HK1228985B - Ultra-seal gasket for joining high purity fluid pathways - Google Patents

Description

Ultra-sealing gaskets for joining high-purity fluid pathways

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Serial No. 61/980,823, filed April 17, 2014, entitled “ULTRA-SEAL GASKET FOR JOINING HIGH PURITY FLUID PATHWAYS,” which is incorporated herein by reference in its entirety.

Technical Field

Background Art

Embodiments of the present invention relate to a gasket (gasket) that is forged, mainly metal, for the joint (joint) between the various parts of sealing fluid path. Many combinations of interface (interface) structure and related gasket are well-known in the design of fluid conveying equipment. These structures include flange (flange), gland (gland), assembly connection and other functional parts, which enable various equipment components to be mechanically assembled to form various interconnected fluid paths. Representative fluid conveying equipment is found in the industrial equipment for producing fine chemicals, petroleum products, flat panel electronic displays or semiconductors, and may be subject to vacuum or pressure or purity requirements and their combination. The fluid path between the elements intended for manipulating process materials in semiconductor manufacturing equipment usually needs to pay attention to the high purity of the reactant being conveyed, and usually also has a much smaller cross-section than the fluid path used in, for example, petrochemical plants. In many cases, practitioners have found that metal gaskets provide excellent performance that is superior to polymer materials, especially about the diffusion of process fluids or pollutants by gaskets and the resistance to undesirable leakage that follows.

One known type of fluid passage joint utilizes an annular gasket, initially flat in the radial direction, which is squeezed axially between nominally similarly shaped annular projections that surround the circular conduit opening of the opposing equipment component. The annular projections are pressed axially toward each other, causing permanent plastic deformation of the ductile metal gasket, creating a seal that will resist even difficult leaks to contain fluids such as helium. Representative examples of such joints can be found in U.S. Patent No. 3,208,758 issued to Carlson and Wheeler (known as a flange), U.S. Patent No. 3,521,910 issued to Callahan and Wennerstrom (known as a joint), and U.S. Patent No. 4,303,251 issued to Harra and Nystrom.

Another known type of fluid passageway fitting utilizes an annular gasket of a predetermined cross-sectional profile that is squeezed between annular protrusions of nominally the same shape that surround the circular conduit openings of opposing equipment components. Representative examples of such fittings can be found in the following patents: U.S. Patent No. 4,854,597 issued to Leigh, U.S. Patent No. 5,505,464 issued to McGarvey, and U.S. Patent No. 6,135,155 issued to Ohmi et al. (an early version of the W-Seal fitting type). The Ohmi et al. patent additionally provides a separate retainer component for holding and centering the gasket during fitting assembly. Other separate retaining structures can also be found in the following patents: U.S. Patent Nos. 5,673,946 and 5,758,910 issued to Barber and Aldridge, and U.S. Patent No. 7,140,647 issued to Ohmi et al.

Yet another known type of fluid pathway fitting, known as a C-Seal fitting, utilizes a complex-shaped annular metal gasket that is squeezed between opposing equipment components having simple, flat surfaces that contact the gasket. Most commonly, a face of at least one of the equipment components has a circular counterbore depression to accommodate the gasket. Representative examples of such fittings can be found in U.S. Patent Nos. 5,797,604 to Inagaki et al., 6,357,760 and 6,688,608 to Doyle, and 6,409,180 to Spence and Felber. The '180 patent issued to Spence and Felber additionally provides a separate retaining member for holding and centering the gasket during fitting assembly. Other separate retaining structures can also be found in the following patents: U.S. Patent No. 5,984,318 issued to Kojima and Aoyama, U.S. Patent No. 6,845,984 issued to Doyle, and U.S. Patent No. 6,945,539 issued to Whitlow et al. In addition, U.S. Patent No. 5,992,463 issued to the inventor Kim Ngoc Vu et al. and U.S. Patent No. 5,730,448 issued to Swensen et al. show that a retainer of appropriate thickness can alternatively provide the extrusion limiting function of the counterbore sidewall and allow the use of a gasket between simple flat opposing surfaces.

High purity fluid delivery components and fluid path elements are typically made of vacuum refined variants of 316L stainless steel or nickel alloys such as . Both of these metal materials can only be hardened by mechanical work and cannot be hardened by heat treatment, so there is a risk of damage by local forces associated with metal gaskets. High purity fluid delivery components made of polymeric materials are also well known and are often used when controlling the flow of certain liquid fluids in situations where potential contamination with metal ions is a concern. In many polymeric device designs, fluid path joints also use opposing flat surfaces (with or without countersunk holes) with intermediate gaskets. Gaskets made of polymeric materials for such joints can also benefit from the inventive designs described in this disclosure.

Summary of the Invention

Embodiments of the present invention relate to annular gaskets for sealingly engaging opposing fluid conduit ports. The fluid conduit ports may correspond to adjacent fluid conduit ports of a fluid delivery system, such as a semiconductor gas panel, a petrochemical production or distribution system, or the like. The gasket has a body traversed by a hole that creates a fluid passage and defines a radially inner surface, the body also having a radially outer surface, a first axial end surface, and a second axial end surface. At least one of the first axial end surface and the second axial end surface has a stress concentration feature radially adjacent to a gasket sealing area, the gasket sealing area being constructed and arranged to contact a face surface of the corresponding fluid conduit port. In one embodiment, the stress concentration feature defines a lip in the gasket sealing area that includes a protective ridge and a sealing surface. Prior to assembly of the joint, the sealing area lip desirably protrudes axially outward beyond the corresponding axial end surface.

In one embodiment, the stress concentrating feature comprises a groove in one or both of the axial end surfaces and adjacent to one or both corresponding gasket sealing areas. In another embodiment, the stress concentrating groove undercuts one or both sealing areas. In some embodiments, the stress concentrating groove has a V-shape that undercuts one or both sealing areas, and in other embodiments, the stress concentrating groove has a U-shape with substantially parallel sides that undercuts one or both sealing areas.

In yet another embodiment, the stress concentrating features include regularly spaced blind cavities extending into either or both of the axial end surfaces. In another embodiment, the regularly spaced stress concentrating blind cavities undercut one or both sealing area lips. In another embodiment, the circumferential phase relationship of the blind cavities can be aligned or interspersed in anti-phase.

In yet another embodiment, the first axial end surface has stress-concentrating features comprising regularly arranged blind cavities that undercut the first sealing area, and the second axial end surface has a second sealing area that is initially flat in the radial direction. In another embodiment, the first axial end surface has stress-concentrating features comprising grooves that undercut the first sealing area, and the second axial end surface has a second sealing area that is initially flat in the radial direction. The grooves may have a V-shape or a U-shape with substantially parallel sides. In either embodiment, one or both of the axial end surfaces may have a circumferential region adjacent to the radially outer surface of the gasket, which serves as a stopper to limit compression of the deformable sealing area.

The annular gaskets of various embodiments described herein may be formed from a wrought material. The wrought material may include: a single metallic material selected from the group consisting of stainless steel alloys, chromium alloys, nickel alloys, commercially pure nickel, copper alloys, and commercially pure copper; a single metallic material substantially identical to a 316 series stainless steel alloy; a single polymeric material selected from the group consisting of polypropylene (PP), polyvinylidene fluoride (PVDF), perfluoroalkoxy polymer (PFA), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), and polyimide; or a single polymeric material substantially identical to polyimide.

