Welded pipe is the common pipe material in gas pipeline, which is greater than 426 mm in diameter (508 mm) or the welded pipe is generally referred to as the large diameter solder pipe, according to the welding as a way for tube, the solder steel pipe can be divided into spiral pipe and straight seam welding tube. Spiral welded pipe is the low carbon carbon structural steel and low alloy structural steel strip according to certain helix Angle (also called the molding Angle) rolled into a tube billet, and then solder pipe joints made up, it can use a narrow strip in the production of large diameter steel tube, straight seam solder pipe is hot rolled plate after molding machine molding, roll deformation of steel coil for round cylinder, using high frequency current skin effect and proximity effect or flux layer burning under the arc soldering, the tube billet is heated to melt, and fusion under certain extrusion effect, after the final cooling forming.

Welded tube is made of steel plate or steel strip after crimp forming, and then after welding. Divided into the form of the weld seam welded tube and spiral welded pipe, straight seam steel tube forming technique of common UOE forming process, JCOE steel pipe forming process. According to the application, it is divided into general welded pipe, galvanized welded tube, oxygen blowing metric pipe, welded tubes, wire casing, roller tube, deep well pump tubes, auto tube, transformer, electric soldering thin wall pipe, welded pipe and spiral welded tube.

Seamless soldering technology in the welded pipe soldering shows excellent performance, not only help eliminate mold weld, but also enhances the precision of parts accordingly, smoothness and appearance is considerable. At the same time, the seamless soldering technology implemented effective control in the process of plastic injection forming, shorten the mould processing cycle. Due to the production of the product has excellent surface finish, so there is no need to use the secondary plating and annealing, also avoids the size change due to secondary shrinkage. According to the technological requirements of the new technology, processing similar mesh mold core and cavity, in order to avoid its mobile and the second clamping, use the fourth axis milling machine tool, so that we can improve the tolerance dimension precision. Plate finned and water chamber cooling pipes have been more widely used, further improve the product quality and seamless welded finish.