Triple Offset Metal-Seated Flanged Butterfly Valve

The triple-offset metal-seated flanged butterfly valve is a high-performance valve featuring a triple-offset geometry, metal-to-metal hard sealing seat, and flanged end connections. It is mainly composed of a valve body, disc, stem, sealing ring, and actuating device.

The stem axis and disc center are designed with a triple-offset configuration, which ensures that the disc remains substantially friction-free or experiences only minimal friction contact with the seat during opening and closing cycles. This effectively reduces wear on the sealing surfaces. The metal-to-metal hard sealing construction offers excellent resistance to high temperatures, high pressures, erosion, and corrosion, making this valve ideally suited for severe-service industrial applications.

Operating Principle – Triple-Offset Metal-Seated Flanged Butterfly Valve：
The triple-offset butterfly valve is operated by driving the stem to rotate the disc around the offset axis, thereby achieving opening and closing of the medium flow.

The triple-offset design is embodied in the following three key eccentricities:

• First Offset: The stem axis is offset from the centerline of the disc.
• Second Offset: The stem axis is offset from the centerline of the valve body bore.
• Third Offset: The axis of the sealing cone forms a specific angle with the pipeline centerline.

Opening Cycle：Upon actuation, the driving device rotates the stem, gradually moving the disc away from the metal seat. Thanks to the triple-offset geometry, the disc creates a significant clearance from the seat at the very beginning of the opening stroke, substantially reducing friction and wear on the sealing surfaces. The valve reaches its fully open position when the disc rotates to a position approximately parallel to the pipeline flow direction.

Closing Cycle：During closing, the stem rotates in the reverse direction, driving the disc toward the closed position. As the disc approaches the seat, the sealing ring of the disc engages the seat progressively along a specifically designed conical trajectory. A reliable, leak-tight seal is achieved through the combined effect of mechanical compression between the metal sealing surfaces and the pressure of the process medium, resulting in complete shut-off of the flow.