According to aspects described herein, a method of forming a high-purity fluid fitting is provided wherein a gasket is initially formed as a closed ring of malleable material having an undeformed gasket sealing surface angled relative to a proximal interior axis of the gasket ring shape, and the gasket is then compressed between opposing fluid handling equipment components until a portion of the gasket sealing surface bends substantially perpendicular to the proximal interior axis of the gasket ring shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. For clarity, not every component may be labeled in every figure. In the accompanying drawings:

FIG1A is a first representative washer taken diametrically;

FIG1B is an enlarged cross-section of the first representative gasket shown in FIG1A;

FIG2A is a second representative washer taken diametrically;

FIG2B is an enlarged cross-section of the second representative gasket shown in FIG2A ;

FIG3A is a third representative washer taken diametrically;

FIG3B is an enlarged cross-section of the third representative gasket shown in FIG3A ;

FIG3C is a third representative gasket of FIG3A shown in perspective;

FIG4A is a fourth representative washer taken diametrically;

FIG4B is an enlarged cross-section of a fourth representative gasket;

FIG5A is a fifth representative gasket taken at two locations;

FIG5B is a plan view of a fifth representative gasket showing a non-diametric (inverse phase) relationship of two interception locations;

FIG6A illustrates a fourth representative gasket positioned by a keeper and within a fluid conduit port counterbore prior to application of an axial sealing force to form a joint;

FIG6B illustrates a fourth representative gasket in a fluid conduit port counterbore after a joint has been formed;

FIG7A is a sixth representative washer taken diametrically;

FIG7B is an enlarged cross-section of the sixth representative gasket shown in FIG7A ;

7C is an enlarged cross-section of an alternative example of a sixth representative washer in which the stress concentrating feature on the first axial end surface of the washer comprises a stress concentrating groove;

FIG8A illustrates a sixth representative gasket positioned by a retainer and located between a fluid conduit port counterbore having a flat bottom and a fluid conduit port counterbore having a formed annular protrusion prior to application of an axial sealing force to form a joint;

FIG8B illustrates a sixth representative gasket between corresponding fluid conduit port counterbores after a joint has been formed;

FIG9A is a seventh representative washer taken diametrically;

FIG9B is an enlarged cross-section of the seventh representative gasket shown in FIG9A ;

FIG. 10A illustrates a seventh representative gasket positioned by a retainer and within a fluid conduit port counterbore prior to application of an axial sealing force to form a joint; and

10B illustrates the seventh representative gasket in the fluid conduit port counterbore after the joint has been formed.

DETAILED DESCRIPTION

The examples of the apparatus and methods discussed herein are not limited in application to the details of construction and arrangement of components set forth in the following description or illustrated in the accompanying drawings. These apparatus and methods are capable of other embodiments and can be implemented or realized in various ways. Furthermore, the words and terms used herein are for descriptive purposes and should not be construed as limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein is intended to encompass the terms listed thereafter and their equivalents and additional terms.

Forming a fluid pathway joint having a sealing integrity sufficient to minimize leakage at the molecular level (e.g., a helium leak rate of less than 1× ^10-9 std.cc/sec) involves special design considerations. It is known to skilled designers that the use of metal gaskets to form joints that successfully mate with metal fluid conveying equipment components is largely due to plastic deformation of the gasket sealing area that contacts the equipment element. When changing from a gasket material with a relatively large Poisson's ratio and a lower yield strength, such as copper, to a gasket material with a smaller Poisson's ratio and a higher yield strength, such as stainless steel, it becomes more difficult to obtain the appropriate deformation. In addition, very large axial forces may be necessary to achieve any axial strain in the metal gasket. One design approach involves manufacturing gaskets with axially oriented sealing areas that have a significantly reduced contact area to promote plastic deformation of the gasket's sealing area without a problematic increase in the required axial engagement force.

A related and commonly used concurrent technique for more easily achieving plastic deformation of gaskets is to anneal the gasket material to a maximally soft condition. Another known design challenge is the relatively high Young's modulus (elastic modulus) of metals, which results in less reversible metal gasket rebound after elastic deformation and also limits the amount of strain that can be imparted to the metal gasket before plastic deformation occurs. As is known from material mechanics research, annealing does not significantly affect the stiffness (elastic modulus) of the gasket, but will significantly reduce its yield strength. The strain hardening that occurs after the initial yield of many gasket materials can be an important contributor to the final rebound properties of the gasket. Another design challenge is that a gasket lacking sufficient bulk hardness may exhibit cold flow relaxation over time, and thus develop leaks, despite being initially reasonably tight.

The aforementioned problematic deformation characteristics may make the axial dimensional tolerances of the joint more critical than is desirable in mass production and also present a problem that can be described as insufficient residual expansion forces within the gasket to ensure seal integrity. To these challenges, one design solution selectively removes material from the block of the annular component to produce a gasket cross-sectional profile that induces an intentional effective stress concentration. This stress concentration results in a smaller axial force being required when a net elastic axial strain is produced and may produce strain hardening in certain interior areas of the gasket block. The resulting reversible elastic axial displacement versus axial force relationship provides a gasket that exhibits greater resilience than would otherwise be achieved, thereby forming a more reliable joint with a smaller total required equipment component mating force. The material removal can be achieved, for example, by machining away portions as in the previously cited Doyle patent and the Spence and Felber patent, or by forming the sheet stock into a torus with a "C" shaped cross section as shown in U.S. Patent Nos. 5,730,448 and 5,713,582 issued to Swensen et al., or by actually incorporating a toroidal spring as in the Inagaki patent or by other manufacturing techniques to achieve the desired spring-like behavior. The Doyle and Spence and Felber designs remove material in the radial direction and are therefore limited by the requirement to maintain a minimum wall thickness between the internal fluid passage of the gasket and the external environment. In this regard, manufacturing tolerances can also have negative consequences.

In many of the previously cited U.S. patent examples, there is a considerable risk of adversely scratching the axially oriented sealing area of the gasket prior to fitting assembly, such damage rendering a leak-free fitting impossible. Centering the gasket by a separate retainer provides the desired alignment consistency between the fluid path conduit port and the central passage through the gasket. In some fluid delivery devices or apparatus used in semiconductor manufacturing processes, multiple types of fluid path fittings are used simultaneously, and therefore, a gasket configuration that allows for independent customization of the physical shape of the gasket sealing surfaces on the opposing gasket sealing areas and/or the mechanical behavior of the opposing gasket sealing areas is desirable.

A first representative example 100 of the applicant's annular gasket is illustrated in Figures 1A and 1B. A gasket body 150 is penetrated by a hole 151 that defines a fluid passage bore 155 and includes a radially inner surface 156 that can be substantially straight to reduce fluid turbulence in a fluid delivery device coupling. The radially outer extent of the gasket body is defined by a radially outer surface 190 that can have a circumferential groove 192 for accommodating a keeper (not shown in Figure 1A) that is used to position the gasket 100 in an assembly of a fluid delivery assembly (also not shown in Figure 1A).

