Advantages and disadvantages of the new butterfly

At present, as a component used to realize the on-off and flow control of pipeline system, butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower and so on. In the well-known butterfly valve technology, its sealing form mostly adopts sealing structure, and the sealing materials are rubber, polytetrafluoroethylene, etc. Due to the limitation of structural characteristics, it is not suitable for industries such as high temperature resistance, high pressure resistance, corrosion resistance and wear resistance

a relatively advanced butterfly valve is a three eccentric metal hard seal butterfly valve. The valve body and valve seat are connected components, and the sealing surface of the valve seat is overlaid with temperature resistant and corrosion-resistant alloy materials. The multi-layer soft laminated seal ring is fixed on the valve plate. Compared with the traditional butterfly valve, this butterfly valve has the advantages of high temperature resistance, light operation, and no friction when opening and closing. When closing, it compensates for the seal as the torque of the transmission mechanism increases, which improves the sealing performance of the butterfly valve and extends its service life

however, there are still the following problems in the use of this butterfly valve:

first, because the multi-layer soft and hard laminated seal 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 scoured, which directly affects the sealing performance

second, due to the structural conditions, this structure is not suitable for valves with a diameter below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large

III. due to the principle of three eccentric structure, the sealing between the sealing surface of the valve plate and the valve seat depends on the torque of the transmission device to press the valve plate towards the valve seat. In the positive flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium in the channel flows against the flow, with the increase of the 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

the 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 the soft T-shaped sealing ring. The sealing surface of the valve plate and the valve seat is an inclined conical structure, and the inclined conical surface of the valve plate is overlaid with temperature resistant and corrosion-resistant alloy materials; The spring fixed between the pressing plates of the adjusting ring is assembled with the adjusting bolt on the pressing plate

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 of the valve in the process of two-way interchangeable medium transmission. The soft T-shaped multi-layer stainless steel sheets on both sides are used to form the sealing ring, which has the dual "scheme" of metal hard sealing and soft sealing. It is proposed that Fushun Petrochemical Company is one of the key enterprises relying on the development of raw material industry, and it has zero leakage sealing performance under both low and high temperatures

the test shows that when the pool is in a positive flow state (the medium flow direction 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 medium pressure on the safety and cost of 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. In the counter current state, the sealing between the valve plate and the valve seat is pressed against the valve seat by the torque of the driving device. With the increase of the reverse medium pressure, when 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 adjusting ring after being loaded can compensate the tight pressure on the sealing surface of the valve plate and the valve seat and play an automatic compensation role. Therefore, unlike the existing technology, the utility model is also very important to install a soft and hard multi-layer sealing ring on the valve plate, but is directly installed on the valve body, and adding an adjusting ring between the pressing plate and the valve seat is a very ideal two-way hard sealing method. It will replace gate valve, globe valve and ball valve