Double Flanged Butterfly Valves for Large-Bore Water Mains
Technical guide · Supreme Valves India · Updated 2026-10-28
Direct answer: On large-bore water mains (often DN600 and above), prefer double flanged butterfly valves over wafer. They install like a flanged spool, handle weight and alignment better, and simplify removal. Wafer and lug remain correct for many smaller process and HVAC lines.
Our archive shows DN450–DN700 PN16 / 1.6 MPa butterfly lines on water and solar/utility BOQs — flange type must be explicit.
Wafer vs lug vs double flanged (large bore)
| Body | Large-bore water note |
|---|---|
| Wafer | Light and cheap; long through-bolts and handling get difficult as DN grows |
| Lug | Dead-end capable if rated; still lug-thread limited on very large sizes |
| Double flanged | Preferred for mains, pump discharge headers, buried vaults with flanged pipe |
Standards language
- EN 593 / EN 1092 PN10 or PN16 — metric water
- AWWA C504 — large diameter waterworks (US practice)
- API 609 — industrial butterflies (often smaller process)
Operators on large DN
Gearboxes are normal above roughly DN200–DN300 depending on ΔP and seat torque. Add limit switches when the DCS needs open/close feedback. Manual levers are not appropriate on large mains.
RFQ checklist
- Double flanged (state clearly)
- DN + PN16 or Class 150
- Disc / seat materials (DI, SS304/316, EPDM, etc.)
- Gear + switches
- Face-to-face series (EN 558 / AWWA)
Related: lug vs wafer, WCB CL150 butterfly RFQ.
Frequently asked questions
Why not use wafer butterflies on DN600 water mains?
Weight, flange alignment and maintenance favour double flanged bodies on large diameters. Wafer through-bolts become long and awkward; double flanged valves bolt like a short flanged spool.
Is double flanged the same as lug?
No. Lug bodies use tapped lugs; double flanged valves have two full flange faces with through-bolt patterns matching the pipe flanges.
PN16 or Class 150 for large water?
Municipal and metric projects usually PN10/PN16 EN flanges. Process water on ASME isometrics may be Class 150. Match the pipe.