Introduction to the method of classification of steel pipes
As an important part of steel products, steel pipes are divided into two types: seamless steel pipes (round billets) and welded steel pipes (plates and strips) due to their different manufacturing processes and the shape of the pipe blanks used.
Due to different manufacturing processes, it is divided into two types: hot-rolled (extrusion) seamless steel pipe and cold drawn (rolled) seamless steel pipe. Cold drawn (rolled) tubes are divided into two types: round tubes and shaped tubes.
a. Process overview
Hot rolling (extrusion seamless steel pipe): round tube billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → blank tube → straightening → water pressure Test (or flaw detection) → mark → into storage.
Cold drawn (rolled) seamless steel pipe: round tube billet → heating → perforation → head → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → Hydraulic test (inspection) → mark → storage.
b. Seamless steel pipes are divided into the following varieties due to their different uses:
GB/T8162-1999 (seamless steel pipe for structure). Mainly used for general structural and mechanical structures. Its representative material (brand): carbon steel 20, 45 steel; alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo and so on.
GB/T8163-1999 (seamless steel pipe for conveying fluid). Mainly used for conveying fluid pipelines on engineering and large equipment. The representative material (brand) is 20, Q345, etc.
GB3087-1999 (seamless steel pipe for low and medium pressure boilers). It is mainly used for pipes for conveying low and medium pressure fluids in industrial boilers and domestic boilers. The representative material is steel No. 10 and No. 20.
GB5310-1995 (seamless steel tubes for high pressure boilers). It is mainly used for high temperature and high pressure conveying fluid gathering boxes and pipelines on power stations and nuclear power plant boilers. Representative materials are 20G, 12Cr1MoVG, 15CrMoG, etc.
GB5312-1999 (carbon steel and carbon-manganese steel seamless steel pipe for ships). It is mainly used for I and II pressure pipes for ship boilers and superheaters. Representative materials are 360, 410, 460 steel grades, etc.
GB1479-2000 (seamless steel pipe for high pressure fertilizer equipment). It is mainly used to transport high temperature and high pressure fluid pipelines on fertilizer equipment. Representative materials are 20, 16Mn, 12CrMo, 12Cr2Mo and the like.
