Seamless Steel Pipe Manufacturing Process

Hot-rolled seamless pipes

Hot-rolled seamless pipes are typically manufactured using automatic pipe rolling units. The process involves inspecting the solid tube blank, removing surface defects, cutting it to the required length, centering it on the perforated end, and then heating and piercing it on a punching machine. As the tube blank rotates and advances during hole piercing, it gradually hollows out, forming the gross pipe. Subsequently, it undergoes continuous rolling on an automatic pipe rolling machine. The wall thickness is then evened out by a leveling machine, and the diameter is adjusted by a sizing machine to meet specification requirements. Utilizing continuous pipe rolling units for the production of hot-rolled seamless steel pipes represents a more advanced approach.

Cold rolling seamless pipes

Cold rolling is typically conducted using a two-roll mill, where the steel pipe is rolled in a circular pass consisting of a variable cross-section circular groove and a fixed conical head. Cold drawing, on the other hand, is commonly done using a single-chain or double-chain cold drawing machine ranging from 0.5 to 100T.

Extrusion method

In the extrusion method, the heated tube blank is inserted into a closed extrusion cylinder. The perforated rod and extrusion rod move together, causing the extruded part to come out through a smaller die hole. This technique is capable of producing steel pipes with smaller diameters.