Seamless Steel Pipe Technology Knowledge
Dec 20, 2023
Seamless Steel Pipe Supplier-GNEE
1.1 The nominal outer diameter of seamless steel pipe is 88.9mm and the nominal wall thickness is 6.45mm.
1.2 The allowable deviations of the outer diameter and wall thickness of steel pipes shall comply with the provisions of Table 1. Table: Permissible deviation of outer diameter + 0.50mm～0.20mm; allowable deviation of wall thickness + 0.97mm～0.77mm.
2 The usual length of steel pipe is 9400mm~9750mm.
3 Appearance 3.1 The bending degree of the steel pipe shall not be greater than 1.0mm/m.
3.2 The end surfaces of both ends of the steel pipe should be perpendicular to the axis of the steel pipe, and the burrs on the incisions should be removed.
4 Weight Steel pipes are delivered according to actual weight or theoretical weight. The theoretical weight per meter of steel pipe is 13.115kg/m.
5. The allowable deviation of the chemical composition of the finished steel pipe should comply with the relevant provisions of GB/T 222.
6. Delivery status: Steel pipes are delivered in a hot-rolled state.
7. Mechanical properties After appropriate heat treatment, the mechanical properties of the steel pipe should meet the requirements of N80 steel grade in API SPEC 5CT.
8. Compactness Steel pipes should be subjected to eddy current testing one by one to check the compactness of the steel pipes. The diameter of the artificial defect hole in the eddy current testing comparison sample is φ2.2mm±0.01mm.
As an important part of steel products, steel pipes are divided into two categories: seamless steel pipes (round billets) and welded steel pipes (plates, strip billets) due to their different manufacturing processes and shapes of the pipe blanks used.
Seamless steel pipes are divided into two types: hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes due to different manufacturing processes. Cold drawn (rolled) pipes are divided into round pipes and special-shaped pipes. Hot rolling (extruded seamless steel pipe): round tube blank → heating → perforation → three-roll cross rolling, continuous rolling or extrusion → tube removal → sizing (or diameter reduction) → cooling → billet tube → straightening → quality inspection Wall thickness → hydrostatic test (or flaw detection) → marking → storage.
Cold drawn (rolled) seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → Quality inspection of wall thickness → hydrostatic test (flaw detection) → marking → storage. GB/T8162-2008 (seamless steel pipe for structural use). Mainly used for general structures and mechanical structures. Its representative materials (grades): carbon steel 20, 45 steel; alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.
