With the advancement of skills, there is an increasing demand for high temperature, high pressure, deep cooling, high vacuum, strong corrosion, radioactivity, flammability, and explosive high parameter and chaotic working conditions in industrial production. Therefore, higher and stricter requirements have been put forward for the safety, functionality, and service life of valve operation.
Due to the phenomenon of corrosion occurring in the spontaneous interaction between metals and the surrounding environment, the key to corrosion prevention is to isolate metals from the surrounding environment or to use more non-metallic synthetic materials. Corrosion of valves is usually understood as the damage that valve metal materials are subjected to in chemical or electrochemical environments.
The corrosion of valve bodies can take two forms, namely 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 valve body material. The corrosion rate can be divided into six categories:
1. Complete corrosion resistance: corrosion rate below 0.001 millimeters per year;
2. Extreme corrosion resistance: corrosion rate from 0.001 to 0.01 millimeters per year;
3. Corrosion resistance: corrosion rate from 0.01 to 0.1 millimeters per year;
4. Corrosion resistant: corrosion rate from 0.1 to 1.0 millimeters per year;
5. Poor corrosion resistance: corrosion rate of 1.0 to 10 millimeters per year;
6. Not corrosion-resistant: The corrosion rate is greater than 10 millimeters per year.
Although there is a wealth of information on corrosion prevention for valve bodies, it is not easy to choose the appropriate one because the issue of corrosion is complex. So, what are the protection methods for valve body corrosion?
Firstly, choose the correct materials. The difficulty in selecting valve body materials lies not only in considering corrosion issues, but also in considering factors such as pressure and temperature resistance, economic feasibility, and ease of purchase.
Secondly, lining measures should be taken, such as lining with lead, aluminum, engineering plastics, natural rubber, and various synthetic rubbers. If the media conditions permit, this is actually a cost-effective method.
Again, in situations where pressure and temperature are not high, using non-metallic materials as the main body of valves can often effectively prevent corrosion.
In addition, the surface of the valve body is also subject to atmospheric corrosion, and steel materials are generally protected by painting- Provided by Morgan Valve Technology Department
|
