A metal sealing system for a triple eccentricity butterfly valve includes a dynamic metal seal, having a metal core surrounded by an external coating; a metal case with an external surface that has an inclined conical shape, including a first housing inside which the dynamic metal seal is mounted; a metal cover fixed to the metal case to allow it to close by flush fitting of the upper or lower faces of the metal cover and the metal case, the metal case having a second housing into which the metal cover fits, the dynamic metal seal being located between the metal cover and the surface of the metal case defining the first housing.