Patent ID: 6857638

Claim:
A gasket for use in a joint between a pair of sanitary pipe flange faces having flat and grooved portions, said gasket comprising an O-ring portion for alignment with said grooved portion of said flange faces and at least one flat portion of compressible material having an uncompressed axial thickness (T) for forming a fluld-tight seal about the lumen of said pipe and a portion made of incompressible material, the axial thickness of said incompressible portion being dimensioned with respect to the axial thickness and percentage radial expansion of said compressible portion so as to limit axial compression of said compressible portion to an amount (t), the percentage radial expansion of said compressible portion being greater than the percentage of axial compression by the factor ( 1 1 - t T ) , whereby the greater percentage radial expansion of said compressible portion is prevented from entering said lumen.