Wafer Check Valves: Reliable Backflow Prevention for Industrial Pipelines

Design Variants: With or Without Spring Return

The choice between a spring-return and a gravity-close wafer check valve is one of the most consequential decisions in the specification process, particularly for pump discharge lines. In a gravity-close valve, the disc relies entirely on its own weight to return to the seat once forward flow stops. This is acceptable in vertical pipelines with upward flow, or in horizontal lines where flow velocities are low and the risk of water hammer — the destructive pressure surge caused by abrupt flow reversal — is minimal. However, in horizontal installations or on fast-stopping pump systems, gravity closure is too slow. The disc waits for flow to fully reverse before it begins to close, and the resulting slam generates pressure spikes that can damage pipework, fittings and pumping equipment.

A spring-return valve solves this problem by beginning to close the disc as soon as forward flow starts to decelerate — well before reversal occurs. The spring force also makes the valve suitable for installation in any orientation, including horizontal and vertical downward-flow pipelines where a gravity-close valve would simply remain open under the weight of the disc. One practical point to note: the spring increases the minimum differential pressure needed to open the valve, known as the cracking pressure. This is rarely a limiting factor in standard industrial service, but it should be verified at very low operating pressures. For PTFE and metal seats, a spring return is always required regardless of installation orientation, since both materials have lower elastic recovery than rubber elastomers and need spring force to achieve reliable low-pressure sealing.

Body and Seat Materials

Stainless steel 1.4408 (AISI 316 / CF8M) is the standard body material for service involving corrosive or demanding process media. The austenitic chromium-nickel-molybdenum alloy resists chloride-bearing fluids, moderately aggressive acids, alkalis and many organic compounds. It is the correct specification for chemical processing, food and beverage production, pharmaceuticals, drinking water distribution, offshore installations and any application where iron contamination of the process medium cannot be tolerated. At maximum service temperature, stainless steel wafer check valves are rated to +200 °C with PTFE seats and +300 °C with metal seats.

Galvanised steel 1.0619 is the economical alternative for neutral, non-corrosive service such as general water supply, HVAC circuits and industrial utilities. The zinc coating provides adequate corrosion protection in damp conditions and outdoor environments. It is not appropriate for aggressive or acidic process media, food contact applications or high-temperature service above 120 °C.

The seat material determines the valve's chemical compatibility and temperature ceiling, and must be matched to the process fluid with care. NBR (nitrile rubber) is the all-round standard seat for water, mineral oils, fuels, hydraulic media and general sewage service, rated to approximately 80 °C. It is not suited to hot water, steam or oxidising chemicals. EPDM is the preferred seat for drinking water, hot water circuits, steam and dilute aqueous solutions, rated to 120 °C, but incompatible with hydrocarbons. PTFE covers the broadest chemical spectrum — virtually inert to acids, alkalis, solvents and oxidising agents, FDA-compliant and rated to 200 °C — and is the seat of choice for aggressive chemical service. FKM/Viton handles fuels, aromatic hydrocarbons and concentrated acids at elevated temperatures to 180 °C, offering better elastic recovery than PTFE where spring-free installation is required. Metal seats are specified for high-temperature steam, abrasive slurries and any service where elastomers are not permissible, with temperature capability up to 300 °C.

Installation Guidance

Wafer check valves are clamped between pipe flanges conforming to DIN EN 1092-1 Form B, DIN 2632/2633 or ASME B16.5. Through-bolts are tightened symmetrically to draw the body evenly against both flange faces. Flange gaskets must be sized correctly for the pipe bore — a gasket that protrudes into the bore will restrict disc movement and prevent the valve from opening fully, which is a common installation error. Before tightening bolts to final torque, confirm that the disc swings freely through its full travel without obstruction from gaskets or flange faces.

The flow direction arrow stamped or cast on the valve body must always align with the intended process flow direction. In horizontal installations, the hinge pin axis should be horizontal so that gravity assists disc closure. In vertical upward-flow pipelines, both spring and gravity-close versions work correctly. For vertical downward-flow, a spring-return version is mandatory. Provide at least one to two nominal pipe diameters of straight pipe upstream and downstream of the valve — elbows, reducers or tees immediately adjacent to a check valve generate turbulent flow conditions that accelerate seat wear and reduce disc stability.

Application Areas

Wafer check valves are found across an exceptionally wide range of industries and installations. In water supply and treatment, stainless steel bodies with EPDM seats — approved to DVGW W 270, KTW, ACS and WRAS for direct potable water contact — are standard on pump station discharge lines, waterworks distribution headers and desalination plant pipework. In chemical and process plants, stainless steel bodies with PTFE or FKM seats handle aggressive acids, alkalis, solvents and chloride-bearing streams, while spring-return versions ensure fast closure and prevent cross-contamination in pump cycling service.

HVAC and building services make extensive use of galvanised steel and stainless steel wafer check valves on heating circuits, chilled water systems and condenser water loops, where the compact wafer body simplifies plant room pipework compared to heavier flanged swing check valves. In food, beverage and pharmaceutical production, stainless steel 1.4408 valves with FDA-compliant EPDM or PTFE seats provide the hygienic surface finish and material compliance required for direct product contact lines. Power generation applications include cooling water systems, condensate return lines and auxiliary pipework, often at PN 25 or PN 40 ratings with metal seats for high-temperature service.

In oil, gas and petrochemical plants, stainless steel wafer check valves with FKM seats are used on hydrocarbon and fuel lines in ANSI Class 150 and 300 flange dimensions for compliance with international pipeline standards. For biogas and gas-fired plant, NBR seat valves are the standard choice for gas compressor discharge lines and gas-fired boiler pipework. For raw biogas containing hydrogen sulphide, FKM seats are recommended — our technical team can advise on the correct specification for the specific gas composition involved.

Wafer Check Valve or Dual Plate Check Valve?

Both valve types are installed between flanges and prevent backflow automatically, but they differ in closure speed, water hammer performance and the size ranges where they are most effective. The single-flap wafer check valve is the right choice for general-purpose backflow prevention at smaller and medium bore sizes — typically DN 32 to DN 100 — where flow velocities are moderate and a spring-return valve provides adequate protection against pressure surges. It is cost-effective, simple to install and available in a wider range of body materials and seat options than the dual plate design.

The dual plate check valve becomes the preferred specification from DN 100 upwards, particularly on pump discharge lines and large-diameter mains where water hammer is a primary concern. Its two lightweight spring-loaded half-discs close simultaneously from the centre outward in milliseconds as forward flow decelerates — well before any reverse velocity can develop — providing dramatically better water hammer suppression than a single-flap valve at equivalent sizes. The dual plate design also generates lower pressure drop in the open position, as both discs lie flat and parallel to the flow direction. For DN 100 and above on any high-flow or pump discharge application, the dual plate check valve is the industry-standard solution.

Why Choose Fergo for Wafer Check Valves

Fergo has supplied industrial valves and pipeline fittings since 2004, building a stock programme of 439 wafer check valve configurations covering the complete DN 32 to DN 400 size range in both stainless steel and galvanised steel, across all seat material and spring-return variants. Full technical documentation — data sheets, 3D models, declarations of conformity and material certificates — is available for all stock items as a direct download, without prior request. For non-standard requirements including special alloy bodies, PVC-U or PP-H plastic housings, alternative flange drillings or 3.1 material test certificates per EN 10204, the technical sales team is available directly by phone or email. All standard stock positions are available for next-day delivery within Germany.