Double Offset Butterfly Valve

A Double Offset Butterfly Valve, also known as a Double Eccentric Butterfly Valve, is designed for large pipelines where reliable shut-off, low operating torque, and reduced seat wear are important. Unlike a conventional concentric butterfly valve, the stem is offset from the valve and disc centreline. This allows the disc to move away from the seat during opening, reducing friction and contact.

African Valve, A Double Offset Butterfly Valve Suppliers in Morocco for water, wastewater, desalination, mining, power, oil & gas, chemical, and general industrial applications across Africa.

Design & Operation

The valve operates through a 90° quarter-turn rotation. Because the shaft is offset from the pipeline centreline and disc centre, the disc quickly moves away from the seat when the valve opens. This reduces rubbing and helps extend seat life.

During closing, the disc returns to the seat to provide shut-off. Depending on the service, the valve can be supplied with resilient or metal seats and operated by gearbox, pneumatic, electric, or hydraulic actuators.

Technical Specifications

Materials

Common construction materials include WCB, LCB, CF8, CF8M, Duplex, and Super Duplex for the body and disc. Shaft materials may include 316 stainless steel, 17-4PH, Duplex, and Super Duplex. Seat options include EPDM, NBR, PTFE, and metal-to-metal configurations.

Standards & Testing

Depending on the valve design and project specification, applicable standards may include EN 593, ISO 5208, ISO 5752, EN 558, API 609, and API 598. Testing may include shell pressure, seat leakage, and dimensional inspection.