A first representative gasket example may have a first axial end surface 110 including a stress concentrating feature 120, which is present as a groove in the first axial end surface 110. The stress concentrating groove 120 removes gasket body material from the area immediately adjacent to the intended gasket sealing area, thereby forming a lip 130 that preferably protrudes axially outward beyond the first axial end surface before forming the joint. The lip 130 includes an axially raised protective ridge 132 and an immediately adjacent sealing surface 134. During normal factory operation, when the gasket slides over rough surfaces, the protective ridge 132 may be damaged, but the sealing surface 134 will remain intact. The sealing surface 134 is a circumferential sector that exhibits a substantially constant angle relative to the axis of the gasket bore 155 and the plane of the first axial end surface 110, but a slightly convex shape may be advantageous for some gasket materials. The gasket sealing area lip 130 can be understood as a frustoconical shell flaring outward from the gasket bore 155 toward the radially outer surface 190. The radial extent of the sealing surface 134 is advantageously greater than the reduced contact area of existing designs to create a much longer radially leak-proof contact between the gasket and the fluid conduit port face. When the gasket 100 is fabricated into a leak-proof fluid passage joint by axial compression between opposing flat equipment faces, the protective ridge 132 plastically deforms by virtue of the groove 120 that allows the lip 130 to flex, and the sealing surface 134 deflects slightly radially outward with further axial compression, contacting the flat equipment face.

A first representative gasket example may have a second axial end surface 160 including a stress concentrating feature 170, which is present as a groove in the second axial end surface 160. The stress concentrating groove 170 removes gasket body material from the area immediately adjacent to the intended gasket sealing area, thereby forming a lip 180 that desirably protrudes axially outward beyond the second axial end surface before forming the joint. The lip 180 includes an axially raised protective ridge 182 and an immediately adjacent sealing surface 184. During normal factory operation, when the gasket slides over rough surfaces, the protective ridge 182 may be damaged, but the sealing surface 184 will remain intact. The sealing surface 184 is a circumferential sector that exhibits a substantially constant angle relative to the axis of the gasket bore 155 and the plane of the second axial end surface 160, but a slightly convex shape may be advantageous for some gasket materials. The radial extent of the sealing surface 184 is advantageously greater than the reduced contact area of existing designs to create a much longer radially leak-proof contact between the gasket and the fluid conduit port face. When the gasket 100 is fabricated into a leak-proof fluid passage joint by axial compression between opposing planar equipment faces, the protective ridge 182 will plastically deform by virtue of the groove 170 that allows the lip 180 to flex, and the sealing surface 184 will deflect slightly radially outward with further axial compression, contacting the planar equipment face.

Gasket designers will appreciate how the axial end surfaces 110, 160 can act as relatively hard stops that prevent the gasket lips 130, 180 from being over-extruded by contacting the facing surfaces of the corresponding fluid conduit ports. Slight compositional variations and manufacturing tolerances within the gasket 100 can cause one of the axial end surfaces 110, 160 to contact the corresponding fluid conduit port face before the other axial end surface 160, 110 during the gasket extrusion process when forming the joint. The described hard stop function ensures that the two opposing gasket lips 130, 180 are ultimately equally and fully extruded. It will also be appreciated that the end regions 157, 158 of the fluid passageway aperture 155 preferably have a smaller axial extent than the axial end surfaces 110, 160 to prevent the formation of a virtual leak cavity within the fluid passageway when the joint is fully mated. Designers will also appreciate that the presence of an unchanging central material within the washer body 150 allows the deformation behavior of the first axial end surface lip 130 to be substantially independent of the deformation behavior of the second axial end surface lip 180 .

A second representative example 200 of the applicant's annular gasket is illustrated in Figures 2A and 2B and is similar to the first example. A gasket body 250 is penetrated by a hole 251 that defines a fluid passageway aperture 255 and includes a radially inner surface 256 that can be substantially straight to reduce fluid turbulence in a fluid handling device coupling. The radially outer extent of the gasket body is defined by a radially outer surface 290 that can have a circumferential groove 292 to accommodate a retainer (not shown in Figures 2A and 2B) that is used to position the gasket 200 in an assembly (also not shown) of a fluid handling component.

A second representative gasket example can have a first axial end surface 210 and a second axial end surface 260 including stress concentrating features 220, 270 that appear as grooves in the axial end surfaces 210, 260. The stress concentrating grooves 220, 270 remove gasket body material from areas immediately adjacent to the two intended gasket sealing areas, thereby forming lips 230, 280 on the axial end surfaces 210, 260 that desirably project axially outward beyond the corresponding axial end surfaces 210, 260 prior to forming the joint. The stress concentrating grooves 220, 270 have inner walls 221, 271 closest to the gasket radial inner surface 256 that form an acute angle with the plane of each associated gasket axial end surface 210, 260, thereby forming an undercut of each gasket sealing area. Each lip 230, 280 includes an axially raised protective ridge 232, 282 and an immediately adjacent sealing surface 234, 284. During normal factory operation, when the gasket slides over rough surfaces, the protective ridge 232, 282 may be damaged, but the sealing surfaces 234, 284 will remain intact. The sealing surfaces 234, 284 are circumferential sectors that exhibit a substantially constant angle relative to the axis of the gasket bore 255 and the plane of each associated axial end surface 210, 260, but may advantageously have a slightly convex shape for some gasket materials. The gasket sealing area lips 230, 280 can be understood as being like oppositely oriented frustoconical shells that flare outward from the gasket bore 255 toward the radially outer surface 290. The radial extent of the sealing surfaces 234, 284 is advantageously greater than the reduced contact area of existing designs, creating a much longer radially leak-proof contact between the gasket and the fluid conduit port face. When the gasket 200 is fabricated into a leak-proof fluid pathway joint by axial extrusion between opposing planar equipment faces, the protective ridges 232, 282 will plastically deform as the undercut grooves 220, 270 allow the gasket lips 230, 280 to controllably flex, and the sealing surfaces 234, 284 will deflect slightly radially outward with further axial extrusion into contact with the planar equipment faces.

Similarly, considering the second representative gasket example, designers can appreciate how the axial end surfaces 210, 260 can act as relatively hard stoppers that prevent the gasket lips 230, 280 from being over-extruded by contacting the corresponding fluid conduit port faces. Slight compositional variations and manufacturing tolerances within gasket 200 can cause one of the axial end surfaces 210, 260 to contact the corresponding fluid conduit port face before the other axial end surface 260, 210 during the gasket extrusion process when forming the joint. The illustrated hard stop function ensures that the two opposing gasket lips 230, 280 are ultimately equally and fully extruded. It should also be appreciated that the end regions 257, 258 of the fluid passageway aperture 255 preferably have a smaller axial extent than the axial end surfaces 210, 260 to prevent the formation of a virtual leak cavity within the fluid passageway when the joint is fully mated. Designers will also appreciate that the presence of a constant central material within the gasket body 250 renders the deformation behavior of the first axial end surface lip 230 substantially independent of the deformation behavior of the second axial end surface lip 280. This independence in the deformation behavior between the opposing axial end surface lips 230, 280 can, at the designer's option, allow for the manufacture of gaskets having intentionally different properties on opposing sides. Skilled designers will recognize that the lip bending characteristics can be adjusted by selecting the undercut angle and the groove depth and width. Thus, for example, one or more of the undercut angle, groove depth, and groove width can be different on one side of the gasket relative to the undercut angle, groove depth, or groove width on the opposite side of the gasket. Furthermore, the annular gasket may have a stress concentrating groove similar to the stress concentrating groove 120 shown in Figures 1A-1B on one axial end surface, and a stress concentrating groove similar to the stress concentrating groove 220 shown in Figures 2A-2B on the opposite axial end surface, wherein the inner wall 271 of the stress concentrating groove 220 closest to the gasket radial inner surface is formed to form an acute angle with the plane of the gasket axial end surface 260. Thus, as further described below, the use of first and second axial end surface designs that are completely different from each other in physical structure and/or deformation behavior is also contemplated.

