The understanding of the material of the valve sealing ring is not enough. It is fast, afraid of trouble, and it is easy to cause problems in the installation of the sealing ring due to violation of the operating procedures, resulting in more serious consequences. The seal material is made of metal (aluminum, lead, indium, stainless steel, etc.), non-metallic materials (rubber, plastic, ceramic, graphite, etc.), composite materials (such as rubber-asbestos board, aerogel felt-polyurethane), but The most used is a rubber-based elastomer material.
Valve sealing materials are divided into four categories: fluid sealing materials, non-fluid sealing materials, dynamic seals and static seals. They can withstand the displacement of joints to achieve airtight and watertight shapes and are embedded in the joints of buildings. s material.
Common materials for valve seal materials and their use conditions are as follows:
1. Synthetic rubber: Synthetic rubber has better comprehensive performance than natural rubber because of its oil resistance, temperature resistance and corrosion resistance. General synthetic rubber use temperature t ≤ 150 ° C, natural rubber t ≤ 60 ° C, rubber for nominal pressure PN ≤ 1MPa shut-off valve, gate valve, diaphragm valve, butterfly valve, check valve, pinch valve and other valves.
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 ≤ 32 MPa.
3. Polytetrafluoroethylene: Polytetrafluoroethylene is mostly used for shut-off valves, gate valves, ball valves, etc. with temperature t ≤ 232 °C and nominal pressure PN ≤ 6.4 MPa.
4. Cast iron: Cast iron is used for gate valve, globe valve and plug valve for temperature t ≤ 100 °C, nominal pressure PN ≤ 1.6MPa, gas and oil.
5. Babbitt alloy: Babbitt alloy is used for ammonia shut-off valve with temperature t -70~150 °C and nominal pressure PN ≤ 2.5MPa.
6, copper alloy: copper alloy commonly used materials 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 °C and nominal pressure PN ≤ 1.6 MPa. It is commonly used for gate valves, globe valves, check valves, plug valves, etc.
7, chrome stainless steel: chrome stainless steel commonly used grades 2Cr13, 3Cr13 after quenching and tempering treatment, good corrosion resistance. It is commonly used on valves of water, steam and petroleum media with temperature t ≤ 450 °C and nominal pressure PN ≤ 32 MPa.
8. Chromium-nickel-titanium stainless steel: The common grade of chrome-nickel-titanium stainless steel is 1Cr18Ni9ti, which has good corrosion resistance, erosion resistance and heat resistance. It is suitable for use in steam, nitric acid and other media with temperature t ≤ 600 °C and nominal pressure PN ≤ 6.4 MPa, for shut-off valves, ball valves, etc.
9. Nitrided steel: The commonly used grade of nitriding steel is 38CrMoAlA, which has good corrosion resistance and scratch resistance after carburizing treatment. Commonly used in power station gate valves with temperature t ≤ 540 °C and nominal pressure PN ≤ 10 MPa.
10. Boronizing: Boronizing is directly processed from the valve body or the valve body material to the sealing surface, and then the boronizing surface treatment is performed, and the sealing surface has good wear resistance. Used for power station drain valve.