Classification of alloy pipes
seamless steel tube
Due to their different manufacturing processes, they are divided into hot rolled (extruded) seamless steel tubes and cold drawn (rolled) seamless steel tubes. Cold drawn (rolled) tubes are divided into round tubes and special-shaped tubes.
Overview of process flow
Hot rolling (extrusion of seamless steel tubes): round tube blank → heating → piercing → three roll cross rolling, continuous rolling or extrusion → pipe stripping → sizing (or reducing) → cooling → blank tube → straightening → hydrostatic test (or flaw detection) → marking → warehousing.
Cold drawn (rolled) seamless steel pipe: round pipe blank → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi pass cold drawn (cold rolled) → blank pipe → heat treatment → straightening → hydrostatic test (flaw detection) → marking → warehousing.
Seamless steel pipes can be divided into the following categories due to their different uses:
GB/T8162-2008 (Seamless Steel Tubes for Structures). It is mainly used for general structures and mechanical structures. Its representative material (grade): carbon steel 20, 45 steel; Alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.
GB/T8163-2008 (Seamless Steel Pipe for Fluid Transmission). It is mainly used for conveying fluid pipelines on engineering and large equipment. Representative materials (grades) are 20, Q345, etc.
GB3087-2008 (Seamless Steel Tubes for Low and Medium Pressure Boilers). It is mainly used for industrial boilers and domestic boilers to transport low and medium pressure fluids. The representative materials are 10 # and 20 # steel.
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