Designers experienced in high-purity applications will recognize that it is desirable to place the stress concentrating features 220, 270 outside the "wetted" fluid passage to minimize passage pockets that could trap contaminants, resulting in a design having gasket sealing area lips 230, 280 that flare outward from the gasket hole 255. Applications more concerned with sealing relatively high passage internal pressures will likely benefit from the fluid-energized sealing effect achieved by having gasket sealing area lips that flare inward toward the gasket hole. In this alternative design, internal fluid pressure will push against the inwardly flaring gasket sealing lips and force them against their corresponding equipment components, achieving a tighter seal along the radial contact area. This alternative gasket embodiment will require placing one or more stress concentrating features closest to the gasket hole and the adjacent sealing area lips radially farther from the gasket hole.

A third representative example 300 of the applicant's annular gasket is illustrated in Figures 3A, 3B, and 3C. A gasket body 350 is penetrated by a hole 351 that defines a fluid passageway aperture 355 and includes a radially inner surface 356 that can be substantially straight to reduce fluid turbulence in a fluid handling device coupling. The radially outer extent of the gasket body is defined by a radially outer surface 390 that can have a circumferential groove 392 for accommodating a retainer (not shown in Figures 3A, 3B, and 3C) for positioning the gasket 300 in an assembly of a fluid handling assembly (also not shown in these figures).

A third representative gasket example may have a first axial end surface 310 including stress concentrating features 320, which consist of regularly arranged blind cavities extending into the first axial end surface 310. Stress concentrating cavities 325, 326, 327, etc., remove gasket body material from the area immediately adjacent to the intended gasket sealing area, thereby forming a lip 330 on the first axial end surface 310. The lip 330 preferably protrudes axially outward beyond the first axial end surface before forming the joint. The lip 330 includes an axially raised protective ridge 332 and an immediately adjacent sealing surface 334. The sealing surface 334 is a circumferential sector that exhibits a substantially constant angle relative to the axis of the gasket bore 355 and the plane of the first axial end surface 310, but may advantageously have a slightly convex shape for some gasket materials. The gasket sealing area lip 330 can be understood as resembling a frustoconical shell flaring outward from the gasket bore 355 toward the radially outer surface 390. The radial extent of the sealing surface 334 is advantageously greater than the reduced contact area of existing designs to create a much longer radially leak-proof contact between the gasket and the fluid conduit port face. During normal plant operation, when the gasket slides over rough surfaces, the protective ridge 332 may be damaged, but the sealing surface 334 will remain intact. When the gasket 300 is fabricated into a leak-proof fluid passage joint by axial compression between opposing flat equipment faces, the protective ridge 332 will plastically deform due to the cavities 325, 326, 327, etc. that allow the lip 330 to flex, and the sealing surface 334 will deflect slightly radially outward with further axial compression.

A third representative gasket example may have a second axial end surface 360 including stress concentrating features 370 comprising regularly arranged blind cavities extending into the second axial end surface 360. Stress concentrating cavities 375, 376, 377, etc., remove gasket body material from areas immediately adjacent to the intended gasket sealing area, thereby forming a lip 380 on the second axial end surface 360. The lip 380 preferably protrudes axially outward beyond the corresponding axial end surface prior to forming the joint. The lip 380 includes an axially raised protective ridge 382 and an immediately adjacent sealing surface 384. The sealing surface 384 is a circumferential sector that exhibits a substantially constant angle relative to the axis of the gasket bore 355 and the plane of the second axial end surface 360, but may advantageously have a slightly convex shape for some gasket materials. The radial extent of the sealing surface 384 is advantageously greater than the reduced contact area of existing designs, creating a significantly longer radially leak-proof contact between the gasket and the fluid conduit port face. During normal factory operation, when the gasket slides over a rough surface, the protective ridge 382 may be damaged, but the sealing surface 384 will remain intact. When the gasket 300 is fabricated into a leak-proof fluid path joint by axial compression between opposing flat equipment faces, the protective ridge 382 will plastically deform by virtue of the cavities 375, 376, 377, etc., which allow the lip 380 to flex, and the sealing surface 384 will deflect slightly radially outward with further axial compression. Although the stress concentration cavities 325, 326, 327 and 375, 376, 377, disposed on opposing axial faces of the gasket 300, are shown as being in phase with one another around the circumference of the gasket, it will be appreciated that they may alternatively be disposed in anti-phase with one another, as further described below with respect to FIG. 5A and FIG. 5B .

Similarly, considering the third representative gasket example, designers can appreciate how the axial end surfaces 310, 360 can act as relatively hard stoppers that prevent the gasket lips 330, 380 from being over-extruded by contacting the corresponding fluid conduit port face surfaces. Slight compositional variations and manufacturing tolerances within the gasket 300 can cause one of the axial end surfaces 310, 360 to contact the corresponding fluid conduit port face before the other axial end surface 360, 310 during the gasket extrusion process when forming the joint. The illustrated hard stop function ensures that the two opposing gasket lips 330, 380 are ultimately equally and fully extruded. It should also be appreciated that the end regions 357, 358 of the fluid passageway aperture 355 preferably have a smaller axial extent than the axial end surfaces 310, 360 to prevent the formation of a virtual leak cavity within the fluid passageway when the joint is fully mated. Designers will also appreciate that the presence of an unchanging central material within the washer body 350 allows the deformation behavior of the first axial end surface lip 330 to be substantially independent of the deformation behavior of the second axial end surface lip 380 .

4A and 4B illustrate a fourth representative example 400 of the applicant's annular gasket, similar to the third example. Gasket body 450 is penetrated by hole 451, which defines a fluid passage hole 455 and includes a radially inner surface 456, which can be substantially straight to reduce fluid turbulence in the fluid delivery device coupling joint. The radially outer extent of the gasket body is defined by a radially outer surface 490, which can have a circumferential groove 492 to accommodate a locating member (not shown in FIG. 4A and FIG. 4B), which is used to locate the gasket 400 in an assembly (also not shown) of a fluid delivery component.

A fourth representative gasket example may have first and second axial end surfaces 410 and 460 including stress concentrating features 420, 470 comprising regularly arranged blind cavities 425, 475 extending into the two axial end surfaces 410, 460. The stress concentrating cavities 425, 475 remove gasket body material from areas immediately adjacent to the two intended gasket sealing regions, thereby forming lips 430, 480 on the axial end surfaces 410, 460, which preferably protrude axially outward beyond the corresponding axial end surfaces 410, 460 prior to forming the joint. Each of the plurality of stress concentrating cavities 425, 475 has a separate volumetric axis 421, 471 that forms an acute angle with the plane of the associated gasket axial end surface 410, 460, thereby forming a plurality of undercuts of the gasket sealing regions. Each lip 430, 480 includes an axially raised protective ridge 432, 482 and an immediately adjacent sealing surface 434, 484. During normal factory operation, when the gasket slides over rough surfaces, the protective ridge 432, 482 may be damaged, but the sealing surfaces 434, 484 will remain intact. The sealing surfaces 434, 484 are circumferential sectors that exhibit a substantially constant angle relative to the axis of the gasket bore 455 and the plane of each associated axial end surface 410, 460, but may advantageously have a slightly convex shape for some gasket materials. The gasket sealing area lips 430, 480 can be understood as being like oppositely directed frustoconical shells that flare outwardly from the gasket bore 455 toward the radially outer surface 490. The radial extent of the sealing surfaces 434, 484 is advantageously greater than the reduced contact area of existing designs to create a much longer radially leak-proof contact between the gasket and the fluid conduit port face. When the gasket 400 is fabricated into a leak-proof fluid pathway joint by axial extrusion between opposing planar equipment faces, the protective ridges 432, 482 will plastically deform and the sealing surfaces 434, 484 will deflect slightly radially outward with further axial extrusion because the undercut cavities 425, 475 allow the gasket lips 430, 480 to flex in a controlled manner.

