H76H/W wafer double disc swing check valve
• PN16/PN25/PN40 wafer double-disc swing check valve, DN50–DN600, ≤425°C
• Compact wafer alternative to H44 flanged swing check valve
• Spring-assisted dual semi-circular discs for rapid closure and low water hammer
• Three material grades: 2Cr13, 1Cr18Ni9Ti (304), 1Cr18Ni12Mo2Ti (316)
- • Fits between flanges; supports vertical and horizontal installation
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Product Details
The H76H / H76W wafer double-disc swing check valve stops backflow on a large water, steam or process main without the length of a flanged swing valve. It is a slim wafer body that clamps between two pipe flanges on the existing bolts; inside it, two spring-assisted semi-circular discs hinge open on centre pins and snap shut together the moment forward flow collapses. Being light and spring-loaded they close faster than one large swing disc, saving space and keeping the closure shock low. PN16, PN25 and PN40, DN50 to DN600, wetted parts in 2Cr13 or austenitic stainless steel for service to 425°C.
- PN16 / PN25 / PN40 wafer double-disc swing check valve, DN50–DN600, service to 425°C
- Slim wafer body clamps between existing pipe flanges — compact alternative to the flanged H44H swing check valve
- Two spring-assisted semi-circular discs snap shut together, closing faster than a single-disc swing valve
- Both discs fold flat against the body when open — minimal flow resistance on continuous-duty mains
- Three grades: 2Cr13 for water/steam/oil, 1Cr18Ni9Ti (AISI 304) and 1Cr18Ni12Mo2Ti (AISI 316) for corrosion service
- Installs horizontally or vertically with upward flow; the flow direction is marked on the body
Product Overview
In international specifications this valve is most often called a dual plate check valve; dual plate and double disc refer to the same wafer design with two spring-assisted half discs.
The H76H (2Cr13 bodies) and H76W (austenitic stainless bodies) are wafer-type double-disc swing check valves built to fit between standard pipe flanges using the existing bolt set. The twin semi-circular discs are mounted on central hinge pins inside an ultra-slim body. When forward line pressure exceeds the spring preload the two discs swing inward and lie flat against the body wall, presenting almost nothing to the flow; when flow stops or reverses, reverse pressure plus the springs snap both discs shut in near-simultaneous fashion. That dual, spring-loaded closure is faster than a single large swing disc falling back under gravity, so the water-hammer spike on pump trip is smaller — which is the two reasons engineers reach for this pattern: the space it saves and the closure behaviour it gives.
Choose the wafer double-disc when the line is too big for a lift check valve but there is not the face-to-face length for a flanged swing valve, and the medium is clean enough for a spring-and-hinge pattern. It is not the right answer on a heavily soiled line, where the hinge pins want protective straining; and where water hammer must be capped precisely, the HH46X controls the closing rate far better.
What the Model Code Means
Read as a GB/T (JB/T 308) designation: H = check valve, 7 = wafer / clamped-between-flanges connection, 6 = the double-disc swing structure; the seat/body letter gives the grade — H76H is the 2Cr13 carbon-steel series, H76W the austenitic stainless series. The number after the dash is the PN class (16, 25, 40) and the trailing letter marks the exact material: C = 2Cr13, P = 1Cr18Ni9Ti (304), R = 1Cr18Ni12Mo2Ti (316), so H76H-16C, H76W-16P and H76W-16R are the three PN16 variants. Manufacturer coding for wafer check valves varies, so send the nameplate you are replacing, or confirm the reading in the Valve Model Decoder.
Core Strengths
Double-Disc Swing Design
Two spring-loaded semi-circular discs swing open on center hinges when forward flow pressure is applied, and snap shut simultaneously by spring force plus flow reversal—delivering faster closure than single-disc swing valves.
Ideal H44 Flanged Replacement
Designed as the compact wafer alternative to traditional H44 flanged swing check valves. Delivers equivalent or better performance at a fraction of the face-to-face space requirement and significantly lower installed cost.
Ultra-Low Water Hammer Effect
Lightweight dual discs respond almost instantly to flow reversal, closing before significant reverse velocity can develop. This dramatically reduces water hammer pressure spikes that can damage pumps and pipelines.
