Abstract: Disclosed is a self-sealing dispensing tap for use on flexible packages. The tap includes a piercing end configured for piercing the wall of a flexible container, and a flexible member that rides along the tap as it is inserted into the container and expands once installed so as to prevent its withdrawal from the container. A clamping device is provided on the outside of the container which draws the flexible member against the interior wall of the container so as to provide a barrier preventing product within the container, bacteria, or oxygen from inadvertently passing between the interior and exterior of the container.