Cold drawn (rolled) seamless steel tube: round tube blank → heating → piercing → start → annealing → pickling → oil coating (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → Hydrostatic test (flaw detection) → mark → storage.

Hot rolling (extrusion seamless steel pipe): round billet → heating → perforation → three-roller oblique rolling, continuous rolling or extrusion → stripping → sizing (or reducing) → cooling → blank tube → straightening → water pressure Test (or flaw detection) → mark → storage.