Wafer vs Lug Butterfly Valve — Dead-End Service & Flange Bolting
Wafer and lug butterfly valves look similar in the line, but the body bolting pattern decides whether you can remove one flange for dead-end service or maintenance. Wrong pattern on a BOQ is a frequent site hold-up.
Quick selection
Wafer for sandwich mounting between two flanges with through-bolts — both flanges normally required. Lug when one-side removal or dead-end service is needed — tapped lugs bolt independently to each flange.
Comparison table
| Factor | Wafer | Lug |
|---|---|---|
| Mounting | Clamped between two flanges | Bolted to each flange via tapped lugs |
| Dead-end service | Not preferred — needs both flanges | Suitable when rated for dead-end |
| Flange removal | Usually disturb both sides | One flange can be removed if designed for it |
| Cost / weight | Typically lighter and lower cost | Heavier body, higher cost |
| Alignment | Relies on flange bolts for centering | Lugs help locate and support the valve |
| Common ratings | PN10/PN16, Class 150 | PN10/PN16, Class 150 (check dead-end rating) |
When to specify wafer
- Continuous pipe runs with flanges on both sides that stay installed.
- Space and cost driven water, HVAC, and utility lines.
- Projects that explicitly allow wafer body per datasheet.
When to specify lug
- Dead-end service, end-of-line isolation, or filter/strainer spool removal.
- Maintenance plans that require removing one mating flange.
- Equipment isolation where wafer sandwich bolting is impractical.
Also consider double-flanged
For large diameters, high integrity, or buried/transmission service, double-flanged (or flanged) butterfly bodies may be preferred over wafer/lug. Confirm face-to-face (ISO 5752 / AWWA) on the RFQ.
RFQ checklist
- Wafer, lug, or double-flanged — state body type.
- PN or Class, face type, disc/seat MOC (EPDM, NBR, PTFE, SS).
- Concentric vs eccentric (double/triple offset) for temperature/pressure.
- Operator: lever, gear, pneumatic/electric actuator.
FAQ
Can wafer be used for dead-end?
Lug or flanged patterns are preferred for dead-end service. Wafer typically needs both flanges. Confirm dead-end rating on the RFQ.
Are wafer and lug face-to-face the same?
Often similar for a given standard, but always confirm ISO 5752 / manufacturer FTF before ordering spares or replacements.
Does lug mean fire-safe?
No. Lug is a body mounting style. Fire-safe relates to seat/trim and test standard (e.g. API 607), not wafer vs lug.
Wafer vs wafer-lug hybrid?
Some bodies have both through-holes and tapped lugs. Treat hybrids as project-specific — ask for the GA drawing.
Send enquiry
Include size, pressure class or PN, ends, MOC, quantity, and destination. We return a techno-commercial offer from Ahmedabad.