Feedwater Valve
Gate / globe / check · pressure seal bonnet
- Body
- A105N, A182 F11, F22
- Size
- NPS 2-20 (DN 50-500)
- Class
- Class 1500, 2500
- Temp
- 150-300 °C typical
- End
- BW, RTJ, RF
- Standard
- ASME B16.34
Boiler Feedwater
The highest-pressure water in the plant, at moderate temperature. Cavitation and check valve dynamics - not creep - are what to engineer against.
Typical conditions
| Parameter | Value | Basis |
|---|---|---|
| Pressure | Above drum pressure plus static head plus losses Often exceeds main steam pressure. Size from the pump curve. | typical |
| Temperature | 150-300 °C | typical |
| Medium | Deaerated feedwater, condensate | standard |
| Class | Class 1500-2500 common | typical |
The trip case governs the check valve
With pumps in parallel, the design case is one pump tripping while the others keep running. If its discharge check valve closes slowly, reverse flow spins the tripped pump backwards and can damage the coupling or the motor. Closure time is a system calculation, not a valve catalogue figure - we supply the disc data your surge analysis needs.
Recirculation is not an isolation valve duty
Minimum-flow recirculation runs continuously at high differential pressure with flashing. It needs a multi-stage recirculation valve designed to stage the pressure drop. Putting a throttled gate valve in that position destroys the seat within months. This is one of the most common and most expensive specification mistakes in the feedwater system.
Heater isolation and bypass
Feedwater heater isolation valves are full-bore, high-class, and normally operated only for maintenance and heater trips. The bypass valve, by contrast, may be operated under differential pressure - and should be selected accordingly rather than as a copy of the isolation valve.
Material is straightforward, class is not
A105N, F11 or F22 covers most feedwater duties, with WB36 where the design is European in origin. The care is needed on the pressure class: feedwater at Class 2500 alongside main steam at Class 1500 is normal, not an error.
Materials commonly used here
Indicative only. The grade is set by the piping class and the ASME B16.34 rating at your design temperature - see the material matrix.
Recommended products
Pressure Seal Check Valve
check · pressure seal bonnet
- Body
- A105, A182 F11, F22, F91, F92
- Size
- NPS 2-24 (DN 50-600)
- Class
- Class 600 - 4500
- Temp
- up to 650 °C / 1200 °F
- End
- BW, SW, RTJ, RF
- Standard
- ASME B16.34
Pressure Seal Gate Valve
gate · pressure seal bonnet
- Body
- A105, A182 F11, F22, F91, F92
- Size
- NPS 2-24 (DN 50-600)
- Class
- Class 600 - 4500
- Temp
- up to 650 °C / 1200 °F
- End
- BW, SW, RTJ, RF
- Standard
- ASME B16.34
Forged Power Plant Check Valve
check · bolted + pressure seal
- Body
- A105, A182 F11, F22, F91, F92, F3…
- Size
- NPS 1/2-24 (DN 15-600)
- Class
- Class 150-2500
- Temp
- up to 650 °C / 1200 °F
- End
- BW, SW, NPT, RTJ, RF
- Standard
- ASME B16.34
Frequently asked questions
Swing or piston lift check on the pump discharge?
Piston lift where pumps run in parallel and reverse flow must be stopped quickly; swing where flow is steady and pressure drop matters more. The deciding input is the surge analysis, not a preference. Send the pump data and line geometry.
Is WB36 a substitute for F22?
No. It is a different alloy with different strength at temperature and different welding requirements. If your specification names WB36 we treat it as a hard requirement. If it names F22, we do not substitute WB36 to be helpful.
Further reading
Discuss this application
Send the system conditions and we will come back with what we would supply, the rating basis, and any point where we would question the specification.