The present invention relates broadly to a gasket construction for providing a fluid seal intermediate a pair of opposed, mating parts or structures, and more specifically to such a construction which is particularly adapted for use in tube fitting connections commonly found in hygienic, i.e., sanitary, fluid systems.
Hygienic tube fitting connections or couplings are used in a variety of processes such as found in the food, beverage, diary, pharmaceutical, and biotech industries. Such connections are employed in the coupling of stainless steel or other tubing lines for fluids to another such line or to a fluid component such as a valve, regulator, or manifold. The connections are terms “hygienic” or “sanitary” as they are designed to be easily disassembled for cleaning and to minimize fluid entrapment which could cause contamination in the fluid line. The design of such connections is prescribed by various industry standards such as ASME BPE, 3-A, and ISO 2852.
In basic construction, the tubing connections of the type herein involved typically include a length of tubing having a butt end which terminates in a formed, machined, brazed, welded, or other flange. The face of the flange may itself be formed as having an annular groove into which a ring-shaped gasket may be seated.
Such gaskets, which conventionally are formed of a rubber, may be generally flat but as having an upstanding lobe or bead on each side thereof. With one of beads seated within the groove on the face of the flange, the bead on the other side of the gasket may be seated within a corresponding grooved formed on a mating flange which may be on another length of tubing or on a fluid component. The flanges as so mated are secured with the gasket interposed therebetween with a surrounding clamp. As the clamp is tightened, the gasket is compressed to provide the connection with a fluid-tight seal.
Hygienic tubing connections and gaskets therefor are further described in U.S. Pat. Nos. 5,971,399; 5,749,586; 6,318,576 and 6,857,638; and in U.S. Pat. Appln. Pub. Nos. US 2002/0074798; 2007/0045968 and 2008/00023960.
As to the gaskets themselves, such gaskets may be formed entirely of rubber or another elastomeric polymeric material, or as a composite of such material and another material such as a PTFE for increased chemical or extrusion resistance. Such other material may be provided in the form of a coating or as an upper and lower layer of the gasket including the beads, which layers may be laminated or otherwise bonded to an internal core of the rubber material. Such gaskets alternatively may be provided as an overmolding of rubber on a plastic or other retainer.
Hygienic gaskets also may be formed as having a lip surrounding the outer diameter thereof. Such lip may be fitted over the outer diameter of one of the flanges to aid in the alignment of the gasket in the connection and/or to better secure the gasket to the flange to facilitate assemble or disassembly of the connection.
Ideally, hygienic tube fitting gaskets of the type herein involved should provide effective sealing under a variety of conditions, at both low and high pressures, and with a minimum of interference with the fluid flow. Also desired would be a gasket which controls the degree of compression of the elastomer to avoid over-compression and thereby ensure more reliable fluid-tight seal and longer service life. It is believed that a hygienic gasket offering such advantages would be well-received by the process industries.
The present invention is directed to a gasket construction particularly adapted for hygienic tube fittings such as including a tube having an open surrounded by a flange with a circumferential receiving groove. The generally-annular gasket includes a plastic or otherwise generally-rigid retainer and an elastomeric seal element which is overmolded or otherwise supported on the retainer. The retainer has an inner perimeter and an outer perimeter and opposing first and second sides. The first and second sides each extends in a radial direction intermediate the inner and outer perimeter and each has a circumferential recess extending from the inner perimeter to an axial end wall adjacent the outer perimeter and an upstanding shoulder surrounding the recess.
The seal element is supported on the retainer in the recesses on each of the sides. The seal element has a first radial face on the first side of the retainer and a second radial face on the second side of the retainer. Each of the radial faces has a circumferential inner diameter bead and a circumferential outer diameter bead extending axially beyond the inner diameter bead. The outer diameter bead on the first radial face of the seal element is configured to be seatable within a groove of the flange of the tubing end with the inner diameter bead being supported on the face of the flange.
The present invention, accordingly, comprises the construction, combination of elements, and/or arrangement of parts and steps which are exemplified in the detailed disclosure to follow. Advantages of the present invention include a gasket for use between a pair of mating flanges wherein the gasket has generally-rigid retainer and an elastomeric seal element. As configured with an upstanding shoulder and/or with additional raised features, such retainer may be used to provide a positive stop ensuring a controlled compression of the seal element.
Additional advantages include such a gasket having the inner diameter beads which provide localized high sealing points on each face of the gasket such that the parallelism of the mating flanges is less critical. Moreover, with the inner perimeter of the retainer being provided to extend radially beyond each of the inner diameter beads, it may be better ensured that the compression of the seal element does not cause the elastomeric material of the seal element to be extruded into the fluid flow path through the fitting. These and other advantages will be readily apparent to those skilled in the art based upon the disclosure contained herein.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:
The drawings will be described further in connection with the following Detailed Description of the Invention.
