To select the correct valve material, engineers must consider the flow medium, pressure, flow rate, and intended purpose, while the temperature of the flow medium and the operating environment are factors that need to be considered for the valve material. Corrosion can occur at higher temperatures. Additionally, temperature can cause different materials to expand and contract at different rates, which can cause leakage issues, excessive binding stress on valve components, or the onset of failure.
Components such as valve actuators, valve seats and valve bodies are often available in materials that offer varying ranges of corrosion, temperature and wear resistance. Commonly used materials include:
1. Ductile Iron: Due to its low cost and availability, ductile iron offers the added benefit of easily absorbing impacts. The downside is that ductile iron has poor corrosion resistance.
2. Brass and Bronze: Brass and bronze valves are also available at low cost and ready for use. Increased corrosion resistance compared to ductile iron.
3. 316 stainless steel: Known for its excellent corrosion resistance, 316 stainless steel valves are more expensive than cast iron, brass and bronze valves.
4. Monel alloy: Nickel-copper alloy Monel has excellent corrosion resistance. It is often used to cover valve trim.
5. Inconel: Inconel is an alloy of nickel, chromium and iron used to handle corrosive media at higher temperatures.