Patent Application
20150054276
1. Field of the Invention
The invention relates generally to seals in high pressure connections, and more particularly to systems and methods for making bidirectional, pressure-energized seals in high-pressure pipe systems.
2. Related Art
While there are a variety of systems and techniques for sealing connections between components of high-pressure pipe systems (e.g., flange couplings or closures) that may be used in oil production, chemical processing, etc.
The use of pipelines or other conduits to carry pressurized fluids is widely known. For instance, such pipelines may be used to transport natural gas or other fluid hydrocarbons. Still other pipelines may be used to transport corrosive, toxic or otherwise dangerous fluids. These systems typically consist of multiple components (e.g., tubulars, end closures, valve bonnets, etc.) that are connected to for a sealed conduit or enclosure. Seals of some type are commonly used to prevent leakage at the connections.
Typically, these pipelines are internally pressurized, and the seals are designed to prevent from leaking out of the conduits. Others are externally pressurized. In some cases, it is desirable to have seals that are bidirectional. In other words, they prevent fluids from escaping from the conduit, and also prevent fluids from entering the conduit. Embodiments of the invention disclosed herein are designed to prevent leakage bi-directionally, and to be energized by fluid pressure differences to which the connection is exposed
One or more of the problems outlined above may be solved by the various embodiments of the invention. Broadly speaking, the invention comprises systems and methods for sealing coupling flanges, tubular, end closures, valve bonnets, or other components of a conduit or enclosure.
One particular embodiment comprises a bidirectional pressure-energized seal ring. The seal ring is generally annular, and has a cross-section which includes a body portion and two sealing portions that extend from the body. Each of the sealing portions is generally V-shaped, having a set of opposing sealing faces with a cavity between them. Fluid pressure within the cavity urges the sealing faces outward from the cavity, toward the faces of the flanges between which the seal ring is installed. The two sealing portions do not face opposite directions, but are instead angled. The sealing portions face directions that are between 90 and 160 (and preferably about 100) degrees apart. Because the sealing portions are angled, the body portion forms a load shoulder which abuts an interior corner of a recess between the flanges of a connection and thereby prevents the fluid pressure from moving the seal ring within the recess. The body portion of the seal ring is solid, and consequently provides resistance to shearing forces between the flanges.
An alternative embodiment comprises a high-pressure connection in a conduit, where the connection includes a bidirectional, pressure-energized seal. In this embodiment, a first flange has a sealing surface that includes a female pocket. A second flange has a sealing surface that includes a male nose. The male nose of the second flange is configured to mate with the female pocket of the first flange. A recess is formed in at least one of the flanges, and a seal ring is seated in the recess to form a seal between the two flanges. The outer peripheries of the two flanges' sealing surfaces are in contact with each other in the assembled connection so that the bending moments imparted by loads on the conduit being sealed and the associated stresses are borne by the flanges, and not to the seal ring. The seal ring is a bidirectional, pressure-energized device. The cross-section of the seal ring includes a solid body and two V shaped sealing portions that extend from the body at an angle between 90 and 160 degrees. Each sealing portion has a set of opposing sealing faces with a cavity between them, so that fluid pressure within the cavity urges the sealing faces outward from the first cavity toward the flanges.
Numerous other embodiments are also possible.
Other objects and advantages of the invention may become apparent upon reading the following detailed description and upon reference to the accompanying drawings.
While the invention is subject to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and the accompanying detailed description. It should be understood, however, that the drawings and detailed description are not intended to limit the invention to the particular embodiment which is described. This disclosure is instead intended to cover all modifications, equivalents and alternatives falling within the scope of the present invention as defined by the appended claims.
One or more embodiments of the invention are described below. It should be noted that these and any other embodiments described below are exemplary and are intended to be illustrative of the invention rather than limiting.
