Seamless steel pipe production line

The SMG GROUP’s technical team is highly proficient in seamless steel pipe production technology, capable of independently designing seamless steel pipe production line processes for clients and supplying high-quality related rolling equipment.

Seamless steel pipes are manufactured by piercing a solid round billet, resulting in a surface free of welds. The production methods for seamless steel pipes are broadly divided into the skew rolling method (Mannesmann process) and the extrusion method. The skew rolling method (Mannesmann process) first uses skew rolling rolls to pierce the tube blank, then employs a rolling mill to extend it. This method offers fast production speeds but places higher demands on the machinability of the billet, making it primarily suitable for producing carbon steel and low-alloy steel pipes.

The seamless transformation of steel pipes is mainly achieved through tension reduction, which involves continuous rolling of a hollow billet without a mandrel. Under the condition of ensuring the welding quality of the parent pipe, the welded pipe tension reduction process entails heating the entire welded pipe to above 950 degrees Celsius, followed by passage through a tension reduction mill (with a total of 24 passes) to produce finished pipes of various outer diameters and wall thicknesses. Steel pipes produced using this process differ fundamentally from ordinary high-frequency welded pipes: after being heated in a furnace, their welds achieve complete consistency with the parent material in terms of microstructure and mechanical properties. Moreover, through multiple passes in the tension reduction mill and automated control, the dimensional accuracy of the steel pipes—especially roundness and wall thickness precision—is superior to that of comparable seamless pipes.

The production equipment comprises a piercing machine, an automatic pipe rolling mill, a sizing mill, a diameter‑setting mill, and a reduction mill, among others. The production process for seamless steel pipes consists of the following steps: round billet → heating → piercing → three‑roll skew rolling, continuous rolling, or extrusion → decapping → diameter setting (or reduction) → cooling → straightening → hydrostatic testing (or nondestructive testing) → marking → warehousing.