Seals have been used to isolate fluids at various pressures and temperatures. Such seals have existed for use in packing rings, seal rings, piston rings, and gland structures in industrial equipment such as cylinders, pumps and valves and in oil-field equipment such as downhole tools and surface equipment, requiring seals, for example, against high pressure and low pressure liquids and gases, for reciprocating rods, for pistons, for valves and for other applications.
However, such seals may be eroded and/or extruded or destroyed for machinery equipment wherein sealing needs to be established at the most severe sealing environments, which include seal gland design, pressures, fluid medias and temperatures.
Such seals, whether of the dynamic or static type, are usually made, or have portions made, of materials which, to some extent, are resilient or at least deformable. In order to seal effectively, it is not necessary, but could be possible, that the sealing device be placed under some compressive loading between the components of the assembly to be sealed. Because of the compressing load, there is a tendency for portions of deformable seals to be subjected to extrusion forces which will either distort the seal and impair its effectiveness as a seal or, in more severe cases, force portions of the seal into clearances between the components to be sealed.
In an attempt to overcome this extrusion problem, workers in the field have resorted to various techniques. One common practice employed to prevent such extrusion is the use of a back-up ring of knitted mesh as shown in U.S. Pat. No. 4,219,204. Additionally, seals having the seal lip configuration with an insert discussed below are also known in the art and are manufactured by Parker Seal Company, polypac seal.