In a press-fit joint system for tight connection between a pocket provided at an open end of a fitting or valve and an open end of a pipe, the pocket of the fitting or valve slidably accommodates the pipe and has an annular seat projecting outwardly that accommodates a compressible ring seal, wherein the connection is formed by imparting a plastic deformation to the a pair formed by the pocket and the pipe, and compressing the ring seal, wherein the ring seal has one or more channels with an upstream opening and a downstream opening such as to allow a passage of fluid from an inside of the system to an outside prior to proper pressing between the pipe and the fitting or valve and to occlude and to prevent the passage of fluid upon application of proper pressing between pipe and fitting or valve.