Similarly, considering the fourth representative gasket example, designers will appreciate how the axial end surfaces 410, 460 can act as relatively hard stoppers that prevent the gasket lips 430, 480 from being over-extruded by contacting the corresponding fluid conduit port face surfaces. Slight compositional variations and manufacturing tolerances within gasket 400 can cause one of the axial end surfaces 410, 460 to contact the corresponding fluid conduit port face before the other axial end surface 460, 410 during the gasket extrusion process when forming the joint. The illustrated hard stop function ensures that the two opposing gasket lips 430, 480 are ultimately equally and fully extruded. It should also be appreciated that the end regions 457, 458 of the fluid passageway aperture 455 will preferably have a smaller axial extent than the axial end surfaces 410, 460 to prevent the formation of a virtual leak cavity within the fluid passageway when the joint is fully mated. Designers will also appreciate that the presence of an unchanging central material within the washer body 450 allows the deformation behavior of the first axial end surface lip 430 to be substantially independent of the deformation behavior of the second axial end surface lip 480 .

Skilled gasket designers will further appreciate that the relatively independent first and second axial end surface shapes also contemplate a design combination including a stress concentrating recess on one face and multiple stress concentrating cavities on the opposing face. For example, in some embodiments, the stress concentrating feature on one face may be similar to stress concentrating recesses 120, 170 of FIG. 1A-1B or stress concentrating recesses 220, 270 of FIG. 2A-2B , while the stress concentrating feature on the opposing face may include multiple stress concentrating cavities similar to stress concentrating cavities 325, 326, 327 of FIG. 3A-C or stress concentrating cavities 425, 475 of FIG. 4A-B . Furthermore, when multiple stress concentrating cavities are designed into both the first and second axial end surfaces, the volume axes of the opposing cavities may be circumferentially aligned, as in FIG. 4A , or alternatively, may be staggered, as illustrated in FIG. 5A and FIG. 5B , which illustrate a fifth gasket example 500. The corresponding elements in FIG5A include the gasket body 550, the radially inner surface 556, the first axial end surface 510 having the lip 530 and the associated blind cavity 525, and the second axial end surface 560 having the lip 580 and the associated blind cavity 565. The top plan view of FIG5B illustrates how the cross-sectional view reveals that the cavities of one axial end surface are interspersed substantially in antiphase with the cavities of the opposite axial end surface. It should also be appreciated that FIG5A illustrates a gasket in which the radially outer surface 590 does not have a groove for a locator, as the locator groove is optional in all examples.

6A and 6B illustrate how a seal is achieved when a fourth example shaped annular metal gasket 400 is squeezed between opposing device components 605, 660 having simple flat surfaces 630, 680 that contact the gasket 400. As shown in FIG6A , when the device components 605, 660 are threadedly pressed toward each other by a fastener or mating component, the sealing area lips 430, 480 initially contact the flat surfaces 630, 680 of the fluid delivery device component along the protective ridges 432, 482. A thin retainer 495 that engages the outer circumferential groove 492 helps position the gasket 400 between the opposing fluid conduit ports 610, 690. As shown in FIG6B , after axial compression of the resulting joint is complete, the opposed device elements 605, 660 abut the axial end surfaces 410, 460 of the gasket, and the gasket lips 430, 480 have been bent outwardly so that the sealing surfaces 434, 484 are in flat contact with the fluid conduit port-facing surfaces 614, 664 of the corresponding fluid delivery device elements. It should be appreciated that, as shown in FIG6A and 6B , the radial extent of the radially outer surface 490 of the gasket 400 is preferably less than the radial extent of the flat surfaces 630, 680 of the opposed device elements, both before and after compression between the opposed device elements 605, 660.

A sixth representative example 700 of the applicant's annular gasket is illustrated in Figures 7A and 7B. A gasket body 750 is penetrated by a hole defining a fluid passage aperture 755. The fluid passage aperture 755 includes a radially inner surface 756 that can conveniently be substantially straight to reduce fluid turbulence in a fluid transfer device coupling. The radially outer extent of the gasket body is defined by a radially outer surface 790 that can have a circumferential groove 792 to accommodate a locating member (not shown in Figures 7A and 7B) for locating the gasket 700 in an assembly (also not shown) of a fluid transfer assembly.

A sixth representative gasket example may have a first axial end surface 710 including stress concentrating features, including regularly arranged blind cavities 718, 719, 720, etc. and 725, 726, 727, etc. extending into the first axial end surface 710. The stress concentrating cavities 725, etc. remove gasket body material from the area immediately adjacent to the intended gasket sealing area, thereby forming a lip 730 on the first axial end surface 710. The lip 730 preferably protrudes axially outward beyond the corresponding first axial end surface 710 before forming the joint. Each of the plurality of stress concentrating cavities 725, etc. has a separate volume axis 721 that forms an acute angle with the plane of the associated first gasket axial end surface 710, thereby forming multiple undercuts of the gasket sealing area. The lip 730 includes an axially raised protective ridge 732 and an immediately adjacent sealing surface 734. During normal factory operation, when the gasket slides over rough surfaces, protective ridge 732 may be damaged, but sealing surface 734 will remain intact. Sealing surface 734 is a circumferential sector that exhibits a substantially constant angle relative to the axis of gasket bore 755 and the plane of the associated first axial end surface 710, but a slightly convex shape may be advantageous for some gasket materials. The radial extent of sealing surface 734 is advantageously greater than the reduced contact area of existing designs, creating a much longer radially leak-proof contact between the gasket and the fluid conduit port face. When gasket 700 is fabricated into a leak-proof fluid passage joint by axial compression between opposing flat equipment faces, protective ridge 732 will plastically deform, as undercut cavity 725 and the like allow for controlled flexing of gasket lip 730, causing sealing surface 734 to deflect slightly radially outward with further axial compression. It should be appreciated that the groove stress concentration feature described previously in the first and second gasket examples can alternatively be applied to the first axial end surface of the presently described gasket example. This alternative example 701 of applicant's sixth representative gasket example is illustrated in FIG7C , where reference numerals 710, 720, 730, 732, 734, and 757 correspond to features 110, 120, 130, 132, 134, and 157 previously described with respect to FIG1A-1B . Although not shown, it will be appreciated that stress concentrating grooves similar to those described with respect to FIG2A-2B may alternatively be used.

A sixth representative gasket example may have a second axial end surface 760 including an external chamfer 770 that, for convenience, merges into a radially outer surface 790. A sealing area 785, initially flat in the radial direction, suitable for use with fluid-handling elements having an annular protrusion surrounding a circular conduit opening, is formed as a circumferential sector generally perpendicular to the axis of the gasket bore 755 and parallel to the plane of the second axial end surface 760. The axial extent of the initially flat sealing area 785 may advantageously be smaller than the second axial end surface 760 so as to be effectively recessed within the second axial end surface 760. During normal factory operation, when the gasket slides over rough surfaces, the second axial end surface 760 may be damaged, but the sealing surface 785 will remain intact. When the gasket 700 is fabricated into a leak-proof fluid pathway joint by axial extrusion between opposing fluid-handling element conduit ports, as described further below, the annular protrusion will cause permanent plastic deformation of the gasket sealing area 785.

