Seal element for isolation gasket

Abstract

A gasket for use between adjoining pipe flanges includes a retainer which defines a bore and includes a first face and an opposite second face. The retainer is constructed and arranged with a first groove in the first face and with a second groove in the second face, the first groove includes a first form for seal retention and the first seal element includes a first cooperating form for retention of the seal element within the first groove. A second seal element is received within the second groove and the retention of each seal element within its respective groove is accomplished without the use of a bonding material.

Claims

1. A gasket for use between adjoining pipe flanges, said gasket comprising: a retainer defining a bore and including, a first layer, a second layer, and an intermediate layer which is positioned between said first layer and said second layer, said retainer defining a first annular channel formed in said first layer in cooperation with said intermediate layer and a second annular channel formed in said second layer in cooperation with said intermediate layer said first layer defining an annular aperture and said intermediate layer defining an annular groove comprising generally flat axial side walls, said annular aperture and said annular groove cooperating to form said first annular channel, said annular aperture including a radially-inner, angled surface extending into a undercut formed between the first and intermediate layers and which extends in a radially inward direction from said angled surface, and including a radially-outer angled surface extending to one of the generally flat axial side walls; and a first seal element received within said first annular channel and generally substantially filling the annular channel, said first seal element including a seal retention portion comprising a radially inner annular lip extending radially from the first seal element into said annular groove and said undercut, and the first seal element contacting the one of the generally flat axial side walls and the radially-outer angled surface.

2. The gasket of claim 1, which further includes: a second seal element received within said second annular channel.

3. The gasket of claim 2, wherein said second seal element has an axial thickness of approximately 0.105 inches.

4. The gasket of claim 1, wherein said first seal element has an axial thickness of approximately 0.105 inches.

5. The gasket of claim 1, wherein said retainer has an axial thickness of approximately 0.25 inches.

6. The gasket of claim 1, wherein assembly and retention of said first seal element into said first annular channel is accomplished without the use of a bonding material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a top plan view of an isolation gasket according to one embodiment of the present disclosure.

(2) FIG. 2 is a side elevational view, in full section, of the FIG. 1 isolation gasket as viewed along line 2-2 in FIG. 1.

(3) FIG. 3 is a partial, enlarged detail of two seal elements as installed in the FIG. 1 isolation gasket.

(4) FIG. 4 is a top plan view of an alternative form of the FIG. 1 isolation gasket.

(5) FIG. 5 is a side elevational view, in full section, of the FIG. 4 isolation gasket as viewed along line 5-5 in FIG. 4.

(6) FIG. 6 is a side elevational view of the FIG. 3 seal element, in full form and in full section.

(7) FIG. 7 is an enlarged side elevational view, as a lateral section, of the FIG. 6 seal element.

(8) FIG. 8 is a top plan view of an isolation gasket according to another embodiment of the present disclosure.

(9) FIG. 9 is a side elevational view, in full section, of the FIG. 8 isolation gasket as viewed along line 9-9 in FIG. 8.

(10) FIG. 10 is a partial, enlarged detail of two seal elements as installed in the FIG. 8 isolation gasket.

(11) FIG. 11 is a top plan view of an alternative form of the FIG. 8 isolation gasket.

(12) FIG. 12 is a side elevational view, in full section, of the FIG. 11 isolation gasket as viewed along line 12-12 in FIG. 11.

(13) FIG. 13 is a side elevational view of the FIG. 10 seal element, in full form and in full section.

(14) FIG. 14 is an enlarged side elevational view, as a lateral section, of the FIG. 13 seal element.

(15) FIG. 15 is a top plan view of an isolation gasket according to another embodiment of the present disclosure.

(16) FIG. 16 is a side elevational view, in full section, of the FIG. 15 isolation gasket as viewed along line 16-16 in FIG. 15.

(17) FIG. 17 is a partial, enlarged detail of the seal element as installed in the FIG. 15 isolation gasket.

(18) FIG. 18 is a top plan view of an alternative form of the FIG. 15 isolation gasket.

(19) FIG. 19 is a side elevational view, in full section, of the FIG. 18 isolation gasket as viewed along line 19-19 in FIG. 18.

(20) FIG. 20 is a side elevational view of the FIG. 17 seal element, in full form and in full section.

(21) FIG. 21 is an enlarged side elevational view, as a lateral section, of the FIG. 20 seal element.