Minimal Flow Resistance
When fully open, both discs fold completely against the wafer body interior, creating an unobstructed flow path with minimal pressure drop. Ideal for high-volume continuous-flow applications requiring energy efficiency.
Large DN Coverage up to DN600
Available in sizes from DN50 through DN600 across three pressure classes—the widest size range among wafer check valves. Perfect for large-diameter water mains, cooling towers, and industrial circulation systems.
Triple Material Options for Corrosion Service
Choose 2Cr13 carbon steel for water/steam/oil, 1Cr18Ni9Ti (AISI 304) for nitric acid environments, or 1Cr18Ni12Mo2Ti (AISI 316) for aggressive media including acetic acid and mixed corrosive services.
Performance Specifications
| Parameter | PN16 | PN25 | PN40 |
|---|---|---|---|
| Model (Carbon Steel) | H76H-16C | H76H-25 | H76H-40 |
| Model (Stainless 304) | H76W-16P | H76W-25P | H76W-40P |
| Model (Stainless 316) | H76W-16R | H76W-25R | H76W-40R |
| Nominal Pressure (MPa) | 1.6 | 2.5 | 4.0 |
| Shell Test Pressure (MPa) | 2.4 | 3.8 | 6.0 |
| Seal Test Pressure (MPa) | 1.8 | 2.8 | 4.4 |
| Max. Working Temperature | ≤425°C | ≤425°C | ≤425°C |
| Body Material | 2Cr13 / 1Cr18Ni9Ti / 1Cr18Ni12Mo2Ti Stainless Steel | 2Cr13 / 1Cr18Ni9Ti / 1Cr18Ni12Mo2Ti Stainless Steel | 2Cr13 / 1Cr18Ni9Ti / 1Cr18Ni12Mo2Ti Stainless Steel |
Nominal, shell and seal test pressures are per PN class; the 425°C ceiling and the three stainless grades apply across the whole range. For anything above these conditions, or where the medium carries solids, move to a flanged H44H swing check valve or a purpose-built design.
Material Selection Guide
| Material Grade | Valve Body | Disc | Best Suited For |
|---|---|---|---|
| 2Cr13 (Carbon Steel) | 2Cr13 | 2Cr13 | Water, Steam, Oil, Petroleum |
| 1Cr18Ni9Ti (AISI 304) | 1Cr18Ni9Ti | 1Cr18Ni9Ti | Nitric Acid Environments |
| 1Cr18Ni12Mo2Ti (AISI 316) | 1Cr18Ni12Mo2Ti | 1Cr18Ni12Mo2Ti | Nitric Acid, Acetic Acid, Severe Corrosive Media |
The three grades share the body pattern and dimensions; only the wetted metallurgy changes. Specify 304 for nitric acid service and 316 for acetic acid and mixed corrosive duty, and confirm the exact medium and concentration with us before ordering.
Main Dimensions & Weights
PN10 / PN16
| Nominal size | L (face-to-face, mm) | D (outer dia., mm) | Weight (kg) |
|---|---|---|---|
| DN50 | 60 | 109 | 1.8 |
| DN65 | 67 | 129 | 2.6 |
| DN80 | 73 | 144 | 4.2 |
| DN100 | 73 | 164 | 5.2 |
| DN125 | 83 | 194 | 6.7 |
| DN150 | 98 | 220 | 9.4 |
| DN200 | 127 | 275 | 18.7 |
| DN250 | 146 | 333 | 29.4 |
| DN300 | 181 | 388 | 48.5 |
| DN350 | 184 | 448 | 66 |
| DN400 | 198 | 498 | 90 |
| DN450 | 203 | 558 | 130 |
| DN500 | 219 | 630 | 186 |
| DN600 | 222 | 734 | 298 |
PN25
| Nominal size | L (face-to-face, mm) | D (outer dia., mm) | Weight (kg) |
|---|---|---|---|
| DN50 | 60 | 109 | 2.0 |
| DN65 | 67 | 129 | 3.2 |
| DN80 | 73 | 144 | 4.8 |
| DN100 | 73 | 170 | 6.0 |
| DN125 | 83 | 198 | 9.0 |
| DN150 | 98 | 228 | 12 |
| DN200 | 127 | 298 | 22 |
| DN250 | 146 | 343 | 38 |
| DN300 | 181 | 403 | 54 |
| DN350 | 184 | 480 | 80 |
| DN400 | 198 | 520 | 118 |
PN40
| Nominal size | L (face-to-face, mm) | D (outer dia., mm) | Weight (kg) |
|---|---|---|---|
| DN50 | 60 | 109 | 2.4 |
| DN65 | 67 | 129 | 3.8 |
| DN80 | 73 | 144 | 5.6 |
