CA1290641C

CA1290641C - Composite rupture disk assembly

Info

Publication number: CA1290641C
Application number: CA000575512A
Authority: CA
Inventors: Stephen Farwell; Mitchel Rooker
Original assignee: BS&B Safety Systems LLC
Current assignee: BS&B Safety Systems LLC
Priority date: 1988-06-24
Filing date: 1988-08-24
Publication date: 1991-10-15
Anticipated expiration: 2008-10-15
Also published as: FR2633362B1; GB2220032A; JPH0211977A; JPH0625677U; DE3901586A1; JPH0736217Y2; DE3901586C2; GB2220032B; FR2633362A1; GB8829910D0

Abstract

PATENT
E.D. 145 Abstract of the Disclosure An improved composite rupture disk assembly adapted to be supported between inlet and outlet supporting members is provided. The assembly is comprised of a resilient sealing member and a rupture member having a plurality of elongated openings formed therein which extend outwardly from a cen-tral portion thereof. At least one rupture pressure deter-mining score is formed in the rupture member connecting the inner ends of two or more of the elongated openings so that rupture of the composite assembly occurs when pressure is exerted on the sealing member and transmitted to the rupture member at a level equal to or exceeding the rupture pressure of the rupture member.

Description

~2~0~
PATENT
E.D. 145 COMPOSITE RUPTURE DISK ASSEMBLY
Background of the Invention -l. Field of the Invention The present invention relates to a composite rupture disk assembly, and more particularly, to an improved com-posite rupture disk assembly of the type which includes a resilient sealing member and a rupture member.

2. Description of the Prior Ar_ A variety of saEety pressure relief devices of the rup-turable type have been developed and used heretofore.
Commonly, such devices include a rupture member or disk which is of a particular strength whereby it ruptures when a predetermined fluid pressure is exerted thereon. The rup-ture disk is most often clamped between a pair of annular supporting members positioned in a pressure relief passage-way or conduit connected to a pressure vessel or system being protected by the rupture disk.
While safety pressure relief devices comprised of a single rupture disk supported between supporting members are commonly utili2ed in particular applications, composite rup-ture disk assemblies comprised of two or more parts are also commonly used. A particular type of composite rupture disk assembly to which this invention relates is comprised of a metallic or other rigid material rupture member positioned adjacent a resilient sealing member. Such composite rup-ture disk assemblies are adapted to be clamped between annular supporting members, and often include several other parts in addition to the rupture member and resilient sealing member.
The rupture member includes openings formed therein whereby when fluid pressure is exer-ted on the sealing mem-ber, the sealing member is pressed against the rupture mem-ber and the fluid pressure is transmitted to the rupture member. When the pressure reaches a predetermined rupture pressure, i.e., the pressure at which the rupture member is designed to fail, rupture occurs whereby -the rupture member as well as the sealing member tear open and fluid pressure is relieved through the annular supporting members.
In applications where reverse pressures can be encoun-tered, e.g., a vacuum can be generated within the vessel or -1- a~

system being protected, a support member is provided which is positioned on the side of the resilient sealing member opposite the rupture member. When reverse pressure is applied to the composite assembly, the sealing member is pressed against the support member which either prevents the sealing member from rupturing, or the support member rup-tures when the reverse pressure reaches a predetermined rup-ture pressure thereby relieving fluid pressure in the reverse direction.
Heretofore, the rupture member of the above-described type of composite rupture disk assembly has included a plurality of elongated openings formed therein, generally in the form of slits, which extend outwardly from a central portion towards the periphery of the rupture member. The slits have included enlarged circular holes at the inner and outer ends thereof, and the slits and holes have defined sector shapes in the rupture member. In order to control and predetermine the rupture pressure of the rupture member, the distance between the closest of the holes at the inner ends of adjacent slits and the thickness of the material from which the rupture member is formed have been variedO
That is, a trial and error procedure has been employed whereby one or more rupture members of an initial material thickness with a particular hole distance are manufactured and tested. Depending upon the resultant rupture pressure of the initial rupture members, additional rupture members are produced and tested with changes in the hole distance and/or in the material thickness until the desired rupture pressure is obtained. A group of rupture members is then produced identical in material thickness and hole distance to the rupture member having the desired rupture pressure.
As is well understood by those skilled in the art, the trial and error procedure described above is tedious, time-consuming and expensive. By the present invention an improved rupture member and composite rupture disk assembly including the rupture member are provided wherein the holes at the ends of the slits can optionally be eliminated and, more i~portantly, instead of controlling the rupture pres-sure by means of the distance between adjacent holes or the thickness of the material forming the rupture member, one or ~L2~ 41 more scores are formed in the rupture member between at least two of the elongated openings formed therein. Such score or scores are easily formed in a rupture member, and allow a single thickness of material to be used for rupture members having a variety of predetermined rupture pressures as well as a more economical trial and error procedure to be followed and a more economical composite rupture disk assembly to be produced.

