Papers by Keyword: High Temperature Ball Valve

Abstract: Four kinds of coating materials and two kinds of brush plating materials were screened and sprayed on the surface of valve ball by plasma spraying technology and brush plated on the surface of valve seat by electrical brush technology, respectively. The wear resistance of the sealing pairs and the properties of the plasma sprayed coatings were tested. The results indicate that the sealing pair composed of the valve ball with the plasma sprayed coating of Al2O3-TiO2 and the valve seat with the brush plating layer of nickel tungsten has best combination property. The gap of the sealing pair at room temperature and the leakage rate at elevated temperature of the high temperature ball valve were obtained by FEM method and analysis method, respectively. Therefore, the open and close torque of the high temperature ball valve was determined. According to the results of the research, the failed ball valve was remanufactured, and the performance inspection was also conducted. The remanufactured ball valve has much longer service life than the original one and its sealing behavior was also improved significantly.

Abstract: Three kinds of coating materials, namely Cr2O3 ceramic, Al2O3-TiO2 ceramic and WC-Co cermet, were screened and sprayed on the surface of valve ball by plasma spraying technology, and two kinds of brush plating materials, namely high speed nickel and nickel tungsten, were also screened and brush plated on the surface of valve seat by electrical brush technology. The microstructure and morphology of the plasma sprayed coatings were analyzed by means of scanning electron microscopy. The tribological properties of the plasma sprayed coatings sliding against the high speed nickel and nickel tungsten layers were investigated on a pin-on-disc friction and wear tester. The microhardness, thermal shock property and bonding strength of the coatings were also tested. The results indicate that the sealing pair composed of the valve ball with the plasma sprayed coating of Al2O3-TiO2 and the valve seat with the brush plating layer of nickel tungsten has the best combination property.