High-pressure threaded union with metal-to-metal seal, and metal ring gasket for same
View Patent ↗A metal ring gasket provides a high-pressure temperature tolerant metal-to-metal seal between subcomponents of a threaded union. The metal ring gasket is received in an annular cavity formed between mating surfaces of the subcomponents of the threaded union. The metal ring gasket is capable of maintaining a fluid seal even at very high temperatures resulting from direct exposure to fire. At high fluid pressures the metal ring gasket is energized because hoop stress induced by the fluid pressure forces the metal ring gasket into tighter contact with the subcomponents of the threaded union.
1. A threaded union for providing a fluid-tight, metal-to-metal seal in a fluid conduit, the threaded union comprising:
first and second subcomponents having respective mating ends that are drawn into contact by a single nut, the mating end of the first subcomponent including a first annular groove that mates with a complementary second annular groove in the mating end of the second subcomponent, said complementary first and second annular grooves respectively having a sloped annular inner face and a sloped annular outer face that are respectively convergent to a planar annular bottom surface of the respective annular grooves; and
a metal ring gasket having a central axis received in the respective annular grooves, the metal ring gasket having a single planar top face, a single planar bottom face that is parallel to the planar top face, a cylindrical outer face that is coaxial with the central axis of the metal ring gasket and that is perpendicular to the top and bottom faces, and single annular converging sloped surfaces between each of the planar top face and bottom face and the cylindrical outer face, the metal ring gasket being oversized with respect to the first and second sloped outer faces of the annular grooves to an extent that the metal ring gasket is elastically deformed without plastic deformation by contact between only the respective first and second sloped annular outer faces of the respective first and second annular grooves and the annular converging sloped surfaces of the metal ring gasket to provide the fluid-tight seal between the first and second subcomponents after the first and second subcomponents are drawn together by the nut.
2. The threaded union as claimed in claim 1 wherein the metal ring gasket is oversized by about 0.003″ with respect to the respective sloped annular outer faces of the respective annular grooves.
3. The threaded union as claimed in claim 1 further comprising a gap of at least 0.003″ between an inner side of the metal ring gasket and the respective sloped annular inner faces of the respective annular grooves after the mating ends of the first and second subcomponents are drawn into contact by the nut.
4. The threaded union as claimed in claim 1 wherein the nut is constructed in three parts so that a main body of the nut is a single piece construction for greater strength.
5. The threaded union as claimed in claim 4 wherein the nut has an upper annular shoulder that extends radially inwardly from a top of the main body of the nut, the upper annular shoulder abuts a flange that extends radially outwardly from an adapter collar that is a generally annular multi-piece body having an inner diameter dimensioned to slide over an outer surface of the second subcomponent until a bottom surface of the adapter collar abuts an annular shoulder of the second subcomponent, and when torque is applied to the nut the upper annular shoulder is forced downwardly on the flange which in turn exerts a downward force on the upper annular shoulder, thereby forcing the mating end of the second subcomponent against the mating end of the first subcomponent to elastically deform the metal ring gasket into the respective annular grooves.
6. A threaded union for providing a fluid-tight, metal-to-metal seal in a fluid conduit, the threaded union comprising, in combination:
first and second subcomponents having respective mating ends that are drawn into contact by a single nut, each of the respective mating ends including an annular groove having a sloped annular inner face and a sloped annular outer face that are respectively convergent to a planar annular bottom surface of the respective annular grooves; and
a metal ring gasket having a central axis received in the annular grooves, the metal ring gasket comprising a single planar top face, a single planar bottom face that is parallel to the planar top face, a cylindrical outer face that is coaxial with the central axis of the metal ring gasket and that is perpendicular to the top and bottom faces, and single annular converging sloped surfaces between each of the planar top and bottom faces and the cylindrical outer face, the metal ring gasket being oversized with respect to the first and second sloped outer faces of the annular grooves to an extent that the metal ring gasket is elastically deformed without plastic deformation by contact between only the respective first and second sloped annular outer faces of the respective first and second annular grooves and the annular converging sloped surfaces of the metal ring gasket to provide the fluid-tight seal between the first and second subcomponents when the first and second subcomponents are drawn together by the nut;
wherein the metal ring gasket is elastically deformed without plastic deformation in the annular grooves to provide the fluid-tight seal between the first and second subcomponents, and gaps remain between said sloped annular inner faces, said respective planar bottom faces of the respective annular grooves and the metal ring gasket after the first and second subcomponents are drawn into contact by the nut.
7. The threaded union as claimed in claim 6 wherein the metal ring gasket is oversized by about 0.003″ with respect to the sloped annular outer faces of the respective annular grooves.
8. The threaded union as claimed in claim 6 wherein the metal ring gasket is octagonal in cross-section.
9. The threaded union as claimed in claim 6 wherein the annular converging sloped surfaces between each of the planar top and bottom faces and the cylindrical outer face of the metal ring gasket are sloped at an angle of about 23° with respect to the cylindrical outer face.
10. The threaded union as claimed in claim 6 wherein the mating end of the first subcomponent comprises a pin end received in a socket of the mating end of the second subcomponent, the annular groove in the first mating end is located in the pin end and the annular groove in the second mating end is located in a bottom of the socket.
11. The threaded union as claimed in claim 6 wherein the mating end of the first subcomponent comprises a pin end received in a socket of the mating end of the second subcomponent, the annular groove in the first mating end is located in the pin end and the annular groove in the second mating end is located in a bottom of the socket.
12. A threaded union for providing a fluid-tight, metal-to-metal seal in a fluid conduit, the threaded union comprising:
first and second subcomponents having respective mating ends that are drawn into contact by a single nut, the mating end of the first subcomponent including a first annular groove that mates with a complementary second annular groove in the mating end of the second subcomponent, said complementary first and second annular grooves respectively having sloped annular outer faces that are respectively convergent to a planar annular bottom surface of the respective annular grooves; and
a metal ring gasket having a central axis received in the respective annular grooves, the metal ring gasket having a single planar top face, a single planar bottom face that is parallel to the planar top face, a cylindrical outer face that is coaxial with the central axis of the metal ring gasket and that is perpendicular to the top and bottom faces, and single annular converging sloped surfaces between each of the planar top face, the planar bottom face, and the cylindrical outer face, the metal ring gasket being oversized with respect to the first and second sloped outer faces of the annular grooves to an extent that the metal ring gasket is elastically deformed without plastic deformation by contact between only the respective first and second sloped annular outer faces of the respective first and second annular grooves and the annular converging sloped surfaces of the metal ring gasket to provide the fluid-tight seal between the first and second subcomponents after the first and second subcomponents are drawn together by the nut.
13. The threaded union as claimed in claim 12 wherein the metal ring gasket is compressed by about 0.003″ by the contact between only the respective first and second sloped annular outer faces of the respective first and second annular grooves and the annular converging sloped surfaces of the metal ring gasket.
14. The threaded union as claimed in claim 12 wherein the metal ring gasket is octagonal in cross-section.
15. The threaded union as claimed in claim 12 wherein the metal ring gasket has an a cylindrical inner face that is coaxial with the central axis of the metal ring gasket.
16. The threaded union as claimed in claim 12 wherein the annular converging sloped surfaces of the metal ring gasket are sloped at an angle of about 23° with respect to the cylindrical outer face.