Considering the sixth representative gasket example, a designer can appreciate how the first axial end surface 710 can act as a relatively rigid stopper that prevents the gasket lip 730 from being over-extended by contacting the corresponding facing surface of the first fluid conduit port. It should also be appreciated that the first end region 757 of the fluid passageway aperture 755 preferably has a smaller axial extent than the first axial end surface 710 to prevent the formation of a virtual leak cavity within the fluid passageway when the joint is fully mated. The designer can also appreciate that the presence of a constant central material within the gasket body 750 allows the deformation behavior of the first axial end surface lip 730 to be substantially independent of the deformation behavior of the second axial end surface sealing region 785. As further described below with respect to Figures 8A and 8B, this independence of deformation behavior is advantageously utilized in the sixth representative gasket example.

Figures 8A and 8B illustrate how a seal is achieved when a sixth exemplary shaped annular metal gasket 700 is squeezed between opposing fluid delivery device components 805, 860. Figure 8A illustrates the sixth representative gasket positioned by a retainer 795 and located between an upper fluid conduit port counterbore 830 having a flat bottom and a lower fluid conduit port counterbore 880 having a formed annular protrusion 885, prior to application of an axial sealing force to form the joint. Figure 8B illustrates the sixth representative gasket 700 between the corresponding fluid conduit port counterbore holes after the joint is formed. As shown in Figure 8A, when the device components 805, 860 are pressed toward each other by a fastener (or mating component threads or other means), the sealing area lip 730 initially contacts the flat surface 830 of the fluid delivery device component along the protective ridge 732, and the initially flat sealing area 785 contacts the annular protrusion 885. A thin retainer 795, which engages the outer circumferential groove 792, helps position the gasket 700 between the opposing fluid conduit ports 810, 890. During the gasket compression process when forming the joint, the hard stop function of the first axial end surface 710 against the upper fluid conduit port counterbore 830 ensures that all additional tightening action to engage the opposing fluid conduit ports 810, 890 will result in the initially flat sealing area 785 being properly compressed by the lower fluid conduit port annular protrusion 885. As shown in FIG8B , after axial compression of the formed joint is complete, the gasket lip 730 has flexed outward, bringing the sealing surface 734 into flat contact with the corresponding fluid conduit port-facing surface 830 of the fluid delivery device component, while the initially flat sealing area 785 has been deformed by the compression of the annular protrusion 885 therein. When the device components 805, 860 contact the retainer 795, further gasket compression is no longer possible. The axial extent of the second axial end surface 760 can be selected in conjunction with the thickness of the locating member 795 to ensure that there is clearance between the second axial end surface 760 and the bottom of the lower fluid conduit port counterbore 880. A clearance may be desirable to ensure that sealing occurs only between the formed annular protrusion 885 and the initially flat (but now deformed) second axial end surface sealing area 785, while also allowing for the performance of a helium leak detection method for testing the integrity of the joint. It will be appreciated that, as shown in Figures 8A and 8B, the radial extent of the radially outer surface 790 of the gasket 700 is preferably smaller than the radial extent of the counterbore 830 of the fluid transport device element 805 and the radial extent of the counterbore 880 of the fluid transport device element 860, both before and after compression between the opposing device components 805, 860.

The seventh representative example 900 of the applicant's annular gasket is illustrated in Figures 9 A and 9 B and is similar to the first and second representative examples. The gasket body 950 is passed through by a hole 951, and the hole 951 defines a fluid passage hole 955. The fluid passage hole 955 includes a radially inner surface 956, and the radially inner surface 956 can be substantially straight to reduce the fluid turbulence in the fluid conveying device coupling joint. The radially outer range of the gasket body is defined by a radially outer surface 990, and the radially outer surface 990 can have a circumferential groove 992 to accommodate a locating member (not shown in Figures 9 A and 9 B), which is used to locate the gasket 900 in the assembly (also not shown) of the fluid conveying component. As described above with respect to the previous representative gasket example, the presence of the groove 992 for accommodating the locating member is optional in this representative example.

The seventh representative gasket example can have first and second axial end surfaces 910 and 960 including stress concentrating features 920, 970, which in turn are present as grooves in the axial end surfaces 910, 960. The stress concentrating grooves 920, 970 remove gasket body material from areas immediately adjacent to the two intended gasket sealing areas, thereby forming lips 930, 980 on the axial end surfaces 910, 960, which preferably protrude axially outward beyond the corresponding axial end surfaces 910, 960 prior to forming the joint. In a manner similar to the second representative gasket example shown in Figures 2A and 2B, the stress concentrating grooves 920, 970 have inner walls closest to the gasket radial inner surface 956 that form an acute angle with the plane of each associated gasket axial end surface 910, 960, thereby forming an undercut of each gasket sealing area. However, in contrast to the second representative gasket example of Figures 2A and 2B , the stress concentrating grooves 920, 970 of this seventh representative gasket example have radially inner and outer groove walls that are substantially parallel to one another, thereby defining a U-shaped groove, rather than the substantially V-shaped grooves 220, 270 depicted in the second representative gasket example of Figures 2A and 2B . The substantially parallel radially inner and outer groove walls of the stress concentrating grooves 920, 970 thus each form an acute angle with the plane of each associated gasket axial end surface 910, 960. As in the aforementioned representative gasket example, the lips 930, 980 each include an axially raised protective ridge 932, 982 and an immediately adjacent sealing surface 934, 984. The protective ridge 932, 982 may be damaged, for example, when the gasket slides over a rough surface during normal factory operation, but the sealing surface 934, 984 will remain intact. The sealing surfaces 934, 984 are circumferential sectors that exhibit a substantially constant angle relative to the axis of the gasket bore 955 and the plane of each associated axial end surface 910, 960, but may advantageously have a slightly convex shape for some gasket materials. It should be appreciated that the gasket sealing area lips 930, 980 may also resemble oppositely directed frustoconical shells that flare outwardly from the gasket bore 955 toward the radially outer surface 990. As in the aforementioned representative gasket examples, the radial extent of the sealing surfaces 934, 984 is advantageously greater than the reduced contact area of prior designs to create a much longer radially leak-proof contact between the gasket and the fluid conduit port face. When the gasket 900 is fabricated into a leak-proof fluid pathway joint by axial extrusion between opposing planar equipment faces, as further described with respect to Figures 10A and 10B, because the undercut grooves 920, 970 allow the gasket lips 930, 980 to flex in a controlled manner, the protective ridges 932, 982 will plastically deform and the sealing surfaces 934, 984 will deflect slightly radially outward with further axial extrusion, contacting the planar equipment faces.

Similarly considering the representative gasket example described above, designers can appreciate how the axial end surfaces 910, 960 can act as relatively hard stoppers that prevent the gasket lips 930, 980 from being over-extruded by contacting the corresponding fluid conduit port face surfaces. Slight compositional variations and manufacturing tolerances within the gasket 900 can cause one of the axial end surfaces 910, 960 to contact the corresponding fluid conduit port face before the other axial end surface 960, 910 during the gasket extrusion process when forming the joint. However, the illustrated hard stop function ensures that the two opposing gasket lips 930, 980 are ultimately equally and fully extruded. It should also be appreciated that the end regions 957, 958 of the fluid passageway hole 955 preferably have a smaller axial extent than the axial end surfaces 910, 960 to prevent the formation of a virtual leak cavity within the fluid passageway when the joint is fully mated.

