Double Eccentric Lug‑Type Butterfly Valve, also known as Double Offset Lug Butterfly Valve, is an industrial butterfly valve featuring double‑offset geometry and lug‑style connection. Its stem axis is offset from both the valve body centerline and the disc sealing centerline. This design allows the disc to lift off the seat rapidly during opening and closing cycles, so as to reduce friction and wear between sealing faces. Compared with conventional concentric butterfly valves, the double‑offset construction delivers lower operating torque, superior sealing performance and extended service life.
The lug‑type structure is equipped with individual bolt lugs on both sides of the valve body, which can be connected to both ends of the pipeline separately by means of studs or bolts. The valve offers reliable pipeline positioning capability, and is especially suitable for working conditions requiring single‑side pipeline disassembly, equipment maintenance or end‑of‑line installation.
Working Principle of Double‑Offset Lug‑Type Butterfly Valve：
Instant Opening (Seat Lift‑off): When the valve starts rotating from the fully closed position, driven by the dual‑offset geometry, the disc acts like a cam and lifts off the seat sealing surface almost immediately at the initial rotation stage. This eliminates continuous rubbing of sealing faces across the full 90‑degree travel found in conventional butterfly valves, resulting in low operating torque and minimal wear.
Closing Stroke (Seat Compression): In the final phase of closing, the reverse cam effect pulls or presses the disc firmly against the seat. This design generates reliable sealing force upon valve closure with a self‑tightening tendency.
Manual butterfly valves are widely used in industrial piping systems for fast and reliable flow isolation and regulation. Key parameters including working temperature, medium, pressure rating, valve size and connection standard should be confirmed before ordering for proper valve selection. Customized valve sizes, pressure ratings, connection types, sealing materials and body materials are available for diverse industrial and non-standard applications. (Unit: mm)
| NPS | NPS | Type/Class | Part No | A | B | C | L | H | P | J | K | M | F | K |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 65 | 2.5″ | TD372-150LB | TD342P150XLX2.5 | 59 | 111.1 | 82.5 | 48 | 82 | 11.2 | 125.4 | 22.4 | M10 | 180 | 139.7 |
| 80 | 3″ | TD372-150LB | TD342P150XLX3 | 73 | 120.5 | 93 | 48 | 82 | 11.2 | 125.4 | 22.4 | M10 | 190 | 152.4 |
| 100 | 4″ | TD372-150LB | TD342P150XLX4 | 96 | 133.3 | 110 | 54 | 82 | 11.2 | 125.4 | 22.4 | M10 | 230 | 190.5 |
| 125 | 5″ | TD372-150LB | TD342P150XLX5 | 111 | 135 | 120 | 57 | 82 | 11.2 | 125.4 | 22.4 | M10 | 255 | 215.9 |
| 150 | 6″ | TD372-150LB | TD342P150XLX6 | 142 | 152.4 | 135 | 57 | 82 | 14 | 125.4 | 22.4 | M10 | 280 | 241.3 |
| 200 | 8″ | TD372-150LB | TD342P150XLX8 | 188 | 187.3 | 172 | 64 | 82 | 15.9 | 125.4 | 22.4 | M10 | 345 | 298.5 |
| 250 | 10″ | TD372-150LB | TD342P150XLX10 | 236 | 231.8 | 202 | 71 | 97 | 20.6 | 142.7 | 37.3 | M12 | 405 | 362 |
| 300 | 12″ | TD372-150LB | TD342P150XLX12 | 282 | 260.3 | 241.3 | 81 | 97 | 23.8 | 142.7 | 37.3 | M12 | 485 | 431.8 |
| 350 | 14″ | TD372-150LB | TD342P150XLX14 | 314 | 315 | 295 | 92 | 105 | 28.7 | 142.7 | 37.3 | M16 | 535 | 476.3 |
Double‑offset lug‑type butterfly valves can be equipped with hand lever, gear operator, pneumatic actuator or electric actuator for manual, pneumatic and electric control. They are widely applied in oil, natural gas, chemical, power, water treatment, metallurgy, HVAC and industrial piping systems.
