Patent ID: 7063330

Claim:
A spherical annular seal member which has a cylindrical inner surface defining a through hole in a central portion thereof, a partially convex spherical outer surface, and an annular end face on a large-diameter side of the partially convex spherical outer surface, and which is used in an exhaust pipe spherical joint of an automobile, comprising: a reinforcing member made from a compressed metal wire net and provided in an inner portion of said spherical annular seal member which extends from the cylindrical inner surface to the partially convex spherical outer surface; a heat-resistant material containing compressed and expanded graphite, phosphorus pentoxide and a phosphate, and provided in the inner portion of said spherical annular seal member, said heat-resistant material being composed of 0.05 to 5.0 wt. % of phosphorus pentoxide, 1.0 to 16.0 wt. % of the phosphate, and 79.0 to 98.95 wt. % of expanded graphite, and filling meshes of said metal wire net of said reinforcing member and compressed in such a manner as to be formed integrally with said reinforcing member in mixed form, said phosphorus pentoxide and said phosphate being mixed into said compressed and expanded graphite to suppress consumption of said compressed and expanded graphite due to oxidation of the same at temperatures of 600° C. to 700° C., the partially convex spherical outer surface being formed into a smooth surface where an outer surface layer of said heat-resistant material containing said compressed and expanded graphite, phosphorus pentoxide, and the phosphate, which are mixed into said compressed and expanded graphite to suppress consumption of said compressed and expanded graphite due to oxidation of the same at temperatures of 600° C. to 700° C., and said reinforcing member made from the metal wire net and formed integrally with said heat-resistant material in mixed form are exposed.