Ductile Iron Dual Disc Check Valve (Wafer Type)

By Nico Yin · Qingdao Zhaoyuqi Machinery Co., Ltd.

Overview

A dual disc check valve — also called a dual plate or wafer check valve — is a compact, one-way valve in which two semicircular spring-loaded plates open under forward flow and snap shut the instant the flow stops or reverses. Its defining advantage is closing speed: because the plates travel only a short distance and are assisted by torsion springs, they seal before the reverse flow can fully accelerate, sharply reducing the water hammer that slams conventional swing checks shut. Typical ratings are 125/200/250 PSI WOG with nominal sizes from 2" to 24", and bodies are sand cast in ductile iron to ASTM A536.

Dual disc check valves are the standard choice at pump discharges, in fire pump skids, cooling-water headers, and any installation where space, weight, and slam prevention matter. The wafer body clamps between two flanges, cutting face-to-face length by 80–90% compared with a flanged-body swing check and cutting cost and weight accordingly. At our foundry, bodies are resin-sand cast in ASTM A536 ductile iron, precision-machined to clamp standards, and fitted with stainless steel springs, discs, and resilient NBR/EPDM seats before hydrostatic and leakage testing.

Specifications

Typical values for reference only — final parameters to be confirmed against customer drawings.

Working Principle

Inside the wafer body, two half-discs sit on a central hinge pin, with torsion springs holding them lightly against the seat. Forward flow presses the plates open against spring torque, splitting the path into two streamlined half-bores with minimal obstruction. The critical action happens on shutdown: as forward velocity decays, the springs drive the plates back onto the seat, so closure completes in a fraction of the swing-check disc travel time — typically before significant reverse flow develops. Less reverse velocity means less pressure surge, which is why dual disc valves are specified wherever water hammer would damage pumps, pipework, or fittings. Each plate also carries half the load, and the short arc of movement reduces impact on the seat. Installation is flexible — horizontal, vertical-up, or vertical-down — but the flow arrow on the body must match the line direction.

Customization & Sampling

We customize from the casting up: body drilling to ANSI B16.1, EN 1092, JIS, or customer patterns; spring rates tuned to your minimum flow; NBR or EPDM seats; retainerless designs for drinking-water lines; and special epoxy systems for buried service. Because we cast in-house, we can also supply mating flanged adapters and fittings from our own catalog. For sampling, send drawings or a used sample; we produce first articles with full dimensional and material reports before batch production. Sample lead time is typically 2–4 weeks with existing tooling. OEM brands, trading companies, and EPC contractors are served under confidential terms.

Quality Inspection & Packaging

Each lot follows a fixed QC sequence: casting soundness inspection (wall thickness, no shrinkage at pressure zones), machining dimension checks (bore, seat, wafer width, bolt-hole alignment), then shell hydrostatic test and seat leakage test referenced to API 598 / MSS SP-61 practice at agreed pressures. Springs are function-checked for opening and closing behavior. ASTM A536 chemical composition and tensile data are recorded and traceable by heat number; certificates ship with the goods on request. Valves are plastic-wrapped with end-face protectors and packed in export plywood cases on fumigation-free pallets; mixed loading with our elbows, couplings, and fittings is routine.

FAQ

1. Dual disc vs swing check valve — how do I choose?

Choose dual disc (wafer) when you need fast closure to prevent water hammer, limited space, light weight, or pump-discharge protection. Choose swing check when you want a full-port, lowest-pressure-drop path for large flows or wastewater solids. Many plants use dual disc at pump outlets and swing checks on gravity or low-velocity lines.

2. Can the valve be installed vertically?

Yes — dual disc check valves work in horizontal lines and in vertical lines with upward or downward flow, provided the flow arrow matches the direction of flow. Spring assistance keeps closing reliable regardless of orientation, which is an advantage over weight-dependent swing designs. Confirm orientation at enquiry stage so we set the spring and pin configuration correctly.

3. What information do you need to quote accurately?

Nominal size, connection flange standard and rating, working pressure and media, temperature, and installation orientation. If replacing an existing valve, the wafer width and bolt pattern of the old unit help us match it exactly.

Related Products

• Check Valve — full-port swing type for large-bore, low-pressure-drop lines

• Fire Protection Butterfly Valve — isolating valve for sprinkler and fire mains

• Grooved Flange Adapter — connect wafer valves into grooved piping systems

• Concentric Reducer — size transitions on pump discharge headers

• Sway Brace Swivel Attachment — seismic bracing for mechanical rooms with valve arrays

• Casting Advantages & Classification — overview of our ductile iron casting capabilities

Get a Quote

Tell us your size, flange standard, and working pressure — we will confirm a dual disc check valve specification and return a factory quotation within one working day. Samples for testing are available before batch orders.

WhatsApp: +86 185 6156 7088 — send drawings or photos of your current valve for a fast match.

Need a formal quotation? Send your Ductile Iron Dual Disc Check Valve (Wafer Type) drawing, quantity and target price through our quotation request form — it goes straight to the foundry inbox, and we reply with a priced offer, material certificate draft and production lead time within one business day.