What is the corrosion of the valve?
The corrosion of the valve is usually understood to be damaged by the chemical or electrochemical environment of the metal material of the valve. Because corrosion occurs in the spontaneous interaction between metal and surrounding environment, how to separate metal from surrounding environment or use more non-metal synthetic materials is the key point of anti-corrosion. The valve body (including the valve cover) takes up most of the weight of the valve, and is also in constant contact with the medium. Therefore, selecting valves is usually based on valve body materials.
The corrosion of the valve body is not in two forms, chemical corrosion and electrochemical corrosion. Its corrosion rate is determined by the temperature, pressure, chemical properties of the medium and the corrosion resistance of the body material. The corrosion rate can be divided into six types:
1, complete corrosion resistance: the corrosion rate is less than 0.001 mm / year;
2, extremely anticorrosion: corrosion rate of 0.001 to 0.01 mm / year;
3, corrosion resistance: corrosion rate of 0.01 to 0.1 mm / year;
4, Shang Naishi: corrosion rate of 0.1 to 1 mm / year;
5, poor corrosion resistance: corrosion rate of 1 to 10 mm / year;
6. Corrosion resistance: the corrosion rate is more than 10 mm / year.
How to prevent valve corrosion?
The anticorrosion of the valve body is mainly the correct selection of material. Corrosion is very rich, but can choose properly, or not easy, because the corrosion problem is very complex, such as sulfuric acid in low concentrations are very corrosive to steel, makes steel at high concentrations produce passive film, corrosion proof; hydrogen under high pressure at high temperature is corrosive for steel is very strong, chlorine corrosion in the dry state is not large, but when a certain humidity, corrosion resistance strong, many materials can be used. The difficulty of selecting valve body material is not only to consider the corrosion problem, but also to consider the factors of pressure and temperature resistance, whether the economy is reasonable, whether the purchase is easy or not. So it is necessary to be careful.
First, we take the lining measures, such as lining lead, lining aluminum, lining engineering plastics, lining natural rubber and various synthetic rubber, etc. If the medium conditions permit, this is a way of saving.
Secend, again, under the pressure, the temperature is not high, with fluorine valve main material, often can be very effective to prevent corrosion.
Third, in addition, the external surface of the valve is also subjected to atmospheric corrosion, and the general steel materials are protected by paint.