Skilled designers will appreciate that the presence of a constant central material within the gasket body 950 allows the deformation behavior of the first axial end surface lip 930 to be substantially independent of the deformation behavior of the second axial end surface lip 980. This independence in the deformation behavior between the opposing axial end surface lips 930, 980 can, at the designer's option, allow for the manufacture of gaskets having intentionally different properties on opposing sides. Skilled designers will appreciate that the lip bending characteristics can be adjusted by selecting the acute undercut angle and the groove depth and width. Thus, for example, one or more of the acute undercut angle, groove depth, and groove width can be different on one side of the gasket relative to the acute undercut angle, groove depth, or groove width on the opposite side of the gasket. Furthermore, an annular gasket can have a stress concentrating groove similar to the stress concentrating groove 120 shown in Figures 1A-1B or the stress concentrating groove 220 shown in Figures 2A-2B on one axial end surface and another stress concentrating feature similar to the stress concentrating groove 920 or 970 described above on the opposing axial end surface. Alternatively, the annular gasket may have stress concentrating features similar to the stress concentrating grooves 920, 970 described above on one axial end surface, with the opposing axial end surface being configured in the manner previously described with respect to Figures 7A and 7B to form a fluid-tight seal with a fluid-conveying element having an annular protrusion surrounding a circular conduit opening. It should be appreciated, therefore, that the various representative gasket designs disclosed herein are not limited to gaskets having substantially symmetrical axial end surfaces, as the use of first and second axial end surfaces that are substantially different from one another in physical structure and/or deformation behavior is also contemplated.

Designers experienced in high purity applications will recognize that it is desirable to place the stress concentrating features 920, 970 outside of the "wetted" fluid passage to minimize passage pockets that could trap contaminants, resulting in a design having gasket sealing area lips 930, 980 that flare outward from the gasket hole 255. Applications more concerned with sealing relatively high passage internal pressures will likely benefit from the fluid-driven sealing effect achieved by having gasket sealing area lips that flare inward toward the gasket hole. In this alternative design, the internal fluid pressure will push against the inwardly flaring gasket sealing lips and force them against their corresponding equipment components, achieving a tighter seal along the radial contact area. This alternative gasket embodiment will require placing one or more stress concentrating features closest to the gasket hole and the adjacent sealing area lips radially farther from the gasket hole.

10A and 10B illustrate how a seal is achieved when a seventh example shaped annular metal gasket 900 is squeezed between opposing device components 605, 660 having simple flat surfaces 630, 680 that contact the gasket 900. As shown in FIG10A , when the device components 605, 660 are pushed toward each other by fasteners or mating component threads, the sealing area lips 930, 980 initially contact the flat surfaces 630, 680 of the fluid delivery device component along the protective ridges 932, 982. A thin retainer 995 that engages an outer circumferential groove 992 of the gasket 900 helps position the gasket 900 between the opposing fluid conduit ports 610, 690. As shown in FIG10B , after axial compression of the resulting joint is complete, the opposed device elements 605, 660 abut the gasket axial end surfaces 910, 960, and the gasket lips 930, 980 have been bent outwardly so that the sealing surfaces 934, 984 have formed flat contact with the fluid conduit port faces 614, 664 of the corresponding fluid delivery device elements. It should be appreciated that, as shown in FIG10A and 10B , both before and after compression between the opposed device elements 605, 660, the radial extent of the radially outer surface 990 of the gasket 900 is preferably less than the radial extent of the flat surfaces 630, 680 of the opposed device elements.

The various gasket designs described herein are particularly useful in the context of high-purity fluid delivery equipment where the gasket material may have mechanical properties similar to those of the equipment element to which the fluid is to be sealed. The use of fluid delivery system components made of high-purity 316L stainless steel having fluid conduit ports with flat bottom counterbores is well known. The difficulty of achieving molecular level leak tightness with such components can be alleviated by using the designs described. In high-purity liquid delivery equipment made of polymeric materials, essentially the same problems exist and these designs are similarly applicable to these situations.

As will be appreciated in light of the above disclosure, the various gasket designs described herein allow the opposing axial faces of the gasket to be independently customized to meet the physical and mechanical requirements of the adjacent facing surfaces of the fluid handling equipment to which they abut. Thus, for example, a gasket sealing surface on one side of the gasket may be configured to sealingly engage an annular protrusion surrounding a circular conduit opening in one equipment component, while the opposite side of the gasket may be configured to sealingly engage a recessed flat surface surrounding the circular conduit opening in the opposing equipment component.

Having thus described several aspects of at least one embodiment of the present invention, it will be appreciated that various changes, modifications, and improvements will readily occur to those skilled in the art. Such changes, modifications, and improvements are intended to be part of this disclosure and are intended to fall within the scope of the present invention. Therefore, the foregoing description and drawings are intended to be exemplary only.

Claims (30)

