With the advancement of skills, high-parameter and messy working conditions such as high temperature, high pressure, deep cold, high vacuum, strong corrosion, radioactivity, highly toxic, flammable and explosive, etc. in industrial production are increasing, and the safety and function of the valve application are increased. Higher and stricter requirements are proposed in terms of performance and service life.
Since the "corrosion" phenomenon occurs in the spontaneous interaction between the metal and the surrounding environment, how to isolate the metal from the surrounding environment or use more non-metallic synthetic materials is the focus of corrosion prevention. Corrosion of the valve is usually understood as the damage to the metal material of the valve under the action of a chemical or electrochemical environment.
The corrosion of the valve body is nothing more than two forms, namely chemical corrosion and electrochemical corrosion. Its corrosion rate depends on the temperature, pressure, chemical properties of the medium and the corrosion resistance of the valve body material. The corrosion rate can be divided into six levels:
1. Complete corrosion resistance: the corrosion rate is less than 0.001 mm/year;
2. Extremely resistant to corrosion: the corrosion rate is 0.001 to 0.01 mm/year;
3. Corrosion resistance: the corrosion rate is 0.01 to 0.1 mm/year;
4. Still corrosion resistant: the corrosion rate is 0.1 to 1.0 mm/year;
5. Poor corrosion resistance: the corrosion rate is 1.0 to 10 mm/year;
6. Not corrosion resistant: the corrosion rate is greater than 10 mm/year.
Although the valve body has a wealth of anti-corrosion materials, it is not easy to choose the right one, because the problem of corrosion is very complicated. Then, what are the ways to protect the valve body from corrosion?
First, choose the right materials. The difficulty in selecting valve body materials lies in not only considering corrosion problems, but also considering factors such as pressure and temperature resistance, whether it is economically reasonable, and whether it is easy to purchase.
The second is to take lining measures, such as lining lead, lining aluminum, lining engineering plastics, lining natural rubber and various synthetic rubbers. If the media conditions permit, this is an economical method.
Thirdly, when the pressure and temperature are not high, using non-metal as the valve body material can often be very effective in preventing corrosion.
In addition, the outer surface of the valve body is also subject to atmospheric corrosion. Kaixin Pipeline Technologies Co.,Ltd recommends that general steel materials be protected by painting.