(DOM) Drawn Over Mandrel
Technically, DOM is not a type of steel tube, but rather the process in which the tube is finished. It is considered a high quality tube, and is normally constructed from SAE 1020 or 1026 steel. The first stages of manufacturing are identical to ones used to make electric resistance welded tube, but in the finishing stages the entire flash weld is removed and the tube is cold drawn over a mandrel. The cold drawn process provides the tube with better dimensional tolerances, improved surface finish and the strongest weld strength achievable. DOM is often incorrectly referenced as “seamless tube” when it actually does have a seam (although it is almost invisible).
Seamless Mechanical Tubing
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.
Basically there are two types of seamless tube:
Cold Drawn Seamless (CDS) normally made from SAE 1018, having precise tolerances and good surface finish
Hot Finished Seamless (HFS) normally made from SAE 1026, having less critical tolerances and a scaly finish – Not as strong as CDS
