Welded Pipe Manufacturing

At the start of the welded pipe manufacturing process so called slabs or billets are cast in a steel mill. Dependent on the external dimensions and wall thickness there are different methods of producing welded pipes and tubes: Electric Resistance Welding (ERW), Fusion Welding (EFW) and Double Submerged Arc Welding (DSAW). In the ERW and EFW manufacturing process welded pipes are formed by hot or cold rolling plate and welding the seam. In order to keep the outside (O.D.) surface of a welded pipe smooth and uniform a cutting tool called scarfing blade is used to remove the weld flash. Scarfing from the inside (I.D.) welded flash is also possible. With a heat treating at the end of the manufacturing process the weld zone of the steel pipe can be made less visible. Due to the weld seam lower operating pressures are stated in accordance with ASME compared to seamless pipes. 

In general welded tubes possess tighter dimensional tolerances than seamless pipes and are less costly if produced in same quantities.