FLANGE GASKET

Abstract

A corrugated metal gasket for use between two flanges wherein the corrugated metal gasket is produced by a method comprising the steps of providing an annular gasket substrate and machining into that substrate a plurality of substantially uniform and generally concentric corrugations.

Claims

1. A corrugated metal gasket product for use between two pipe flanges, said corrugated metal gasket product being produced by a process comprising the following steps: providing a material stock piece having an annular ring shape with a circular opening that defines a longitudinal axis, the material stock piece having an axial thickness that spans between a first face and a second face; and machining said first face and said second face by a chip removal process for shaping each face with a plurality of substantially uniform and generally concentric corrugations by removing a portion of both of said first face and said second face and a portion of said material stock piece to form a sealing core that is positioned between said machined corrugations, said machined corrugations include a plurality of alternating peaks and troughs arranged such that said peaks of said first face are aligned with said troughs of the second face and said corrugations each have a curved shape, said sealing core extending in a radial direction from an inner diameter to an outer diameter of said material stock piece and said sealing core having an axial thickness in an uncompressed state spanning between the troughs of the first face and the troughs of the second face.

2. The corrugated metal gasket of claim 1 which further includes an outer guide ring positioned exteriorly on said sealing core.

3. The corrugated metal gasket of claim 2 wherein said outer guide ring is integrated with said sealing core as a unitary corrugated metal gasket.

4. The corrugated metal gasket of claim 3 wherein the pitch of said corrugations is selected from the group consisting of approximately 0.125 inches and approximately 0.250 inches.

5. The corrugated metal gasket of claim 4 wherein an uncoated thickness of said corrugations is selected from the group consisting of approximately 0.093 inches, approximately 0.125 inches and approximately 0.250 inches.

6. The corrugated metal gasket of claim 5 wherein said corrugations are coated with graphite.

7. The corrugated metal gasket of claim 6 wherein an outside diameter of said corrugated metal gasket is approximately 6.88 inches.

8. The corrugated metal gasket of claim 6 wherein an outside diameter of said corrugated metal gasket is approximately 6.12 inches.

9. The corrugated metal gasket of claim 8 wherein an inside diameter of said corrugated metal gasket is approximately 4.87 inches.

10. The corrugated metal gasket of claim 1 wherein the pitch of said corrugations is selected from the group consisting of approximately 0.125 inches and approximately 0.250 inches.

11. The corrugated metal gasket of claim 1 wherein an uncoated thickness of said corrugations is selected from the group consisting of approximately 0.093 inches, approximately 0.125 inches and approximately 0.250 inches.

12. The corrugated metal gasket of claim 1 wherein said corrugations are coated with graphite.

13. The corrugated metal gasket of claim 1 wherein an outside diameter of said corrugated metal gasket is approximately 6.88 inches.

14. The corrugated metal gasket of claim 1 wherein an outside diameter of said corrugated metal gasket is approximately 6.12 inches.

15. The corrugated metal gasket of claim 1 wherein an inside diameter of said corrugated metal gasket is approximately 4.87 inches.

16. The corrugated metal gasket of claim 2 wherein said outer guide ring is a separate component which is assembled into said sealing core.

17. The corrugated metal gasket of claim 16 wherein said sealing core is constructed and arranged with an annular groove.

18. The corrugated metal gasket of claim 17 wherein said outer guide ring is assembled into said annular groove.

19. A corrugated metal gasket for use between two pipe flanges for sealing, said corrugated metal gasket comprising: an annular gasket substrate having a circular opening that defines a longitudinal axis, the gasket substrate having a first plurality of corrugations in a first face and a second plurality of corrugations in a second face, wherein said corrugations result from a machining step of material removal rather than material compression, the first plurality of machined corrugations and the second plurality of corrugations each include a plurality of alternating peaks and troughs arranged in a sinusoidal shape, wherein the peaks of the first plurality of machined corrugations are aligned with the troughs of the second plurality of machined corrugations, the gasket substrate having a sealing core with an axial thickness in an uncompressed state spanning between the troughs of the first plurality of machined corrugations and the troughs of the second plurality of machined corrugations , the sealing core extending radially from an inner diameter to an outer diameter of the gasket substrate.

