AU616200B2 - Flat laminated seal ring - Google Patents

Description

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616200 COMMONWEALTH OF AUSTRAL PATENTS ACT 1952 COMPLETE SPECIFICATION FOR OFFICE USE Form Short Title: Int. Cl: '0 o 0 1 96.* S 00 0 0 000 00 S 0 00 0 0S 0S 0

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Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: II- TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: THE BABCOCK WILCOX COMPANY 1010 Common Street, New Orleans, Louisanna 70160, U.S.A.

James Henry Hipple and Don William Smith GRIFFITH HACK CO.

71 YORK STREET SYDNEY NSW 2000

AUSTRALIA

i Complete Specification for the invention entitled: FLAT LAMINATED SEAL RING The following statement is a full description of this invention, including the best method of performing it known to me/us:- 9614A/ls 1A- CASE 4893 FLAT LAMINATED SEAL RING BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to a durable, nonasbestos sealing 5 gasket capable of withstanding high temperature and pressure for oo* 0 use in water level gauge ports.

oo DESCRIPTION OF THE RELATED ART *a There are many different types of gaskets used in high temperature and-pressure applications. For example, U.S. Patent No. 4,477,094 of Yamamoto, et al discloses the use of a thin core sheet of a metal plate having a multiplicity of small projections on either one side or both sides. This sheet normally has gasketing material applied to both surfaces. This reference also teaches the use of a gasketing material such as sheet of a paper material which can be formed from a rubber or resin. Asbestos fibers, mica powder or even graphite flakes may be mixed in with the slurry. Sheetp of asbestos or expanded graphite are also well known in the art.

U.S. Patent No. 4,477,094 discloses a gasket formed from a variety of materials but primarily vermiculite surrounding a 1A.

2 CASE 4893 metal plate. This reference discusses the use of graphite as unique filler material equivalent to asbestos.

U.S. Patent No. 4,463,959 of Usher, et al, discloses a composite gasket with two spaced rings of refractory sheet material and a ring of knitted wire mesh. The wire mesh extends So into and outward from the refractory rings. This reference teaches of the use of a flexible sheet of graphite, Grafoil, a registered trademark of Union Carbide Corp. along with mica paper e rings. It points out that the differences betweeen the two are relatively insignificant when compared in that invention.

U.S. Patent No. 4,507,521 of Goellner, discloses a high p.

S. .pressure and.temperature electical conductivity probe employing a o flexible expanded graphite gasket in the cylindrical recesses.

The graphite gasket may include wire reinforcement.

These patents reflect the state of the art showing that flexible graphite material makes a suitable gasket for high temperature.

The Applicants encountered problems with the state of the art gaskets collapsing; leaking, or physically breaking down when used in water level gauge ports. Even though graphite is an adequate gasket for high temperature, when it encounters high pressure, it tends to extrude thereby causing leakage. The application service 2 i I j 1 1 1 1 1 0 0 0 o limits of these components are about 3000 psig at abut 6967F Additionally, due

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0 to the softer 'materials and nonmetallic materials in these components, there had to be no metal-to-metal sealing.

The present invention when tested was superior to spiral wound gaskets or gaskets made from mica. It has the desirable characteristics of being retrofitable, offering rigidity, resiliency without any leakage, and not requiring retorquing.

SUMMARY OF THE INVENTION The present invention resides in a flat laminated seal ring which comprises flexible graphite material with a metallic washer situated therebetween. An opening coinciding with that of the washer passes through the seal ring.

According to one aspect of the present invention there is provided a flat laminated seal ring, comprising: a metallic washer having a first and second side with an opening therethrough; and a coating of flexible graphite material on both sides of said washer, said graphite material being coextensive with said washer.

According to another aspect of the present invention there is provided a flat laminated seal ring for use in a water level gauge port having a coverplate assembly with fasteners and a centerplate assembly with a port pocket and access 20 opening, comprising: a metallic washer having a first and second side with an opening therethrough, said opening having a greater diameter than the inner diameter of "said access opening in said centerplate assembly; and a coating of flexible graphite material on both sides of said washer, said 25 graphite material being coextensive with said washer.

An object of the invention is to provide a leak-proof seal which is capable of withstanding high temperature and pressure. It has a particularly useful application when sealing smooth, softer and nonmetallic material such as water level gauge ports.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawings in which: '940-JC o 3 o 0 0 0 0 0 o a °0

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0 0 0 So 4 CASE 4893 BRIEF DESCRIPTION OF THE DRAWINGS Figure is a perspective view of the present invention.

Figure 2 is a horizontal cross-section II-II from Figure 1.

Figure 3 is an exploded view of a water level gauge port in which the present invention is utilized.

0* DESCRIPTION OF THE PREFERRED EMBODIMENT **e A smooth, corrosion resistant metallic washer having a first 0 0* and second side or center spacer ring 4 is laminated on each side e with a flexible graphite material 6. The opening 8 passing through the laminated seal ring 2 is such that the inner diameter of the flexible graphite material 6 is coextensive with that of the washer 4, as shown in Fig. 2. The laminated seal ring 2 is preferred to be flat although minor. variations in shape probably would not deter its efficiency. The shape of the flat laminated :seal ring 2 would of course ultimately depend upon its application.

