Manufacturing process of seamless pipes

Release time：2025-09-01    Click：55

　　1. Hot rolled (extruded seamless pipes): round tube blank → heating → perforation → three roll cross rolling, continuous rolling or extrusion → pipe stripping → sizing (or reducing) → cooling → straightening → hydrostatic test (or flaw detection) → marking → warehousing

　　The raw material for rolling seamless pipes is round tube blank. The round tube blank shall be cut and processed by the cutter, and the blank with a growth of about 1m shall be sent to the furnace for heating through the conveyor belt. The billet is sent to the furnace for heating at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Temperature control in furnace is a key problem After the round tube blank is discharged from the furnace, it shall be pierced through the pressure piercer. Generally, the more common piercer is the cone roll piercer. This kind of piercer has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of steel grades. After perforation, the round tube blank is successively rolled by three roll cross rolling, continuous rolling or extrusion. After extrusion, take off the pipe for sizing. The sizing machine rotates into the steel embryo at high speed through the conical drill to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the sizing machine bit. After sizing, the steel pipe enters the cooling tower and is cooled by water spray. After cooling, the steel pipe will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydrostatic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. Steel pipes should be strictly selected by hand after quality inspection. After the steel pipe is inspected, the number, specification, production batch number, etc. shall be sprayed with paint. And hoisted into the warehouse by crane.

　　2. Cold drawn (rolled) seamless pipes: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → hydrostatic test (flaw detection) → marking → warehousing.

　　The rolling method of cold drawn (rolled) seamless pipes is more complex than that of hot rolled (extruded seamless pipes). The first three steps of their production process are basically the same. The difference starts from the fourth step. After the round tube blank is emptied, it needs to be started and annealed. After annealing, special acid liquid shall be used for pickling. After pickling, apply oil. Then it is followed by multi pass cold drawing (cold rolling) and special heat treatment. After heat treatment, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydrostatic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. Steel pipes should be strictly selected by hand after quality inspection. After the steel pipe is inspected, the number, specification, production batch number, etc. shall be sprayed with paint. And hoisted into the warehouse by crane.

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