20. A corrugated metal gasket for use between two pipe flanges for sealing, said corrugated metal gasket comprising: an annular sealing substrate having a circular opening that defines a longitudinal axis, the sealing substrate having a first plurality of corrugations in a first face and a second plurality of corrugations in a second face, wherein said corrugations result from a machining step of material removal rather than material compression, said first plurality and said second plurality of corrugations have a plurality of alternating peaks and troughs arranged in a repeating sinusoidal shape wherein said peaks of said first plurality of machined corrugations are aligned with said troughs of said second plurality of machined corrugations, said sealing substrate having a sealing core with an axial thickness in an uncompressed state spanning between said troughs of said first plurality of machined corrugations and said troughs of said second plurality of machined corrugations, said sealing core extending radially from an inner annular edge to an outer annular edge of said sealing substrate.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0028] FIG. 1 is a partial, side elevational view, in full section, of a prior art corrugated metal gasket.

[0029] FIG. 2 is a partial, side elevational view, in full section, of a prior art kammprofile gasket.

[0030] FIG. 2A is a top plan view, in full form, of the FIG. 2 gasket.

[0031] FIG. 3 is a partial, side elevational view, in full section, of a machined, corrugated metal gasket according to this disclosure.

[0032] FIG. 3A is a top plan view of the FIG. 3 gasket.

[0033] FIG. 4A is an enlarged, partial, side elevational view of the FIG. 3 gasket.

[0034] FIG. 4B is an enlarged, partial, side elevational view of an alternative gasket construction.

[0035] FIG. 4C is an enlarged, partial, side elevational view of an alternative gasket construction.

[0036] FIG. 5 is an enlarged, partial, side elevational view of the FIG. 3 gasket based on alternative dimensions.

[0037] FIG. 6 is an enlarged, partial, side elevational view of the FIG. 3 gasket based on alternative dimensions.

[0038] FIG. 7 is an enlarged, partial, side elevational view of the FIG. 3 gasket based on alternative dimensions.

[0039] FIG. 8 is a graph showing gasket comparisons with gasket stress and thickness defining the axes.

[0040] FIG. 9 is a partial, side elevational view, in full section, of a machined, corrugated metal gasket according to this disclosure.

[0041] FIG. 10 is a partial, side elevational view, in full section, of a machined, corrugated metal gasket according to this disclosure.

[0042] FIG. 11 is a partial, side elevational view, in full section, of a machined, corrugated metal gasket according to this disclosure.

[0043] FIG. 12 is a graph showing gasket comparisons with gasket stress and thickness defining the axes.

DETAILED DESCRIPTION

[0044] For the purposes of promoting an understanding of the disclosure, 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 disclosure is thereby intended, such alterations and further modifications in the illustrated device and its use, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.

[0045] Referring first to FIG. 1, a prior art style of annular flange gasket 20 for use in a bolted flange joint is illustrated in partial, cross-sectional form. The focus of FIG. 1 is on the cross-sectional shape of the corrugations 22 which have a generally sinusoidal shape in a radial direction. The letter “R” reference with arrows are added to FIG. 1 to show the radial direction. This style of gasket is typically referred to as a corrugated metal gasket (CMG). The corrugations 22 are generally concentric with a generally uniform shape and a generally uniform spacing. The relevant dimensional information includes the peak-to-peak pitch (A), the overall height or thickness (B), and the material thickness (C). While these dimensions may vary a little, the most common dimensions which are typical of the majority of prior art constructions set the pitch (A) at approximately 0.125 inches (3.175 mm), the corrugation height or thickness (B) at approximately 0.125 inches (3.175 mm), and the overall material thickness (C) at approximately 0.031 inches (0.787 mm), which is in the range of a 22 gauge material.