1. An annular gasket for sealingly engaging opposing fluid conduit ports, the gasket comprising: A gasket body having a radially outer surface, a first axial end surface, and a second axial end surface, the gasket body being penetrated by a hole that creates a fluid passage and defines a radially inner surface, at least one of the first axial end surface and the second axial end surface having a stress concentration feature formed in the gasket body to define a lip on at least one of the first axial end surface and the second axial end surface, the lip projecting axially outward beyond at least one of the first axial end surface and the second axial end surface, and including a sealing surface adjacent to a protective ridge, the lip having a radial undercut formed by the stress concentration feature, the bottom of the radial undercut extending radially and axially toward at least a portion of the interior of the lip, the lip being constructed and arranged to plastically deform in response to contact between the sealing surface and the face surface of a corresponding fluid conduit port. 2. The gasket according to claim 1, wherein the stress concentration feature is outside the fluid passage. 3. The gasket according to claim 1 or 2, wherein the stress concentration feature includes a groove formed in at least one of the first axial end surface and the second axial end surface. 4. The gasket according to claim 1 or 2, wherein the stress concentration feature includes a groove formed in at least one of the first axial end surface and the second axial end surface, the wall of the groove closest to the radial inner surface forming an acute angle with the plane of at least one of the first axial end surface and the second axial end surface to form the radial undercut. 5. The gasket according to claim 1 or 2, wherein the stress concentration feature includes a U-shaped groove formed in at least one of the first axial end surface and the second axial end surface, the parallel walls of the groove forming an acute angle with the plane of at least one of the first axial end surface and the second axial end surface to form the radial undercut. 6. The washer according to claim 1 or 2, wherein the stress concentration feature includes a groove formed in at least one of the first axial end surface and the second axial end surface, the wall of the groove closest to the radial inner surface forming an acute angle with the plane of at least one of the first axial end surface and the second axial end surface to form the radial undercut, the outer periphery of the groove being surrounded by a portion of at least one of the first axial end surface and the second axial end surface, the portion extending axially outward to a smaller extent than the lip before the washer is installed. 7. The gasket according to claim 1 or 2, wherein the stress concentration feature comprises regularly arranged cavities extending into at least one of the first axial end surface and the second axial end surface. 8. The gasket according to claim 1 or 2, wherein the stress concentration feature includes a plurality of cavities extending into at least one of the first axial end surface and the second axial end surface, the plurality of cavities having a respective volume axis, each volume axis forming an acute angle with a plane of at least one of the first axial end surface and the second axial end surface to form a plurality of radial undercuts. 9. The gasket according to claim 1 or 2, wherein the stress concentration feature comprises a plurality of cavities extending into at least one of the first axial end surface and the second axial end surface, the plurality of cavities having a respective volume axis, each volume axis forming an acute angle with a plane of at least one of the first axial end surface and the second axial end surface to form a plurality of radial undercuts, wherein a circumferential portion of at least one of the first axial end surface and the second axial end surface radially adjacent to the radially outer surface extends axially outward to a smaller extent than the gasket sealing area prior to installation of the gasket. 10. An annular gasket for sealingly engaging opposing fluid conduit ports, the gasket comprising a gasket body having a radially outer surface, a first axial end surface, and a second axial end surface, the gasket body being perforated by a bore that creates a fluid passage and defines a radially inner surface, the first axial end surface having a first stress concentration feature outside the fluid passage, the first stress concentration feature being formed in the gasket body to define a first lip radially adjacent to the first stress concentration feature on the first axial end surface, the first lip projecting axially outward beyond the first axial end surface and including a first sealing surface adjacent to a first protective ridge, the first lip having a first radial undercut formed by the first stress concentration feature, the bottom of the first radial undercut extending radially and axially toward at least a portion of the interior of the first lip. The first lip is configured and arranged to plastically deform in response to contact between the first sealing surface and the face surface of the first fluid conduit port. The second axial end surface has a second stress concentration feature outside the fluid passage. The second stress concentration feature is formed in the gasket body to define a second lip radially adjacent to the second stress concentration feature on the second axial end surface. The second lip axially protrudes outward beyond the second axial end surface and includes a second sealing surface adjacent to a second protective ridge. The second lip has a second radial undercut formed by the second stress concentration feature. The bottom of the second radial undercut extends radially and axially toward at least a portion of the interior of the second lip. The second lip is configured and arranged to plastically deform in response to contact between the second sealing surface and the face surface of the second fluid conduit port. 11. The gasket according to claim 10, wherein the first stress concentration feature is the same as the second stress concentration feature. 12. The gasket according to claim 10, wherein the first stress concentration feature is different from the second stress concentration feature. 13. The gasket according to claim 10, wherein the first stress concentration feature is one of a groove and a plurality of cavities formed in the first axial end surface, and the second stress concentration feature is another of a groove and a plurality of cavities formed in the second axial end surface. 14. The gasket of claim 10, wherein the first stress concentration feature includes a first plurality of cavities formed in the first axial end surface, each of the first plurality of cavities having a volume axis that forms an acute angle with a plane of the first axial end surface to form a plurality of first radial undercuts of the first lip, and the second stress concentration feature includes a second plurality of cavities formed in the second axial end surface, each of the second plurality of cavities having a volume axis that forms an acute angle with a plane of the second axial end surface to form a plurality of second radial undercuts of the second lip. 15. The gasket according to claim 14, wherein the corresponding volume axis of each of the first plurality of cavities is configured to be inversely related to the volume axis of the corresponding cavity in the second plurality of cavities. 16. The gasket of claim 10, wherein the first stress concentration feature includes a first groove formed in the first axial end surface, the wall of the first groove closest to the radial inner surface forming an acute angle with the plane of the first axial end surface to form a first radial undercut, and the second stress concentration feature includes a second groove formed in the second axial end surface, the wall of the second groove closest to the radial inner surface forming an acute angle with the plane of the second axial end surface to form a second radial undercut. 17. The gasket of claim 10, wherein the first stress concentration feature includes a first U-shaped groove formed in the first axial end surface, the parallel wall of the first U-shaped groove forming an acute angle with the plane of the first axial end surface to form a first radial undercut, and the second stress concentration feature includes a second U-shaped groove formed in the second axial end surface, the parallel wall of the second U-shaped groove forming an acute angle with the plane of the second axial end surface to form a second radial undercut. 18. The washer according to claim 14, 16 or 17, wherein the circumferential portion of the first axial end surface radially adjacent to the radial outer surface extends axially outward to a smaller extent than the first lip before the washer is installed, and the circumferential portion of the second axial end surface radially adjacent to the radial outer surface extends axially outward to a smaller extent than the second lip before the washer is installed. 19. The gasket of claim 18, wherein the radial contact range between the first sealing surface and the second sealing surface and the surface surfaces of the first fluid conduit port and the second fluid conduit port, respectively, is greater than the radial contact range achieved by the plastic deformation of the seal having a reduced contact area to promote plastic deformation. 20. An annular gasket for sealingly engaging an opposing fluid conduit port, the gasket comprising a gasket body having a radially outer surface, a first axial end surface, and a second axial end surface, the gasket body being penetrated by a bore that creates a fluid passage and defines a radially inner surface, wherein the first axial end surface has a first stress concentration feature formed in the gasket body to define a lip on the first axial end surface, the lip projecting axially outward beyond the first axial end surface and including a sealing surface adjacent to a protective ridge, the sealing surface being formed as a circumferential sector extending axially and radially outward toward the protective ridge, the sealing surface being configured and arranged to contact a face surface of the first fluid conduit port, the second axial end surface having a flat second gasket sealing region, the second gasket sealing region being formed as a circumferential sector perpendicular to the axis of the bore and parallel to a plane of the second axial end surface prior to installation of the gasket. 21. The gasket of claim 20, wherein the first stress concentration feature includes a first plurality of cavities formed in the first axial end surface, each of the first plurality of cavities having a volume axis that forms an acute angle with a plane of the first axial end surface to form a first plurality of undercuts. 22. The gasket of claim 20, wherein the first stress concentration feature includes a first groove formed in the first axial end surface, the wall of the first groove closest to the radial inner surface forming an acute angle with the plane of the first axial end surface to form an undercut. 23. The washer of claim 22, wherein the outer periphery of the first groove is surrounded by a portion of the first axial end surface, the portion extending axially outward to a smaller extent than the lip before the washer is installed. 24. The gasket of claim 20, wherein the first stress concentration feature includes a first U-shaped groove formed in the first axial end surface, the parallel walls of the first U-shaped groove forming an acute angle with the plane of the first axial end surface to form an undercut. 25. The washer according to any one of claims 1, 2, 10-17 or 20-24, wherein the washer comprises a malleable material. 26. The gasket according to any one of claims 1, 2, 10-17 or 20-24, wherein the gasket comprises a single metallic material selected from the group consisting of: stainless steel alloys, chromium alloys, nickel alloys, commercially pure nickel, copper alloys and commercially pure copper. 27. The washer according to any one of claims 1, 2, 10-17 or 20-24, wherein the washer comprises a 316 series stainless steel alloy. 28. The gasket according to any one of claims 1, 2, 10-17 or 20-24, wherein the gasket comprises a single polymer material selected from the group consisting of polypropylene (PP), polyvinylidene fluoride (PVDF), perfluoroalkoxy polymer (PFA), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE) and polyimide. 29. The gasket according to any one of claims 1, 2, 10-17 or 20-24, wherein the gasket comprises polyimide. 30. A method for forming a high-purity fluid connector, wherein, A gasket, initially a closed ring made of malleable material, comprises a gasket body having a radially outer surface, a first axial end surface, and a second axial end surface. The gasket body is perforated by a bore that creates a fluid passage and defines a radially inner surface. At least one of the first and second axial end surfaces has a stress concentration feature formed in the gasket body to define a lip on the at least one of the first and second axial end surfaces. The lip projects axially outward beyond the at least one of the first and second axial end surfaces and includes an undeformed gasket sealing surface angled relative to a nearby inner axis of the gasket ring shape. The lip has a radial undercut formed by the stress concentration feature, the bottom of which extends radially and axially toward at least a portion of the interior of the lip. The gasket is pressed between opposing fluid delivery device elements until a portion of the gasket's sealing surface bends perpendicular to the nearest inner axis of the gasket's ring shape.