Patent ID: 8602420

Claim:
A spherical annular seal member for use in an exhaust pipe joint, comprising: a spherical annular base member defined by a cylindrical inner surface, a partially convex spherical surface, and large- and small-diameter-side annular end faces of the partially convex spherical surface; and an outer layer formed integrally on the partially convex spherical surface of said spherical annular base member, wherein said spherical annular base member includes a reinforcing member made from a metal wire net and a heat-resistant material containing expanded graphite, filling meshes of said reinforcing member, and compressed in such a manner as to be formed integrally with said reinforcing member in mixed form, and wherein, in said outer layer, a heat-resistant material containing expanded graphite, a solid lubricant constituted of a lubricating composition containing at least 70 to 85 wt. % of hexagonal boron nitride, 0.1 to 10 wt. % of boron oxide, and 5 to 20 wt. % of hydrated alumina, and a reinforcing member made from a metal wire net are compressed such that said solid lubricant and said heat-resistant material are filled in meshes of said metal wire net of said reinforcing member, and said solid lubricant, said heat-resistant material, and said reinforcing member are integrally formed in mixed form, an outer surface of said outer layer being formed into a smooth surface in which a surface constituted of said reinforcing member and a surface constituted of said solid lubricant are present in mixed form.