What are Valve sealing materials?
The sealing material is actually the very critical surface of the valve. The quality of the sealing material is affecting the service life of the valves. The sealing material is actually very important factor in making sure to maintain the quality of the sealing surface
The valve seals are the key part to determine the valve performance. The factors such as friction, flash, corrosion, oxidation and ECT should be used when selecting the sealing surface materials. Valve seals are divided into 2 categories one is known as soft seal which is also known as rubber that includes fluoro and butane rubber. The other and the second one is hard seal which includes copper alloys and it is used for low pressure valves, nickel base alloys, satellite alloys and chromium stainless steels.
Top 10 valve sealing materials
1. Synthetic rubber
Synthetic rubber is superior to the natural rubber in its temperature, resistance and corrosion resistance. The temperature of synthetic rubber is lower than 150 degree Celsius. Natural rubber is lower than 60 degree Celsius. Rubbers are used for shut off valve, butterfly valve, check valve, pinch valve and other valves whose pressure is smaller than 1 MPa.
Nylon has the characteristics of good corrosion resistance and small friction coefficient. Nylon is mostly used for globe valves and ball valves with the temperature less than 90 degree Celsius. The nominal pressure is smaller than 32 MPa.
Teflon is mostly used for the gate valves, shut off valves, ball valves etc. it contains a temperature that is more than 232 degree Celsius and nominal pressure of 6.4 MPa.
4. Cast iron
Cast iron is used for globe valves, gate valves and plug valves for oil transportation and for gas. The temperature is more than 100 degrees Celsius and nominal pressure of 1.6 MPa.
5. Babbitt alloy
Babbitt alloy is used for ammonium shut off valves. The temperature is between t – 70 to t – 50 degrees Celsius and nominal pressure of 2.5 MPa.
6. Copper alloy
Common materials for copper alloys are 6 -6 -3 tin bronze and 58 – 2- 2 manganese brass. Copper alloy has very good wear resistance and it is suitable for steam and water. The use of temperature is more than 200 degrees Celsius and nominal pressure of 1.6 MPa. It is commonly used for plug valves, globe valves, gate valves and check valves etc.
7. Chrome nickel titanium stainless steel
The common grade of Chrome nickel titanium stainless steel is 1 Cr18Ni9ti. It has good corrosion resistance, heat resistance and erosion resistance. It is suitable for mediums such as nitric acid and steam. These are used for ball valves and shut off valves.
Boronizing is directly processed by the body of the valve or the material of the valves to the sealing surface. The bronzing surface is treated and the sealing surface has good wear resistance. It is used for power station drain valves.