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Problems Encountered When Using Soft Seal Butterfly Valve
May 31, 2018

Problems encountered when using soft seal butterfly valve

Problems encountered when using soft seal butterfly valve

The butterfly plate of the soft seal butterfly valve is installed in the diameter direction of the pipe. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation is 90°, the valve is fully opened. The characteristics of the new high-life stainless steel butterfly valve and the use of the butterfly valve in the use process are generally horizontal. Soft seal butterfly valve can be divided into flange type soft seal butterfly valve, wafer type soft seal butterfly valve and welded soft seal butterfly valve according to the connection mode.


Soft seal butterfly valve as a component used to achieve pipeline system cut off and flow control, has been widely used in many fields such as petroleum, chemical, metallurgy, and hydropower. In the known butterfly valve technology, the sealing structure is mostly a sealed structure, and the sealing material is rubber, PTFE, and the like. Due to structural characteristics, it is not suitable for high temperature, high pressure, corrosion and wear resistance industries. The existing one of the more advanced butterfly valves is a three-eccentric metal hard-seal butterfly valve. The valve body and the valve seat are connected components, and the valve seat sealing surface layer is surfacing with temperature-resistant and corrosion-resistant alloy materials. The multi-layer soft stack seal is fixed on the valve plate. Compared with the traditional butterfly valve, this type of butterfly valve has high temperature resistance, easy operation, no friction when opening and closing, and the seal is increased when the torque of the transmission mechanism is increased during closing and the butterfly valve is improved. The sealing performance and the advantages of prolonged service life.

Problems during use

First, because the multi-layer soft and hard stack seals are fixed on the valve plate, when the valve plate is always open, the media forms a frontal flush against its sealing surface, and after the soft seal tape in the metal plate interlayer is washed, it directly affects the sealing performance.

Second, subject to structural constraints The structure is not adapted to the following diameter DN200 valves, because the overall structure of the valve plate is too thick, large flow resistance.

Third, due to the principle of triple eccentric structure, the seal between the sealing surface of the valve plate and the valve seat is to press the valve plate against the valve seat by the torque of the transmission device. In the normal flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium of the flow passage is reversed, the seal begins to leak when the positive pressure between the valve plate and the valve seat is smaller than the pressure of the medium as the pressure of the medium increases.

The high performance soft sealing butterfly valve is characterized in that: the valve seat sealing ring is composed of multiple layers of stainless steel sheets on both sides of a soft T-shaped sealing ring.

The sealing surface of the valve plate and the valve seat is an inclined conical structure, and a temperature-resistant, corrosion-resistant alloy material is surfacing on the oblique conical surface of the valve plate; the structure of the spring fixed between the adjusting ring pressure plate and the adjusting bolt of the pressure plate is assembled together. This structure effectively compensates for the tolerance band between the sleeve and the valve body and the elastic deformation of the valve stem under the medium pressure, and solves the sealing problem of the valve in the process of two-way exchange of the medium.

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