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Butterfly Valve Structure and Common Issues
Created on 2024.08.05
The high-performance triple eccentric two-way hard seal butterfly valve is characterized in that: the valve seat sealing ring is composed of multiple layers of stainless steel sheets on both sides of the soft T-shaped sealing ring. The sealing surface of the valve plate and the valve seat is an oblique conical structure, and the temperature-resistant and corrosion-resistant alloy materials are surfacing on the surface of the oblique cone of the valve plate; A structure in which the spring fixed between the adjusting ring pressure plate and the adjusting bolt on the pressure plate are assembled together.
This structure effectively compensates for the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under medium pressure, and solves the sealing problem of the valve in the process of two-way interchangeable medium transportation. The sealing ring is composed of multi-layer stainless steel sheets on both sides of the soft T-shape, which has the dual advantages of metal hard sealing and soft sealing, and has zero leakage sealing performance regardless of low temperature and high temperature.
The test proves that when the tank is in the positive flow state (the medium flow direction is the same as the rotation direction of the butterfly plate), the pressure of the sealing surface is generated by the torque of the transmission device and the effect of the medium pressure on the valve plate. When the pressure of the forward medium increases, the tighter the squeezing of the oblique cone surface of the valve plate and the sealing surface of the valve seat, the better the sealing effect. In the reverse flow state, the seal between the disc and the seat is pressed against the seat by the torque of the actuator. With the increase of the pressure of the reverse medium, when the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation energy stored by the spring of the adjusting ring after load compensates for the tight pressure of the valve plate and the sealing surface of the valve seat to play an automatic compensation role. Therefore, the utility model discloses is not like the prior art, a soft and hard multi-layer sealing ring is installed on the valve plate, but is directly installed on the valve body, and an adjusting ring is very ideal two-way hard sealing mode is added in the middle of the pressing plate and the valve seat. It will replace gate valves, globe valves and ball valves.
At present, a relatively advanced butterfly valve is a three-eccentric metal hard seal butterfly valve, the valve body and the valve seat are conjoined components, and the surface layer of the valve seat seal is welded with temperature-resistant and corrosion-resistant alloy materials. The multi-layer soft-stacked sealing ring is fixed on the valve plate, this butterfly valve has high temperature resistance compared with the traditional butterfly valve, light operation, no friction in opening and closing, and compensates for the sealing with the increase of the torque of the transmission mechanism when closing, which improves the sealing performance of the butterfly valve and the advantages of prolonging the service life.
However, this butterfly valve still has the following problems during use:
1. Because the multi-layer soft and hard stacked sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium forms a positive scouring on its sealing surface, and the soft sealing belt in the metal sheet interlayer is directly affected by the erosion.
2. Due to the limitation of structural conditions, the structure is not suitable for valves with a diameter of DN200 or less, because the overall structure of the valve plate is too thick and the flow resistance is large.
3. Due to the principle of three eccentric structure, the sealing between the sealing surface of the valve plate and the valve seat is pressed to the valve seat by the torque of the transmission device. In the positive flow state, the higher the medium pressure, the tighter the sealing and extrusion. When the flow channel medium is reversed, with the increase of medium pressure, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, and the seal begins to leak.
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