(22) FIG. 22 side elevational view of an alternative seal element which is suitable for use in the FIG. 15 isolation gasket.

(23) FIG. 23 is an enlarged side elevational view, as a lateral section, of the FIG. 22 seal element.

DESCRIPTION OF SELECTED EMBODIMENTS

(24) For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. One embodiment of the invention is shown in great detail, although it will be apparent to those skilled in the relevant art that some features that are not relevant to the present invention may not be shown for the sake of clarity.

(25) Referring to FIGS. 1-3, there is illustrated an isolation gasket 20 which is within the category or style which does not include a spring energized seal as shown in the isolation gasket style of FIGS. 8-14. Gasket 20 is a ring type gasket (Type F) and according to industry standards for this general type of gasket does not include any bolt holes. Referring to FIGS. 4 and 5, there is illustrated a Type E isolation gasket 22 which does include bolt holes. Gasket 22 is otherwise similar to gasket 20 in construction and function, except that a Type E gasket, according to industry standards, is a full face gasket which includes bolt holes. In the exemplary embodiment, gasket 22 includes four bolt holes 24 which are of generally the same size and diameter, are equally spaced apart and are centered on the same bolt circle 25. It will be understood that the bolts and bolt pattern of the flanges being joined in combination with gasket 22 determine the number, size and spacing of bolt holes 24. With the exception of size differences and the presence of bolt holes 24 in gasket 22, gaskets 20 and 22 are structurally and functionally essentially the same, including the material choices and options.

(26) Gasket 20 includes a retainer 26 and a pair of annular seal elements 28 and 30. The retainer 26 has a generally cylindrical body 32 defining a central bore 34 and including a pair of substantially flat opposing faces 36 and 38. Face 36 defines an annular groove 40 for the receipt of seal element 28. Face 38 defines an annular groove 42 for the receipt of seal element 30. Letters are used to represent the various dimensions and sizes for various embodiments of gaskets 20 and 22. Suitable and compatible dimensional combinations are set forth in Table I, as one example.

(27) TABLE-US-00001 TABLE I B B NPS A Ring Full Face C D E 0.5 0.62 1.76 3.5 0.945 0.07 2.38 0.75 0.82 2.13 3.88 1.195 0.07 2.75 1 1.05 2.5 4.25 1.395 0.07 3.12 1.25 1.38 2.88 4.62 1.745 0.07 3.5 1.5 1.61 3.26 5 1.995 0.07 3.88 2 2.07 4 6 2.55 0.085 4.75 3 3.07 5.25 7.5 3.75 0.085 6 3.5 3.55 6.25 8.5 4.25 0.085 7 4 4.03 6.75 9 4.75 0.085 7.5 5 5.05 7.62 10 5.75 0.085 8.5 6 6.07 8.62 11 6.75 0.085 9.5 8 7.98 10.87 13.5 8.76 0.085 11.75 10 10.02 13.25 16 11.01 0.085 14.25 12 12 16 19 13.01 0.105 17 14 13.25 17.63 21 14.27 0.105 18.75 16 15.25 20.13 23.5 16.27 0.105 21.25 18 17.25 21.5 25 18.27 0.105 22.75 20 19.25 23.75 27.5 20.27 0.105 25 24 23.25 28.12 32 24.27 0.105 29.5

(28) In terms of the disclosed embodiment, the retainer thickness of approximately 0.125 inches is one of the dimensions of importance and of interest. It is also noted that in the free or uncompressed state seal element 28 extends beyond the surface of face 36 allowing for compression of seal element 28 before the retainer 26 is contacted by the corresponding pipe flange. Similarly, seal element 30 extends beyond the surface of face 38 allowing for compression of seal element 30 before the retainer 26 is contacted by the corresponding pipe flange.

(29) Each gasket 20 and 22 is constructed and arranged for general applications where electrical flange isolation and corrosion control are desired. These gaskets are constructed and arranged to be used between the flanges of adjoining pipe sections which contain water, waste water, gas, natural gas, oil and other hydrocarbon-based medias up to approximately 302 degrees F. (150 degrees C.). Gasket 20 which is constructed and arranged for a ring type joint flange can also be configured for raised face joint flanges as well as flat faced joint flanges. Gasket 22 is constructed and arranged as a full face gasket and this is why bolt holes are provided.

