Factors to consider in the selection of valve sealing surface material
The valve sealing surface is the most crucial working area of the valve. Sealing surface quality directly determines the valve’s service life. The sealing surface material is also a vital factor in ensuring this quality. Therefore, consider the following factors when selecting valve sealing surface materials:
corrosion preventive
Corrosion is the degradation of a sealing surface by a medium. Once the surface deteriorates, sealing performance is compromised. Thus, sealing surface material must resist corrosion. Corrosion resistance primarily depends on the material’s molecular structure and chemical stability.
The sealing surface material must exhibit scratch resistance.
Scratching refers to the damage caused by friction when seal surfaces move against each other. This damage causes seal failure. Therefore, sealing materials must have excellent scratch resistance, especially in задвижки. The material’s scratch resistance depends mainly on its own properties.
The sealing surface material must be resistant to erosion.
Erosion is damage from high-speed media flow on a sealing surface. This is especially problematic in throttling and safety valves with high-temperature, high-pressure steam, greatly affecting sealing. Thus, erosion resistance is essential for sealing surface materials.
The valve sealing surface material must maintain a certain hardness and limit its decrease at the specified working temperature.
The linear expansion coefficient of the sealing surface and the body material should be similar. This is particularly significant for insert sealing ring structures to prevent additional stress and loosening under high temperature.
When used under high temperature conditions, the sealing surface material must possess sufficient oxidation resistance, thermal fatigue resistance, and thermal cycling capability.
It is difficult to find sealing surface materials that meet all requirements. Engineers must focus on the most important criteria for each valve. For example, valves with high-speed media need strong erosion resistance. Valves with solid contaminants need harder materials.
