Stainless steel seamless steel pipe is a long strip of steel with a hollow section and no joints on the periphery.
First, the thicker the wall thickness of the seamless tube stainless, the more economical and practical it is. The thinner the wall thickness, its processing cost will rise significantly; secondly, the process of the seamless tube stainless determines its limited performance such as low precision of general seamless steel pipe: uneven wall thickness, low brightness on the inside and outside of the pipe, high cost of sizing, and there are pits and black spots on the inside and outside that are not easy to remove; third, the detection and shaping of stainless steel seamless pipes must be processed offline. Therefore, it embodies its superiority in terms of high pressure, high strength, and mechanical structural materials.
The rolling method is divided into hot rolling, hot extrusion and cold drawing (rolling) stainless steel pipe.
According to the different metallographic structure of stainless steel, it is divided into semi-ferritic semi-martensitic stainless steel pipe, martensitic stainless steel pipe, austenitic stainless steel pipe, austenitic-ferritic iron stainless steel pipe, etc.
According to the provisions of GB14975-94 "Stainless Steel Seamless Pipe", steel tubes usually have a length (indefinite length) of hot-rolled steel tubes of 1.5-10m, and hot-extruded steel tubes are equal to and greater than 1m. For cold drawn (rolled) steel pipes with a wall thickness of 0.5～1.0mm, 1.0～7m; for those with a wall thickness greater than 1.0mm, 1.5～8m.
There are 45 kinds of hot-rolled (hot-extruded) steel pipes with a diameter of 54-480mm and 36 kinds with a wall thickness of 4.5-45mm. There are 65 kinds of cold drawn (rolled) steel pipes with a diameter of 6-200mm; 39 kinds with a wall thickness of 0.5-21mm.
There shall be no cracks, folds, cracks, cracks, rolling, delamination and scarring defects on the inner and outer surfaces of stainless seamless tube. These defects shall be completely removed (except for pipes for mechanical processing). The outer diameter exceeds the negative deviation. Other minor surface defects that do not exceed the allowable negative deviation may not be removed.
Hot-rolled and hot-extruded steel pipes, with a diameter less than or equal to 140mm, not greater than 5% of the nominal wall thickness, and the maximum depth is not greater than 0.5mm; cold drawn (rolled) steel pipes are not greater than 4% of the nominal wall thickness, and the maximum depth is not greater than 0.3 mm.
Both ends of the seamless steel pipe should be cut at right angles and burrs should be removed.