(30) The following details regarding retainer 26 are applicable to retainer 44 of gasket 22. The retainer 26 of gasket 20 defines groove 40 in one face and groove 42 in the opposite face. Each groove is constructed and arranged with an inclined edge geometry, referring to inclined edge surfaces 40a and 42a. This particular groove geometry, see FIG. 3, is designed to improve the elastic memory of each seal element 28, 30 which is received within its corresponding groove 40, 42. The result is a high sealing reliability with a comparative low bolt load. Suitable materials for retainer 26 include G10 fiberglass and phenolic. Suitable materials for each seal element 28, 30 include PTFE (Teflon), nitrile (Buna-N), silicone, Viton and synthetic rubber such as EPDM (ethylene propylene diene monomer).

(31) The more specific descriptions provided for retainer 26, seal elements 28 and 30 and groove 40 and 42 are fully applicable to gasket 22 which includes retainer 44, annular seal elements 46 and 48 and annular grooves 50 and 52.

(32) The inclined edge geometry of grooves 40 and 42 provides the radially-outer groove surfaces 40a and 42a which compresses a portion of the corresponding seal element 28 (in groove 40) and seal element 30 (in groove 42). Each seal element is an annular, single-piece component, see FIGS. 6 and 7, which has a generally rectangular lateral cross-section. The seal element 28 which is illustrated in FIGS. 6 and 7 is representative of seal elements 30, 46 and 48. When this annular form is wedged into the corresponding annular groove, the compression along one side of the lateral section increases the size of the opposite side of the lateral section. This results in improved elastic memory of each seal element. A representative dimension is shown and the variable dimensions depending on NPS size, are denoted by letters. Table II provides the actual dimensions of each variable based on the corresponding NPS size.

(33) TABLE-US-00002 TABLE II NPS Seal OD C Seal Width W 0.5 0.945 0.070 0.75 1.195 0.070 1 1.395 0.070 1.25 1.745 0.070 1.5 1.995 0.070 2 2.550 0.085 2.5 3.250 0.085 3 3.750 0.085 3.5 4.250 0.085 4 4.750 0.085 5 5.750 0.085 6 6.750 0.085 8 8.760 0.085 10 11.010 0.085 12 13.010 0.105 14 14.270 0.105 16 16.270 0.105 18 18.270 0.105 20 20.270 0.105 24 24.270 0.105

(34) Referring to FIGS. 8-12, there is illustrated an isolation gasket 60 which is within the category or style which includes a spring energized seal. Gasket 60 is a ring type gasket (Type F) and according to industry standards for this general type of gasket, does not include any bolt holes. With reference to FIGS. 11 and 12, there is illustrated a Type E isolation gasket 62. Gasket 62 is otherwise similar to gasket 60 in construction and function, except that a Type E gasket, according to industry standards, is a full face gasket which includes bolt holes. In the exemplary embodiment, gasket 62 includes four bolt holes 64 which are of generally the same size and diameter, are equally spaced apart and are centered on the same bolt circle 65. It will be understood that the bolts and bolt pattern of the flanges being joined in combination with gasket 62 determine the number, size and spacing of bolt holes 64. With the exception of size differences and the presence of bolt holes 64 in gasket 62, gaskets 60 and 62 are structurally and functionally essentially the same, including material choices and options. Accordingly the detailed construction and assembly of gasket 60 will be provided with an understanding that the same applies to gasket 62.

(35) Gasket 60 includes a retainer 66 which is a laminate structure having a metal core 68 and a corresponding G10 or G11 fiberglass laminate layer 70, 72 on each face of the metal core 68. These three layers are securely bonded together into an integral, unitary structure. The retainer 66 is a generally cylindrical lamination defining a central bore 74. Gasket 60 also includes an annular seal element 76 associated with and secured within layer 70 and an annular seal element 78 associated with and received within layer 72. Received within annular seal element 76 is an annular metal spring 80 having a generally circular lateral cross section. Received within annular seal element 78 is an annular metal spring 82 having a generally circular lateral cross section. These metal springs 80, 82 provide a spring energizing force to each seal element 76 and 78, respectively.

(36) Letters are used to represent the variable dimensions and sizes of the various embodiments of gaskets 60 and 62. Suitable and compatible dimensional combinations are set forth in Table III based on and corresponding to the NPS sizes, as one example.

