Valve Operating Temperature
The operating temperature of a valve is determined by the material it is made of. The operating temperatures of commonly used valve materials are as follows:
| Valves | Operating Temperature |
| Gray cast iron valves | -15~250°C |
| Malleable cast iron valves | -15~250°C |
| Ductile cast iron valves | -30~350°C |
| High nickel cast iron valves | Maximum operating temperature is 400°C |
| Carbon steel valves | -29~450°C, recommended operating temperature t<425°C according to JB/T3595-93 standard |
| 1Cr5Mo alloy steel valves | Maximum operating temperature is 550°C |
| 12Cr1MoVA alloy steel valves | Maximum operating temperature is 570°C |
| 1Cr18Ni9Ti, 1Cr18Ni12Mo2Ti stainless steel valves | -196~600°C |
| Copper alloy valves | -273~250°C |
| Plastic valves (nylon) | Maximum operating temperature 100°C |
| Plastic valves (fluorinated polyether) | Maximum operating temperature 100°C |
| Plastic valves (polyfluoroethylene) | Maximum operating temperature 60°C |
| Plastic valves (PTFE) | -60~120°C |
When rubber or plastic is used for valve linings, the temperature resistance of the rubber or plastic is the primary factor. Ceramic valves, due to their poor resistance to rapid temperature changes, are generally used in operating conditions below 150℃. Recently, a high-performance ceramic valve has emerged that can withstand temperatures up to 1000℃. Glass valves, with poor resistance to rapid temperature changes, are generally used in operating conditions below 90℃. Enameled valves, whose temperature resistance is limited by the sealing ring material, have a maximum operating temperature not exceeding 150℃.
Valve Operating Pressure
The operating pressure of a valve is determined by the material it is made of.
| Valves | Maximum allowable nominal pressure |
| Gray Cast Iron Valves | 1MPa |
| Malleable Cast Iron Valves | 2.5MPa |
| Ductile Iron Valves | 4.0MPa |
| Steel Alloy Valves | 2.5MPa |
| Titanium Alloy Valves | 2.5MPa |
| Carbon Steel Valves | 32MPa |
| Alloy Steel Valves | 300MP |
| Stainless Steel Valves | 32MPa |
| Plastic Valves | 0.6MPa |
| Ceramic, Glass, Enamel Valves | 0.6MPa |
| Fiberglass Valves | 1.6MPa |
Relationship between Valve Temperature and Pressure
Valve operating temperature and pressure are intrinsically linked and mutually influential. Temperature is the dominant factor; a valve with a certain pressure rating is only suitable for a specific temperature range, and changes in valve temperature affect its operating pressure.
For example, a carbon steel valve has a nominal pressure of 10 MPa. When the medium working temperature is 200℃, its maximum working pressure P20 is 10 MPa; when the medium working temperature is 400℃, its maximum working pressure PN4.0 is 5.4 MPa; and when the medium working temperature is 450℃, its maximum working pressure PN2.0 is 4.5 MPa.