Summary of the Invention An improved composite rupture disk assembly adapted to be supported between inlet and outlet annular 3upporting members is provided. The assembly is comprised of a resi-lient sealing member and an adjacently positioned rupture member having a plurality of elongated openings formed therein. At least one rupture pressure determining score is formed in the rupture member connecting the ends of two or more of the elongated openings so that rupture of the assem-bly occurs when pressure is exerted on the sealing member and transmitted to the rupture member at a level equal to or exceeding the rupture pressure of the rupture member.
In preferred embodiments, the elongated openings extend outwardly from a central portion defining a plurality of sector shapes in the rupture member, or the elongated open-ings lie on a line defining a substantially circular shape in the rupture member.
It is, therefore, an object of the present invention to provide an improved composite rupture disk assembly.
A further object of the present invention is the provi-sion of an improved rupture member for use in a composite rupture disk assembly having one or more rupture pressure determining scores formed therein thereby making the rupture member manufacturing procedure less complicated and less expensive to carry out.
Another object of the present invention is the provision of an improved composite rupture disk assembly which is less expensive to produce.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of pre-1L2~3~
ferred embodiments which follows when taken in conjunctionwith the accompanying drawings.

Brief Description of the Drawings FIGURE 1 is an exploded perspective view showing the various parts of one form of a composite rupture disk assembly of the present invention.
FIGURE la is a view similar to FIGURE 1 showing an alternate form of composite rupture disk assembly of the present invention.
FIGURE 2 is a top plan view of a rupture member of the present invention utilized in the assembly illustrated in FIGURE 1.
FIGURE 2a is a top plan view of an alternate form of rupture member of the present invention which can be uti~
lized in the assembly of FIGURE 1.
FIGURE 2b is a top plan view of another alternate form of rupture member of the present invention which can be uti-lized in the assembly of FIGURE 1.
FIGURE 3 is a vertical cross-sectional view of the com-posite rupture disk assembly of the present invention mounted between a pair of annular support members.
FIGURE 4 is a vertical cross-sectional view similar to FIGURE 4 but showing the composite rupture disk assembly after rupture has taken place.

Description of Preferred Embodiments Referring now to the drawings and particularly to FIGURES 1-4, one form of composite rupture disk assembly of the present invention is illustrated and generally desig-nated by the numeral 10. The assembly 10 includes an annu-lar positioning member 12, a rupture member 14 positioned adjacent the positioning member 12, a resilient sealing member 16 positioned adjacent the rupture member 14, and a support member 18 positioned adjacent the sealing member 16.
The positioning member 12 is formed of rigid material and includes a central upstanding frusto~conical portion 20 and an annular flat flange portion 22. The use of -the posi-tioning member 12 with the assembly 10 is optional, but when included it functions to position the assembly in annular . ~ :

