Description
Classification of stainless steel square pipe: square pipe is divided into seamless steel pipe and welded steel pipe (slotted pipe). According to the section shape, it can be divided into square and rectangular pipes. Circular steel pipes are widely used, but there are also some special-shaped steel pipes such as semicircular, hexagonal, equilateral triangle and octagonal.
For the stainless steel square pipe bearing fluid pressure, hydraulic test shall be carried out to check its pressure resistance and quality. It is qualified if there is no leakage, wetting or expansion under the specified pressure. Some steel pipes shall also be subject to crimping test, flaring test, flattening test, etc. according to the standard or the requirements of the demander. Specification of square tube: 5 * 5 ~ 150 * 150 mm thickness: 0.4 ~ 6.0 mm Square tube material: 304, 304L, TP304, TP316L, 316, 316L, 316Ti, 321, 347h, 310S Metals can react with oxygen in the atmosphere to form an oxide film on the surface. The iron oxide formed on ordinary carbon steel will continue to oxidize, expanding the corrosion and finally forming holes. This can use paint or oxidation resistant metal for electroplating to protect the surface of carbon steel, but this protective layer is only a thin film. If the protective layer is damaged, the underlying steel will begin to rust again. Whether the stainless steel pipe is corroded is related to the chromium content in the steel. When the chromium content in the steel reaches 12%, a layer of passivated and dense chromium rich oxide is formed on the surface of the stainless steel pipe in the atmosphere to protect the surface and prevent further reoxidation. This oxide layer is very thin. Through it, you can see the natural luster of the steel surface, which makes the stainless steel have a unique surface. If the chromium film is damaged, the chromium in the steel and the oxygen in the atmosphere will regenerate the passive film to continue to play a protective role. In some special environments, stainless steel will also fail due to some local corrosion, but unlike carbon steel, stainless steel will not fail due to uniform corrosion, so the corrosion allowance is meaningless for stainless steel pipes.