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 face of the sealing surface of the material is to ensure the quality of the sealing surface is an important factor. Therefore, the selection of valve sealing surface materials should consider the following factors:

    ① corrosion resistance.

    "Corrosion" that is, the sealing surface in the media, the surface is damaged by the process. If the surface is subject to such damage, sealing can not be guaranteed, therefore, the sealing surface material must be corrosion-resistant. Corrosion resistance of the material depends mainly on the material and its chemical stability.

    ② Scratch resistance.

    "Scuffing" that is, the sealing surface of the relative movement process, the material caused by friction and damage. This damage will inevitably cause damage to the sealing surface, therefore, the sealing surface material must have good anti-scratch performance, especially the gate valve. Resistance to abrasion of the material is often determined by the internal nature of the material.

    ③ erosion resistance.

    "Erosion" that is, the medium flows through the sealing surface at high speed, so that the sealing surface was damaged process. This damage in high temperature, high pressure steam medium used in throttle valves, safety valves more obvious, the sealing damage has a great impact, therefore, erosion resistance is also one of the important requirements of the sealing surface materials.

    ④ should have a certain degree of hardness, and in the specified operating temperature under the hardness of a large drop.

    ⑤ The coefficient of linear expansion of the sealing surface and the body material should be approximate, which is more important for the structure of the sealing ring, so as not to easily generate additional stress and cause loosening at high temperatures.

    For use under high temperature conditions, there should be sufficient resistance to oxidation, thermal fatigue and thermal cycling.

    In the current situation, to find a comprehensive meet the above requirements of the sealing surface material is very difficult to do, can only be based on different types of valves and uses, focusing on meeting certain aspects of the requirements. For example, in the high-speed medium in the use of the valve should pay special attention to the sealing surface of the erosion resistance requirements; and the medium contains solid impurities should be selected when the sealing surface material with high hardness.