insulation ball valve working environment

With the continuous development of the domestic industry, the demand for the thermal ball valve used on the pipeline has also increased, and the requirements for the thermal insulation ball valve are also getting higher and higher. When the user chooses the thermal insulation ball valve, the special attention is paid to whether the valve has good sealing performance. To prevent the leakage of the medium. Because the reliability of the imported thermal ball valve is good, the user adopts the imported thermal insulation ball valve for important parts, but the imported safety ball valve is expensive, the delivery period is long, and the after-sales service is inconvenient, which seriously affects the operation of the whole casing line. In order to reduce the pipeline cost and realize the localization of the thermal insulation ball valve, domestic manufacturers are constantly improving the quality and sealing reliability of the domestic thermal insulation ball valve, and strive to replace the imported thermal insulation ball valve. This paper analyzes the heat-resistant ball valve and proposes improvement measures.

1 Ask a question

At present, the heat preservation ball valve in the prior art is also called a jacketed ball valve, which is a metal jacket welded on the basis of the ball valve, and a heat preservation channel is formed between the jacket and the valve body, and steam or other heat insulating medium is injected into the channel to ensure the valve. The media works fine. The heat preservation ball valve has good heat preservation characteristics, and the diameter of the valve is consistent with the pipe diameter, and at the same time, the heat loss of the medium in the pipeline can be effectively reduced. Mainly used in petroleum, chemical, metallurgy, pharmaceutical, food and other systems to transport high viscosity medium that will solidify at room temperature.

Due to the valve sealing structure and its corresponding sealing material, the temperature used is less than 200 °C. And it is used for a long time under the condition of 200 °C, and the life is short. Although the valve seat can be selected to withstand high-strength graphite materials with a short time of 300 °C, there are still many parts in the valve that need to be sealed and can not be sealed at high temperatures. Especially for radial sealing, high-strength graphite materials are not suitable for diameter. Sealed. The usual thermal sealing of the ball valve is O-ring sealing structure, so the operating temperature of the whole valve is directly restricted by the temperature of the O-ring. The O-ring used on the current ball valve is fluororubber, and the use of fluororubber The temperature is within 200 ° C and cannot be used for a long time at this extreme temperature. It is far from meeting the requirements of many media in the market. For example, when the working medium is rosin, it requires the temperature of the heat-insulating ball valve to be 300 °C, which is beneficial to the ideal fluidity of the rosin medium. Traditionally, O-rings are used. When sealing parts, they cannot meet their requirements.

2 Improvement measures

According to the problems existing in the heat preservation ball valve, it is determined that the sealing material and structure of the heat preservation ball valve are improved.

(1) Firstly, the structure of Fig. 1 between the support ring and the valve body is usually modified by the O-ring for radial sealing, and the sealing structure using the O-ring is eliminated, and the step structure is directly processed on the support ring of Fig. 2. Make a sealed cavity between the support ring and the valve body. Install a sealing ring with high temperature resistant flexible graphite material in the sealed cavity, and install a gasket with a cone cross section behind the sealing ring. Install a screw plug with a special structure behind the gasket, so that the screw plug will force the force by screwing the screw plug. For the gasket, the cone section of the gasket will squeeze the sealing ring, and the sealing ring will be deformed so as to be in contact with the bearing ring and the valve body radially inside and outside, so that the heat insulating ball valve can obtain a high temperature resistant sealing structure in the radial direction, and at the same time, through the rotation Tightening the plug causes a pre-tightening force between the ball and the seat to seal it.

2) Corresponding improvement is also made on the seat sealing structure. The in-line structure is used to dig the valve body and the support ring out of the groove. The bottom end of the groove is filled with flexible graphite with excellent sealing performance and high temperature resistance. It acts as a sealing function at the bottom end of the valve seat, and can also compensate for the thermal expansion and contraction between the seal pairs. The high-temperature resistant metal seat is mounted on the flexible graphite, and the use temperature can be increased to 425 ° C for a long time, thus solving the situation that the insulated ball valve can not be used for more than 200 ° C for a long time. And different sizes of valve seats can be selected according to the requirements of actual working conditions.

(3) The bottom end pipe which is discharged in Figure 1 is screwed to the plug. When the temperature rises, the sealing of the threaded portion is difficult to ensure. It is decided to cancel the plug. In Figure 2, the bottom end is connected to the pipe. The plug is replaced with a stepped drain plug, and the connecting end is sealed with a winding mat to ensure the sealing reliability of the bottom end.

3 Conclusion

By improving the sealing structure of the insulated ball valve, the sealing performance is excellent, especially the improved flexible graphite replaces the O-ring, and is widely used in the working condition of temperature ≤ 425 °C. With the development of domestic industrial level and technological progress, its performance will continue to increase and the scope of application will continue to expand. The thermal insulation ball valve is designed and manufactured according to the market demand. The valve has the characteristics of compact overall structure, convenient operation, reliable sealing and long service life. At present, the thermal insulation ball valve works well in the user's working condition, and all performance indexes are designed. Claim. It has excellent properties for liquid media with easy solidification and high viscosity, and is especially suitable for viscous media such as rosin.