Wafer Butterfly Valve

Wafer butterfly valves are most commonly rated for:

• ASME Class 150: 275 psi (19 bar) at 100°F (38°C)
• ASME Class 300: 720 psi (49.6 bar) at 100°F (38°C)
• European PN ratings: PN10 (145 psi), PN16 (232 psi), PN25 (363 psi)

Most standard wafer valves are Class 150. Class 300 is available from most manufacturers. Note that pressure ratings decrease as operating temperature increases — always refer to the manufacturer's pressure-temperature chart for exact values at your service temperature.

The fundamental difference is in the body design and bolting method:

• Wafer valve: Through-holes in the body. Long bolts pass through both pipe flanges and the valve body. Requires both flanges for clamping. Cannot provide dead-end isolation.
• Lug valve: Threaded inserts (lugs) in the body. Each pipe flange bolts independently to the valve. Can provide dead-end isolation. Downstream pipe can be removed independently.

Lug valves typically cost 15-25% more than equivalent wafer valves. Choose wafer for continuous pipelines where dead-end service is not required. Choose lug for pipe ends, pump isolation, or maintenance teardown points

Disc material options, from most common to specialized:

• Ductile Iron (ASTM A536 65-45-12) – Standard for water, wastewater, and HVAC service. Cost-effective with good corrosion resistance when epoxy coated.
• Nylon 11 Coated Ductile Iron – Enhanced corrosion resistance for mildly aggressive water and wastewater. The nylon coating provides a smooth surface that reduces scaling.
• 316 Stainless Steel (CF8M) – For chemical processing, food processing, pharmaceutical, and corrosive environments.
• Aluminum Bronze (C95800) – Excellent seawater and brackish water resistance. Ideal for marine, desalination, and coastal applications.
• Duplex Stainless Steel (1.4469 / F51) – For aggressive environments including high-chloride water, sour gas, and severe chemical service.
• Nickel-Aluminum Bronze – Specialized for high-strength seawater service and offshore applications.

Wafer butterfly valves are fitted with a standard ISO 5211 mounting pad, making them compatible with:

• Lever handle (2"–12"): Manual quarter-turn operation for low-torque applications. Lockable handle available for safety positions.
• Gear operator (8"–48"): In-line handwheel or bevel gear with chainwheel. Reduces operating torque and provides self-locking in any position.
• Pneumatic actuator: Double-acting or spring-return (fail-safe). For automated on-off control and remote operation.
• Electric actuator: On-off or modulating (4-20 mA position feedback). For SCADA integration and precise flow control.

All operators are factory-mounted and torqued to match the specific valve size and pressure class. Actuator sizing should account for the maximum differential pressure and disc-seat interference torque.

Follow these steps for proper wafer butterfly valve installation:

1. Ensure the two pipe flanges are parallel and properly aligned.
2. Open the valve disc to approximately 10-20 degrees (not fully closed, not fully open).
3. Insert the wafer valve between the flanges, centering it using the alignment ridges on the body faces.
4. Insert flange bolts through the pipe flanges and valve body through-holes. Use sufficiently long bolts to achieve full thread engagement.
5. Hand-tighten all bolts, then torque them in a star/cross pattern in at least three passes.
6. After torquing, operate the valve fully open and fully closed to verify smooth operation.
7. Never install a wafer valve at a dead-end pipe termination.

In typical water distribution service (clean water, moderate flow velocity, standard operating temperatures), a wafer butterfly valve with a vulcanized EPDM seat has an expected service life of 15-25 years. Key factors affecting service life include:

• Operating frequency – Valves cycled daily have more seat wear than valves operated once or twice per year. We recommend full-cycle operation every 6-12 months to prevent seat set.
• Media abrasiveness – Sand, sediment, or slurry in the fluid accelerates seat and disc wear.
• Temperature – Continuous operation near the maximum temperature limit reduces elastomer life.
• Chemical compatibility – Incompatible chemicals cause swelling, softening, or embrittlement of the seat material.

Every Laux Valve wafer butterfly valve undergoes the following tests before shipment:

• Shell (hydrostatic) test: Valve body tested at 1.5x rated pressure per API 598 / AWWA C504. No visible leakage through body wall or flange connections.
• Seat (closure) test: Bubble-tight shut-off verified at 1.1x rated pressure differential. Zero leakage required for resilient-seated valves.
• Hydrostatic test duration: 15 seconds (2"-8"), 30 seconds (10"-18"), 60 seconds (20"-30"), 90 seconds (36"+).
• Operational test: Full open-to-close cycle to verify smooth operation and proper torque.

Test records are available upon request. Additional testing (fire-safe per API 607, fugitive emission per ISO 15848-1, or high-pressure closure test) is available as optional extras.

Wafer butterfly valves are manufactured to match the following flange drilling standards:

• ASME B16.5 Class 150 / Class 300 RF – North American standard, 2"-24"
• ASME B16.1 Class 125 / Class 250 FF – Older North American standard for cast iron flanges
• EN 1092-2 PN10 / PN16 / PN25 – European standard
• AS 4087 PN16 / PN21 – Australian standard
• JIS B2220 10K / 20K – Japanese standard

The valve body through-holes are designed to accommodate bolts for the specified flange standard. When ordering, please specify your flange standard so the correct bolt circle and hole size are provided.

Yes. As an OEM manufacturer since 2011, Laux Valve offers private labeling and custom branding services for wafer butterfly valves. We can provide:

• Your company name, logo, and specifications cast on the body
• Custom nameplates with your part numbers
• Custom packaging and documentation
• Custom operator combinations and special coatings

Minimum order quantities and lead times vary by size and specification. Contact our OEM sales team with your requirements.