US Patent 10544653 Downhole tool

A downhole valve has a housing with a longitudinal main passage and at least one valve port extending from the main passage and through the housing, a valve member is arranged in the main passage, the valve member arranged to cover the at least one valve port, wherein at least a part of the valve member is made of a degradable material which is reactive to water or a well fluid, and has a surface coating of a material which is non-reactive to water or the well fluid.