The pipe is manufactured by one of the following processes:
Seamless (SMLS) pipe is made by a process that does not involve welding at any stage of production.
Welded (WLD) pipe is made using an automatic welding process with no addition of filler during the welding process.
Heavily cold-worked (HCW) pipe is made by applying cold working of not less than 35% reduction in thickness of both wall and weld to a welded pipe prior to the final annealing. No filler is used in making the weld.