A tubular membrane module and its method of manufacture are disclosed wherein tubular membranes form an interference self-sealing fit with hard tube sheets with the aid of a hard hollow mandrel inserted at the end of the tubular membranes. The tubular membranes are comprised of porous, compressible PTFE and / or fluorocopolymers. The self-sealing method described herein requires no heat treatment, allows for ease of manufacture without destruction of the tubular membranes and without the processing complexity of utilizing any additional potting agent, extrusion, or chemical cross-linking of any polymeric adhesives. The self sealing PTFE tubular membranes have superb chemical resistance and temperature resistance, and through the benefits of this invention, offer higher pull-out resistance than typically observed with potting materials such as polyurethane and epoxy. In addition, the self-sealing method is reversible and non-destructive (whereas chemical potting and sealing methods using heat are not), as one can easily remove one or more damaged tubes and replace them.