The present disclosure relates generally to a seal assembly, and, more particularly, to a seal assembly that provides a fluid-tight seal between two members.
In connections between two members, such as a conduit and a flange, a fitting may be required to ensure a fluid-tight seal between the two members. This is particularly important for systems in which a highly pressurized fluid, such as a pressurized gas or liquid, flows through the two members, and where the two members may vibrate or otherwise move relative to one another. For example, in a cooling system for a generator, conduits may be used to transfer coolant to and from the generator. The conduits are connected to flanges of the generator using fluid-tight seals and clamps. In such systems, a lack of a fluid-tight seal, or a failure thereof, may result in pressure drops and loss of fluid. Such fluid-tight seals may fail due to misalignments between the two members, due to planar translation or polar tilting (i.e., translation or tilting relative to a longitudinal axis of the flange) either before or after tightening of the clamps. In addition, when a hard joint is used, i.e., a joint by which two metal members are joined by a bolt or a screw, vibrations of one or both of the two members may result in failure of the fluid-tight seals.
Known fittings typically use threaded connections that accommodate some level of misalignment between a conduit and a flange. For example, as described in U.S. Pat. No. 9,267,627 B2 (the “'627 patent”), two conduit gripping devices are used together in a conduit fitting assembly, and are held together as a cartridge or subassembly prior to assembly with the fitting components. One or both of the two conduit gripping devices include a retaining structure by which the devices are mechanically connected together as a subassembly, and may include a front ferrule and a back ferrule that are snapped together as part of a tube fitting.
Using threaded connections in fittings requires additional sealing means to ensure a fluid tight seal between the conduit and the flange. In addition, using rigid components, such as ferrules, reduces an amount by which the fitting can accommodate misalignment and/or vibrations between the conduit and the flange. Further, using a clamp to secure the two members together requires securing a flexible seal between the clamp and the two members. As a connection between the clamp and the two members tightens, the seal may deform to tightly fit against the two members, i.e., to form an interference fit. Problems arise, however, if the connection between a clamp and at least one of the members becomes over-tightened, causing extrusion and possibly failure or breakage of the flexible seal. In addition, as a complexity of such connections increases, it is possible that the connections can be installed and assembled incorrectly, leading to failure or breakage of the flexible seal.
The seal assembly according to the present disclosure may solve one or more of the problems of the devices of the '627 patent, and/or other problems in the art.
In one aspect, an unloaded annular flexible seal is provided for use in a seal assembly configured to receive an end of a conduit and to provide a seal between the conduit and a flange of a machine. The seal may include a base having an inner surface, an upper surface, an outer surface, and a lower surface, and a leg having an inner surface, an upper surface extending from the inner surface of the base, an outer surface extending from the lower surface of the base, and a lower surface. A surface area of the outer surface of the leg is greater than a surface area of the lower surface of the leg.
In another aspect, a seal assembly is configured to receive an end of a conduit and to provide a seal between the conduit and a flange of a machine. The seal assembly may have an annular flexible seal that includes a seal base having an inner surface, an upper surface, an outer surface, and a lower surface, and a seal leg having an inner surface, an upper surface extending from the inner surface of the seal base, thereby forming a groove, an outer surface extending from the lower surface of the seal base, and a lower surface. A surface area of the outer surface of the seal leg is greater than a surface area of the lower surface of the seal leg. The seal assembly also includes an annular back-up member having an L-shaped cross section, including a back-up member base and a back-up member leg configured to sit in the groove of the flexible seal.
