Three eccentric metal seal butterfly valve advantages and disadvantages co-exist

At present, the butterfly valve, as a component used to realize on-off and flow control of pipeline system, has 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 structure adopts the sealing structure, the sealing material is rubber, polytetrafluoroethylene and the like. Due to the structural characteristics of the restrictions, do not meet the high temperature, high pressure and corrosion-resistant, anti-wear and other industries. A more advanced butterfly valve is a three-eccentric metal seal butterfly valve, the valve body and the valve seat as a single component, seat sealing surface layer surfacing temperature, corrosion resistant alloy material. Multi-layer soft stacked ring fixed to the valve plate, this butterfly valve compared with the traditional butterfly valve with high temperature, light operation, opening and closing without friction, closed with the torque of the transmission mechanism to compensate for increased sealing, improved butterfly valve The sealing performance and extend the service life of the advantages. However, this type of butterfly valve still has the following problems during use: First, as the multi-layer hard and soft stacked ring is fixed on the valve plate, when the valve plate is normally open, the medium forms a positive erosion on the sealing surface, In the soft seal by the erosion, a direct impact on the sealing performance. Second, by the structural conditions of the structure does not adapt to do the following DN200 valve, because the overall structure of the valve plate is too thick, large flow resistance. Third, due to the principle of three eccentric structure, the seal between the sealing surface of the valve plate and the valve seat is pressed against the valve seat by the torque of the transmission device. The positive flow state, the higher the media pressure seal squeeze tight. When the flow medium countercurrent media pressure increases with the pressure between the valve plate and valve seat unit pressure is less than the medium pressure, the seal began to leak. High-performance three eccentric two-way hard sealing butterfly valve, characterized in that: the seat ring seal by the soft T-ring multi-layer stainless steel sheet on both sides. The sealing surface of the valve plate and the valve seat is an oblique conical structure, and a temperature-resistant and corrosion-resistant alloy material is deposited on the oblique conical surface of the valve plate; the spring fixed between the adjusting ring plate and the adjusting bolt on the pressure plate is arranged 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 existing in the process of transporting the valve in the bidirectional interchangeable medium. The soft T-shaped multi-layer stainless steel sheet on both sides of the seal ring, with the advantages of both metal seal and soft seal, both in low temperature and high temperature conditions, have zero leakage of sealing performance. Experiments show that pool positive flow state (medium flow direction and disk rotation in the same direction), the sealing surface pressure is the torque of the actuator and the medium pressure on the role of the valve plate. Positive media pressure increases when the valve plate oblique cone surface and seat sealing surface squeeze the more tight, the better the sealing effect. In counter-current conditions, the seal between the valve plate and the valve seat presses the valve plate against the valve seat due to the moment of the drive. As the pressure of the reverse medium increases, the positive pressure between the valve plate and the valve seat is less than the pressure of the medium. The deformation stored by the spring of the adjusting ring after the load is absorbed can compensate for the tight pressure on the sealing surface of the valve plate and the valve seat Play a role in automatic compensation. Therefore, unlike the prior art, the utility model has the advantages that the soft and hard multi-layer sealing ring is mounted on the valve plate and is directly mounted on the valve body, and an adjusting ring is provided between the pressing plate and the valve seat which is a perfect bidirectional hard sealing method . It will replace gate valves, globe valves and ball valves.

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