Swing, lift, dual plate, tilting disc, axial nozzle and ball check valves, chosen for the flow, the pipe size and the risk of slam. Made in Britain by Young & Cunningham, selected, supplied and supported in the GCC by Petromarsh.
Tap a part to see what it does. The blue line is forward flow, which lifts the disc; the dashed outline is the closed disc on its seat. The chart shows why slam happens: after a pump trip the flow slows and reverses, and a slow disc closes against the reversed flow.
Body. The pressure shell, with a chamber big enough for the disc to swing clear of the flow. Face-to-face length follows ASME B16.10 or API 594.
Cover. A bolted cover over the disc chamber. Remove it to inspect or replace the disc, hinge and seat without taking the valve out of the line.
Hinge pin. The pin the disc arm swings on. It is the main wear point: in pulsing flow the disc flutters and the pin and its bushes wear, so the valve must be sized to be held fully open.
Disc. Lifted by forward flow and closed by gravity and reverse flow. Its weight and swing distance decide how fast it closes, and so how hard it slams.
Seat. The ring the disc closes onto, often set at an angle so gravity helps the disc close. Hard-faced or soft-seated depending on the tightness needed.
Flow arrow. Cast or marked on the body. A check valve only works one way, so the arrow must point in the direction of normal flow when it is installed.
A check valve lets fluid flow one way and stops it flowing back. It has no handwheel or actuator: forward flow pushes the disc open, and when flow stops or reverses the disc closes onto the seat. It protects pumps, compressors and systems from reverse flow.
The flow must be strong enough to hold the disc fully open. If the valve is too big for the flow, the disc flutters, wears the hinge and seat and fails early. Size by flow velocity, not by pipe size.
When a pump stops, flow slows and then reverses. A slow, heavy disc is still open when reverse flow starts, then slams shut against moving fluid. That noise is the slam, and it damages the valve and pipe.
Stopping a moving liquid suddenly creates a pressure wave that travels down the line. A slam makes this worse. Fast-closing, spring-assisted designs such as dual plate and axial nozzle valves close before flow reverses.
The design decides how fast the valve closes, how much pressure it costs and how it can be installed. Tap a type to see where it fits.
A disc on a hinge swings open with the flow and leaves an almost straight path, so pressure drop is low. It closes by gravity and backflow, so it can slam on fast-stopping pump systems.
Common on cooling water, utility and hydrocarbon transfer lines.
Built like a globe valve: a disc or piston lifts off the seat and drops back when flow stops, often helped by a spring. Short travel means quick closing, but the pressure drop is higher.
Typical on small bore steam, condensate and high-pressure lines.
Two half-plates on a central hinge pin fold open with the flow. Springs start closing them as flow slows, so they shut before flow reverses. Short and light, it fits between two flanges.
Widely used on pump discharge, seawater and firewater lines in the GCC.
The pivot sits just above the disc centre, so the disc floats in the flow and closes with a short, fast swing. Less slam than a swing check, with low pressure drop.
Used on large water transfer and cooling water pumps.
A light disc on a short axial stroke, closed by a spring, in a venturi-shaped body. It closes very fast as flow slows, giving the lowest slam and very low pressure drop. The most expensive design.
Specified on compressor discharge and critical pipeline pump stations.
A ball lifts off the seat with flow and rolls back when flow stops. Few parts, self-cleaning and good with thick or dirty fluids such as sewage and slurries.
Common on wastewater, drainage and small dosing pumps.
A check valve sees the same fluid as the pipe around it, so the body follows the piping class. The disc, hinge and springs move every time the pump starts, so they need materials that resist wear and fatigue as well as corrosion.
| Part | Iron and carbon steel | Stainless and duplex | Bronze and special alloys |
|---|---|---|---|
| Body and cover | Cast or forged carbon steel, ductile iron for waterA216 WCB · A105 · EN-GJS-400 | 316 stainless, duplex and super duplexA351 CF8M · A995 4A / 5A | Bronze and aluminium bronze for seawater and marine dutyB62 · B148 C95800 |
| Disc and plates | 13% chrome or stainless, hard-faced seats for erosive dutyCA15 · 410 SS · Stellite | 316, duplex or super duplexCF8M · 4A · 5A | Aluminium bronze, alloy 625 or titanium for seawaterC95800 · alloy 625 |
| Springs and hinge pins | Inconel X-750 or 316 springs for dual plate and axial valves; stainless or alloy hinge pins and bushesInconel X-750 · 17-4PH · 316 | ||
Your piping class and datasheet name the code. Pipeline checks follow API 6D; plant checks follow API 594, BS 1868 or API 602.
Wafer, lug, double-flanged and butt-weld check valves: Type A dual plate and single plate, Type B swing.
Swing, axial and other check valves for pipelines.
Steel check valves with flanged and butt-weld ends for petroleum duty, still quoted on many datasheets.
Compact forged steel lift and swing check valves, usually 4 inch and below.
Pressure and temperature ratings, wall thickness and materials.
Face-to-face lengths for flanged and butt-weld check valves.
Shell and seat leak tests, including the backflow seat test for check valves.
Cast iron check valves for water and general industrial service.
Material and hardness limits for hydrogen sulphide service.
Your engineers red-line our drawings, you approve the design twice before production starts, and you can witness the tests. Tap a step to see what happens and which documents you receive.
Young & Cunningham has made valves in Britain since the 1920s, with a long history of supplying the UK Ministry of Defence, and some of their valves supplied over 30 years ago are still in service. Their check valves include swing, spring, angle, globe, lift, ball and dual plate designs, in bronze, cast iron, ductile iron, carbon steel and stainless steel. Petromarsh is their exclusive representative in the GCC.
A check valve is sized for the flow, not just the pipe. Send the items on the right and we will choose a design that stays fully open in normal running and closes without slam.
