A steel pipe with welds is distributed in a spiral relative to the axis of the pipe body. Mainly used as transportation pipelines, pipe piles, and some structural pipes. Product specifications: outer diameter 300~3660mm, wall thickness 3.2~25.4mm.
The characteristics of spiral welded pipe production are:
(1) Pipes with various outer diameters can be produced from strips of the same width;
(2) The pipe has good straightness and precise dimensions. The internal and external spiral welds increase the rigidity of the pipe body, so there is no need for sizing and straightening processes after welding;
(3) Easy to realize mechanization, automation, and continuous production;
(4) Compared with other equipment of similar scale, it has smaller dimensions, less land occupation and investment, and is faster to construct;
(5) Compared with straight seam welded pipes of the same size, the weld seam per unit length of the pipe is longer, so productivity is lower.

The production process flow of spiral welded pipe:
The raw materials of spiral welded pipes include strips and plates. A plate is used when the thickness is above 19mm. When using strips, to ensure continuous material supply during butt welding of the front and rear coils, a looper device can be used, or a fly welding trolley can be used for a butt welding connection. The entire material preparation operation from uncoiling to butt welding can be carried out along the track on the fly welding trolley. Completed during the move. When the tail of the front strip steel is caught by the rear clamp of the butt welding machine, the trolley is pulled forward at the same speed as the forming and pre-welding machine. After the butt welding is completed, the rear clamp is released and the trolley returns on its own. to the original position. When using plates, single steel plates need to be butt-welded into strips outside the operating line, and then sent to the operating process line to be butt-welded and connected with a flying welding car. Butt welding is performed using automatic submerged arc welding, which is performed on the inner surface of the pipe. The areas that are not penetrated are formed and pre-welded, and then repaired on the outer surface of the pipe, and then the spiral welds are welded internally and externally. Before the strip enters the forming machine, the edge of the strip must be pre-bent to a certain curvature based on the pipe diameter, wall thickness, and forming angle, so that the deformation curvature of the edge and the middle part after forming is consistent with prevent the “bamboo” defect of protruding weld areas. After pre-bending, it enters the spiral former for forming (see spiral forming) and pre-welding. To improve productivity, a forming and pre-welding line is often used to match multiple internal and external welding lines. This can not only improve the quality of welds but also significantly increase production. Pre-welding generally uses shielded gas arc welding or high-frequency resistance welding with faster welding speed, and full-length welding. This welding uses multi-pole automatic submerged arc welding.

The main development direction of spiral welded pipe production is because the bearing pressure of pipelines is increasing day by day, the use conditions are becoming increasingly harsh, and the service life of pipelines must be extended as much as possible, so the main development directions of spiral welded pipes are:
(1) Produce large-diameter thick-walled pipes to improve pressure resistance;
(2) Design and produce new structural steel pipes, such as double-layer spiral welded pipes, which are welded into double-layer pipes with strip steel half the thickness of the pipe wall. Not only are their strengths higher than single-layer pipes of the same thickness, but they will not cause brittle damage;
(3) Develop new steel types, improve the technical level of smelting processes, and widely adopt controlled rolling and post-rolling waste heat treatment processes to continuously improve the strength, toughness, and welding performance of the pipe body;
(4) Vigorously develop coated pipes. For example, coating the inner wall of the pipe with an anti-corrosion layer can not only extend the service life, but also improve the smoothness of the inner wall, reduce fluid friction resistance, reduce wax and dirt accumulation, reduce the number of pipe cleaning times, and reduce maintenance.