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Valf korroziyasının qarşısını necə almaq və müalicə etmək lazımdır?

Vaxt: 2022-10-12 Oxunub: 18

What is valve corrosion?
Corrosion of valves usually refers to the damage of valve metal materials under chemical or electrochemical environmental effects. As the "corrosion" phenomenon occurs in the spontaneous interaction between metal and the surrounding environment, how to isolate metal from the surrounding environment or use more non-metallic synthetic materials is the focus of corrosion prevention. The valve body (including bonnet) of the valve occupies most of the weight of the valve and is in constant contact with the medium, so the valve is often selected from the valve body materials.
The corrosion rate of the valve depends on the temperature, pressure, chemical properties of the medium and the corrosion resistance of the valve body material. Corrosion rate can be divided into six grades:
1. Complete corrosion resistance: the corrosion rate is less than 0.001 mm/year;
2. Extreme corrosion resistance: corrosion rate 0.001 to 0.01 mm/year;
3. Corrosion resistance: corrosion rate 0.01 to 0.1 mm/year;
4. Corrosion resistance: corrosion rate 0.1 to 1.0 mm/year;
5. Poor corrosion resistance: corrosion rate 1.0 to 10 mm/year;
6. Non corrosion resistance: the corrosion rate is greater than 10mm/year.
How to prevent valve corrosion?
The anti-corrosion method of valve body is mainly to select correct materials. Although the information on anti-corrosion is very rich, it is not easy to choose the right one. The problem of corrosion is very complex. For example, sulfuric acid is very corrosive to steel at a low concentration, while at a high concentration, it makes steel produce a passive film, which can prevent corrosion; Hydrogen only shows strong corrosivity to steel at high temperature and high pressure. When chlorine is dry, the corrosivity is not great, but when there is a certain humidity, the corrosivity is strong... The difficulty in selecting valve body materials lies in not only the corrosion problem, but also the factors such as pressure and temperature resistance, economic rationality, and ease of purchase. WALTER valve provides you with some anti-corrosion suggestions.
First, take lining measures, such as lead lining, aluminum lining, engineering plastics lining, natural rubber lining and various synthetic rubber lining. If the medium conditions permit, this is a saving method.
Second, in the case of low pressure and temperature, fluorine lining as the main material of the valve can often effectively prevent corrosion.
Third, the external surface of the valve is usually corroded by the atmosphere, so the steel materials are generally protected by painting.
It is recommended to use cheap ductile iron lined EPDM valve seat for water medium