Stainless steel tubes are mainly categorized by their rolling process into hot rolled, hot extruded, and cold drawn (rolled) stainless steel tubes. They are also differentiated by the microstructure of the stainless steel, including ferritic-martensitic, martensitic, austenitic, and austenitic-ferritic stainless steel tubes, among others.
In terms of specifications, the dimensions of stainless steel pipes mainly follow the provisions of GB14975-94 " Seamless Stainless Steel Pipes", where precision stainless steel thick-walled pipes generally have lengths (not fixed) of 1.5-10m for hot-rolled pipes and greater than or equal to 1m for hot-extruded pipes. Cold drawn (rolled) stainless steel pipes with wall thickness of 0.5-1.0mm have lengths of 1.0-7m; those with wall thickness greater than 1.0mm have lengths of 1.5-8m.
There are approximately 45 types of hot rolled (hot extruded) stainless steel pipes with diameters ranging from 54 to 480mm, and about 36 types with wall thicknesses from 4.5 to 45mm. A total of 65 types of cold drawn (rolled) stainless steel pipes with diameters from 6 to 200mm, and 39 types with wall thicknesses from 0.5 to 21mm.
Exterior and interior surfaces of precision stainless steel thick-walled pipes must not have cracks, folds, fissures, cracks, rolled edges, delamination, or scabs. Such defects must be completely removed (unless specifically for machining purposes), and the wall thickness and outer diameter should not exceed negative tolerances after cleaning. Minor surface defects that do not exceed allowable negative tolerances may not require removal.
Stainless steel straight bars have specific depth requirements as well. Hot-rolled, hot-extruded steel pipes, stainless steel pipes with a diameter of 140mm or less, and those not exceeding 5% thicker than the nominal wall thickness, should have a depth of 0.5mm or less. Cold drawn (rolled) stainless steel pipes should not exceed 4% of the nominal wall thickness and have a depth of 0.3mm or less.