| DN100 | 73 | 170 | 7.5 |
| DN125 | 83 | 198 | 11 |
| DN150 | 98 | 228 | 15 |
| DN200 | 127 | 293 | 27 |
| DN250 | 146 | 355 | 48 |
| DN300 | 181 | 420 | 78 |
| DN350 | 184 | 480 | 116 |
| DN400 | 198 | 549 | 152 |
L = face-to-face length of the wafer body, D = outer diameter, weights in kilograms; all values for reference only and certified for each order at quotation. The PN25 and PN40 tables end at DN400 — DN450 to DN600 are supplied in the PN10 / PN16 class only on this series. Flange facings and drilling follow GB/T 9113 / JB/T 79 / HG/T 20592; tell us the mating flange standard.
Wafer Double-Disc, Flanged Swing or Wafer Lift: Which Non-Return Valve
| Selection factor | H76H / H76W wafer double-disc (this page) | H44H flanged swing check valve | H71H / H71W wafer lift check valve |
|---|---|---|---|
| Nominal size | DN50–DN600 | DN50–DN600 | DN15–DN150 |
| Pressure classes | PN16 / PN25 / PN40 | PN16 through PN100 | PN16 / PN25 / PN40 |
| Flow resistance when open | Low — both discs fold flat | Lowest — one disc lifts fully clear of the flow | Higher — guided disc, longer flow path |
| Installation space | Wafer; minimal face-to-face, no flanges of its own | Flanged; longest face-to-face of the three | Wafer; the slimmest, small bore only |
| Orientation | Horizontal or vertical (upward flow) | Horizontal only | Horizontal or vertical |
| Closure / water hammer | Fast dual-disc + spring, reduced hammer | Gravity return, audible slam on large bore | Light guided disc, quick and low-hammer |
| Maintenance | Hinge pins + springs, replace discs as a pair | Bolted top cover, easiest seat access | Simplest — all-metal, fewest parts |
| Best for | Big bore in a tight space, low slam wanted | Largest mains, minimum head loss, high class | Small bore, low flow, compact and cheap |
In short: the flanged H44H wins where there is room and the class or bore is extreme; the wafer H71H wins on small bores where cost and space dominate; the H76H/H76W sits between them, covering the large DN50–DN600 sizes a lift valve cannot while staying wafer-slim and closing more gently than a single swing disc.
Structure Drawing
Design & Manufacturing Standards
- Design Standard: GB/T 12236
- Face-to-Face Dimensions: GB/T 12221
- Flange Standards: GB/T 9113, JB/T 79, HG/T 20592
- Testing & Inspection: GB/T 13927, JB/T 9092
- Applicable International Standards: EN 13709, API 594, ISO 5752 (optional)
Installation & Maintenance Guidelines
- Wafer Mounting: Install the wafer valve between two flanges using the same bolt set. Ensure the valve bore aligns perfectly with the pipeline centerline. Use full-face gaskets on each side for proper sealing between flange faces.
- Flow Direction: Verify correct orientation against the flow direction arrow marked on the valve body. Incorrect installation direction will prevent proper disc operation and may cause damage under reverse pressure.
- Dual Orientation Capability: Can be installed on both horizontal and vertical piping without performance degradation. For vertical installations, ensure upward flow direction for optimal disc swing action.
- Bolt Tightening Sequence: Use a star-pattern torque sequence to compress the wafer body evenly between flanges. Avoid over-torquing which may distort the thin-profile body and impede free disc movement on hinge pins.
