds are affected. Beautiful. In addition, during the construction process, the intersecting line welds at the joints of the spiral welded mother pipe split the spiral seams, resulting in greater welding stress, which greatly weakened the safety performance of the components. Therefore, the non-destructive testing of the welds of the spiral welded pipes should be strengthened. Ensure welding quality, otherwise it is not suitable to use spiral submerged arc welding pipes in important steel structure occasions.