| 摘要 |
PURPOSE:To improve the durability of a valve cage, by forming a protective layer member, consisting of a material with larger resistance against a cavitation phenomenon or the like than that of the material of the valve cage, in the downstream peripheral edge part in an internal hole brought into contact with a valve unit of the valve cage, in the case of a valve in which the internal hole of the valve cage is closed by the valve unit. CONSTITUTION:In a valve, for instance, butterfly valve, a protective layer member 3 is annularly secured removably by machine screws 5 to the whole peripheral part brought into contact with a valve unit 2 in an internal hole in the downstream side of a valve cage 1. Then the protective layer member 3, being formed by metal of FC, FCD, etc. and ceramic or the like, can prevent a cavitation phenomenon or the like while the protective layer mamber 3 can be replaced when it is damaged by the cavitation phenomenon or the like. In this way, the valve cage 1 can be prevented from damaging its own internal peripheral surface enabling durability of the vavle to be improved even if the cavitation phenomenon or the like is generated in the valve cage 1 in the downstrem side of the valve unit 2 due to a valve opening. |
