Hot-rolled seamless steel pipe is a large category of seamless steel pipe, which is divided according to the production method. Hot rolling is relative to cold rolling, cold rolling is carried out rolling at room temperature, and hot rolling is carried out rolling at the recrystallization temperature. Seamless steel pipe is named relative to the welded steel pipe, seamless steel pipe is usually made of round steel perforation and reprocessing, welded steel pipe is usually welded by steel plate in different ways. The diameter of hot-rolled seamless steel pipe is usually above 38mm. Seamless steel pipe with smaller diameter can be obtained by cold rolling or cold drawing.
The process of hot-rolled seamless steel pipe:
Hot-rolled seamless steel pipe is generally produced on automatic rolling mill units. The solid bar is inspected and cleared of surface defects. Then it is cut into the required length, and centered on face of the perforation end of the pipe billet. And then it will be sent to the heating furnace to heat, and bore a hole on the puncher. In the perforation, the solid bar will continue to rotate and forward at the same time, in the role of the roll and the head, the tube billet internal will be gradually formed cavity, that is said capillary. And then it will be sent to the automatic rolling mill to continue rolling. Finally, it will be reeled the wall thickness by reeling mill, sized by sizing mill, to achieve the specifications. It is a more advanced method that using continuous rolling mill to produce hot-rolled seamless steel pipe. Generally process of hot-rolled seamless steel pipe: round bars → heating → piercing → three-roll cross rolling, rolling or extrusion → detached → sizing (or reducing) → cooling → parison tube → straightening → hydrostatic test (or flaw detection) → mark → storage.