[0046] Referring next to FIG. 2, a prior art style of annular flange gasket 30 for use in a bolted flange joint is illustrated in partial, cross-sectional form. The focus of FIG. 2 is on the machined grooves 32 and their cross-sectional shape and dimensions. The machined grooves 32 are uniformly sized and shaped and are equally-spaced apart (concentric) into the radial pattern (i.e., concentric sequence) which is also illustrated in the top plan view of FIG. 2A. This style of flange gasket is typically referred to as a “kammprofile” flange gasket. The machined groove depth (d) is typically 0.015 inches (0.381 mm) and the sidewall angles (a) are each typically 45 degrees off of vertical or horizontal. These machined grooves 32 are essentially used to receive and hold a graphite coating. While conceivably machined grooves 32 could be machined into only one facing surface of the core metal (i.e., substrate), it is more common in terms of prior art constructions, and clearly in the vast majority, for the grooves 32 to be machined into both facing surfaces of the core metal in a uniform pattern (see FIG. 2).

[0047] According to the present disclosure and consistent with the claimed construction, it has been discovered that it is possible to change the construction or fabrication method for the type and style of the gaskets of FIGS. 1 and 2 and thereby create an improved product by the selected fabrication process, as disclosed herein. Some of the advantages and disadvantages of each of the prior art gasket style of FIGS. 1 and 2 have been identified in the Background portion herein.

[0048] What has been discovered is that forming or machining a corrugated geometry (i.e., generally sinusoidal shape) into a substrate of greater material thickness (i.e. overall height in an axial direction) by a metal working process creates a unique gasket structure with added advantages and with fewer disadvantages as compared to the two prior art gasket styles disclosed and discussed herein in the context of FIGS. 1 and 2. This new corrugated gasket geometry, according to an exemplary embodiment based on the present disclosure, is illustrated in FIGS. 3, 3A, 4A, 4B and 4C. A partial, cross-sectional view of essentially the entire flange gasket 40 is illustrated in FIG. 3. FIG. 3A provides a top plan view of gasket 40. An enlarged view of the machined corrugations 42 of one embodiment is illustrated in FIG. 4A. The corrugations 42 are formed into the exposed face surfaces 42a and 42b of a thicker annular gasket substrate 46 as compared to the corrugations of FIG. 1 which are formed using a compression die or by a roll forming process. The annular gasket substrate 46 is also referred to herein as the sealing core 46 due in part to its structural relationship with the outer guide ring 44. The rounded corrugations 42 have a uniform, generally sinusoidal shape and repeating pattern which is significantly different from the shallow, 45 degree grooves 32 which are machined into the thicker FIG. 2 substrate for that kammprofile style of gasket.

[0049] In the FIG. 4A illustration of gasket 40, the inner portion (i.e., sealing core) 46 of machined corrugations 42 in each opposed face surface is assembled with an optional annular outer guide ring 44. When the disclosed gasket 40 is used with raised face flanges, the outer guide ring 44 which surrounds the outer annular edge of the substrate is used for alignment purposes in the flanges. The outer guide ring 44 is not used with recessed flanges, such as male to female flanges. In this style of flange joint, only the sealing core 46b of the machined corrugations is used, see FIG. 4C. The preferred material for the sealing core 46 is 316 stainless steel.

[0050] The outer guide ring 44, when used, is preferably a separate component which is securely joined to the sealing core 46 (see FIG. 4A). An alternative construction is to fabricate (i.e., machine) the outer guide ring 44 as an integral part of the sealing core 46, see FIG. 4B. In this drawing, the integral outer guide ring is item or portion 44a and the sealing core is item or portion 46a. The overall gasket representing this unitary construction is item 40a. In terms of the fabrication, the preferred construction of having two separate components as in FIG. 4A means that an annular groove 48 is machined into and around the outer annular edge face 49 of the sealing core 46. The outer guide ring 44 is installed (i.e., inserted) into this annular groove. These two components can be additionally secured together to avoid separation when the sealing core 46 is manipulated as part of flange assembly.