In still another aspect, a seal assembly is configured to provide a fluid-tight seal between a tube, a flange, and a clamp. The seal assembly may have an annular flexible seal including a seal base having an inner surface, an upper surface, an outer surface, the upper surface and the outer surface being configured to sit in a groove formed by the clamp and the flange, and a lower surface, and a seal leg having an inner surface, an upper surface extending from the inner surface of the seal base, thereby forming a groove, an outer surface extending from the lower surface of the seal base, and a lower surface. A surface area of the outer surface of the seal leg is greater than a surface area of the lower surface of the seal leg. The seal assembly also includes an annular back-up member having an L-shaped cross section, including a back-up member base configured to sit in a groove of the clamp, and a back-up member leg configured to sit in the groove of the seal. When the tube is inserted into the seal assembly, and the tube, the flange, the clamp, and the seal assembly are secured to each other, the seal base is compressed between the clamp, the flange, and the back-up member.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” “having,” including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. Moreover, in this disclosure, relative terms, such as, for example, “about,” “generally, “substantially,” and “approximately” are used to indicate a possible variation of ±10% in the stated value.
The flange 100 may include a main fluid channel 112 and an expanded tube opening 108 at an open end of the flange 100. The main fluid channel 112 and the expanded tube opening 108 may be generally cylindrical, although other shapes are possible. The flange 100 may be formed of a rigid material, such as steel.
The tube 102 may be cylindrical and formed of a material, such as steel, stainless steel, aluminum, polymerizing vinyl chloride (PVC), or ceramic, for example. An inner diameter of the tube 102 may be approximately equal to an inner diameter of the main fluid channel 112, and an outer diameter of the tube 102 may be smaller than the diameter of expanded tube opening 108, so as to be received therein.
The clamp assembly 104 may extend from an open end of flange 100, and may include a cap 118 and a clamp member 116 positioned between the cap 118 and the flange 100. An annular lock ring 120 may be positioned at an inner interface between the cap 118 and the clamp member 116. The clamp member 116 and the cap 118 may have generally the same shape, namely, a cylinder having a central opening generally corresponding in shape to the expanded tube opening 108 of the flange 100. Diameters of the central openings of the clamp member 116 and the cap 118 are generally the same as a diameter of the tube opening 108 of the flange 100. In addition, openings 117 and 119 are provided in the clamp member 116 and the cap 118, respectively, and are arranged to be coextensive with a clamp opening 110 in the flange 100. Each of the openings 110, 117, and 119 may be threaded, or just the clamp opening 110 may be threaded to engage with threads of bolts 114. The lock ring 120, which is an annular member, has a central opening generally corresponding in shape and size to the tube opening 108 of the flange 100.
An inner circumferential surface of the clamp member 116 has a series of protrusions and grooves shaped to fit the lock ring 120 and the tube seal assembly 106. In particular, the inner circumferential surface of the clamp member 116 has an upper groove 192 and a lower groove 194 shaped to fit the tube seal assembly 106, as shown in
The tube seal assembly 106 may include a back-up ring 122 and a seal 124. Both the back-up ring 122 and the seal 124 are annular members, each having a central opening. Cutaway views of the back-up ring 122 and the seal 124 are shown in
Referring to
As shown in
The geometric relationships between the surfaces of the back-up ring 122 and the characteristics of the surfaces of the back-up ring 122 (e.g., planar) may vary from those described above. In addition, the details of the edges of the back-up ring 122 may vary from those described above.
The back-up ring 122 may be formed of a material that is relatively more rigid than the seal 124, and that is less hard than a metal. In addition, the back-up ring 122 is formed of a material that is flexible, meaning that the material has some elasticity and is soft enough bend. For example, the back-up ring 122 may be formed of polytetrafluoroethylene (PTFE), and, more specifically, glass-filled PTFE. The back-up ring 122 formed of PTFE may comprise 20% to 30% glass fill, and, more specifically, 25% glass fill.
Referring to
The inner surface 158 and the upper surface 160 are generally planar and perpendicular to each other, and an edge 174 between the inner surface 158 and the upper surface 160 may be a rounded edge. The upper surface 160 and the outer surface 162 are generally planar and perpendicular to each other, and an edge 176 between the upper surface 160 and the outer surface 162 may be a rounded edge. The outer surface 162 and the lower surface 164 are generally planar and perpendicular to each other, and an edge 178 between the outer surface 162 and the lower surface 164 may be a square edge.
