Straight seam steel pipe is a kind of welded steel pipe that is transformed into a cylindrical shape after forming a hot-rolled steel coil through a forming machine. The high-frequency current skin effect and proximity effect or arc combustion under the flux layer are used for welding, so that the edge of the tube blank is heated and melted under a certain extrusion pressure and finally cooled and formed.

The production process based on high-frequency welded pipe is relatively simple, so relatively speaking, the production efficiency of high-frequency welded pipe is higher, but on the basis of the continuous development of double-sided submerged arc welded pipe, its production efficiency has also been further improved.

Welding seam is an important symbol of welded pipe quality and the life of the welded pipe. Therefore, analysis and treatment of welding section quality defects should be carried out around the welded seam. The main defects of the welded seam include weld cracks, cracks, incomplete penetration, overburning and perforation, Dislocation of welds, etc.

Hot-rolled seamless pipe is an ultra-thin, strong, detailed and stable chromium-rich oxide film (protective film) formed on its surface to prevent oxygen atoms from re-wetting and re-oxidizing, thereby obtaining professional anti-corrosion ability.

Tube billet is the billet for the production of seamless steel pipes, and the most widely used in my country are round continuous casting billets and rolling billets. According to the production method of tube billet, it can be divided into: ingot, continuous cast billet, rolled billet, segment billet and hollow cast billet.

The following principles can be followed to minimize the occurrence of welding deformation.1. Do not over solder, 2. Intermittent weld, 3. Welding sequence, 4. Removal of shrinkage force after welding