Port closure apparatus for differentially pressured vessels

A low profile device for sealing a differentially pressured vessel having an entry port, comprising:

• low profile port means having a central passage therethrough and being secured to the vessel with the central passage in axial alignment with the entry port by non-protrudable means, the low profile port means comprising a cylindrical ring means including a circumferentially outer and (with respect to the vessel) inner threaded portion protected by a (with respect to the vessel) outer shoulder and a circumferentially inner and (with respect to the vessel) outer threaded bore of greater diameter and outer of an annular sealing surface surrounding the central passage;
• and a sealing ring seat on the annular sealing surface;
• low profile sealing plug means the sealing plug means comprising a cylindrical plug having circumferentially outer threads for engagement with the cylindrical ring means in the circumferentially inner threaded bore, and having an inner (with respect to the vessel) flat end surface for sealing contact with the sealing ring means in bearing upon the annular sealing surface, insertable within the central passage in pressure-tight sealing connection between the annular sealing surface and the sealing plug means;
• manifold means disposed over the sealing plug means and port means and sealingly connected about the outer periphery of the port means having an inner circumferential threaded portion and providing sealed fit over the port means;
• access means formed through the manifold means to enable selective fluid communication between the exterior and interior of the manifold means;
• and
• stem means sealingly disposed through the manifold means in rotatable realtionship for rotatable affixture to the plug means thereby to enable manipulation of the plug means into and out of sealing connection within the central passage of the port means;
• further characterized that;
• manipulation of the plug means by means of the stem means into sealing connection within the central passage of the port means seals the differentially pressured vessel to enable removal of the manifold means and stem means thereby to reveal a low profile seal of the differentially-pressured vessel.