(37) TABLE-US-00003 TABLE III B B NPS A Ring Full Face C D E 0.5 0.62 1.76 3.5 0.945 0.075 2.38 0.75 0.82 2.13 3.88 1.195 0.075 2.75 1 1.05 2.5 4.25 1.395 0.075 3.12 1.25 1.38 2.88 4.62 1.745 0.075 3.5 1.5 1.61 3.26 5 1.995 0.075 3.88 2 2.07 4 6 2.55 0.092 4.75 3 3.07 5.25 7.5 3.75 0.092 6 3.5 3.55 6.25 8.5 4.25 0.092 7 4 4.03 6.75 9 4.75 0.092 7.5 5 5.05 7.62 10 5.75 0.092 8.5 6 6.07 8.62 11 6.75 0.092 9.5 8 7.98 10.87 13.5 8.76 0.092 11.75 10 10.02 13.25 16 11.01 0.092 14.25 12 12 16 19 13.01 0.092 17 14 13.25 17.63 21 14.27 0.092 18.75 16 15.25 20.13 23.5 16.27 0.092 21.25 18 17.25 21.5 25 18.27 0.092 22.75 20 19.25 23.75 27.5 20.27 0.092 25 24 23.25 28.12 32 24.27 0.092 29.5
In terms of the disclosed embodiment, the retainer thickness of approximately 0.250 inches is one of the dimensions of importance and of interest. This dimension is sufficient for receipt of a spring energized seal element of the type disclosed.

(38) It is also noted that in the free or uncompressed state, seal element 76 extends beyond the surface of face 77 allowing for compression of seal element 76 before the retainer is contacted by the corresponding pipe flange. Similarly, seal element 78 extends beyond the surface of face 79 allowing for compression of seal element 78 before the retainer 66 is contacted by the corresponding pipe flange.

(39) These gasket are constructed and arranged to be used between the flanges of pipes containing gas, natural gas, oil and other hydrocarbon-based medias up to approximately 392 degrees F. (200 degrees C.). The disclosed style of isolation gasket is suitable for flat face, raised face and ring type joint flanges from 0.5 inches to 24 inches, ANSI 150-2500# and API 2-10K. Suitable materials for the seal elements include PTFE (Teflon), nitrile (Buna-N) and Viton. Gasket 62 is constructed and arranged as a full face gasket and this is why bolt holes are required.

(40) Metal core 68 has a substantially uniform thickness throughout. Each laminate layer 70, 72 has a substantially uniform thickness throughout. One substantially flat face 84 of metal core 68 defines an annular groove 86 which is constructed and arranged to receive a portion of seal element 76. In a cooperating and complimenting manner, laminate layer 70 is shaped with an annular aperture 88. Aperture 88 includes a radially-inner, angled surface 90 with an annular undercut edge 92, which creates an offset, annular lip which cooperates with groove 86 to capture lip 96. The radially-outer surface 94 of aperture 88 is also angled. The combination of groove 86 and edge 92 creates an annular space which captures the annular lip 96 of seal element 76. The capturing of lip 96 in cooperation with the angled shape of surface 94 allows annular seal element 76 to be pressed into position and it becomes secure in that position without the need to use any bonding agent or bonding material, such as glue or adhesive. Seal element 76 cannot become loose or fall out due to normal handling and positioning of gasket 60 (and similarly of gasket 62).

(41) The other substantially flat face 104 of metal core 68 defines an annular groove 106 which is constructed and arranged to receive a portion of seal element 78. In a cooperating and complimenting manner, laminate layer 72 is shaped with an annular aperture 108. Aperture 108 includes a radially-inner, angled surface 110 with an annular undercut edge 112. The radially-outer surface 114 of aperture 108 is also angled. The combination of groove 106 and edge 112 creates an annular space which captures the annular lip 116 of seal element 78. The capturing of lip 116 in cooperation with the angled shape of surface 114 allows annular seal element 78 to be pressed into position and it becomes secure in that position without the need to use any glue or adhesive. Seal element 78 cannot become loose or fall out due to normal handling and positioning of gasket 60 (and similarly of gasket 62). The gasket 60 and gasket 62 constructions disclosed herein each combine the technology of a press-in, pressure activated seal with a unique groove that retains the seal element without the use of glue or adhesive on the key or critical contact surfaces.

