With the continuous development of the domestic industry, the demand for insulated ball valves used in the pipeline also increases, and the requirements for the insulated ball valves are also getting higher and higher. When users choose the insulated ball valve, they pay special attention to whether the valve has good sealing performance To prevent media leakage. Due to the reliability of imported ball valve insulation is better, so the user more important parts on the use of imported ball valve, but the imported ball valve is expensive, delivery cycle is longer, inconvenient after-sales service, seriously affecting the operation of the entire pipeline. In order to reduce pipeline costs, to achieve localization of ball valve, the domestic manufacturers are constantly in the quality of domestics ball valve, seal reliability excellence, and strive to replace imported ball valve. In this paper, the problem of high temperature resistant ball valve for analysis and propose improvements. 1 raised the question At present, the insulation ball valve in the prior art, also known as jacketed ball valve, is a metal jacket welded on the basis of the ball valve, the jacket and the valve body constitute a heat preservation channel, the channel into the steam or other insulation medium, Make sure valve medium is working properly. Insulation ball valve has a good insulation properties, and the valve diameter and diameter of the same, but can effectively reduce the pipeline medium heat loss. Mainly used in petroleum, chemical, metallurgy, pharmaceutical, food and other systems to transport high temperature medium will be solidified at room temperature. Due to the valve sealing structure and its corresponding sealing material constraints, the use of the temperature is less than 200 ℃. And long time at 200 ℃ under the conditions of use, shorter life expectancy. Although the valve seat can be used for a short time can withstand 300 ℃ high-strength graphite material, but there are many valves need to seal the site still can not be sealed in high temperature applications, especially radial sealing, high-strength graphite material is not suitable for diameter To seal. The usual thermal ball valve radial seal is O-ring seal structure, so the entire valve temperature directly by the O-ring temperature constraints, the current O-ring used in the insulation ball valve is fluorine rubber, and the use of fluorine rubber The temperature is within 200 ℃, and can not be used in this limit temperature for a long time. Far from being able to meet the requirements of many media in the market. For example, when the working medium is rosin, the temperature of the heat-preservation ball valve is required to be 300 ° C., so that the rosin medium can be obtained with better fluidity. Conventionally, an O-ring is used as Sealing parts, they can not meet their requirements. 2 improvement measures According to the existence of insulation ball valve problems, to determine the insulation ball valve sealing material and structure improvements. (1) First, between the supporting ring and the valve body, the O-ring is usually adopted as a structure for radial sealing to be improved, the sealing structure using the O-ring is canceled, the step structure is directly processed on the supporting ring of the figure, Between the body composed of a sealed chamber. Install a sealing ring of flexible graphite material with high temperature resistance in the sealed chamber, install a washer with a conic section behind the sealing ring, and attach a plug with a special structure behind the washer, so that the force is transmitted by tightening the plug and plug To the washer, the washer cone section will squeeze the seal ring, the seal deformation, it is radially inside and outside the support ring and the valve body, so that the insulation in the radial ball valve to obtain high temperature sealing structure, at the same time, through the spin Tight plug, the ball and the seat pre-tight seal between the force to make it sealed. (2) In the valve seat sealing structure also made the corresponding improvements, using inlaid structure, the valve body and bearing ring dug groove, groove bottom into the sealing performance and high temperature resistant flexible graphite, both Can play the role of sealing the bottom of the valve seat, but also play a compensatory role due to thermal expansion and contraction between the sealing pair. Flexible graphite in the top mounted on the metal valve seat temperature, the use of temperature can be increased to 425 ℃ for a long time to use, thus solving the insulation ball valve can not be used in more than 200 ℃ for a long time. And also according to the actual conditions of the request of different materials of the valve seat. (3) At the bottom of the discharge effect from the take over and the plug is a threaded connection, when the temperature rises, the threaded part of the seal is difficult to guarantee, decided to cancel the plug, take over the bottom of the plug connected to step Sewage plug, the connection end with a wound gasket seal to ensure that the bottom of the seal reliability. 3 Conclusion Improved insulation ball valve seal structure, excellent sealing performance, especially the improved flexible graphite instead of the O-ring, the temperature ≤ 425 ℃ operating conditions are widely used. With the development of the domestic industrial level and technological progress, its performance will continue to improve, the scope of application will continue to expand. Insulating ball valve is designed and manufactured according to the market demand. The valve has the advantages of compact overall structure, convenient operation, reliable sealing and long service life. At present, the ball valve works well in the user's working condition and all the performance indexes reach the design Claim. For easy solidification, high viscosity liquid medium has excellent performance, especially suitable for thick media such as rosin.
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