Certain terminology may be employed in the following description for convenience rather than for any limiting purpose. For example, the terms “forward” and “rearward,” “front” and “rear,” “right” and “left,” “upper” and “lower,” and “top” and “bottom” designate directions in the drawings to which reference is made, with the terms “inward,” “inner,” “interior,” or “inboard” and “outward,” “outer,” “exterior,” or “outboard” referring, respectively, to directions toward and away from the center of the referenced element, the terms “radial” or “horizontal” and “axial” or “vertical” referring, respectively, to directions or planes which are perpendicular, in the case of radial or horizontal, or parallel, in the case of axial or vertical, to the longitudinal central axis of the referenced element, and the terms “downstream” and “upstream” referring, respectively, to directions in and opposite that of fluid flow. Terminology of similar import other than the words specifically mentioned above likewise is to be considered as being used for purposes of convenience rather than in any limiting sense.
In the figures, elements having an alphanumeric designation may be referenced herein collectively or in the alternative, as will be apparent from context, by the numeric portion of the designation only. Further, the constituent parts of various elements in the figures may be designated with separate reference numerals which shall be understood to refer to that constituent part of the element and not the element as a whole. General references, along with references to spaces, surfaces, dimensions, and extents, may be designated with arrows. Angles may be designated as “included” as measured relative to surfaces or axes of an element and as defining a space bounded internally within such element therebetween, or otherwise without such designation as being measured relative to surfaces or axes of an element and as defining a space bounded externally by or outside of such element therebetween. Generally, the measures of the angles stated are as determined relative to a common axis, which axis may be transposed in the figures for purposes of convenience in projecting the vertex of an angle defined between the axis and a surface which otherwise does not extend to the axis. The term “axis” may refer to a line or to a transverse plane through such line as will be apparent from context.
For purposes of illustration, the precepts of the hygienic gasket construction are described principally in connection with its configuration for use as a seal between the mating flanges of a pair of tubing ends or other such pairs of fluid components, such as a tubing end and a valve, regulator or manifold, in a hygienic fluid system. In view of the discourse to follow, however, it will be appreciated that aspects of the present invention may find utility in other fluid sealing applications, such as for liquid, gas, particulate solids, and/or plasmas, requiring a gasket of the type herein involved. Use within those such other applications therefore should be considered to be expressly within the scope of the present invention.
Referring then to the figures wherein corresponding reference characters are used to designate corresponding elements throughout the several views with equivalent elements being referenced with prime or sequential alphanumeric designations, shown generally at 10 in the respective topside and underside perspective views of
Retainer 12 may be configured and sized as shown for interposition between the mating flange surfaces. In this regard, retainer 12 may extend about the diameter or other radial dimensions defined by the orthogonal horizontal or radial axes referenced at 20a-b in
With additional and, for the moment, particular reference to the cross-sectional view of gasket 10 shown in
Each of the recesses 36 may be generally planar relative to the axes 20 (
With continuing reference to
Retainer 12 may be cast, machined, molded, stamped, or otherwise fabricated from, as compared to the seal element 14, a more rigid material such as a metal or ceramic. For hygienic fluid systems applications, however, retainer 12 preferably may be molded of a plastic which may be reinforced or otherwise filled, i.e., a composite, or unfilled. Suitable plastic materials for the construction of retainer 12 include generally resilient materials such as a poly(ether ether ketone), polyimide, polyamide, polyolefin, polyetherimide, polybutylene terephthalate, fluoropolymer, polyvinyl chloride, polysulfone, polyester, acetal homo or copolymer, a TPEs such as a thermoplastic polyurethane (TPU), thermoplastic olefin (TPO), thermoplastic vulcanizate (TPV), or copolyester thermoplastic elastomer (COPE) or polyamide TPE, or a copolymer, blend, mixture, laminate, composite, or other combination of one or more of the foregoing materials. Typically, the plastic material of construction for the molding or other forming of the retainer 12 may have a hardness of between about 85 Shore A and about 65 Shore D.
Returning again to the perspectives views of
(
Each of the seal radial faces 60a-b has a respective circumferential inner diameter bead, 62a (
Although each of the beads 62a-b and 64a-b are shown to be continuous, each independently may be provided alternatively as discontinuous, i.e., segmented or otherwise interrupted, and as single, double, or multiple beads, lobes, or other rings. Each of the beads 62 and 64, moreover, may be shaped as is shown to have a generally circular or elliptical cross-sectional geometry, but alternatively may be configured as being lobe or otherwise arcuately-shaped.
