Precision stainless steel pipes are highly distinctive in terms of specifications and appearance. Firstly, the thicker the wall of this type of stainless steel pipe, the higher its cost-effectiveness and practicality; conversely, thinner walls significantly increase processing costs. Furthermore, the performance limitations of stainless steel pipes depend on the processing technology. Seamless steel pipes typically have lower precision, uneven wall thickness, lower surface gloss on both the inner and outer surfaces, and higher fixed-length costs. They are also prone to pitting and black spots on the inner and outer surfaces, which are difficult to remove. Additionally, the inspection and shaping of thick-walled precision stainless steel pipes must be done offline. Therefore, stainless steel pipes demonstrate significant advantages in high-pressure, high-strength mechanical structural applications.
Stainless steel pipes are mainly classified according to their rolling process into hot-rolled, hot-extruded, and cold-drawn (rolled) stainless steel pipes. Based on differences in metallographic structure, they are mainly classified into semi-ferritic semi-martensitic stainless steel pipes, martensitic stainless steel pipes, austenitic stainless steel pipes, and austenitic-ferritic stainless steel pipes.
According to specifications, stainless steel pipes are mainly regulated by GB14975-94 “Seamless Stainless Steel Pipes”. For precision stainless steel thick-walled pipes, the general length (unspecified length) is 1.5-10m for hot-rolled steel pipes and 1m or more for hot-extruded steel pipes. Cold-drawn (rolled) stainless steel pipes have a wall thickness of 0.5-1.0mm and a length of 1.0-7m; those with a wall thickness greater than 1.0mm have a length of 1.5-8m.
Hot-rolled (hot-extruded) stainless steel pipes have approximately 45 different diameters (54-480mm) and approximately 36 different wall thicknesses (4.5-45mm). Cold-drawn (rolled) stainless steel pipes have 65 different diameters (6-200mm) and 39 different wall thicknesses (0.5-21mm).
The inner and outer surfaces of thick-walled precision stainless steel tubes must be free from defects such as cracks, folds, fissures, roll folds, delamination, and scale. These defects must be completely removed (unless the tube is specifically intended for machining), and the wall thickness and outer diameter must not exceed the negative tolerance after removal. Minor surface defects that do not exceed the allowable negative tolerance do not need to be removed.
The allowable depth of straight sections in stainless steel tubes is also subject to requirements. For hot-rolled and hot-extruded steel tubes, and stainless steel tubes with a diameter less than or equal to 140mm and not exceeding 5% of the nominal wall thickness, the depth must be less than or equal to 0.5mm. For cold-drawn (rolled) stainless steel tubes, the depth must not exceed 4% of the nominal wall thickness, and the depth must be less than or equal to 0.3mm.
Finally, it is important to note that before application, thick-walled precision stainless steel tubes must be cut at right angles at both ends, and burrs in the tube wall must be removed.
Post time: Dec-16-2025