How to choose the material of flanged gate valve seat

The sealing surface of flanged gate valve is an important working surface for the valve to block the medium and control the fluid. The quality of the sealing surface determines whether the valve is guaranteed to have no internal leakage, impermeability and other direct influence factors, which can be said to determine the service life of the valve. If the sealing surface is damaged, the valve will not work properly. Among them, the material selection of the sealing surface is a very important factor, and it is very important to guarantee the quality of the sealing surface. Therefore, the following factors should be considered when selecting the valve sealing surface material:

1. Corrosion resistance
Whether the medium is pure water or other, it will cause certain corrosion to the flanged gate valve. The surface of the sealing surface will inevitably be damaged under the action of the high-speed passage of the medium. Delaying this process is our primary consideration when selecting sealing surface materials. Once the surface of the sealing surface is damaged, the sealing performance of the valve cannot be guaranteed, and the medium will easily leak from the damaged part of the sealing surface. Therefore, the sealing surface material must be corrosion resistant. The corrosion resistance of a material mainly depends on the chemical stability of the material. But secondly, we must consider the medium conditions to see if it matches the sealing material.
2. Friction resistance
Because the medium and the sealing surface move relative to each other, and it is a high-speed process, damage to the material due to friction is inevitable. Such damage will eventually inevitably cause damage to the sealing surface. Therefore, the sealing surface material must have good friction resistance, especially for flanged gate valves. The wear resistance of the sealing material is often determined by the internal properties of the material. At the same time, pay attention to the valve installation location to meet the needs.
3. Erosion resistance
The image of the erosion phenomenon is a process in which the sealing surface is destroyed when the medium flows through the sealing surface at a high speed. This kind of damage is more obvious in the throttle valve used in high temperature and high pressure steam medium, because it needs to be opened and closed frequently, which has a great impact on the damage of sealing. Therefore, erosion resistance is also one of the important requirements of the sealing surface material.
4. The sealing surface of flanged gate valves should have a certain degree of hardness, and the hardness will drop greatly under the specified working temperature.
5. The linear expansion coefficient of the sealing surface of the gate valve and the body material should be similar, which is more important for the structure of the inlaid sealing ring, so as to avoid excessive stress and loosening at high temperatures.
6. When used under high temperature conditions, it must have sufficient anti-oxidation, thermal fatigue resistance and thermal cycling.
When faced with real working conditions, it is difficult to find a sealing surface material that fully meets the above requirements. It is appropriate to match and choose according to different valve types and uses. There are several key points such as: often need to open and close, or in high-speed medium, the sealing material of flanged gate valve used here should be specially marked with erosion resistance requirements, and if it contains solid impurities, the hardness should be selected The higher the sealing surface material, the better the durability.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Video of resilient seated gate valve: https://youtu.be/AI-LT1dy2sU

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