Lift Check Valve
General / GeneralDefinition
A lift check valve uses a disc, piston, or ball that lifts vertically off a seat when forward flow creates sufficient pressure differential, and falls back onto the seat when flow stops or reverses. Unlike a swing check valve where the disc pivots on a hinge, the lift check's closure member moves in a straight line — like a globe valve disc lifting off its seat. This linear motion creates a tight, consistent seal but at the cost of higher pressure drop, since the flow must redirect around the lifted disc. Lift check valves are common on smaller-diameter, higher-pressure services where tight shutoff matters more than low pressure drop.
Working Principle
Forward flow creates a pressure differential across the disc or piston. When the upstream pressure exceeds the downstream pressure by enough to overcome the disc weight (and any spring force), the disc lifts off the seat, allowing flow through the annular gap around it. The flow path redirects 90° or more as it passes around the disc and through the seat opening — similar to the tortuous path in a globe valve. When flow stops or reverses, backpressure pushes the disc back onto the seat, assisted by gravity and any spring. The relatively short stroke and direct seating action give lift check valves faster response and tighter shutoff than swing checks.
Key Components
| Disc / Piston / Ball | Closure member that lifts off the seat on forward flow |
| Seat | Machined surface in the body; often replaceable |
| Guide | Keeps the disc/piston aligned during lift and reseat |
| Body | Globe-pattern body with inlet and outlet at 90° or straight-through |
| Bonnet / Cover | Provides access; may house a spring or guide |
| Spring (optional) | Assists closing and allows vertical or horizontal installation |
Types & Variants
| Variant | Closure Member | Installation | Typical Use |
|---|---|---|---|
| Piston lift check | Cylindrical piston in a dashpot | Vertical (flow up) preferred | High-pressure steam, boiler feedwater |
| Disc lift check | Flat disc guided by ribs or stem | Vertical or horizontal (with spring) | General process, chemical lines |
| Ball lift check | Free ball in a cage | Any orientation (with spring) | Small-diameter instrument and sampling lines |
Materials
Forged carbon steel (A105) for high-pressure steam and boiler feedwater (Class 600+). Cast carbon steel (A216 WCB) for general process to Class 300. Stainless steel (CF8M / F316) for corrosive chemicals and seawater cooling. Bronze for low-pressure water and HVAC. Disc/piston: typically 13Cr or 316SS, matching or exceeding the body corrosion resistance. Seat facing: integral body seat for economy, Stellite overlay for erosive service, or elastomer-inserted for zero leakage on low-pressure water.
Applicable Standards
API 600 (steel gate/globe/check — includes lift check variants), BS 1868 (steel check valves), MSS SP-80 (bronze check valves), MSS SP-134 (check valves for industrial applications). API 594 covers swing and tilting-disc check valves but not most lift check designs.
Applications
Boiler feedwater systems: piston lift check valves on pump discharge prevent backflow into idle pumps at pressures up to 2500 psi. High-pressure steam service: lift check valves on turbine extraction and bypass lines where tight shutoff and compact size are needed. Chemical process lines: spring-loaded disc lift checks on small-diameter corrosive services where a swing check would be oversized. Instrument and sampling lines: ball lift check valves (often 1/4" to 1/2") prevent reverse flow in analyzer and sample conditioning systems. Any application needing tighter shutoff than a swing check provides.
Advantages
- Tighter shutoff than swing check valves — direct disc-to-seat contact
- Faster response — short stroke and spring assist available
- Compact — sh
Related Resources