The flexible graphite material 6 used in the present invention is compressed graphite flakes such as Grafoil, which is a registered.trademark pf the Union Carbide Corp. The graphite material 6 is initially attached to the washer 4 by means of a temperature, pressure adhesive known in the art. Once the CAE 89 laminated seal ring has been installed the uniform contact bearing stresses will keep it sealed. The graphite material 6 offers good sealing properties, does not deteriorate from service, provides resilience without induced creep, does not extrude, and will not *damage the mating components. The graphite material 6 provides @000 for sealing at high temperatures up to about 6960F The metallic washer 4 further provides the support necessary .06. *so that the graphite material 6 will not extrude at high pressure a:up to about 3000 psig. The washer 4 has a thickness of about 0.094 -0.099 inches and is preferably made of stainless steel.

so. The thickness of the graphite material 6 on each side of the metallic washer 4 is limited by resiliency and extrusion. The preferred thickness for application in water level gauge ports is 00 0about 0.015 in. If the graphite material 6 is thicker, it will extrude under high pressure. Conversely, if it is thinner, some of its resiliency is lost. Again, depending upon the exact application, the graphite materials' 6 thickness is another important factor.

The periphery'l0 of the metallic washer 4 can extend beyond that of the graphite material 6. In its preferred use in a water 0level gauge port, as is depicted in Fig. 3, the periphery 10 is chamferred to match the port so as to be retrofitable. This *4 0 6 CASE 4893 gasket configuration is'retrofitable for the port pocket depth of about 0.485 inch and thus does not require new port components.

The gasket will not collapse or physically break down as other types of gaskets when overloaded, and does not require retorque.

An important feature in the present invention is the flat laminated rings' 2 gasket design. There is no metal-to-metal sealing. This feature is imperative when sealing softer materials 1 and nonmetallic materials, as used in a water level gauge port configuration.

The present invention provides a durable, easily maintained, nonasbestos sealing gasket for water level gauge ports where *o smooth finishes and nonmetallic components are used at relatively low cost, without sacrificing the present equipment and *g* o* component configurations. The application service limits are about 3000 psig and about 696 0

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When the present invention was compared with a spiral wound gasket used in conjunction with a Grafoil protection gasket and a Grafoil sheet laminate gasket which required a new coverplate (see Fig. it was superior in rigidity, retrofitability, resiliency, and no leakage.

S The present invention provides a leak-proof seal in an environment of high temperature and high pressure. Referring to 7 CASE 4893 Fig. 3, there is shown the present invention being employed in a water level'gauge port. There is a centerplate assembly 12 in which the laminated seal ring 2 fits securely. Internal components 14, 16, 18 referred to as the coverplate assembly abut the seal ring 2 and fit within the centerplate assemby 12. A coverplate 20 with fasteners 22 firmly retain the seal ring 2 in the centerplate assembly 12. The construction of a water level gauge port is known in the art.

The outer diameter of the access opening 24 in the centerplate assembly 12 is about 2.062 inches with a port pocket depth of about 0.485 inches and an inner diameter 26 of about one

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inch. The flat laminated seal ring 2 has an outer diameter of about 2.052 inches with an inner diameter of about 1.420 inches.

The periphery 10 of the washer 4 is chamferred about 0.016 inch on both sides to form a frustoconical outward appearance. This allows the seal ring 2 to fit into the pocket of the centerplate 0 assembly 12. Immediately abutting the seal ring 2 is a circular laminated layered mica 14 to act as a protective media. It has an outer diameter-about equal to that of the seal ring 2. Abutting the layered mica 14 is a circular piece of glass 16 with a Grafoil wrap. The outer diameter of the glass 16 is about 1.304 inch and it has a thickness of about 0.628 inch. The glass 16 fits flush in the So 0 S- n o 8 CASE 4893 projection 28 on the coverplate 20. A protective washer 18 protects the glass 1'6 from inside metal-to-metal contact with the coverplate The coverplate assembly by means of fasteners 22 securely retains the seal ring 2 in the centerplate assembly. The fasteners 22 are initially torqued to about 25 ft/lb. and do not require retorque.

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From the nature of the present invention, it is readily apparent that its shape or form need not only be circular. This will depend on the type of water level gauge port employed or particular application. The present invention may have many S* different shapes without departing from the gist of the invention.

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Claims (7)

1. A flat laminated seal ring, comprising: a metallic washer having a first and second side with an opening therethrough; and a coating of graphite material on both sides of said washer, said graphite material being coextensive with said washer.

2. A flat laminated seal ring, as defined in claim 1, S. wherein said graphite material is about 0.015 in. thick on each side of said washer. i 3. A flat laminated seal ring, as defined in claim 1, wherein said metallic washer has a periphery slightly extending beyond said graphite material.

4. A flat laminated seal ring, as defined in claim 3, 00 0 wherein said extending periphery is chamferred. A flat laminated seal ring for use in a water level gauge port having a coverplate assembly with fasteners and a centerplate assembly with a port pocket and access opening, comprising: i- 10 CASE 4893 a metallic washer having a first and second side with an opening therethrough, said opening having a greater diameter than the inner diameter of said access opening in said centerplate assembly; and a coating o graphite material on both sides of said washer, said graphite material being coextensive with said washer. .000 **6

6. A flat laminated seal ring, as defined in claim wherein said graphite material is about 0.015 inch thick on each side of said washer. SO S7. A flat laminated seal ring, as defined in claim wherein said metallic washer is about 0.094 inch thick.

8. A flat laminated seal ring, as defined in claim S wherein said metallic washer has a periphery slightly extending beyond said graphite material.

9. A flat laminated seal ring, as defined,in claim 8, wherein said extending periphery is chamferred. j rAL L j i A flat laminated seal ring substantially as hereinbefore described with reference tocithe accompanying drawings. Dated this 9th day of September, 1988 ae 5 soap C C 550i~~ e 9 9.5. 0O 0 0O S. *5 5 6* 0 Old 6a a. seep 50 40 THE BABCOCK WILCOX COMPANY By their Patent Attorneys GRIFFITH HACK CO. 0 o, 0

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