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Manufacturing process of seamless stainless steel pipe

Manufacturing process of seamless stainless steel pipe

Time:2022-03-17 Source:China Wuxi JiaNuo Special Steel Co.


1. Hot-rolled (extruded seamless steel pipe): round pipe billet → heating → perforation → three-roll slant rolling, continuous rolling or extrusion → deburring → sizing (or reducing) → cooling → straightening → hydrostatic test (or flaw detection) → marking → storage


The raw material for rolling seamless pipes is a round pipe billet. The round pipe embryo is cut and processed into a billet of about 1 meter in length by a cutting machine and sent to the furnace for heating via a conveyor belt. The billet is sent to the furnace to be heated at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Temperature control in the furnace is a key issue. After the round billet is discharged from the furnace, it is hollowed out by a pressure piercing machine. The more common perforating machine is the conical roller perforating machine, which has high productivity, good product quality, large perforation and expansion capacity, and can perforate a variety of steel grades. After perforation, the round pipe billet has been three rolls of oblique rolling, continuous rolling or extrusion. After extrusion, the tube should be sized. Sizing machine through the conical drill bit high-speed rotation into the steel embryo perforation, the formation of steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the sizing machine bit. After sizing, the steel pipe enters the cooling tower and is cooled by water spray, and after cooling, the steel pipe is straightened. Steel pipe is straightened and sent by conveyor belt to the metal flaw detector (or hydraulic test) for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. The steel pipe quality inspection is followed by a strict hand selection. After quality inspection, the steel pipe is sprayed with paint with number, specification, production lot number, etc. And lifted into the warehouse by crane.

2. Cold-drawn (rolled) seamless steel pipe: round billet → heating → piercing → beating → annealing → pickling → oiling (copper plating) → multi-pass cold-drawing (cold rolling) → billet → heat treatment → straightening → hydraulic test (flaw detection) → marking → storage. The rolling method of cold-drawn (rolled) seamless steel pipe is more complex than that of hot-rolled (extruded seamless steel pipe). The first three steps of their production process are basically the same. The difference starts from the fourth step, after the round pipe billet is hollowed out, it has to be tapped and annealed. After annealing, it is pickled with a special acidic liquid. After pickling, oil is applied. Then it is immediately followed by multiple passes of cold drawing (cold rolling) and then billet pipe, a specialized heat treatment. After heat treatment, it has to be straightened.