The double flanged U-type butterfly valve is a resilient seated butterfly valve — also referred to as a "concentric", "rubber lined", or "rubber seated" butterfly valve. It features a resilient rubber seat vulcanized directly onto the body, between the external diameter of the disc and the internal wall of the valve, ensuring reliable bubble-tight sealing across a wide range of 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 partially open, it operates as a flow regulating valve, allowing precise control at various opening angles.

In terms of installation method, the U-type is classified as a wafer-type valve. Although it features two integral flanges cast onto the body, its face-to-face dimensions are the same as standard wafer type — compact in design, fitting between two pipeline flanges with studs passing through from one side to the other. The valve is held in place and sealed by gaskets under stud tension. The integral flanges are specifically designed to assist alignment and installation, making this configuration the preferred choice for larger pipe sizes.

At Nortech, resilient seated butterfly valves in wafer type and lug type cover DN32–DN600. For larger diameters, the U-type flanged butterfly valve is used — offering the same proven resilient seat construction in sizes DN350–DN1200 (14″–48″).