2. The hardening and surface treatment of spheres are three ways to improve the quality of sealing pairs of pneumatic ball valves. The pneumatic ball valve sphere is generally processed by 2Cr13. Its surface hardness is about HB217, which is easy to be damaged not only in working conditions, but also in the process of assembly and testing. Our company adopts solid chromizing process for test, which has been proved to be very effective after one year's practice. After chromizing, the surface hardness is higher than HV1000 degrees. After the carbon steel ball is infiltrated, the surface chromium content is as high as 60% - 80%. After grinding, the corrosion resistance in seawater, nitric acid, acetic acid and other media exceeds that of the impermeable 2Cr13

3、 When the cryogenic liquid passes through the throttling element, with the change of pressure, vaporization and bubble extrusion may occur, which will cause great damage to the valve. For valves with this phenomenon, special consideration should be given to the structure of the valve and the material of the valve core internals. For flashing phenomenon, hard alloy (such as stelled) should be used as the valve core material. For cavitation phenomenon, the valve core should adopt a stepwise pressure reduction structure (such as cavitation cage structure) to eliminate cavitation.