A seamless tube is a tube that does not have any welding seam. The seamless tube will ideally be a solid metal tube with each end connected to another tube without having any welding joint. These tubes have threads either at one end or at both ends and can be threaded to the end of another hollow tube or pipe.

The presence of any seam on a welded tube acts as a weak point, however, if the tube is seamless, it tends to be solid and overcome various industrial forces and pressures while in operation. A seamless tube may also be known as a seamless pipe.

The seamless tube is manufactured using a process called “extrusion”. During this process a solid steel bar is pierced through the center using a die, turning the solid round into a round tube.

Basically, there are two types of seamless tube:

#1 Cold Drawn Seamless (CDS) normally made from SAE 1018, having precise tolerances and good surface finish.

Benefits of Cold Drawn Seamless (CDS):

Good surface finish

Superior machinability

Increased dimensional tolerances

High strength to weight ratio

#2 Hot Finished Seamless (HFS) normally made from SAE 1026, having less critical tolerances and a scaly finish. Not as strong as CDS.

Benefits of Hot Finish Seamless (HFS):

Cost effective material

Good Machinability

Wide range of sizes