As described herein, various embodiments of the invention comprise systems and methods for making connections in high-pressure conduits, where the connections incorporate bidirectional pressure-energized seals. In an exemplary embodiment, a connection utilize a seal ring that has cavities between opposing sealing surfaces to enable fluid pressure to urge the sealing surfaces toward the respective flanges of the connection. The portion of the seal ring that is energized by external fluid pressure is angled with respect to the portion that is energized by internal fluid pressure. The angle provides a load shoulder in each direction which prevents the fluid pressure from moving the seal ring. A central body of the seal ring is solid to provide shear resistance. Recesses may be provided in the sealing surfaces of the seal ring in order to multiply the contact pressure between the sealing surfaces of the seal ring and the flanges of the connection. The flanges may include recesses to relieve stresses that induce rotation of the seal ring as the connection is assembled.
Referring to
Referring to
Flange 110 has a male nose 112. Male nose 112 is an outwardly-facing conic section that appears as a tapered surface in the figures. Male nose 112 is configured to fit within female pocket 122 of flange 120 as shown in
Flange 110 also has a recess 114 in which seal ring 150 is seated in the assembled connection. The outer peripheries (113, 123) of the flanges' contact surfaces contact each other in the assembled connection. In other words, the flanges bottom out against each other, while leaving space in recess 114 for seal ring 150. This allows the connection to withstand greater bending stresses without placing unnecessary and possibly damaging stresses on seal ring 150.
Seal ring 150 provides a bidirectional, pressure-energized seal. In other words, seal ring 150 is designed to be energized by fluid pressure, either from the interior of the connection, or from the exterior of the connection. This is achieved by providing V-shaped portions that have cavities which are exposed to fluid paths from the interior and exterior of the connection, respectively. The fluid pressure in the cavity urges the legs of the V-shape outward, toward the sealing surfaces of the flanges (i.e., the fluid pressure energizes the seal). Because seal ring 150 is seated in a corner of the gap between flanges 110 and 120, the fluid pressure in either cavity does not cause the seal ring to move.
Referring to
Central portion 310, and two sealing portions 320 and 330. These three portions of the seal ring are integral, and are separately identified only to facilitate the description of the seal ring. The first sealing portion 320 extends radially outward from the axis of the ring (facing the outer periphery of the connection) in a first direction, A. The second sealing portion 330 faces downward and slightly inward toward the seal ring's axis in a second direction, B. The angle (θ) between directions A and B is approximately 100 degrees in this embodiment, but this may vary in other embodiments from approximately 90 degrees to approximately 160 degrees.
Each of the sealing portions (320, 330) is roughly V-shaped (or U-shaped), having a pair of legs (e.g., 321, 322) with a cavity (e.g., 323) between them. An outer face of each leg has a sealing surface that contacts the face of a corresponding one of the flanges. For example, the outer (upper) face of leg 321 contacts male flange 110 and forms a seal against this flange, while the outer (lower) face of leg 322 contacts female flange 120 and forms a seal against it. When fluid pressure is applied to the interior of the cavity (e.g., 323), the pressure urges the legs outward from the cavity toward the respective ones of flanges 110 and 120. The fluid pressure thereby energizes the seal and increases the contact pressure between the seal ring and the flanges over the loading applied when the connection is assembled. The seal ring is bidirectional—the first sealing portion (320) is energized when the fluid pressure exterior to the connection is greater than the fluid pressure interior to the connection, and the second sealing portion (330) is energized when the fluid pressure interior to the connection is greater than the fluid pressure exterior to the connection.
As noted above, sealing portions 320 and 330 are angled with respect to each other. As a result, central portion 310 forms a load shoulder which abuts flange 110 in the corner of recess 114. The load shoulder prevents the seal ring from moving away from the pressure. For example, when fluid pressure is applied to cavity 323, in addition to urging legs 321 and 322 toward flanges 110 and 120, respectively, it will urge the seal ring in the direction opposite direction A. Because central portion 310 is butted against flange 110, however, the seal ring will not move away from direction A. Similarly, when fluid pressure is applied to cavity 333, it will urge the seal ring in the direction opposite direction B, but since central portion 310 is butted against flange 110, the seal ring will not move away from direction B.
