不锈钢蝶阀是在其表面形成的一层极薄而坚固细密的稳定的富铬氧化膜（保护膜），以防止氧原子的连续渗透和氧化，并获得抗腐蚀的能力。一旦薄膜因某种原因不断损坏，空气或液体中的氧原子将不断穿透或金属中的铁原子将不断分离，形成疏松的氧化铁，金属表面将不断腐蚀。
不锈钢蝶阀的优点：
不锈钢蝶阀能在大气中抗氧化，在酸、碱、盐介质中耐腐蚀。因此，全不锈钢蝶阀具有耐磨、耐腐蚀的特点。这些特性可以充分体现不锈钢的优点，但在某些特殊环境介质中仍可能发生锈蚀。以下是一些：
1、不锈钢蝶阀表面附着有机汁（如瓜菜、面汤、痰等），在水和氧气的情况下，有机汁构成有机酸。长期以来，有机酸对金属表面的腐蚀会减少。
2、不锈钢蝶阀表面有含有其他金属元素或异种金属颗粒附着物的灰尘。在潮湿的空气中，附件和不锈钢之间的冷凝液将它们连接成微型电池，从而导致电化学反应并损坏保护膜，这称为电化学腐蚀。
3、不锈钢蝶阀表面含有酸、碱、盐等物质（如碱水、石灰水溅在装饰墙上），造成局部腐蚀。
4、不锈钢蝶阀在受污染的空气（如含有大量硫化物、碳氧化物和氮氧化物的大气）中，遇到冷凝液形成硫酸、硝酸和乙酸液点，造成化学腐蚀。上述情况会导致不锈钢表面的保护膜损坏并导致腐蚀。
为确保不锈钢不生锈，建议经常清洁和擦洗装饰性不锈钢表面，以清除附着物并消除导致修改的外部因素。合理选择适合自身工作条件的不锈钢材料。
Stainless steel resists corrosion through a very thin, strong, dense and stable chromium-rich oxide film on its surface. This protective layer limits oxygen penetration and oxidation. If it is repeatedly damaged, oxygen from air or liquid can penetrate, or iron atoms can leave the metal, forming loose iron oxide and allowing continued surface corrosion.
Advantages of stainless steel butterfly valves
Stainless steel provides atmospheric oxidation resistance and corrosion resistance in suitable acid, alkali and salt environments. All-stainless-steel butterfly valves therefore offer wear and corrosion resistance. However, rust can still develop under particular conditions:
- Organic deposits, such as vegetable juices, soup or saliva, can form organic acids in the presence of water and oxygen and corrode the surface over time.
- Dust containing other metals or attached dissimilar-metal particles can combine with moisture to form small galvanic cells. The resulting electrochemical corrosion damages the protective film.
- Acids, alkalis or salts on the surface, such as splashes of alkaline water or limewater, can cause localized corrosion.
- Polluted air containing sulfides, carbon oxides or nitrogen oxides can react with condensation to form acidic droplets, including sulfuric, nitric and acetic acids, causing chemical corrosion.
These conditions can damage the protective film. Clean stainless steel surfaces regularly to remove deposits and external causes of corrosion, and choose a stainless steel grade appropriate for the actual operating conditions.
