Triple Eccentric Butterfly Valve

The Triple Eccentric Butterfly Valve is designed for isolation and flow control where conventional resilient-seated butterfly valves may not provide the required sealing performance, temperature capability or service life. Its shaft and disc are positioned away from the valve body centreline, while the sealing surface has an additional angular offset. This geometry creates a cam-like closing movement in which the disc moves away from the seat soon after opening and contacts it mainly during final closure. The reduced rubbing between sealing surfaces helps control wear, operating torque and seat damage during repeated cycling. African Valve is a top Triple Eccentric Butterfly Valve Suppliers in Nigeria, supplying valves in different body materials, pressure classes, seat arrangements and operating configurations for industrial pipeline systems.

Where Are Triple Eccentric Butterfly Valve Used?

Triple Eccentric Butterfly Valves are selected for pipelines that require dependable shut-off, low seat friction and stable operation over repeated cycles. Their metal-seated construction makes them particularly suitable where elastomeric seats may be affected by high temperature, pressure or process conditions.

They are used in water transmission, desalination, power generation, chemical processing, mining utilities, fire-water systems, marine service and other industrial pipelines. Metal-seated versions are also suitable for steam and other elevated-temperature duties where tight shut-off and resistance to seat wear are important.

Selection should consider the fluid, pressure differential, temperature, required leakage performance, flow direction and actuator torque rather than valve size alone.

Engineering Design & Operation

The valve operates through a quarter-turn rotation of the disc. Three offsets are used in the sealing geometry. The shaft is offset from the seat sealing plane, positioned away from the pipe centreline, and the seat cone is arranged at an additional angular offset.

This geometry allows the sealing surfaces to separate quickly during opening instead of sliding against each other through the full disc movement. During closing, the disc approaches the seat through a controlled cam action and develops the required sealing contact near the final position.

Depending on the service, the valve may use a laminated metal seat or solid metal-to-metal sealing arrangement. Manual gearboxes are generally used for larger manually operated valves, while pneumatic, electric or hydraulic actuators can be selected for automated service. Actuator sizing should consider seating torque, bearing friction, packing friction and differential-pressure torque.

Technical Specifications

For larger pipeline systems, flanged construction is commonly selected because it provides a rigid connection and stable valve alignment. Pressure class, flange drilling and face-to-face dimensions should match the piping specification before final selection.

Materials & Components

• Body: ASTM A216 WCB / ASTM A352 LCB / ASTM A351 CF8 / ASTM A351 CF8M / ASTM A890 Duplex / ASTM A890 Super Duplex / Alloy Steel

• Disc: ASTM A536 Ductile Iron / ASTM A216 WCB / ASTM A351 CF8M / ASTM A890 Duplex / ASTM A890 Super Duplex

• Stem: AISI 316 / UNS S17400 (17-4PH) / UNS S31803 Duplex / UNS S32750 Super Duplex

• Seat: Metal-to-Metal / Laminated Metal / Stellite-Faced

• Shaft: AISI 316 / UNS S17400 (17-4PH) / UNS S31803 / UNS S32750

• Bearing: Stainless Steel / PTFE-Based Composite / Bronze

• Retainer: AISI 316 / Carbon Steel / Stainless Steel

• Packing: Graphite / PTFE / Low-Emission Packing

• Fasteners: ASTM A193 B7 / B8 / B8M / ASTM A320 L7 with compatible ASTM A194 nuts

Material combinations should be selected according to fluid compatibility, operating temperature, corrosion conditions, pressure class and required mechanical strength. Seat and disc materials may require separate consideration in high-temperature or corrosive service.

Applications

• Water Transmission: Isolation and flow control in large-diameter pipelines

• Water Treatment: Process and distribution piping

• Wastewater Treatment: Isolation in treated and utility-water lines

• Irrigation: Main transmission and pumping networks

• Desalination: Seawater and desalinated-water systems with suitable materials

• Pumping Stations: Pump discharge and large-bore isolation

• Power Generation: Cooling water, steam and plant utility systems

• Oil & Gas: Utility and process isolation lines

• Mining: Process-water and slurry-free utility systems

• Chemical Processing: Corrosive and temperature-sensitive process services with appropriate material selection

• Steam & High-Temperature Services: Metal-seated isolation where resilient seating is unsuitable

Testing & Standards

Depending on valve construction, pressure rating, body configuration and connection type, applicable requirements may include EN 593, ISO 5752, ISO 5208, EN 558, API 609 and API 598, where relevant to the specific design and project requirements.

Inspection may include shell pressure testing, seat leakage testing, dimensional verification, disc and shaft alignment checks and full-stroke operation. For actuated valves, seating torque, actuator travel and open-close position settings should also be verified. Material traceability, PMI or additional NDT may be specified for critical pressure, temperature or corrosion service.