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Our mission: To fully utilize the effectiveness of industrial control valves to achieve better results
The butterfly plate of the butterfly valve is installed in the diameter direction of the pipeline. The butterfly valve has a simple structure, small size, and light weight. It consists of only a few parts, and can be quickly opened and closed by only rotating 90 °. It is easy to operate, and at the same time, the valve has good fluid control characteristics. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the resistance of the medium flowing through the valve body, so the pressure drop generated through the valve is very small, so it has good flow control characteristics.
If a butterfly valve is required for flow control, it is important to correctly select the size and type of valve. The structural principle of butterfly valves is particularly suitable for making large diameter valves. The commonly used butterfly valves include wafer type butterfly valves and flange type butterfly valves. Wafer type butterfly valves are used to connect the valve between two pipe flanges with double head bolts. Flange type butterfly valves have flanges on the valve, and bolts are used to connect the flanges on both ends of the valve to the pipe flange.
As a component used to achieve on-off and flow control in pipeline systems, butterfly valves have been widely used in many fields, such as petroleum, chemical industry, metallurgy, hydropower, and so on. In the well-known butterfly valve technology, the sealing form mostly adopts a sealing structure, and the sealing material is rubber, polytetrafluoroethylene, etc. Due to the limitations of structural characteristics, it is not suitable for industries such as high temperature and high pressure resistance, corrosion resistance, and wear resistance.
The existing comparative butterfly valve is a triple eccentric metal hard seal butterfly valve. The valve body and valve seat are connected components, and the sealing surface of the valve seat is welded with a temperature resistant and corrosion resistant alloy material. Multilayer soft laminated sealing rings are fixed on the valve plate. Compared to traditional butterfly valves, this type of butterfly valve has the advantages of high temperature resistance, easy operation, frictionless opening and closing, and compensates for sealing as the torque of the transmission mechanism increases during closing, improving the sealing performance of the butterfly valve and extending its service life.
However, the following problems still exist during the use of this butterfly valve:
1、 Due to the multi-layer soft and hard laminated sealing ring fixed to the valve plate, when the valve plate is normally open, the medium forms a positive erosion on its sealing surface, and the soft sealing belt in the metal sheet interlayer is directly affected by the erosion, which directly affects the sealing performance.
2、 Due to structural constraints, this structure is not suitable for valves with diameters below DN200, due to the overall structure of the valve plate being too thick and the large flow resistance.
3、 Due to the principle of a three eccentric structure, the sealing between the sealing surface of the valve plate and the valve seat relies on the torque of the transmission device to press the valve plate against the valve seat. In a positive flow state, the higher the medium pressure, the tighter the sealing pressure. When the medium in the flow path is countercurrent, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure as the medium pressure increases, and the seal begins to leak.
A high-performance three-eccentric two-way hard 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 between the valve plate and the valve seat is of an inclined conical structure, and a temperature resistant and corrosion resistant alloy material is deposited on the inclined conical surface of the valve plate; A structure in which the spring fixed between the adjusting ring pressing plate and the adjusting bolt on the pressing plate are assembled together.
This structure effectively compensates for the tolerance zone between the shaft sleeve and the valve body, as well as the elastic deformation of the valve stem under medium pressure, and solves the sealing problem that exists in the two-way exchange medium transportation process of the valve. The sealing ring is composed of multiple layers of stainless steel sheets on both sides of a soft T-shape, which has the dual advantages of metal hard sealing and soft sealing. It has zero leakage sealing performance regardless of low and high temperatures.
The test proves that when the pool is in a positive flow state (the flow direction of the medium is the same as the rotation direction of the butterfly plate), the pressure on 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 positive medium pressure increases, the tighter the compression between the inclined conical surface of the valve plate and the sealing surface of the valve seat, the better the sealing effect. When in a countercurrent state, the sealing between the valve plate and the valve seat relies on the torque of the driving device to press the valve plate against the valve seat. As the reverse medium pressure increases, when the unit positive pressure between the valve plate and valve seat is less than the medium pressure, the deformation stored by the spring of the adjusting ring after being loaded can compensate for the tight pressure on the sealing surface of the valve plate and valve seat, and play an automatic compensation role. Therefore, unlike the existing technology, the utility model does not install soft and hard multilayer sealing rings on the valve plate, but is directly installed on the valve body. Adding an adjusting ring between the pressure plate and the valve seat is a very ideal two-way hard sealing method. It will replace gate, globe, and globe valves.
