High frequency straight seam welded steel pipes can be divided into straight seam high frequency resistance welded steel pipes and straight seam high frequency induction welded steel pipes according to different high frequency welding processes. The forming process generally adopts roll bending cold forming.
The high-frequency straight seam welded steel pipes are generally produced in smaller diameters, generally with an outer diameter of 660 mm or less than 26 inches. Its characteristics are: fast welding speed. For example, for steel pipes with an outside diameter of less than 1 inch, the maximum welding speed can reach 200 meters/minute. For a 25-inch outer diameter steel pipe, the welding speed can also reach more than 20 meters/minute. The welding method is pressure welding instead of fusion welding. Compared with fusion welding, the welding heat affected zone is relatively small and has little effect on the structure of the base material. The strength and toughness of the weld after welding are different from the parent. According to the use requirements, the internal and external welding burrs can be cleaned or not. Welding can not clean the workpiece, can weld thin-walled tubes, weldable metal tubes.
The ERW steel pipe is a hot-rolled coil formed by a forming machine. The skin effect and proximity effect of high-frequency current are used to heat and melt the edge of the tube blank. Pressure welding is performed under the action of the squeeze roller, pressure welding is carried out to realize the produced product.
The high-frequency resistance welded steel pipe is different from the ordinary welded pipe welding process. The weld seam is formed by melting the base material of the steel belt body, and the mechanical strength is better than the general welded pipe.
The appearance is smooth, the precision is high, the cost is low, and the residual height of the weld is small, which is beneficial to the coating of the 3PE anticorrosive coating. The welding methods of high-frequency welded steel pipes and submerged arc welded pipes are significantly different. Since welding is completed instantly at high speed, it is more difficult to ensure welding quality than submerged arc welding.
The production process mainly depends on the product variety. From raw materials to finished products, a series of processes are required. To complete these processes, various mechanical equipment and welding, electrical control, and testing devices are required. These equipment and devices are in accordance with different process requirements. A variety of reasonable arrangements, high-frequency straight seam welded steel pipe processes: slitting-uncoiling-strip steel leveling-head and tail shear-strip steel butt welding-loop storage-forming-welding-burr removal-sizing-flaw detection- Flying cut-initial inspection?Straightening of Steel Pipes — Processing of Pipe Sections — Hydrostatic Testing — Flaw Detection — Printing and Coating — Finished Products. High frequency straight seam welded steel pipes are mainly used in waterworks, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.
For liquid transportation: water supply and drainage. For gas transportation: coal gas, steam, liquefied petroleum gas. For structural use: for piling pipes and bridges; for pier, road, building structure, etc.