[0051] The machining method for the machined corrugations of the disclosed sealing core begins with the specifying and selection of the appropriate material, based in part on the intended application. An annular ring shape is initially machined from the selected (raw) material stock with an initial size based on the specific application. The machining of this starting material into this starting form uses either a water jet or laser. As another option, a straight strip can be formed into a ring shape and then welded to form a continuous, annular ring. The ring is next mounted on a lathe or CNC machine where the corrugated profile is cut by radial machining. The desired corrugated geometry can be fabricated by means of a milling operation.

[0052] The peak-to-peak pitch (A) has a preferred dimension of 0.125 inches (3.175 mm). The overall substrate height or thickness (B), as machined into corrugations 42, has a preferred dimension of 0.125 inches (3.175 mm). The material thickness (C) of the material which is shaped into the series of corrugations has a preferred dimension of 0.125 inches (3.175 mm). The new machined corrugation construction for flange gaskets 40, 40a and 40b (see FIGS. 3, 4A, 4B and 4C), has been discovered to provide certain of the advantages of both the corrugated metal gasket and the kammprofile gasket as described above in the context of FIGS. 1 and 2, without including all of the disadvantages of these two prior art gasket styles. Machining the corrugated geometry into a substrate with greater material thickness, according to the present disclosure, creates a higher degree of stiffness and allows the gasket to recover more closely to the original corrugated geometry. This thus aids in maintaining critical gasket stress. The ability for the gasket to deflect from a greater thickness to a lesser thickness is compressibility. This compressibility characteristic of the gasket allows the gasket to compensate for misalignment and flange parallelism issues as well as increase the ability to seal imperfect connections. The machined gasket disclosed herein with its corrugated geometry results in a style of gasket which is able to combine certain advantages of both the thin corrugated gasket design as well as the machined serrated gasket design and in so doing eliminate certain disadvantages of both of these prior art styles.

[0053] FIGS. 5, 6, and 7 illustrate three alternative embodiments for a flange gasket according to the machined substrate method and the resulting corrugation configurations, as disclosed herein. The materials and dimensions for each flange gasket 50, 60, and 70 are listed below in Table I.

TABLE-US-00001 TABLE I Gasket Corru- Outer Seal- A B C Ref. gation Guide ing Dimension Dimension Dimension No. Ref. No. Ring Core (inches) (inches) (inches) 50 52 54 56 .125 .125 .125 60 62 64 66 .250 .125 .125 70 72 74 76 .125 .250 .250

[0054] In evaluating the performance characteristics and properties of flange gasket 40, load versus deflection testing was conducted in order to compare several flange gasket styles. Referring to FIG. 8, a graph showing this gasket comparison is provided. The gasket constructions being compared include a corrugated metal gasket (CMG), a kammprofile gasket, a spiral-wound gasket, a double-jacketed (DJ) gasket, and the “new” gasket according to this disclosure. The “new” gasket is identified as “CorruKamm” which represents having beneficial properties of the two prior art constructions referenced herein. A double-jacketed gasket is one of the common designs used in heat exchanger applications. The new gasket construction disclosed herein is suitable as an improved replacement for a double-jacketed gasket. The X-axis of FIG. 8 represents gasket stress in ksi units. The Y-axis of the FIG. 8 graph represents the thickness of the gasket in inches. The gasket comparison process involved subjecting each gasket style to cyclic loading and unloading in an axial direction, as a way to simulate the compression as the flanges are bolted together. This testing approach is used in an effort to try and simulate a more extreme situation where the gasket loading can fluctuate. At each gasket loading level from 5 ksi to 60 ksi for each load cycle, the gasket compression is maintained for approximately sixty (60) minutes.

