Bi-directional unsupported area seal

A packing assembly for sealing an annulus between spaced inner and outer cylindrical surfaces arranged in concentric coaxial relationship with the outer cylindrical surface having an inwardly extending annular shoulder, the packing assembly being positioned within the annulus and comprising:

• a plurality of packing rings in said annular space arranged in contiguous stacked relation with one another and disposed about the inner cylindrical surface in contact therewith for effecting a seal between said spaced inner and outer cylindrical surfaces:
• a pair of retainer rings between which said packing rings are located, each retainer ring being disposed in sleeved relation about said inner cylindrical surface, with one said retainer ring being restrained in one direction of axial movement by said annular shoulder and each retainer ring has an annular end surface remote from said packing rings upon which fluid pressure in the annulus is adapted to act in an axial direction to urge the retainer rings towards one another and thereby compress and squeeze the packing rings against said inner and outer cylindrical surfaces to increase the sealing effect of the packing rings and wherein the surface of each retainer ring at the ends of the packing assembly exceeds the surface area of the adjacent packing ring contacting therewith whereby the force per unit area transmitted by a retainer ring to the packing rings upon application of fluid pressure from either axial direction is amplified to increase the sealing effect of the packing rings as the fluid pressure acting on the sealing assembly increases.