What is Double Eccentric Flange Butterfly Valve?

   The valve body typically features flanged connections (compliant with ANSI, DIN, or other international standards) and can be constructed from cast iron, carbon steel, stainless steel, or specialty alloys. The disc adopts an eccentric butterfly shape, often made of stainless steel or coated with corrosion-resistant materials like PTFE. The stem is forged from high-strength alloy steel and transmits operating torque through its dual-offset design. The sealing ring is mounted on the valve seat, with materials ranging from elastomers (e.g., EPDM, NBR rubber) to metal (for high-temperature/pressure environments). A bearing system employs self-lubricating or bronze bearings to minimize friction, while actuation options include hand levers, gearboxes, pneumatic or electric actuators.

   During opening, the disc instantly disengages from the seat seal (due to the first offset reducing friction) and rotates 90° to reach full-open position. When closing, the second offset design allows the disc to gradually compress the sealing ring, forming uniform linear sealing contact. By adjusting the disc’s rotation angle (0°–90°), precise control over media flow and pressure in the pipeline is achieved.

   This valve is widely used in water supply and treatment systems (e.g., water plants, sewage pumping stations), petrochemical industries for oil/chemical transfer pipelines, power generation facilities in cooling water circuits and flue gas desulfurization (FGD) units, HVAC systems for large-building heating/cooling water circulation, shipbuilding for seawater pipelines and ballast water control, and sanitary processes in food/pharmaceutical industries, adapting to corrosive, high-temperature, and clean media environments.

   Key AdvantagesLow Operating Torque: Dual-offset design reduces friction by over 90%, enabling effortless operation and smaller actuator requirements.Extended Seal Life: Minimal sliding friction between disc and seal virtually eliminates wear, extending lifespan 3–5 times versus conventional butterfly valves.Bidirectional Sealing: Reliable sealing under both forward and reverse pressure (rated for Class 150–600).Broad Temperature Tolerance: Metal seals withstand -196°C to +650°C; elastomer seals suit -40°C to 200°C.Easy Maintenance: Seat rings can be replaced inline without valve body disassembly, minimizing downtime.Compact Design: Saves over 50% space/weight compared to gate or globe valves, reducing installation costs.

   Compared to single-offset butterfly valves (only stem offset from seal center, suitable for low-pressure ambient conditions), the double-offset design substantially improves sealing and durability through its second offset, making it the mainstream solution for medium-to-high pressure applications. Triple-offset butterfly valves add a seat cone angle offset to achieve metal-to-metal hard sealing and zero leakage, better suited for ultra-high temperature/pressure and severe media (e.g., refining units), albeit at significantly higher cost.

    SHANDONG EPOCH EQUIPMENT CO., LTD. is a large-scale professional manufacturer in Shandong Province of China, adheres to the orientation of science and technology, environmental protection, quality and efficiency. At present, it has grown into a trans-regional and multi-industrial enterprise integrating such wide industries as design, development, production and export. Visit our website at https://www.epochpipeline.com/ to learn more about our products. For inquiries, you can reach us at sdepochwater@hotmail.com.