How to make the seamless steel pipe without welding seam?
As we know that the seamless steel pipe must be no welding seam appear on the surface, but how could we make it “seamless”? Usually, we have 4 methods to manufacture the seamless steel pipe, they are hot rolling, cold rolling, cold drawing and casting. Today, let Great Steel Pipe sharing the hot & cold rolling manufacture methods for all of you.
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.
Manufacture process of hot rolling: 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
Cold rolled seamless steel pipe is usually 0.5 ~ 100T single-chain or double-chain cold drawn machine. Finished seamless steel tubes are usually carried out on a two-roll mill where the steel pipe is rolled in a ring-shaped bore formed by a variable cross-section round hole and a stationary tapered head. Cold rolling technology can produce thin wall thickness steel pipe, such as plum tube, hexagonal tube, bread tube, and etc.
Manufacture process of cold rolling: Round bars→inspection→cut off→heating→perforation→rolling pipe→cool down→inspection→pickling, lubrication→cold rolling(cold drawn)→heating→straightening→hydrostatic test (or flaw detection)→anti-rust treatment→mark,packing→storage