The double flange butterfly valve is a resilient seated butterfly valve with integral flanges cast on both ends, allowing direct bolted connection to the pipeline without additional adaptors. Like all resilient seated butterfly valves, it is a quarter-turn valve: a circular disc mounted at the center of the body serves as the closing mechanism, connected to an actuator or handle via a central shaft. A full 90-degree rotation fully opens or closes the valve for isolation service.

When the disc does not rotate to a full quarter-turn, the valve is partially open — enabling precise flow regulation at various opening angles. The rubber seat is fully vulcanized directly onto the body, ensuring reliable bi-directional sealing across the full size range, including demanding vacuum working conditions.

Nortech double flange butterfly valves are designed with a long face-to-face dimension to EN 558-1 Series 13, making them suitable for a wide range of general and heavy-duty applications including water distribution networks, water treatment plants, dams, power plants, and large-diameter pipeline systems. The valve can be used as an isolation valve, a discharge tap at the end of the pipeline, or a flow control device. For large-diameter pipelines, the double flange configuration is the standard choice.