Why does stainless steel flange rust?

Stainless steel flange has the ability to resist atmospheric oxidation, that is, rust resistance, but 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 condition and environmental medium type. For example, 304 steel pipe has absolutely excellent corrosion resistance in dry and clean atmosphere, but when it is moved to the coastal area, it will soon rust in the sea fog containing a lot of salt, while 316 steel pipe performs well. Therefore, not any kind of stainless steel flange can resist corrosion and rust in any environment.

Stainless steel flange is formed on its surface by a very thin and solid fine stable chromium rich oxide film (protective film), to prevent oxygen atoms continue to penetrate, continue to oxidize, and obtain the ability of corrosion resistance. Once there is some reason, the film is constantly damaged, oxygen atoms in the air or liquid will continue to penetrate, or iron atoms in the metal will continue to separate out, forming loose iron oxide, and the metal surface will be constantly corroded. The surface film is destroyed in many ways.

In daily life, several kinds of stainless steel flange rust reasons:

1. There are dust containing other metal elements or attachments of different metal particles on the surface of the stainless steel flange. In the humid air, the condensate between the attachments and the stainless steel flange connects them into a micro battery, causing electrochemical reaction and damaging the protective film, which is called electrochemical corrosion.

2. The surface of stainless steel flange adheres organic juice (such as melon, vegetable, noodle soup, phlegm, etc.), Changsha stainless steel company forms organic acid in the presence of water and oxygen, and the organic acid corrodes the metal surface for a long time.

3. Stainless steel flange surface adhesion contains acid, alkali, salt substances (such as the decoration of the wall of alkaline water, lime water splash), causing local corrosion.

4. In the polluted air (such as the atmosphere containing a large amount of sulfide, carbon oxide and nitrogen oxide), when it meets with condensate water, it forms sulfuric acid, nitric acid and acetic acid, causing chemical corrosion. The above conditions can cause the damage of the protective film on the surface of the stainless steel flange and cause corrosion. Therefore, in order to ensure that the metal surface is permanently bright and not corroded,

Introduction of stainless steel marine flange