How to solve the stress and deformation caused by welding of spiral steel pipe?

　　In the process of spiral steel pipe production, as long as welding is carried out, the stress and deformation will occur on the surface of the spiral steel pipe, but the degree is different. Welding stress and deformation caused by spiral steel pipe often cause the quality of welding products to decrease and even cause cracks. The welding deformation causes the change of the size and shape of the welded parts. After this change is more than a certain value, it may not be able to connect with other spiral steel pipe or not have enough machining allowance to be machined.

　　First, the surface stress of the API 5L Psl 1 SSAW Welded Spiral Steel Pipe, when the material can not produce displacement under the external force, its geometry and size will change, this kind of deformation is called strain. When the material is deformed, the internal force is equal to the opposite force, and the internal force is called the stress at one point. The product of the stress and the micro area is the internal force, or the body is deformed because of the external cause (the force, the temperature change, etc.), and the interaction between the parts of the body is produced. The internal force is used to resist the action of external cause, and to map the object from the deformed position to the position before deformation.

　　From a mechanical point of view, deformation refers to the change in the shape of a structure (or part thereof). Any structure is composed of deformable solid materials, which will produce deformation and displacement under the action of external forces.

　　In the process of spiral steel pipe production, even if it can be corrected, such as mechanical or flame correction, it is not only time-consuming and laborious, but also increases the additional stress of the spiral steel pipe. It is unfavorable to the construction of the welding stress and deformation, and we must reduce the welding stress and deformation and avoid the welding stress and deformation.