Metal sealing wear-resisting ball valve research and design of the door

Summary of 1, with the development of science and technology and the demand of modern industry, metal sealed ball valve door in the transportation of special medium conditions ( Such as pulp, coal-water slurry and silicon powder mixture containing solid particles) Get more and more widely used. According to the working condition requirements, metal seal was developed for ball valve door wear resistance. 2, the structure characteristics of the metal seal wear resistance ball valve door is elastic with automatic compensation function of the valve seat structure, prevent the valve door in the condition of containing particulate medium or high temperature circumstances appear card plug phenomenon, increases the service life of the valve gate. Sphere and valve seat has good shearing and self-cleaning function, suitable for the control of particulate medium and fiber. By applying mounted to the side, the valve rod to ensure packing reliable seal and valve stem blow-out proof. Valve door structure of sealing in both directions, which improved the sealing performance of valve gate, also ensure the sealing performance, when the reverse flow of medium to prevent the backflow medium provides the necessary guarantee. Sphere and valve seat sealing surface spraying high temperature and high pressure resistance, corrosion resistance and wear resistance of cemented carbide. 3, technical processing ( 1) Metal sealing ball valve door sealing pressure ratio is higher, sealing pressure is taken into account in structure design of the required spring pre-tightening force, USES the fixed downstream of the valve seat, upstream of the valve seat after compensation structure setup disc springs. ( 2) Consider the temperature linear expansion of metal materials, high load disc springs. Offers both valve door seal pressure needed initial pre-tightening force, and also avoided because of temperature causes the spheroid and the valve seat jam phenomenon, to ensure the flexible door opening and closing of the valve. Due to solid particle medium into the disc spring tour area can cause failure resistance of disc spring card, add the disc spring protection structure, to ensure that the valve door under the condition of low pressure sealing performance. ( 3) As a result of the transmission medium contains solid grain hardness is higher, the spheroid and the valve seat surface with high hardness. Otherwise, the process of door opening and closing of the valve will have solid particles embedded on the sphere surface, affect the overall sealing performance of the valve gate. So the sphere and valve seat surface spraying tungsten carbide cobalt, nickel base alloy or chromium carbide materials, etc. Make the sealing surface hardness of 56-64 HRC. Different coating materials, different hardness can be obtained. ( 4) Valve seat designs which has the function of self-cleaning scraper structure, in the process of door opening and closing of the valve, can adsorption on the surface of a sphere content scraping, prevent solid particles from entering the valve door sealing surface, increase the service life of the valve gate. ( 5) Sphere and valve seat adopt numerical control machine tool processing, special spherical grinding, grinding machine and special grinding machine matching grinding. 4, design and calculation in floating (- PN6. 3 metal sealing ball valve door as an example, sealing pressure, total friction torque, disc spring load calculation. 4. 1, the parameter analysis ( 1) According to the calculated data available qb ( 2) According to ASME B16. 34 select safe valve door wall thickness and strength of flange and bolt and nut in the calculation. ( 3) According to the calculation of total friction torque for checking the strength of the valve rod, and choose reasonable actuators according to total friction torque. ( 4) Reference structure size is standard, complete the design of a complete set of drawings. 5, epilogue door by strength test, valve seal performance test, the wear resistance test and the certificate of using the actual working condition, the metal seal wear resistance ball valve door is suitable for the working condition of high temperature and high pressure medium contains a lot of solid particles, such as the reaction kettle in polypropylene project working condition of the blanking pipe contains a lot of polypropylene particles, organic silicon projects contain working condition of high hardness of silica particles, etc.