Sealing ring and joint for oil drilling plant

A sealing ring for a joint applicable to a stationary duct and to a rotating pipe of a drilling assembly, the sealing ring having a main axis and being delimited radially by an inner side face and an outer side face radially outside the inner side face, and axially by a support face and a contact face axially spaced apart from the support face, wherein the contact face comprises a contact region provided with a plurality of circumferentially arranged grooves, wherein each groove has a predetermined radial extension on the contact region, is axially lowered, and opens to the inner side face,

• wherein the contact face comprises an annular, frusto-conical inner boundary surface that internally delimits the contact region, is tapered towards the contact region, and is inclined with respect to the contact region by an angle (E),
• wherein the contact face comprises an annular inner surface between the contact region and the inner side face, the annular inner surface being angled from the contact region towards the inner side face,
• wherein the annular inner surface comprises an annular, frusto-conical intermediate surface that is tapered towards the contact region and inclined with respect to the contact region by an angle (D),
• and wherein the angle (E) of the inner boundary surface is greater than the angle (D) of the intermediate surface.