The present invention relates generally to gaskets and, more particularly, to an improved gasket for positioning between facing conduit flanges. These facing flanges are bolted together and some of the bolted joint characteristics are relevant to the type of gasket which is selected. In terms of technological background, one general style of flange gasket is best described as a corrugated metal gasket. One example of such a corrugated metal gasket is disclosed in U.S. Pat. No. 5,421,594, which issued Jun. 6, 1995 to Marine & Petroleum Mfg., Inc. of Houston, Tex. Another general style of flange gasket is best described as a kammprofile gasket whose design and construction are covered by standard EN-12560-6.
Continuing with the technological background, a still further general style of flange gasket can be described as a spiral-wound gasket. One example of such a spiral-wound gasket is disclosed in WO 2007/087643 A2 with an international publication date of Aug. 2, 2007. Another example of a type or style of a spiral-wound gasket is disclosed in WO 2009/058738 A2 with an international publication date of May 7, 2009.
Any bolted joint experiences relaxation and load loss after initial tightening and the ability for the gasket to recover and assist in compensating for this load loss is critical. Existing corrugated metal gasket technologies utilize thin metal cores where the corrugated geometry is formed using a compression die or roll forming process. The result is a corrugated core that is thin and has minimal load bearing characteristics. Once compressed between flanges, the core easily deflects with minimal load and the corrugation memory is minimal. Relaxation in the joint correlates directly to gasket stress loss.
A kammprofile gasket, part of the existing technology, is produced from a machined substrate. This technology incorporates small machined grooves on the sealing surfaces which do not allow for any noticeable deflection in the core and therefore do not contribute to compressibility. The ability for this gasket to compensate for flange misalignment and issues with flange face parallelism are essentially nonexistent.
As described, the prior art shows first forming corrugations into a thinner metal core which is suitable for a compression die or roll forming process. Secondly, the prior art shows machining small V-shaped grooves.
The present disclosure is a hybrid gasket which involves a machining step, but machining to create corrugations. Machining the corrugated geometry into a substrate with greater 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 new construction 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.
Following is a brief summary of the advantages and disadvantages of these two prior art styles of gaskets which are described above. Advantages of a corrugated metal gasket include the following:
Disadvantages of a corrugated metal gasket include the following:
Since “low rigidity” is listed as being both an advantage and a disadvantage, a further explanation may be helpful. Low rigidity can be an advantage because it allows the gasket to be folded and bent in ways which will allow easier installation when there are space restrictions or obstructions. Low rigidity can be a disadvantage as its more fragile nature can allow over-bending which in turn can damage the graphite (or ptfe) facing.
Advantages of a kammprofile gasket include the following:
Disadvantages of a kammprofile gasket include the following:
Contributing to these various advantages and disadvantages of each style or type of gasket is the method of manufacture. The metal forming method using a compression die or roll forming process is tied to some of the listed advantages and disadvantages of the corrugated metal gasket. Similarly, the method of machining a substrate is tied to some of the listed advantages and disadvantages of the kammprofile gasket. In arriving at the disclosed and claimed embodiments of the present invention, there was an effort to try and design a gasket with a greater number of advantages and fewer disadvantages. As disclosed herein, that effort was successful by replacing in the method of manufacture the use of a metal forming operation (compression die or roll forming) with machining operations. By combining the proven concepts of a kammprofile style of gasket with those of a corrugated metal gasket, as embodied by the gasket disclosed herein, the result is a gasket construction which eliminates some of the disadvantages found in both of these prior art designs while including some of the advantages or benefits of each prior art style. For example, by utilizing a heavier core, similar to the kammprofile gasket style, the gasket disclosed herein provides increased rigidity and improved handling characteristics. There is also a high load bearing capability as well as the ability to be used in all pressure classes. By utilizing an alternating series (sinusoidal) of machined corrugations, the gasket disclosed herein has improved recovery and resilience. Further, there is improved compressibility as well as an ability to adapt to alignment deficiencies which may exist in a flange or flange combination. There is also an ability of the disclosed gasket to generate higher stress point contacts on the machined corrugations.
A corrugated metal gasket for use between two flanges wherein the corrugated metal gasket is produced by a method comprising the steps of first providing an annular gasket substrate followed by machining into that substrate a plurality of substantially uniform and generally concentric corrugations.
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.
Referring first to
Referring next to
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
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
In the
The outer guide ring 44, when used, is preferably a separate component which is securely joined to the sealing core 46 (see
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.
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
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
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
With continued reference to
A further point to note is that the actual gasket thickness (t) of flange gasket 80 in the
With continued reference to
With continued reference to
The
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.
This application is a continuation of copending U.S. application Ser. No. 15/621,175 filed on Jun. 13, 2017, which was itself a continuation of U.S. application Ser. No. 13/795,897 filed on Mar. 12, 2013, both of which claim priority to U.S. Provisional Application No. 61/615,441 filed Mar. 26, 2012. All of the foregoing are hereby incorporated by reference.
Number | Date | Country | |
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61615441 | Mar 2012 | US |
Number | Date | Country | |
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Parent | 15621175 | Jun 2017 | US |
Child | 16597330 | US | |
Parent | 13795897 | Mar 2013 | US |
Child | 15621175 | US |