A tank for pressurized gas, such as hydrogen, comprises a structure, a base, a sealing jacket and a ring. The structure has a substantially cylindrical shape along an axis and includes at least one axial opening along the axis. The base is able to be positioned in said opening and comprises, on the inner side, a housing of revolution about the axis and a first fastener, and is pierced with at least one through pipe that is axial along the axis. The sealing jacket is flexible and tight, and is to cover the inner wall of the structure and comprises a neck able to be received in the housing. The ring is substantially of revolution about the axis, and comprises a second fastener able to cooperate with the first fastener in order to assemble the ring with the base, on the inner side, by bringing the ring closer to the base along the axis, so as to progressively press the neck between the ring and the base. The ring comes closer to the base following a movement parallel to the axis from the inside of the tank toward the outside. and A face of the housing opposite the neck and a face of the ring opposite the neck have a small taper.