Why Stainless Steel Flanges Can Rust Sometimes

Stainless steel flanges rely on a thin, sturdy, and dense stable chromium-rich oxide film (protection layer) formed on their surface to prevent the continued penetration of oxygen atoms and further oxidation, thereby gaining anti-corrosion capabilities. Should there be any cause for damage to this film, oxygen atoms from the air or liquid will continuously渗透 into the surface, or iron atoms within the metal will continuously separate out, forming loose ferric oxide. Consequently, the metal surface will be continuously corroded.

1. Stainless steel flange surfaces accumulate adherent materials containing dust with other metallic elements or foreign metal particles. In humid air, condensation between the adherent materials and the stainless steel forms a microbattery, triggering electrochemical reactions. This damages the protective film, a process known as electrochemical corrosion.

2. Stainless steel flange surfaces adhere to organic substances (such as vegetable juices, soup, phlegm, etc.), which, in the presence of water and oxygen, form organic acids. Over time, these organic acids can corrode the metal surface.

3. Stainless steel flange surfaces can be adhered with acidic, alkaline, and salt substances (such as alkali water from wall decoration or lime water splashes), causing localized corrosion.