When there are brown rust spots (spots) on the surface of stainless steel pipes, some people think that "stainless steel is not rusty, and rust is not stainless steel. It may be a problem with the steel". In fact, some stainless steel materials with low nickel content are rusty, so the rusty ones may also be stainless steel. Nowadays, stainless steel tubes are widely used. Stainless steel will rust under certain conditions.
Stainless steel has the ability to resist atmospheric oxidation, that is, rust resistance, and also has the ability to resist corrosion in the medium containing acid, alkali, and salt, that is, corrosion resistance. However, the corrosion resistance of the steel varies with its chemical composition, additive state, service conditions and types of environmental media. For example, 304 steel pipe has absolutely excellent corrosion resistance in a dry and clean atmosphere, but if it is moved to the coastal area, it will rust soon in the sea fog containing a lot of salt; The 316 steel pipe performs well. Therefore, not any kind of stainless steel can resist corrosion and rust under any environment.
Stainless steel is resistant to corrosion by a thin, firm, fine and stable chromium rich oxide film (protective film) formed on its surface to prevent oxygen atoms from penetrating and oxidizing continuously. Once for some reason, this kind of film is constantly destroyed, oxygen atoms in air or liquid will continuously penetrate or iron atoms in metal will continuously separate, forming loose iron oxide, and the metal surface will be continuously corroded. There are many forms of damage to this surface facial mask, which are common in daily life as follows:
1. There are dust containing other metal elements or attachments of heterogeneous metal particles on the stainless steel surface. In the humid air, the condensate between the attachment and the stainless steel connects them into a micro battery, which causes electrochemical reaction and damages the protective film, which is called electrochemical corrosion.
2. The surface of stainless steel is adhered with organic juice, which forms organic acid in the presence of water and oxygen. For a long time, the organic acid will corrode the metal surface.
3. The adhesion of stainless steel surface contains acid, alkali and salt substances, causing local corrosion. 4. When encountering condensate in polluted air, sulfuric acid, nitric acid and acetic acid will form liquid spots, causing chemical corrosion.
The above conditions can cause the damage of the protective film on the surface of stainless steel chemical pump and lead to corrosion. Therefore, to ensure that the metal surface is permanently bright and not corroded, we recommend:
1. The surface of decorative stainless steel chemical pump must be cleaned and scrubbed frequently to remove attachments and eliminate external factors that cause modification.
2. The 316 stainless steel pipe pump shall be used in coastal areas, and the 316 material can resist seawater corrosion.
3. The chemical composition of some stainless steel tubes on the market can not meet the corresponding national standards and can not meet the 304 material requirements. Therefore, it will also cause rust, which requires users to carefully select products from reputable manufacturers.
Production process of ASTM A403 WP316L stainless steel tees
Shengtian Group will go to Iran to participate in the oil and gas exhibition
The connection method of stainless steel pipe reducer
The difference between 304L and 361L stainless steel pipes