In the manufacture of gasket 10, with the retainer 12 being formed, for example, as a plastic molding, seal element 14 may be overmolded onto the retainer such as by injection, compression, transfer, or other molding. Seal element 14 may be formed of a rubber or other elastomeric material which may be selected specifically for high or low temperature performance, flexibility, and otherwise for compatibility with the fluid being handled. Suitable materials, which may be filled, for example, with glass or carbon black, or which may be unfilled, include natural rubbers such as Hevea and thermoplastic, i.e., melt-processible, or thermosetting, i.e., vulcanizable, synthetic rubbers such as: fluoro- or perfluoroelastomers, chlorosulfonate, polybutadiene, butyl, neoprene, nitrile, polyisoprene, buna-N, copolymer rubbers such as ethylene-propylene (EPR), ethylene-propylene-diene monomer (EPDM), acrylonitrile-butadiene (NBR or HNBR) and styrene-butadiene (SBR), and blends such as ethylene or propylene-EPDM, EPR, or NBR. The term “synthetic rubbers” also should be understood to encompass materials which alternatively may be classified broadly as thermoplastic or thermosetting elastomers such as polyurethanes, silicones, fluorosilicones, styrene-isoprene-styrene (SIS), and styrene-butadiene-styrene (SBS), as well as other polymers which exhibit rubber-like properties such as plasticized nylons, polyolefins, polyesters, ethylene vinyl acetates, fluoropolymers, and polyvinyl chloride. As used herein, the term “elastomeric” is ascribed its conventional meaning of exhibiting rubber-like properties of compliancy, resiliency or compression deflection, low compression set, flexibility, and an ability to recover after deformation, i.e., stress relaxation.
Seal elements 14 exhibits a reduced yield stress as compared to retainer 12 and, accordingly, the inner diameter beads 62 thereof are deformable for conforming to irregularities existing between the interfacing surfaces. As will be more fully appreciated hereinafter, as a given compressive load is applied to the beads 62a-b of the seal element 14, an increased bearing stress is provided thereon by virtue of the reduced surface area contact of the beads 62. This increased stress is sufficient to exceed the reduced yield stress of the seal element 16 for the deformation thereof effecting the fluid-tight or other sealing of the interfacing surfaces.
In service, it has been observed that the provision of the inner diameter beads 62 on the seal element 14 advantageously facilitates the installation and replacement of gasket 10 in accommodating for tolerances or other minor differences in the torque load of the clamps, bolts or other fastening members conventionally employed to join the interfacing surfaces. That is, by virtue of the resiliency of the beads 62, the fluid integrity and other sealing of the gasket 10 may be maintained to some degree even if the joint spacing between the interfacing surface is less than exactly uniform. Moreover, the combination of a relatively incompressible retainer 12 and relatively compressible seal element 14 further provides a gasket construction which minimizes torque loss and thereby obviates much of the need for the periodic re-torquing of the fastening members used to secure the interfacing surfaces. That is, it is well-known that gaskets of the type herein involved may develop a compression set which is manifested by fluid leaks as the tension in the clamp or bolts is relaxed and the fluid-tight sealing of the interfacing surfaces is compromised. In this regard, the provision of the beads 62 on the seal elements 14, and the relatively high seal which may be developed thereby, helps to better ensure positive sealing, with retainer 12, in turn, synergistically providing generally non-yielding contact in establishing an alternative load torque path minimizing the compression set and leak potential of the gasket 10. Thus, the use of a retainer allows the mating parts to bear stress loads which otherwise would cause the deformation or extrusion of a gasket which lacked a retainer. In the case of a metal retainer 12 or one which is filled with a metal, ceramic, or other thermally-conductive fillers, such contact additionally affords improved heat transfer between the interface surfaces.
Referring now to the assembly view of
As interposed between the mating faces 108a-b, the opening 26 of the gasket 10 may be aligned in registration with the tube open ends 104a-b with the outer diameter beads 64a-b of the gasket each being seated within a corresponding groove 112a-b of one of the faces 108. Each beads 64 may be sized to fill not more than 100% of the total volume of the corresponding groove 112 so as not to create an undue overfill which could cause extrusion of the material of the seal element 14 into the fluid flow path, represented by the arrow 120, such as could be caused by thermal expansion. As shown, gasket 10 itself may be retained on one of the flanges 106 by means of the interfering engagement of the skirt 50 and tooth 54 thereof about the periphery 110a of flange 106a.
Looking now lastly to
Advantageously, over-compression of the seal element 14 and its extrusion into the fluid flow path 120 and/or a compromise of the integrity of the fluid seal may be controlled by the abutting engagement of the raised areas 40a-b and/or the shoulders 39a-b against a confronting one of the faces 108a-b. Moreover, with the inner perimeter 24 of the retainer 14 extruding radially beyond the inner diameter beads 62, the potential for extrusion of the seal element 14 into the fluid flow path element 120 may be further controlled.
Thus, a unique gasket construction for hygienic fluid systems or other applications is described which exhibits reliable sealing properties while providing for the exclusion of fluid accumulation between the interfacing surfaces.
As it is anticipated that certain changes may be made in the present invention without departing from the precepts herein involved, it is intended that all matter contained in the foregoing description shall be interpreted in as illustrative rather than in a limiting sense. All references including any priority documents cited herein are expressly incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US09/36782 | 3/11/2009 | WO | 00 | 2/16/2011 |
Number | Date | Country | |
---|---|---|---|
61100817 | Sep 2008 | US |