- Maintenance: Periodically inspect both swing discs, hinge pins, and sealing surfaces for wear, corrosion, or debris buildup. Check spring preload tension. Replace worn components as a matched pair to maintain balanced disc operation.
Application Fields
This pattern suits large-diameter, low-head-loss backflow protection where the space is wafer-tight: Municipal Water Supply; Cooling Tower Systems; Industrial Circulating Water; Chemical Processing Plants; HVAC & District Heating; Power Generation Cooling Water; Marine Ballast Systems; Fire Protection Networks. On a clean high-volume main in a compact skid or valve chamber, the double-disc wafer is often the only check valve that fits without extending the pipe run.
What We Need to Quote Your H76H / H76W Valves
- Size and quantity: DN50–DN600; PN25/PN40 sizes are DN50–DN400, PN10/PN16 to DN600.
- Pressure class: PN16, PN25 or PN40, matched to the line design pressure and derated at temperature.
- Medium and temperature: water/steam/oil (2Cr13), nitric acid (304) or severe corrosion (316).
- Pipe flange standard: GB/T 9113, JB/T 79 or HG/T 20592 so the wafer matches your drilling.
- Orientation: horizontal or vertical with upward flow.
- Fluid cleanliness: confirm whether a strainer is needed to protect the hinge pins and springs.
- Documentation: EN 10204 3.1 certificates and test records for tenders.
Send a valve schedule or the flange drawing and we will confirm the class, the wafer centre (D) against your mating flange and the correct material grade. Drawings are in the download center; qualifications on the certifications page.
Frequently Asked Questions
What is the difference between a wafer double-disc check valve and a flanged swing check valve?
Both stop backflow with a swinging disc. The flanged H44H has its own flanges and a long face-to-face, so it needs pipe space and a set of companion flanges. The H76H clamps between your existing line flanges with almost no length, and splits the disc into two light half-discs on springs that close faster and more gently. The trade-off is the reverse: the wafer is serviced as part of the flange joint and prefers a cleaner fluid than a heavy plant swing valve.
Why two half-discs instead of one full disc?
A single full disc on a DN400 or DN600 main is heavy, and when it falls back onto its seat under gravity it makes a large impact and a pressure spike. Two semi-circular discs are far lighter and are spring-assisted, so they close quickly and nearly together, cutting both the slam and the water-hammer spike, and they fold flat so the open flow path stays almost unobstructed.
Can it be installed on a vertical pipe?
Yes. Both discs are spring-assisted, so unlike a gravity-only flanged swing valve the H76H works on vertical runs as well as horizontal ones – with upward flow so the medium helps hold the discs open and gravity still assists the return. Verify the flow arrow on the body matches the direction.
Which body material do I order – 2Cr13, 304 or 316?
Order by medium. 2Cr13 (H76H-…C) is the general grade for water, steam, oil and petroleum to 425 degC. 1Cr18Ni9Ti / AISI 304 (H76W-…P) is for nitric acid environments. 1Cr18Ni12Mo2Ti / AISI 316 (H76W-…R) is for severe corrosive duty including acetic acid. The dimensions are identical, only the wetted metallurgy changes.
What pressure class and how far up in size?
PN16, PN25 and PN40. PN10 / PN16 covers DN50 to DN600; PN25 and PN40 are offered DN50 to DN400 on this series. Match the class to the line design pressure and remember the pressure a valve may take falls as temperature rises, so send the operating temperature too.
How is a wafer check valve maintained?
It comes out when the flange joint is broken, so plan it into a spool that can be racked. Inspect both swing discs, the hinge pins and the sealing faces for wear, corrosion and debris, check the spring preload, and replace worn discs as a matched pair so both leaves still close evenly. Do not over-torque the flange bolts when refitting – that distorts the thin wafer body and the discs jam.
Gaoshan Valve has manufactured industrial valves since 1975 and holds ISO 9001/14001/45001 with CE, API 6D and PED product certification. It is an approved supplier to Sinopec, CNPC and State Grid and exports to more than 30 countries, supplying water utilities, power plants and EPC contractors.
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Contact Gaoshan Valve for dimension sheets, CAD drawings, material recommendations and a class check at your operating temperature. Reply within 24 hours from our overseas sales desk.