The lower surface 164 and the outer surface 166 are generally angled relative to each other, with the outer surface 166 being a curved surface, as shown in
In one embodiment, at least one stress concentrator 190 may be provided on the upper surface 160 and/or the lower surface 164 of the base 154 of the seal 124. The stress concentrator 190 improves contact pressure between the base 154 of the seal 124 and the clamp member 116 and/or the flange 100.
The seal 124 is flexible, in that it may be formed of any material having elasticity and being soft enough to adequately mate and comply to the sealing surfaces of the tube 102, the flange 100, and the clamp member 116, while bending and holding up to the fluid contained in the main fluid channel 112. For example, the seal 124 may be formed of rubber, such as ethylene propylene diene monomer (EPDM) rubber having a hardness value, as measured by the Shore hardness scale, of 75 duro. Alternatively, the seal 124 may be formed of hydrogenated nitrile butadiene rubber (HNBR), or a fluoroelastomer (FKM). The seal 124 may be relatively more flexible than the back-up ring 122.
The geometric relationships between the various surfaces of the seal 124 may vary from those described above. In addition, the details of the edges of the seal 124 may vary from those described above. Further, shapes of the surfaces (i.e., flat surfaces, curved surfaces) may vary from those described above and shown in the figures. In particular, the outer surface 166 of the leg 156 of the seal 124 may be a flat surface.
The sealed coupling 10 of the present disclosure may provide a fluid-tight seal between two members, e.g., the flange 100 and the tube 102, that are fixed together using the clamp assembly 104, while allowing for some movement of the tube 102 relative to the flange 100 and the clamp assembly, and accommodating misalignment between the tube 102 and one or both of the flange 100 and the clamp assembly 104. Further, the sealed coupling 10 forms a semi-enclosed static joint between the tube 102, the flange 100, and the clamp member 116 of the clamp assembly 104 when the clamp assembly 104 is secured to the flange 100. That is, the tube seal assembly 106 of the sealed coupling 10 provides a movable, floatable seal that accommodates compression when the clamp member 116 of the clamp assembly 104 is tightened and secured to the flange 100.
Referring to
When the tube 102 is inserted through the central openings of the cap 118, the lock ring 120, the clamp member 116, the back-up ring 122, and the seal 124, respectively, and into the tube opening 108 of the flange 100, an outer surface of the tube 102 contacts at least the seal 124 and the seal 124 changes from the unloaded state to the loaded state.
Referring to
A fit between the inner surface 130 of the back-up ring 122 and the tube 102 may be as close to a sliding line-to-line fit as possible. A fit between the outer surface 162 of the base 154 of the seal 124 and the clamp member 116 may be a tight clearance fit. Surfaces of the seal 124 that contact the flange 100, the clamp member 116, and the tube 102 may have a surface roughness Ra of 0.2 μm to 15 μm. In addition, edges of the seal 124 that contact the clamp member 116, the flange 100, and the tube 102 may be semi-smooth edges without burrs.
When the tube 102 is inserted into the flange 100, the clamp assembly 104, and the seal assembly 106, and these elements are secured using the plurality of bolts 114, the seal 124 may deform, as it changes from the unloaded state to the loaded state, to ensure a fluid tight seal between the tube 102, the flange 100, and the clamp assembly 104.