(42) The cooperation of annular groove 86 and edge 92 for the snap-fit capture of lip 96 is constructed and arranged on the inner radial side of the seal element 76. A similar inner radial side construction and arrangement exists for annular groove 106 and edge 112 for the snap-fit capture of lip 116. However, as an alternative construction for seal elements 76 and 78, this inner radial side construction of gasket 60 can be flipped or reversed, similar to a mirror image, to the outer radial side. As viewed in FIG. 10, this alternative construction takes the shapes and contours which are on the left side of the metal springs 80, 82 and exchanges or reverses those shapes and contours with the shapes and contours which are on the right side of the metal springs 80, 82. The sizes, shapes and relationships of the disclosed components on one side all remain the same, only switched from side to the opposite side, and vice-versa.

(43) With regard to the construction of isolation gasket 130, as illustrated in FIG. 17, this same type of reversal from the inner radial side to the outer radial side is an option. If an imaginary axial centerline is envisioned as a tangent line to the curved base of annular groove 140, then the switch or reversal is from one side of this axial centerline to the opposite side of this axial centerline. The overall structures and structural relationships remain the same, similar to a mirror image which is a left-to-right flip over of 180 degrees.

(44) Each seal element 76 and 78 is an annular, single-piece component. The description for seal element 78 is essentially the same as for seal element 76. The details of seal element 76 are illustrated in FIGS. 13 and 14. Representative dimensions are shown and the variable dimensions, depending on NPS size, are shown by letters. Table IV provides the actual dimensions for each variable based on the corresponding NPS size.

(45) TABLE-US-00004 TABLE IV NPS Seal OD C Seal Width W Seal Snap S 0.5 0.945 0.075 0.013 0.75 1.195 0.075 0.013 1 1.395 0.075 0.013 1.25 1.745 0.075 0.013 1.5 1.995 0.075 0.013 2 2.550 0.092 0.018 2.5 3.250 0.092 0.018 3 3.750 0.092 0.018 3.5 4.250 0.092 0.018 4 4.750 0.092 0.018 5 5.750 0.092 0.018 6 6.750 0.092 0.018 8 8.760 0.092 0.018 10 11.010 0.092 0.018 12 13.010 0.092 0.018 14 14.270 0.092 0.018 16 16.270 0.092 0.018 18 18.270 0.092 0.018 20 20.270 0.092 0.018 24 24.270 0.092 0.018

(46) Referring now to FIGS. 15-17, there is illustrated an isolation gasket 130 which is constructed and arranged for more critical and extreme applications without using or requiring a steel core. Gasket 130 includes a generally cylindrical retainer 132 which in the preferred embodiment is either a G10 or G11 fiberglass laminate material measuring approximately 0.158 inches thick. Retainer 132 defines a generally concentric generally cylindrical bore 134. Retainer 132 is constructed and arranged with a pair of substantially flat opposing faces 136 and 138. A first face 136 defines an annular groove 140 for the receipt of annular seal element 142. The opposite face 138 defines an annular groove 144 for the receipt of annular seal element 146.

(47) Gasket 130 is a ring type gasket (Type F) and according to industry standards for this general type of gasket, does not include any bolt holes. Gasket 150, referring now to FIGS. 18 and 19, is a Type E isolation gasket according to the present disclosure. Gasket 150 is otherwise similar to gasket 130 in construction and function, except that a Type E gasket according to industry standards, is a full face gasket which includes bolt holes. In the exemplary embodiment gasket 150 includes four bolt holes 152 which are of generally the same size (i.e. diameter), are equally space apart and are centered on the same bolt circle 153. The center bore 154 which is defined by retainer 156 is generally concentric with the bolt circle 153. It will be understood that the bolts and the bolt pattern of the flanges being joined in combination with gasket 150 determines the number, size and spacing of bolt holes 152. With the exception of size differences and the presence of bolt holes 152, gaskets 130 and 150 are structurally and functionally essentially the same, including the material choices and options. The detailed description of gasket 130 generally corresponds to and provides the description of gasket 150.

(48) Letters are used in the drawings to represent the variable dimensions and sizes for various embodiments of gasket 130 and 150. Suitable and compatible dimensional combinations are set forth in Table V, as one example.

