Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for a pipe – conduit – or cable
Reexamination Certificate
1999-04-27
2001-01-16
Melius, Terry Lee (Department: 3628)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for a pipe, conduit, or cable
C277S584000, C285S350000
Reexamination Certificate
active
06173968
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a sealing ring assembly. More particularly, the present invention pertains to a sealing ring assembly including an annular sealing ring and an annular backup ring positioned adjacent the annular sealing ring. The annular backup ring is split to permit radial expansion and has a greater thickness on its outer periphery than on its inner periphery. As a consequence, when the sealing ring assembly is used to seal a joint between two members, such as pipes, in a high pressure application, the annular sealing ring presses against the annular backup ring, causing the annular backup ring to expand radially to cover any gap that might exist between the two members, and so inhibiting extrusion of the sealing ring into such gap.
BACKGROUND OF THE INVENTION
Annular sealing rings, often referred to o-rings, are frequently utilized to provide a fluid seal between two members, such as two pipes, threaded or otherwise joined together. In the absence of a sealing ring, fluid within the pipes might leak through gaps at the joint at which the two members are connected.
Sealing rings are commercially available and are often made of a resilient, rubber-like material, for example rubber, ethylene, or propylene. Such materials are commercially available under the trademarks VITON and KALREZ. These scaling rings provide satisfactory sealing at comparatively low pressures and temperatures. However, at higher pressures and temperatures, for example pressures in excess of 3400 psia and temperatures in excess of 300° F., these sealing rings do not always work satisfactorily. The high temperature might cause expansion of the members being joined, with resultant expansion of any gaps at the joint. The high temperature also might soften the material of the sealing ring. The high pressure then might result in extrusion of the sealing ring into the enlarged gaps. This can result in damage to the sealing ring. When the high pressure and high temperature condition ends, the members being joined contract, but any extruded portion of the scaling ring might not withdraw from the previously enlarged gap. In that event, the sealing ring may be damaged, and when the high pressure and high temperature condition is next experienced, the damaged sealing ring may not provide an adequate seal. This problem is exacerbated with each cycle of high pressure and high temperature.
SUMMARY OF THE INVENTION
The present invention is a sealing ring assembly for sealing a joint between two members. An annular backup ring is positioned downstream of an annular sealing ring of substantially the same diameter. The annular backup ring is split to permit radial expansion and has a greater thickness on its outer periphery than on its inner periphery. When the joint being sealed is under high pressure, the sealing ring urges the backup ring to expand radially to cover any gap between the members being sealed, maintaining the seal even under high temperature conditions, and preventing the sealing ring from extruding into the gap. The sealing ring is made of a resilient rubber-like material such as rubber, ethylene or propylene, for example a VITON™ or KALREZ™ material, while the backup ring is preferably made of a strong, rigid material, such as a metal, for example aluminum, titanium or steel.
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patent: 4840379 (1989-06-01), Thoman, Jr.
patent: 5123662 (1992-06-01), Sugimura
Borate Robert E.
Nelson Steven D.
Melius Terry Lee
Miller William L.
TRW Inc.
Yatsko Michael S.
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