After the clamp assembly 104 is secured to the flange 100, with regard to the base 126 of the back-up ring 122, as shown in
In addition, when the clamp assembly 104 is secured to the flange 100, and the seal 124 is in the loaded state, the base 154 of the seal 124 expands, while the upper surface 160 of the base 154 may remain slightly spaced from the back-up ring 122, and the leg 156 of the seal 124 remains energized against the tube 102. That is, the seal 124 is compressed as a result of the clamp member 116 being secured to the flange 100, and, therefore, expands to at least partially fill the space between the base 154 of the seal 124 and the base 126 of the back-up ring 122. As shown in
A pressure of fluid that flows through the main fluid channel 112 of the flange 100 exerts a force on the surfaces of the seal 124 that sit in the main fluid channel 112, i.e., a portion of the lower surface 164 of the base 154, and the curved outer surface 166 and the lower surface 168 of the leg 156. As a result of the force from the pressure of the fluid, the seal 124 exerts a force on the tube 102. The force of the seal 124 on the tube 102 is, at least in part, a function of the pressure of the fluid in the main fluid channel 112, a function of a surface area of at least the outer surface 166 and the lower surface 168 of the leg 156 of the seal 124, and a function of the elasticity of the seal 124. As a result of the elasticity of the seal 124 and the force of the pressurized fluid on at least the outer surface 166 and the lower surface 168 of seal 124, the seal 124 forms an energized lip seal against the tube 102. The seal 124 thus forms a fluid-tight seal between the tube 102 and the flange 100 when in the loaded state.
In addition, the back-up ring 122 provides a gap into which the base 154 of the seal 124 can expand as it deforms or compresses when the clamp member 116 is secured to the flange 100. That is, with reference to
In addition, when the flange 100, the tube 102, the clamp assembly 104, and the tube seal assembly 106 are assembled and secured with the plurality of bolts 114, the tube seal assembly 106 allows for and complies with tilt and translation of the tube 102 within the flange 100, the clamp assembly 104, and the tube seal assembly 106, while maintaining the fluid tight seal with the tube 102. That is, even if the tube 102 is secured at a tilt or an angle, for example, up to 3°, and/or translates or shifts laterally, for example, up to 1.5 mm, with respect to the longitudinal axis A-A of the flange 100, the seal 124 remains energized against the tube 102 to maintain a fluid-tight seal.
With reference to
With reference to
In the embodiment shown in
By virtue of the tube seal assembly 106 of the present disclosure, a fluid-tight seal between at least the clamp member 116, the flange 100, and the tube 102 can be maintained once the clamp assembly 104 is secured to the flange 100, even if the tube 102 tilts and/or shifts with respect to the longitudinal axis A-A of the flange 100. In addition, the tube seal assembly 106 provides an energized lip seal as a fluid-tight seal between the flange 100, the tube 102, and the clamp assembly 104, both before and after the clamp assembly 104 is secured to the flange 100. The tube seal assembly 106 is thus suited for high pressure tube seal applications with high system misalignments in the form of translation and/or tilting of the tube 102 relative to the flange 100.
Further, the back-up ring 122 of the tube seal assembly 106 provides an L-shaped groove for the base 154 of the seal 124, which provides volume within which the seal 124 can expand during compression (i.e., during securing of the clamp assembly 104 to the flange 100), while helping to prevent over-compression, splitting, and/or extrusion of the seal 124. That is, the back-up ring 122 and the base 154 of the seal 124 form a semi-closed groove seal.
Still further, the tube seal assembly 106 provides a flexible joint that isolates vibration between the tube 102 and the flange 100. That is, by virtue of the seal 124 being formed of an elastic, soft material, and the back-up ring 122 being formed of a relatively more rigid material that is less hard than a metal, contact between the tube 102 and the flange 100 can be prevented. As a result, unlike conventional fittings, vibration in either one of the tube 102 and the flange 100 can be isolated, i.e., is not transmitted to the other one of the tube 102 and the flange 100, by the tube seal assembly 106.
The tube seal assembly 106 of the present disclosure has a two piece symmetrical design that provides for easy installation and assembly. That is, the cross-sectional L-shape of the back-up ring 122 is suited to fit over the inner surface 158 and the upper surface 160 of the base 154 of the seal 124, providing for easy assembly of the tube seal assembly 106.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the system will be apparent to those skilled in the art from consideration of the specification and practice of the lift capacity system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.