(49) TABLE-US-00005 TABLE V B B NPS A Ring Full Face C D E 0.5 0.62 1.76 3.5 0.945 0.07 2.38 0.75 0.82 2.13 3.88 1.195 0.07 2.75 1 1.05 2.5 4.25 1.395 0.07 3.12 1.25 1.38 2.88 4.62 1.745 0.07 3.5 1.5 1.61 3.26 5 1.995 0.07 3.88 2 2.07 4 6 2.55 0.09 4.75 3 3.07 5.25 7.5 3.75 0.09 6 3.5 3.55 6.25 8.5 4.25 0.09 7 4 4.03 6.75 9 4.75 0.09 7.5 5 5.05 7.62 10 5.75 0.09 8.5 6 6.07 8.62 11 6.75 0.09 9.5 8 7.98 10.87 13.5 8.76 0.09 11.75 10 10.02 13.25 16 11.01 0.09 14.25 12 12 16 19 13.01 0.09 17 14 13.25 17.63 21 14.27 0.09 18.75 16 15.25 20.13 23.5 16.27 0.09 21.25 18 17.25 21.5 25 18.27 0.09 22.75 20 19.25 23.75 27.5 20.27 0.09 25 24 23.25 28.12 32 24.27 0.09 29.5
Each gasket 130, 150 is constructed and arranged and suitable for use when electrical isolation and corrosion control are required on pipes containing gas, natural gas, oil and other hydrocarbon-based media up to approximately 392 degrees F. (200 degrees C.). These gasket are constructed and arranged to be suitable for flat face, raised face and ring type joint flanges from approximately 0.5 inches to 24 inches, ANSI 150-2500# and API 2-10K.

(50) Gaskets 20 and 22 are constructed and arranged in order to provide one or more performance benefits for the type of environment and the type of pipe flange applications which have been described. Similarly, gaskets 60 and 62 are constructed and arranged in order to provide one or more performance benefits for the type of environment and the type of pipe flange applications which have been described. Gaskets 130 and 150 are constructed and arranged in a manner which is intended to capture at least one benefit achieved by the construction of gaskets 20 and 22 and at least one benefit achieved by the construction of gaskets 60 and 62. The combination of these one or more extracted benefits is able to be realized by the construction and arrangement of gaskets 130 and 150.

(51) More specifically, a performance benefit of gasket 20 (and of gasket 22) is the absence of metal as part of the gasket construction. For an isolation gasket this is a benefit because it takes metal out of the equation in terms of conductivity and electrical isolation. Gaskets 130 and 150 do not include any metal core nor any metal spring. In the case of gasket 60 (and gasket 62) the thicker retainer 66 (0.25 inches) compared to the thinner construction (0.125 inches) of retainer 26 permits the addition and capture of a more substantial annular seal element 76, 78 which is spring energized. In addition to a balancing of structural features for gasket 130 (and gasket 150) in order to be able to realize performance benefits attributable to the other gasket constructions disclosed herein, gaskets 20 and 60, other structural features were introduced as a type of compromise or balancing in order to provide an improved isolation gasket which blends and balances important characteristics.

(52) For example, as the retainer is made thicker, the concerns (material creep and degradation) regarding thicker glass reinforced apoxy (GRE) materials, begin to appear. Yet a thicker retainer provides more options for the type of seal element to be used. If the GRE material is split into two thinner laminate layers and then separated by a metal core to preserve the overall thickness of the retainer, metal is then introduced into the equation for an isolation gasket.

(53) Gaskets 130 and 150 each represent a structural blend of features which result in a novel and unobvious balance of gasket performance benefits. More specifically, the retainer thickness of the preferred embodiment is approximately 0.158 plus or minus 0.005 inches. This construction is thicker than the retainer 26 of gasket 20 and thereby provides added thickness for the capture of a larger or thicker seal element. While the issues or material creep and degradation for the GRE material increase with increased axial thickness of that material, a compromise dimension of 0.158 plus or minus 0.005 inches is substantially less than the 0.25 dimension of gasket 60, without the introduction of metal into the equation. The absence of metal contributes to the performance of gasket 130 (and of gasket 150) as an isolation gasket. The seal elements 142 and 146 are able to be made larger than seal elements 28 and 30, due to the increased thickness of the retainer 132.

(54) While the axial thickness dimension of 0.158 plus or minus 0.005 inches is regarded as the preferred embodiment, it is recognized that certain existing applications may still need or prefer to have a thicker retainer and while other features of gaskets 130 and 150 provide certain performance benefits, it is recognized that a retainer thickness of 0.250 could be maintained for those specific applications or needs while at the same time still taking advantage of the other design benefits disclosed as part of gaskets 130 and 150.