[0055] The graphic representation for each gasket style illustrates how the gasket can help compensate for these loading fluctuations through physical recovery. The recovery allows the gasket stress to be maintained through the cyclical activity. As illustrated in FIG. 8, there is a clear advantage found with the “new” gasket (CorruKamm) which was constructed for this comparison consistent with the gasket structure disclosed and claimed herein. This “clear advantage” is seen in the form of the extent or degree of gasket thickness recovery points (P.sub.1 and P.sub.2). These recovery points (P.sub.1 and P.sub.2) show that the thickness of the CorruKamm gasket returns closer to its starting gasket thickness than any of the other gasket styles represented on the FIG. 8 graph. A related improvement from the new “CorruKamm” gasket is improved sealability. Other relevant parameters with regard to what is illustrated in FIG. 8 include running this gasket comparison at ambient temperature with a 60 ksi bolt stress in a 4 inch (10.16 cm) 150 class flange. Although the referenced testing, reflected by the FIG. 8 results, was conducted at “ambient temperature”, it is noted that the actual valves may change at different temperatures. However, the relative numbers for comparison of different gasket styles is expected to be generally the same regardless of the temperature.

[0056] FIGS. 9, 10 and 11 illustrate three embodiments of a flange gasket according to the present disclosure, similar to what has already been described for FIGS. 3-7. These three flange gasket embodiments correspond to the three CorruKamm embodiments (C-K80, C-K85 and C-K90) which are represented by the test results of FIG. 12. The FIG. 12 graph, similar to the layout of the FIG. 8 graph, places the gasket thickness (in inches) along the Y-axis and the gasket stress or load (in ksi units) along the X-axis.

[0057] With continued reference to FIG. 9, the illustrated flange gasket 80 has an axial thickness (t) of 0.125 inches (3.175 mm) and a pitch frequency (f) for the machine corrugations of 0.125 inches (3.175 mm). The outside diameter dimension (D) is 6.88 inches (17.475 cm). The inside diameter dimension (d.sub.1) is 4.87 inches (12.370 cm). The outside diameter dimension (d.sub.2) of the corrugation portion is 6.19 inches (15.723 cm). This flange gasket 80 style is denoted in the FIG. 12 graph by the designation label “C-K80” representative of the “CorruKamm” style and the specific embodiment of FIG. 9.

[0058] A further point to note is that the actual gasket thickness (t) of flange gasket 80 in the FIG. 12 graph (C-K80) is approximately 0.197 inches (5.004 mm) based on a starting construction of 0.125 inches (3.175 mm). The increased overall thickness of 0.072 inches (1.829 mm) for the C-K80 gasket as tested is due to the addition of a graphite coating on the starting gasket sizes which are illustrated in each of FIGS. 9, 10 and 11. The FIG. 12 graph includes flange gaskets with a coating while the base constructions of FIGS. 9-11 represent the “as machined” construction, without any coating. The same is true for what is represented by the graph of FIG. 8. The starting thickness is greater than the base core of the flange gasket due to the addition of a coating.

[0059] With continued reference to FIG. 10, the outside diameter dimension (D) of flange gasket 85 is 6.12 inches (15.545 cm). The inside diameter dimension (d) is 4.87 inches (12.370 cm). This flange gasket is identified in the FIG. 12 graph by the designation label “C-K85”. Flange gasket 85 has a thickness (t) of 0.093 inches (2.362 mm) and a pitch frequency (f) for the machined corrugations of 0.125 inches (3.175 mm).

[0060] With continued reference to FIG. 11, the outside diameter dimension (D) of flange gasket 90 is 6.12 inches (15.545 cm). The inside diameter dimension (d) is 4.87 inches (12.370 cm). This flange gasket is identified in the FIG. 12 graph by the designation label “C-K90”. Flange gasket 90 has a thickness (t) of 0.125 inches (3.175 mm) and a pitch frequency (f) for the machined corrugations of 0.250 inches (6.350 mm).

