Butterfly valve has been widely used in many fields, such as petroleum, chemical, metallurgy, water and electricity, as a part to realize the on-off and flow control of pipeline system. In the known butterfly valve technology, the sealing form of sealing structure, sealing materials for rubber, ptfe and so on. Due to the limitation of structure characteristics, it is not suitable for high temperature, high pressure, corrosion resistance, wear resistance and other industries. There is a more advanced butterfly valve is three eccentric metal hard seal butterfly valve, valve body and valve seat are joined component, valve seat sealing surface layer surfacing welding temperature, corrosion resistant alloy material. Multi-layer soft stack sealing ring fixed on the valve plate, this butterfly valve compared with the traditional butterfly valve has high temperature resistance, light operation, opening and closing without friction, closed with the torque of the transmission mechanism to compensate for the sealing, improve the sealing performance of the butterfly valve and prolong the advantages of service life.
Butterfly valve has been widely used in many fields, such as petroleum, chemical, metallurgy, water and electricity, as a part to realize the on-off and flow control of pipeline system. In the known butterfly valve technology, the sealing form of sealing structure, sealing materials for rubber, ptfe and so on. Due to the limitation of structure characteristics, it is not suitable for high temperature, high pressure, corrosion resistance, wear resistance and other industries.
There is a more advanced butterfly valve is three eccentric metal hard seal butterfly valve, look at the valve body and seat are joined components, seat sealing surface layer surfacing welding temperature, corrosion resistant alloy material. Multi-layer soft stack sealing ring fixed on the valve plate, this butterfly valve compared with the traditional butterfly valve has high temperature resistance, light operation, opening and closing without friction, closed with the torque of the transmission mechanism to compensate for the sealing, improve the sealing performance of the butterfly valve and prolong the advantages of service life. However, the following problems still exist in the use of this butterfly valve:
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 the sealing surface, and the soft sealing belt in the interlayer of the metal sheet is washed, which directly affects the sealing performance.
Restricted by structural conditions, the structure is not suitable for valves with diameter below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.
Three, because of the principle of three eccentric structure, the seal between the sealing surface of the valve plate and the valve seat is by the torque of the transmission device to pressure the valve plate to the valve seat. Positive flow state, the higher the medium pressure seal extrusion tighter. When the flow channel medium countercurrent with the increase of medium pressure valve plate and valve seat unit positive pressure is less than the medium pressure, the seal began to leak.
High performance three eccentric bidirectional hard seal butterfly valve is characterized in that the valve seat sealing ring is composed of multiple layers of stainless steel on both sides of the soft T-shaped sealing ring. The sealing surface of valve plate and valve seat is inclined cone structure, and the temperature and corrosion resistant alloy material is surfacing on the surface of valve plate inclined cone; The spring fixed between the regulating ring platen is assembled with the adjusting bolt on the platen. This structure effectively compensates the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under the medium pressure, and solves the sealing problem existing in the process of two-way interchangeable medium transportation of the valve.
The sealing ring is composed of soft T-type multilayer stainless steel sheet on both sides, which has the double advantages of metal hard sealing and soft sealing, and has zero leakage sealing performance under low temperature and high temperature. The test proves that the pressure of sealing surface is produced by the torque of transmission device and the pressure of medium on valve plate when the flow direction of medium is the same as the rotating direction of butterfly plate. Positive medium pressure increases when the valve plate oblique cone surface and valve seat sealing surface extrusion is tighter, the sealing effect is better. When the countercurrent state, the seal between the valve plate and the seat by the torque of the driving device to pressure the valve plate to the seat. With the increase of the reverse medium pressure, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation stored by the spring of the regulating ring under load can compensate the tight pressure of the sealing surface of the valve plate and the valve seat to automatically compensate. Therefore, the utility model does not install soft and hard multilayer sealing rings on the valve plate like the prior art, but directly install them on the valve body, and the regulating ring is added between the pressure plate and the valve seat, which is a very ideal bidirectional hard sealing mode.
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