Resilient seated Butterfly Valve lug type
What is Resilient Seated Butterfly Valve Lug Type?
Resilient Seated Butterfly Valve — also referred to as "concentric", "rubber lined" or "rubber seated" butterfly valve — features a resilient rubber seat between the external diameter of the disc and the internal wall of the valve body, ensuring reliable bubble-tight sealing across a wide range of industrial applications.
A quarter-turn valve that rotates 90° to fully open or close fluid flow. The circular disc — mounted at the center of the valve body — serves as the primary closing mechanism, connected to an actuator or handle via a central shaft. When the disc completes a full 90-degree rotation, the valve functions as an isolation valve.
When the disc does not rotate to a full quarter-turn, the valve is partially open — enabling precise flow regulation at various opening angles.
CV/KV chart of resilient seated butterfly valve lug type is available on request.
Lug type — front & side view
Lug Type Butterfly Valve — designed for end-of-line service where no second flange is available. Threaded lug bosses are cast integrally into the valve body, with tapped holes matching the bolt pattern of the corresponding flange size and pressure class. Bolts thread directly into the lug bosses from each side, allowing the valve to be removed from one side of the pipeline without disturbing the opposite flange.
End-of-line service
Lightweight
Maintenance-free
Cost-effective
Bi-directional sealing
Main features of resilient seated butterfly valve lug type
Compact construction — low weight, minimal storage and installation space
Centric shaft, 100% bi-directional bubble-tight sealing, any installation direction
Full bore body — low flow resistance
Cavity-free flow passage — easy to clean and disinfect, suitable for potable water
Rubber-lined body — fluid never contacts the metal body
Pinless disc design — eliminates leakage paths on the disc
ISO 5211 top flange — easy automation and actuator retrofitting
Low operating torque — economical actuator selection
PTFE-lined bearings — maintenance-free, no lubrication required
Inserted liner — easy to replace, no body corrosion, suitable for end-of-line service
DN32–DN600 All sizes
Rubber sleeve seat design
DN32–DN600
Uniform rubber sleeve design applied across all sizes. The sleeve is fully vulcanised to match the body grooves, providing reliable bi-directional sealing and easy field replacement without special tools.
Shaft design
Precision splined shaft
DN32–DN350
Hexagon shaft
DN400 and above
Valve structure
Cross-section drawing
Lug type
Exploded drawing
Lug type
Technical specifications
Standards
| Design & manufacture | API 609 / EN 593 |
| Face to face | ISO 5752 / EN 558-1 Series 20 |
| Flange end | ISO 1092 PN6/10/16/25 | ANSI B16.1 / B16.5 Class 125/150 |
| Pressure rating | PN6/10/16/25 | ANSI Class 125/150 |
| Test & inspection | API 598 / EN 12266 / ISO 5208 |
| Actuator mounting | ISO 5211 |
Main parts materials
| Body | Ductile iron, carbon steel, stainless steel, duplex stainless steel, Monel, Alu-bronze |
| Disc | Ductile iron (nickel or nylon coated), Alu-bronze, stainless steel, duplex, Monel, Hastelloy |
| Liner | EPDM / NBR / FPM / PTFE / Hypalon |
| Stem | Stainless steel / Monel / Duplex |
| Bushing | PTFE |
| Bolts | Stainless steel |
Body materials
| Material | Grade / Standard | Typical application |
|---|---|---|
| Ductile iron |
|
General serviceHeavy dutyCold servicePetrochemicalPower stations |
| Stainless steel |
|
Food & beveragePharmaceuticalDemineralised water |
| Alu-bronze |
|
Marine serviceSea water |
Disc materials
| Material | Grade / Standard | Typical application |
|---|---|---|
| DI nickel coated |
|
AirNon-corrosive waterHot & cold water |
| DI nylon coated |
|
Potable waterWater up to 70°CpH 4.5–9 |
| DI PTFE lined |
|
Acids & alkalisOilWaterAir |
| Stainless steel |
|
Potable waterDemineralised waterSolvents |
| Duplex SS |
|
Sea waterCooling waterFoodstuffSolvents |
| Alu-bronze |
|
Sea waterPotable waterGas |
| Hastelloy-C |
|
Phosphoric acidHypochloric acidAcetic acidSulfurous |
Rubber sleeve liner
| Grade | Temperature range | Suitable media |
|---|---|---|
| NBR | 0°C ~ 90°C | Aliphatic hydrocarbons, fuels, low-aromatic oils, sea water, compressed air, powders, granular media, vacuum, gas supply |
| EPDM | −20°C ~ 110°C | Water (hot, cold, sea, ozone, swimming pool, industrial), weak acids, weak salt solutions, alcohols, ketones, sour gases, sugar juice |
| Sanitary EPDM | −10°C ~ 100°C | Potable water, foodstuffs, unchlorinated drinking water |
| EPDM-H | −20°C ~ 150°C | HVAC, chilled water, foodstuffs, sugar juice |
| Viton (FPM) | 0°C ~ 200°C | Aliphatic, aromatic and halogen hydrocarbons, hot gases, hot water, steam, inorganic acids, alkalis |
Types of operation for lug butterfly valve
Handle lever
PN10/16, Class 125/150, DN32–DN200
PN25, DN32–DN150
Manual gearbox
Full range DN32–DN600
Pneumatic actuator
Double acting (DA)
Spring return (SR)
Electric actuator
On-off type
Modulating type
Waterproof
Explosion-proof
Free stem
ISO 5211 mounting pad
Stem & ISO flange customised on request
Applications
Water and waste effluent treatment plants
Paper, textiles and sugar industry
Construction industry and drilling production
Heating, air conditioning and cooling water circulation
Pneumatic conveyors and vacuum applications
Compressed air, gas and desulphurization plants
Brewing, distilling and chemical process industry
Transportation and dry bulk handling
Power industry
Resilient seated butterfly valves are certified with WRAS (UK) and ACS (France), specifically for waterworks applications.
WRAS
Water Regulations Advisory Scheme
ACS
Attestation de Conformité Sanitaire
Why choose Nortech?
Q
Quality & service
Over 25 years of OEM/ODM experience serving leading European valve companies.
Q
Quick delivery
Ready for shipment in 1–4 weeks, backed by considerate stock of resilient seated butterfly valves and components.
Q
Quality guarantee
12–24 months warranty on resilient seated butterfly valves.
Q
Quality control
Every single butterfly valve is individually inspected and tested before shipment.
