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Corrosion and Protection of Metal Valve Body

The corrosion of the valve is usually understood as the destruction of the valve metal material under the action of a chemical or electrochemical environment. As the "corrosion" phenomenon occurs in the metal and the surrounding environment spontaneous interaction, how to metal and the surrounding environment or more use of non-metallic synthetic materials, is the focus of anti-corrosion.

Valve body (including the valve cover), occupy most of the weight of the valve, but also in regular contact with the media, so the choice of valves, often from the valve body material.

There are two forms of corrosion of the valve body, namely, chemical corrosion and electrochemical corrosion. Its corrosion rate depends on the temperature of the medium, pressure, chemical properties and corrosion resistance of the valve body material. Corrosion rate can be divided into six:

1, complete corrosion resistance: corrosion rate of less than 0.001 mm / year;

2, very corrosion resistance: corrosion rate of 0.001 to 0.01 mm / year;

3, corrosion resistance: corrosion rate of 0.01 to 0.1 mm / year;

4, still corrosion resistance: corrosion rate of 0.1 to 1.0 mm / year;

5, poor corrosion resistance: corrosion rate of 1.0 to 10 mm / year;

6, not corrosion: corrosion rate greater than 10 mm / year.

The anti-corrosion of the valve body is mainly the correct selection of materials. Although the corrosion of the information is very rich, but the election is appropriate, or not easy things, because the corrosion problem is very complex, such as sulfuric acid in the low concentration of steel is very corrosive, high concentration of steel Passivation film, can be anti-corrosion; hydrogen only in high temperature and pressure showed a strong corrosion of steel, chlorine in a dry state when the corrosion performance is not large, and a certain degree of humidity when the corrosion is strong, many materials can not be used The The difficulty of selecting the valve body material, but also can not only consider the corrosion problem, and must consider the pressure and temperature resistance, whether the economy is reasonable, easy to buy and other factors. So must be heart is.

Followed by taking lining measures, such as lining lead, lining aluminum, lining engineering plastics, lining natural rubber and various synthetic rubber. Such as media conditions permit, this is a way to save.

Again, in the case of pressure, the temperature is not high, with non-metallic valve main material, often can be very effective in controlling corrosion.

In addition, the outer surface of the valve body is also subject to atmospheric corrosion, the general steel materials are to paint to protect.

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