According to the different production methods can be divided into hot-rolled seamless pipe, cold-rolled seamless pipe, cold-draw seamless pipe, extruded tubes.
1. Hot-rolled seamless pipe is generally automatic pipe mill production. Solid tube inspection and removal of surface defects, cut into desired length, and then sent to the furnace heating, punch a hole in the perforated tube end surface-centering. In the hole while constantly rotating and forward rolls and the role of the head tube gradually formed within the cavity, said capillary. And then sent to the automatic rolling machine to rolling. Finally, both the whole, the whole wall thickness, sizing the sizing mill , to achieve the required specifications. The use to continuous production of hot-rolled seamless steel pipe mill is a more advanced method.
2. For smaller and better-quality seamless cold-rolled, drawn or a combination of methods must be used. Cold rolled normally on a two-rolled normally on a two-roll mill, steel becomes the section round hole slot and does not move tapered head circular hole formed in the rolling. Drawing is usually 0.5 to 100Tsingle chain or double chain drawing machine.
Extrusion method is about 1.3-heating tube closed extrusion cylinder, perforated stick together with the extruded rod movement, extrusion from the small hole in the mold. This method can produce a smaller diameter steel pipe.