(55) Referring again to FIG. 17, the specific construction and arrangement of each groove 140 and 144 is illustrated. Each groove includes a radially-outer wall surface 164 which is set at a slight outwardly incline in an axial direction. The annular base surface 166 of each groove 140, 144 is substantially flat and generally parallel with the outer surface of face 136 and with the outer surface of face 138. The radially-inner wall surface 168 of each groove is substantially parallel with the axis of bore 134 and is substantially perpendicular to base surface 166. Extending into groove 140 from surface 168 is an annular lip 170. A similar annular lip 172 exists as part of groove 144. Lip 170, and similarly for lip 172, creates an inner wall channel 174 whose three defining surfaces are provided by a portion of base surface 166, a portion of inner wall surface 168 and lip 170. This channel 174 is constructed and arranged to receive and capture a radially protruding portion 175 of seal element 142, as is illustrated. A similar construction exists with lip 172, groove 144 and seal element 146.

(56) The creation of channel 174 in cooperation with the shape of radially-outer wall surface 164 results in a novel and unobvious way to capture and retain seal element 142 in groove 140 without needing to use any adhesive or glue. Once each seal element 142, 146 is pressed into position and fully seated into its corresponding groove 140, 144, the seal element is essentially locked in position within its corresponding groove and stay in position within the corresponding groove without requiring any bonding agent or bonding material, such as adhesive or glue. The radially protruding portion 175 of each seal element 142, 146 is captured beneath the corresponding annular lip 170, 172. The size and shape of each seal element causes it to fit within its corresponding groove with only very slight radial clearance. Axial pullout due to normal handling and manipulation is prevented by the use of lip 170 (and lip 172), by the nature of the incline provided by wall surface 164 and by the overall shaping and geometry of the corresponding seal element. The gasket 130 and gasket 150 constructions disclosed herein each combine the technology of a press-in, pressure activated seal with a unique groove that retains the seal element without the use of glue or adhesive on the key or critical contact surfaces.

(57) Referring now to FIGS. 20 and 21, the structural details of seal element 142 are illustrated and seal element 146 is of essentially the same construction. Seal element 142 is a unitary, single-piece annular member with a shaping and contouring which is shown in FIG. 21. The representative dimensions of the preferred construction of seal element 142 are included. The variable dimensions which reflect the dimensions for different NPS sizes are denotes by letters. Table VI provides the actual dimensions for these letter designations as a function of the NPS size.

(58) TABLE-US-00006 TABLE VI NPS Seal OD C Seal Width W Seal Snap S 0.5 0.945 0.070 0.031 0.75 1.195 0.070 0.031 1 1.395 0.070 0.031 1.25 1.745 0.070 0.031 1.5 1.995 0.070 0.031 2 2.550 0.090 0.046 2.5 3.250 0.090 0.046 3 3.750 0.090 0.046 3.5 4.250 0.090 0.046 4 4.750 0.090 0.046 5 5.750 0.090 0.046 6 6.750 0.090 0.046 8 8.760 0.090 0.046 10 11.010 0.090 0.046 12 13.010 0.090 0.046 14 14.270 0.090 0.046 16 16.270 0.090 0.046 18 18.270 0.090 0.046 20 20.270 0.090 0.046 24 24.270 0.090 0.046
Suitable materials for seal element 142 include PTFE (Teflon), nitrile and Viton.

(59) Referring now to FIGS. 22 and 23, the structural details of an alternative seal element 180 are illustrated. Seal element 180 is a unitary, single-piece annular member with the shaping and contouring which is shown in FIG. 23. The representative dimensions of the preferred construction of seal element 180 are included. The variable dimensions which reflect the dimensions for different NPS sizes are denoted by letters. Table VII provides the actual dimensions for the letter designations as a function of NPS size.

(60) TABLE-US-00007 TABLE VII NPS Seal OD C Seal Width W Seal Snap S 0.5 0.945 0.075 0.013 0.75 1.195 0.075 0.013 1 1.395 0.075 0.013 1.25 1.745 0.075 0.013 1.5 1.995 0.075 0.013 2 2.550 0.092 0.018 2.5 3.250 0.092 0.018 3 3.750 0.092 0.018 3.5 4.250 0.092 0.018 4 4.750 0.092 0.018 5 5.750 0.092 0.018 6 6.750 0.092 0.018 8 8.760 0.092 0.018 10 11.010 0.092 0.018 12 13.010 0.092 0.018 14 14.270 0.092 0.018 16 16.270 0.092 0.018 18 18.270 0.092 0.018 20 20.270 0.092 0.018 24 24.270 0.092 0.018
Suitable materials for seal element 180 are the same as those suitable materials for seal element 142.

(61) While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.