Operation specification of stop valve

The sealing surface is the most critical working surface of the valve. The quality of the sealing surface directly affects the service life of the valve. The material of the sealing surface is an important factor to ensure the quality of the sealing surface. Therefore, the following factors shall be considered when selecting the sealing surface material of the valve:

① Corrosion resistance“ "Corrosion" refers to the process that the sealing surface is damaged under the action of medium. If the surface is damaged, the sealing performance cannot be guaranteed. Therefore, the sealing surface material must be corrosion-resistant. The corrosion resistance of materials mainly depends on the composition and chemical stability of materials.

② Abrasion resistance“ Scratch "refers to the damage caused by friction during the relative movement of the sealing surface. This damage will inevitably lead to the damage of the sealing surface. Therefore, the sealing surface material must have good scratch resistance, especially the gate valve. The scratch resistance of materials is often determined by the internal properties of materials.

③ Erosion resistance“ "Erosion" refers to the process that the sealing surface is damaged when the medium flows through the sealing surface at high speed. This kind of damage is more obvious in throttle valves and safety valves used in high-temperature and high-pressure steam media, which has a great impact on sealing damage. Therefore, erosion resistance is also one of the important requirements of sealing surface materials.

④ It shall have a certain hardness, and the hardness shall drop greatly at the specified working temperature.

⑤ The linear expansion coefficient of the sealing surface and the body material should be similar, which is more important for the structure of the sealing ring to avoid additional stress and looseness at high temperature.

⑥ When used at high temperature, it should have sufficient oxidation resistance, thermal fatigue resistance and thermal cycle.

At present, it is difficult to find sealing surface materials that fully meet the above requirements. We can only focus on meeting the requirements of some aspects according to different valve types and uses. For example, for valves used in high-speed media, special attention should be paid to the erosion resistance requirements of the sealing surface; When the medium contains solid impurities, the sealing surface material with high hardness should be selected.