Water & Utility
End-of-line and branch isolation on distribution networks.
Butterfly Valve · Lug Type
Lug butterfly valves carry threaded inserts (lugs) that bolt independently to each pipe flange, allowing downstream pipe removal and dead-end service without disturbing the upstream line. Worm gear operators give these valves controlled quarter-turn actuation and self-locking hold for isolation and end-of-line duty in water, process, and utility systems.
Application Foundation
A lug butterfly valve gear operator delivers quarter-turn actuation for valves that bolt to each flange through threaded lugs. Because lug valves can hold line pressure with the downstream pipe removed, the operator's self-locking worm set must hold the disc firmly against full one-side pressure for dead-end and end-of-line service.
Size the operator from the valve break-to-open torque, including the dead-end pressure case if specified, then match the ISO 5211 flange and stem bore. Lug valves typically use F10 to F16 patterns; Matson single-stage models M12–M15 (1,000–3,400 N·m) cover the common range, with larger units for high-pressure or large-bore service.
Engineering Data
| ISO 5211 Flange | Typical Valve Size Band* | Common Valve Families | Matson Models Offering This Flange |
|---|---|---|---|
| F05 | Small bore | Ball, plug, small butterfly | M07 |
| F07 | Small–medium bore | Butterfly (wafer), ball, plug | M07, M10 |
| F10 | Medium bore | Butterfly, ball, plug | M07, M10, M12 |
| F12 | Medium bore | Butterfly (lug), ball, gate top-work | M12, M14 |
| F14 | Medium–large bore | Butterfly, trunnion ball, gate | M12, M14, M14A, M15 |
| F16 | Large bore | Butterfly (double flange / AWWA), ball, gate | M14, M14A, M15, M16 |
| F25 | Heavy / large bore | Large AWWA butterfly, high-pressure ball, large gate | M16 |
*Valve size band is indicative only — actual flange depends on the valve manufacturer's top-work, stem, and torque rating. Flange options and Matson single-stage model data are from the Matson worm gearbox catalog (M07–M16, 200–4,400 N·m). Two-stage and electric-actuator series extend up to 160,000 N·m. Confirm the exact flange against your valve datasheet.
| Variant | Actuation | Typical Torque Driver | Mounting Interface |
|---|---|---|---|
| Lug body | Quarter-turn 90° | Seat friction + ΔP; dead-end case | ISO 5211 F10–F16 |
| Lug (dead-end) | Quarter-turn 90° | Full one-side line pressure | ISO 5211 F12–F16 |
General selection guidance by torque demand and top-flange interface. Match the required break-to-open torque (with safety factor) and the valve top-work flange to a Matson model; exact model and dimensions are confirmed against your valve datasheet — request a datasheet.
Per-model specifications (dimensions, weights, drive bushing details): available on request — request a datasheet. Send your valve tag, bore, pressure class, and required output torque and our engineers return a model recommendation with the matching ISO 5211 interface.
Operation
Verify whether dead-end/end-of-line service is required — it raises the torque case.
Confirm the ISO 5211 flange and stem bore; lug patterns differ between manufacturers.
Choose SS316 housings for corrosive or coastal end-of-line installations.
Engineering
By Industry
End-of-line and branch isolation on distribution networks.
Dead-end service and equipment isolation headers.
Sectional isolation where downstream removal is required.
Larger chilled-water and condenser branches.
Manufacturing Partner
Operators sized against real valve torque charts and top-work drawings — not generic catalog tables.
Standard and adapter mounting for current and legacy valve patterns without field rework.
Private label, locked BOM, and volume pricing for valve OEM and distributor programs.
STEP models, center-height tables, and export certificates issued with the commercial quote.
Common Questions
A lug-type butterfly valve has threaded lugs around its body that bolt directly to each pipe flange. This lets the downstream pipe be removed while the valve stays installed and holds line pressure, supporting dead-end and end-of-line service. A worm gear operator adds controlled quarter-turn actuation.
A wafer butterfly valve is clamped between flanges by the line bolts and cannot hold pressure with the downstream pipe removed. A lug butterfly valve bolts to each flange independently, allowing dead-end and end-of-line service. Both use the same quarter-turn worm gear operators and ISO 5211 mounting.
Yes, lug butterfly valves can be used for dead-end and end-of-line service up to the manufacturer's rated pressure because the lugs bolt to each flange independently. Confirm the rated dead-end pressure on the valve datasheet, as it raises the operator torque case and may need a higher safety factor.
A gear-operated butterfly valve uses a worm gear operator rather than a hand lever to rotate the disc 90°. The worm set multiplies torque, holds the disc without back-driving, and lets one operator close large or high-pressure lug valves safely.
Match the operator to the valve break-to-open torque (including dead-end case if required) and ISO 5211 flange. Lug valves typically use F10–F16; Matson models M12–M15 (1,000–3,400 N·m) cover the common range. Provide your valve datasheet for a specific recommendation.
Send your lug valve bore, pressure class, dead-end requirement, and ISO 5211 flange. We return a worm gear operator recommendation with torque margin and mounting confirmation.