Another feature of seal ring 150 is that central portion 310 provides some shear resistance to the seal ring. As shown in
In the embodiment of
Referring to
The primary difference between seal ring 400 and seal ring 150 is that each of the sealing faces in seal ring 400 has a recess. For example, leg 421 has a recess 425 in its sealing face. Recess 425 is positioned between central portion 410 and the end of sealing portion 420. Recess 425 extends along most of the length of sealing portion 420, but a small portion of the sealing face (426) remains raised so that it contacts the sealing surface of the male flange. Leg 421 pivots to some degree at point 427 at the end of recess 415 nearest central portion 410.
As a result of these recesses, the fluid pressure in cavity 423 that is applied to leg 421 generates increased contact pressure at area 426 at the end of leg 421, rather than along the entire length of leg 421. This multiplies the contact pressure between seal ring 400 (at area 426) and the male flange in comparison to seal ring 150. As shown in the figure, each of the legs (421, 422, 431, 432) of the seal has a corresponding seal face recess that serves as a multiplier of the contact pressure between the seal ring and the corresponding sealing faces of the flanges. In other embodiments, the recesses could be used on any combination of the legs.
It should be noted that, in a preferred embodiment, when seal ring 400 is unstressed (e.g., uninstalled) the contact surface (426) at the end of the leg (421) lies in substantially the same plane as the upper edge 411 of body 410. If contact surface initially lies above this plane, installation of the seal ring in the connection causes the leg to flex inward, toward the cavity. Although this results in some space between the leg and the surface of the flange, the flexed leg does not provide a substantially stationary pivot point (e.g., 427) for the leg and consequently is not as effective as a multiplier of the fluid pressure in the cavity.
In one embodiment, the male flange has a relief recess 450 at the base of the nose. The recess is formed in the portion of the flange surface that is generally perpendicular to the axis of the flange. The recess in this embodiment is rounded and follows a spline curve that reduces stresses in the flange. Recess 450 allows the connection to be assembled without causing twisting of the seal ring between the male nose and the female pocket.
Referring to
The embodiment of
In one embodiment, protrusion 511 and recess 550 may be configured to allow the protrusion to slide easily into and out of the recess. In another embodiment, the sizes and shapes of protrusion 511 and recess 550 may be designed to provide an interference fit of the protrusion into the recess. In this case, the interference between these features would tend to hold protrusion 511 in recess 550, thereby holding seal ring 500 in position against flange 570. This configuration could be advantageous, particularly in subsea environments, because it may prevent mis-positioning of the seal ring as the connection is assembled, as well as possible loss of the seal ring when the connection is disassembled. Protrusion 511 and recess 550 may also include features that interlock with each other, allowing the protrusion to snap into place within the recess. This would more securely hold the seal ring in position against the flange. The specific configuration of the interlocking features can be designed to provide the desired retention strength.
Referring to
Referring to
The benefits and advantages which may be provided by the present invention have been described above with regard to specific embodiments. These benefits and advantages, and any elements or limitations that may cause them to occur or to become more pronounced are not to be construed as critical, required, or essential features of any or all of the claims. As used herein, the terms “comprises,” “comprising,” or any other variations thereof, are intended to be interpreted as non-exclusively including the elements or limitations which follow those terms. Accordingly, a system, method, or other embodiment that comprises a set of elements is not limited to only those elements, and may include other elements not expressly listed or inherent to the claimed embodiment.
While the present invention has been described with reference to particular embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Many variations, modifications, additions and improvements to the embodiments described above are possible. For instance, although the embodiments described above relate to the connection of two pipe-end flanges, alternative embodiments may be used to couple together other components, such as enclosures, conduits, housings, closures, valve, etc. It is contemplated that these variations, modifications, additions and improvements fall within the scope of the invention as detailed within the following claims.
