If the butterfly valve is required to be used as a flow control, the main thing is to choose the correct size and type of valve. The structural principle of the butterfly valve is particularly suitable for making large-diameter valves. Commonly used butterfly valves have two kinds of clip-on butterfly valves and flange-type butterfly valves. The wafer type butterfly valve is connected with the valve between the two pipe flanges with stud bolts. The flange type butterfly valve is provided with a flange on the valve. The bolts are used to connect the upper flanges of the valve to the pipe flange.

Butterfly valve selection

The butterfly valve as a component used to achieve the on-off and flow control of the pipeline system has been widely used in many fields such as petroleum, chemical industry, metallurgy, and hydropower. In the known butterfly valve technology, the sealing structure is mostly a sealed structure, and the sealing material is rubber, PTFE, or the like. Due to the limitation of structural characteristics, it is not suitable for industries such as high temperature resistance, high pressure, corrosion resistance, and wear resistance.

The existing one of the more advanced butterfly valves is a three-eccentric metal hard-seal butterfly valve. The valve body and the valve seat are connected components, and the valve seat sealing surface layer is surfacing with temperature-resistant and corrosion-resistant alloy materials. The multi-layer soft stack seal is fixed on the valve plate. Compared with the traditional butterfly valve, this type of butterfly valve has high temperature resistance, easy operation, no friction when opening and closing, and the seal is increased when the torque of the transmission mechanism is increased to close the butterfly valve. The sealing performance and the advantages of prolonged service life.

However, the butterfly valve still has the following problems in use:

First, because the multi-layer soft and hard stack seals are fixed on the valve plate, when the valve plate is always open, the media forms a frontal flush against its sealing surface, and after the soft sealing tape in the metal plate interlayer is washed away, the sealing performance is directly affected.

Second, subject to structural constraints The structure is not adapted to the following diameter DN200 valves, because the overall structure of the valve plate is too thick, large flow resistance.

Third, due to the principle of triple eccentric structure, the seal between the sealing surface of the valve plate and the valve seat is to press the valve plate against the valve seat by the torque of the transmission device. In the normal flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium of the flow passage is reversed, the seal begins to leak when the positive pressure between the valve plate and the valve seat is smaller than the pressure of the medium as the pressure of the medium increases.

The high-performance three eccentric bidirectional hard seal butterfly valve is characterized in that: the valve seat seal ring is composed of multiple layers of stainless steel sheets on both sides of a soft T-shaped seal ring. The sealing surface of the valve plate and the valve seat is an inclined conical structure, and a temperature-resistant, corrosion-resistant alloy material is surfacing on the oblique conical surface of the valve plate; the structure of the spring fixed between the adjusting ring pressure plate and the adjusting bolt of the pressure plate is assembled 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 of the valve in the process of two-way exchange of the medium. The soft T-shaped multi-layer stainless steel plate on both sides forms a seal ring, which has the dual advantages of metal hard seal and soft seal, and has zero leakage sealing performance under both low temperature and high temperature conditions.

The test shows that the positive flow state of the cell (the direction of flow of the medium is the same as the direction of rotation of the disc), the pressure of the sealing surface is caused by the torque of the transmission device and the pressure of the medium on the valve plate. When the pressure of the medium increases, the tighter conical surface of the valve plate and the seat sealing surface are squeezed tighter, and the sealing effect is better. When in the reverse flow state, the seal between the valve plate and the valve seat is pressed against the valve seat by the torque of the drive device. With the increase of the reverse medium pressure, the unit positive pressure between the valve plate and the valve seat is smaller than the medium pressure, the deformation of the spring of the adjustment ring after being loaded can compensate the tight pressure of the valve plate and the valve seat sealing surface. Plays automatic compensation. Therefore, unlike the prior art, the present invention does not install a soft and hard multi-layer seal ring on the valve plate, but directly mounts on the valve body. It is an ideal two-way hard seal method to add an adjustment ring between the pressure plate and the valve seat. . It will replace gate, globe and ball valves.

Applicable occasions

Butterfly valve is suitable for flow regulation. Because the pressure loss of the butterfly valve in the pipeline is relatively large, the robustness of the butterfly plate to withstand the medium pressure of the pipeline should also be considered. In addition, it is also necessary to consider the limitation of the working temperature that the elastic seat material can withstand at high temperatures. The butterfly valve has a small structural length and overall height, fast opening and closing speeds, and good fluid control characteristics. The structural principle of the butterfly valve is most suitable for making large-diameter valves. When a butterfly valve is required to control the flow, the most important thing is to correctly select the size and type of the butterfly valve so that it can work properly and effectively.

In general, in the throttling, regulating control and slurry media, the required structure length is short, and the opening and closing speed is fast (1/4 turn). Low pressure cut-off (small pressure difference), butterfly valve is recommended.

In the double-position adjustment, necking channel, low noise, cavitation and gasification phenomenon, a small amount of leakage to the atmosphere, with abrasive media, you can use the butterfly valve.

When the butterfly valve is used for throttling under special working conditions, or when strict sealing is required, or when the wear is severe and the temperature is low (cryogenic), special design of the metal sealing tape adjusting device is required for the three eccentric or double eccentric special purpose. Butterfly valve.

The butterfly valve is applicable to fresh water, sewage, seawater, salt water, steam, natural gas, food, medicine, oil and various types of products requiring complete sealing, zero leakage of gas test, high life expectancy, working temperature of -10 degrees to 150 degrees. Acid and other pipelines.

Soft seal eccentric butterfly valve is suitable for bidirectional opening, closing and adjustment of ventilation and dust removal pipelines. It is widely used in gas pipelines and waterways of metallurgy, light industry, electric power, and petrochemical systems.

Metal to metal wire seal double eccentric butterfly valve is suitable for urban heating, gas supply, water supply and other gas, oil, acid and alkali pipelines, as a regulating and throttling device.

The metal-to-metal face seal triple eccentric butterfly valve is not only used as a large-scale pressure swing adsorption (PSA) gas separation device program control valve, but also can be widely used in petroleum, petrochemical, chemical, metallurgy, electric power and other fields, when the gate valve, globe valve is good replacement product.