How to Choose Industrial Valve Sealing Face Materials

 
The sealing face of an industrial valve, as its core working surface, directly affects the sealing performance and service life of the valve. Since the sealing face is subjected to various pressures and erosion from the medium during the industrial valve operation, selecting the appropriate sealing face material is crucial for the reliability and durability of the valve. The following will discuss in detail several key factors to consider when selecting the material for the industrial valve sealing face, as well as some common misconceptions in the selection process.  
The sealing face of an industrial valve is its core working surface and directly impacts the valve's sealing performance and service life. Therefore, the selection of the sealing face material is of paramount importance. Here are several key factors to consider when choosing the material for the industrial valve sealing face.  
The sealing face may be subject to corrosion from the medium during actual use, which can lead to a decline in sealing performance. If the sealing face is corroded, it cannot maintain effective sealing, affecting the normal operation of the industrial valve. Therefore, when selecting the sealing face material, it is essential to ensure it has excellent corrosion resistance. The corrosion resistance of the material usually depends on its chemical stability and physical properties. In corrosive media, materials with high corrosion resistance, such as stainless steel and nickel-based alloys, are commonly chosen.  
During the operation of the industrial valve, the sealing face is often scratched due to friction. These scratches can affect the integrity of the sealing face, thereby affecting the sealing effect of the valve. Especially in the application of gate valves, the scratch resistance of the sealing face is particularly important. When selecting materials, the hardness and internal structure's ability to resist scratches should be considered. For example, some alloy materials may not be very hard, but they have strong wear resistance and scratch resistance.  
In high-speed flowing media, the sealing face is subject to erosion, which is particularly evident in high-temperature and high-pressure steam media, such as throttle valves and safety valves. Erosion can damage the sealing face, affecting sealing performance. Therefore, the sealing face material must have good erosion resistance. When selecting materials, the performance in high-speed flowing media should be considered, such as alloy materials or coated materials.  
The hardness of the sealing face material determines its wear resistance to some extent. However, at high temperatures, the hardness of the material may decrease significantly. Therefore, when selecting the sealing face material, in addition to considering its hardness at room temperature, the hardness stability at working temperatures should also be considered. Generally, the hardness value of the sealing face material should be controlled between HRC 35 and 45 to effectively avoid scratches from hard impurities in the medium.  
The coefficient of linear expansion of the sealing face material should be as close as possible to that of the valve body material, especially in the inlaid structure. A mismatch in the coefficient of linear expansion can lead to additional stress and loosening in high-temperature working environments, affecting the sealing effect of the industrial valve. When selecting materials, the thermal expansion compatibility with the valve body material should be considered to ensure stable sealing performance.  
In high-temperature environments, the sealing face material needs to have oxidation resistance, thermal fatigue resistance, and thermal cycling performance. The material should maintain its structural stability and performance at high temperatures to avoid a decline in sealing performance due to high temperatures. For example, some ceramic materials and high-temperature alloys have excellent high-temperature performance and are suitable for extreme working conditions.  
Some common misconceptions in the selection of industrial valve sealing face materials can lead to improper material selection, thereby affecting the performance and life of the valve. Here are some common misconceptions and their detailed explanations.  
High hardness does not always mean better wear resistance. Experiments have shown that the wear resistance of the sealing face material is mainly determined by the microstructure of the metal material. For example, some austenite-based alloys have excellent wear resistance even if their hardness is not high. In a comprehensive consideration, the hardness value of the sealing face material should be between HRC 35 and 45 to balance wear resistance and cost.  
There is no necessary connection between the price of the material and its performance. For example, cobalt-based alloys are more expensive due to the high import cost of cobalt metal. Although cobalt-based alloys have excellent wear resistance in high-temperature environments, their cost-effectiveness is not high in normal or medium-temperature conditions. Therefore, when selecting the sealing face material, attention should be paid to the comprehensive value of its price and performance, and materials with high cost-effectiveness should be chosen.  
The corrosion resistance of metal materials is complex, and the corrosion resistance under different media and conditions may be very different. For example, a material that performs well in a strong corrosive medium does not necessarily perform the same in other corrosive media. The corrosion resistance of a material can only be determined through experiments and specific application conditions. Therefore, when selecting materials, it is necessary to fully understand its performance in actual working conditions to avoid blind reference.
 
When selecting the material for the industrial valve sealing face, it is necessary to comprehensively consider factors such as the material's corrosion resistance, scratch resistance, erosion resistance, hardness, high-temperature performance, and the coefficient of linear expansion with the valve body material. At the same time, some common misconceptions should be avoided, such as overemphasizing hardness and price. By deeply understanding these factors and their impact on material performance, the appropriate sealing face material can be more accurately selected to ensure the reliability and durability of the industrial valve in practical applications.