Main classification and service conditions of valve sealing materials

Release time：

2023-01-12 10:08

Valve sealing is an important part of the whole valve, its main purpose is to prevent leakage, the valve sealing seat is also called sealing ring, it is an organization that is directly in contact with the medium in the pipeline and prevents the medium from flowing. When the valve is in use, there are various media in the pipeline, such as liquid, gas, oil, corrosive media, etc., and the seals of different valves are used in different places and can adapt to various medium.

Then, valve seal materials can be mainly divided into two categories, namely metal materials and non-metal materials. Non-metal seals are generally used in pipelines with normal temperature and pressure, while metal seals have a wider range of applications and can be used for high temperature and high pressure! The following is a brief introduction to the service conditions of various sealing materials and commonly used valve types.

1. Synthetic rubber

Synthetic rubber is better than natural rubber in terms of oil resistance, temperature resistance and corrosion resistance. Generally, the operating temperature of synthetic rubber is t≤150°C, natural rubber is t≤60°C, and rubber is used for the sealing of globe valves, gate valves, diaphragm valves, butterfly valves, check valves, pinch valves and other valves with nominal pressure PN≤1MPa.

2. Nylon

Nylon has the characteristics of small friction coefficient and good corrosion resistance. Nylon is mostly used for ball valves and globe valves with temperature t≤90°C and nominal pressure PN≤32MPa.

3. Polytetrafluoroethylene

PTFE is mostly used for globe valves, gate valves, ball valves, etc. with a temperature t≤232°C and a nominal pressure PN≤6.4MPa.

4. Cast iron

Cast iron is used for gate valves, globe valves, plug valves, etc. for temperature t≤100°C, nominal pressure PN≤1.6MPa, gas and oil.

5. Babbitt alloy

Babbitt alloy is used for ammonia globe valve with temperature t-70~150℃ and nominal pressure PN≤2.5MPa.

6. Copper alloy

Commonly used materials for copper alloys are 6-6-3 tin bronze and 58-2-2 manganese brass. Copper alloy has good wear resistance and is suitable for water and steam with temperature t≤200℃ and nominal pressure PN≤1.6MPa. It is often used in gate valves, globe valves, check valves, plug valves, etc.

7. Chrome stainless steel

The commonly used grades of chromium stainless steel are 2Cr13 and 3Cr13, which have been quenched and tempered, and have good corrosion resistance. It is often used on valves of water, steam and petroleum with temperature t≤450℃ and nominal pressure PN≤32MPa.

8. Chrome-nickel-titanium stainless steel

The commonly used grade of chromium-nickel-titanium stainless steel is 1Cr18Ni9ti, which has good corrosion resistance, erosion resistance and heat resistance. It is suitable for steam and other media with a temperature t≤600°C and a nominal pressure PN≤6.4MPa, and is used for globe valves, ball valves, etc.

9. Nitriding steel

The commonly used grade of nitriding steel is 38CrMoAlA, which has good corrosion resistance and scratch resistance after carburizing treatment. It is often used in power station gate valves with temperature t≤540℃ and nominal pressure PN≤10MPa.

10. Boronizing

Boronizing directly processes the sealing surface from the material of the valve body or disc body, and then performs boronizing surface treatment. The sealing surface has good wear resistance. For power station blowdown valve.

When the valve is in use, the items that should be paid attention to are as follows: 1. The sealing performance of the valve should be tested to ensure its performance. 2. Check whether the sealing surface of the valve is worn, and repair or replace it according to the situation.

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