The seamless tube is manufactured using a process called “extrusion”. During this process a solid steel bar is pierced though the centre using a die, turning the solid round into a round tube.Precision seamless mechanical tubes feature excellent surface integrity and finish, precise inner diameter tolerances and an overall size and geometry control that can’t be achieved at higher cutting speeds.

Basically there are two types of seamless tube:one is Cold Drawn Seamless(CDS),another is Hot Finished Seamless (HFS),which normally made from ASTM A519 1026, having less critical tolerances and a scaly finish.

Cold Drawn Seamless normally made from ASTM A519 1018, having precise tolerances and good surface finish.

In the cold drawing process,a hot finished seamless tube is used as the material (mother tube),the mother tube,after pretreatment ,is cold drawn by the drawing bench to specified dimensions,as shown in the following diagram.the processed tube is subjected to final heat treatment based on it's intended end use and then sent to the finishing and inspection process.