[0061] The FIG. 12 graph clearly shows that each flange gasket 80, 85 and 90 according to this disclosure exhibits superior properties in terms of recovery through loading cycles. These superior properties exist even when the specifics of the flange gaskets, according to this disclosure, are changed dimensionally, see FIGS. 9, 10 and 11. The actual values of the FIG. 12 graph are presented below in Table II.

TABLE-US-00002 TABLE II (all dimensions are in inches) CorruKamm CorruKamm with ⅛″ CorruKamm with ⅛″ pitch pitch and with ¼″ pitch and ⅛″ core 3/32″ core and ⅛″ core thickness thickness thickness Bolt Flange Gasket Flange Flange Gasket Loading Stress Spiral 80 Gasket 85 90 cycle (ksi) CMG Kammprofile Wound DJ (C-K80) (C-K85) (C-K90) 1st 0 0.085 0.195 0.177 0.132 0.197 0.157 0.192 5 0.082 0.185 0.168 0.128 0.188 0.154 0.189 10 0.076 0.175 0.162 0.121 0.185 0.152 0.185 15 0.073 0.176 0.157 0.117 0.185 0.149 0.183 20 0.071 0.176 0.151 0.115 0.182 0.146 0.178 25 0.07 0.175 0.145 0.113 0.174 0.138 0.172 30 0.068 0.175 0.132 0.107 0.168 0.138 0.169 35 0.067 0.175 0.131 0.102 0.163 0.135 0.166 40 0.067 0.174 0.13 0.097 0.16 0.124 0.163 45 0.066 0.174 0.129 0.095 0.159 0.118 0.161 50 0.066 0.174 0.128 0.094 0.157 0.115 0.158 55 0.066 0.174 0.128 0.093 0.156 0.112 0.155 60 0.065 0.174 0.127 0.091 0.155 0.11 0.152 2nd 0 0.069 0.178 0.135 0.097 0.188 0.149 0.182 5 0.069 0.178 0.134 0.096 0.186 0.146 0.179 10 0.068 0.177 0.132 0.095 0.184 0.144 0.177 15 0.067 0.175 0.13 0.094 0.183 0.142 0.175 20 0.066 0.175 0.128 0.093 0.181 0.137 0.171 25 0.066 0.174 0.128 0.09 0.172 0.134 0.168 30 0.066 0.174 0.127 0.09 0.166 0.132 0.166 35 0.066 0.174 0.127 0.09 0.161 0.129 0.164 40 0.066 0.173 0.127 0.089 0.16 0.126 0.161 45 0.065 0.173 0.126 0.089 0.157 0.124 0.16 50 0.064 0.173 0.126 0.089 0.154 0.121 0.157 55 0.064 0.173 0.125 0.089 0.153 0.118 0.154 60 0.064 0.173 0.125 0.088 0.153 0.115 0.152 3rd 0 0.066 0.175 0.13 0.093 0.187 0.147 0.18 5 0.066 0.175 0.13 0.092 0.186 0.144 0.179 10 0.065 0.175 0.129 0.091 0.183 0.142 0.178 15 0.065 0.173 0.129 0.09 0.181 0.14 0.176 20 0.065 0.173 0.129 0.089 0.18 0.137 0.173 25 0.065 0.173 0.128 0.089 0.179 0.136 0.171 30 0.064 0.172 0.127 0.089 0.164 0.135 0.167 35 0.064 0.172 0.127 0.088 0.16 0.132 0.164 40 0.064 0.172 0.126 0.088 0.159 0.129 0.161 45 0.064 0.172 0.126 0.088 0.155 0.126 0.158 50 0.063 0.172 0.126 0.087 0.152 0.124 0.155 55 0.063 0.172 0.125 0.087 0.151 0.121 0.153 60 0.063 0.172 0.125 0.087 0.151 0.118 0.151

[0062] While the preferred embodiment of the invention has been illustrated and described in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that all changes and modifications that come within the spirit of the invention are desired to be protected.