Importance

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Abstract

An improved elastomeric seal for preventing both low or high pressure fluid from escaping past a rotatable valve stem or similar shaft. The annular seal comprises an outer generally envelope-shaped first plastic member for sealing engagement with the rotatable stem and valve bonnet, and an inner second plastic member substantially encapsulated by the first member. The annular legs of the envelope-shaped member are positioned downstream from fluid pressure, thereby sealing the inner second member from fluid attack. Novel techniques are employed for forming the elastomeric seal outside the valve bonnet by applying a substantial radially-directed force for deforming the first plastic member into the envelope configuration, while deforming the inner plastic member into an elliptical configuration. The seal in the substantially deformed configuration is then assembled within the bonnet cavity while preventing radial expansion of the envelope-shaped member.

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First Claim