A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members. There are two technologies that can be used to manufacture steel pipes that can be produced by seamless and ERW 

Seamless (SMLS) pipe is formed by drawing a solid billet over a piercing rod to create the hollow shell. As the manufacturing process does not include any welding, seamless pipes are perceived to be stronger and more reliable.

ERW pipes are manufactured from the longitudinal welding of steel. The welding process for ERW pipes is continuous as opposed to welding of distinct sections at intervals. ERW process uses steel coil as feedstock.