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supporting members between which it is clamped (as shown in FIGURES 3 and 4) as well as to protect the concave-convex portion of the rupture member 14 from damage during handling.
The rupture member 14 is a substantially circular sec-tion of thin rigid material hving a concave-convex portion 24 connected to an annular flat flange portion 26. A plura-lity oE enlongated openings are formed in the concave-convex portion 24 of the rupture member 14 which extend outwardly from a central portion 25 thereof. In the ~orm illus-tra-ted in FIGURES 1-4, the elongated openings are slits 28 which are equally spaced around the concave-convex portion 24 and which radiate outwardly from the central portion 25. The slits 28 terminate near the annular flat flange portion 26 of the rupture member 14 thereby defining a plurality of sector shaped portions 27 therein.
As illustrated in FIGURE la, the rupture member, desig-nated by the numeral 14a therein, including the slits 28 extending outwardly from the solid portion 25, can be flat.
While the elongated openings 28 are preferably slits as shown, it will be understood that other forms of elongated openings can be utilized in both rupture members including concave-convex portions and rupture members which are flat.
For example, as shown in FIGURE 2a wherein the rupture member is designated by the numeral 14b, the elongated open-ings 28 can be slots. Also as shown in FIGURE 2a, the elon-gated openings 28 can be arcuate and lie on a line defining a substantially circular shape in the rupture member 14b.
The term "substantially circular shape'i is used herein to mean a circle, elipse or a series of straight lines defining a poly-sided shape. Generally, the elongated openings 28 can be straight, curved or other configuration, and can be in the form of slits, slots, a series of connected openings of individual shape or shapes, or very deep scores connect-ing or positioned adjacent openings.
As shown in FIGURE 2b, and as has heretofore been the practice, the elongated openings 28 can terminate in en-larged openings. That is, the rupture member, designated as 14c in FIGURE 2b, can include circular openings 30 at the inner and outer ends of each of slits 28. The openings 30 ~90~
can be located at only the inner ends of the elongated open-ings 28 and can take other shapes such as square, triangu-lar, etc.
In order to control and predetermine the rupture pres-sure of the rupture member 14, at71east one rupture pressure determining score connecting the inner ends of two or more of the elongated openings 28 are Eormed therein. For example, as shown in FIGURES 1 and 2, a plurality of arcuate rupture pressure determining scores 32 forming a continuous circle are formed in the rupture member 14 connecting the inner ends of all of the slits 28. The term "rupture pres-sure determining score" is used herein to mean a groove or indentation or a series of grooves or indentations (similar to a dashed line) formed in a surface of the rupture member having the effect of forming lines of weakness in the rup-ture member whereby when a predetermined rupture pressure is exerted on the rupture member, rupture is initiated by the tearing of the rupture member at such groove or indentation or series of grooves or indentations. The term "connecting the ends" is used herein to mean that the rupture pressure determining score or scores either intersect the end por-tions of two or more elongated openings or terminate in close proximity thereto.
As shown in FIGURES la and 2b, the scores 32 can connect between less than all of the inner ends of the elongated openings 28, or a single score 32 can connect between two of the inner ends of adjacent elongated openings 2~. As shown in FIGURE 2a, the scores 32 can be arcuate and connect be-tween the ends of arcuate elongated openings 28 whereby the scores 32 and the elongated openings 28 lie on a line defin-ing a circle. Also, the score or scores 32 can be straight or of other configuration.
The arrangement illustrated in FIGURE 2 wherein the scores 32 connect between all of the inner ends of the slits 28 is generally utilized in low pressure applications, and because the individual scores 32 form a circle, a single circular die can be utilized for forming the scores. In higher pressure applications where there is more force exerted on the central portion 25 of the rupture member 14 tending to disconnect it from all of the sector shaped por-i~g~

tions defined by the slits 28, the score conEigurationillustrated in FIGURE la can be utilized. That i5, because in the configuration shown in FIGURE la a score does not connect between two of the inner ends of adjacent slits 28, the central portion 25 remains connected to the sector shaped portion defined by those slits. In other applica-tions involving high pressures, a single score connecting between the inner ends of two adjacent scores can be uti-lized. Upon rupture, tearing takes place at the score which causes one sector shaped portion to open. The force of the pressuri~ed fluid flowing through the sector shaped opening formed causes tearing between the inner ends of all but one pair of the other slits 28 whereby full opening occurs with the central portion 25 remaining connected to one of the sector shaped portions.
Positioned adjacent the rupture member 14 on the oppo-site side thereof from the positioning member 12 is the resilient sealing member 16. The sealing member 16 is generally formed of a resilient corrosion resistant plastic material and is of a peripheral size and shape corresponding with the peripheral size and shape of the rupture member 14.
The support member 18 can take a variety of forms. For example, as shown in FIGURE 1, it can be a flat circular member formed of rigid material having a diameter greater than the diameters of the members 12, 1~ and 16 so that a peripheral portion can be folded upwardly forming an annular lip 33. Upon assembly of the members 12, 14, 16 and 18 in nesting relationship, the lip 33 can be folded over the outer peripheral edges of the members 12, 14 and 16 as shown in FIGURES 3 and 4 whereby the members are rigidly clamped together. The îlat circular portion of -the support member 18 includes a plurality of slots 34 radiating outwardly from a central portion 36 and terminating near the periphery thereof forming a plurality of sector shaped portions 38 therein. As indicated above, the support member 18 func-tions to support the sealing member 16 when a reverse pres-sure such as a short-term vacuum is exerted across the assembly 10. In applications where it is desired to posi-tively relieve fluid pressure in both directions through the assembly 10, the support member 18 can itself be a rupture 12~ ;4~

member and function in the same manner as the rupture member 14.
Referring now -to FIGURES 3 and 4, the assembled compos-ite rupture disk assembly 10 is illustrated clamped between a pair of annular supporting members 40 and 41, e.g., pipe flanges. Studs 42 and nuts 44 retain the annular supporting members 40 and 41 in clamped and sealed engagemen-t with the assembly 10 so that fluids undex pressure contained within the condui-t 46 connected to the annular supporting member 40 and to a pressure vessel or system (not shown), are pre-vented from passing into the annular supporting member 41 and a conduit 48 connected thereto. A conventional gasket is positioned between the assembly 10 and the annular supporting member 40.
The annular supporting members 40 and 41 include raised face portions 50 which coact with the annular flange por-tions of the assembly 10. The upstanding frusto-conical portion 20 of the positioning member 12 extends within the annular supporting member 41 thereby automatically position-ing the assembly 10 centrally within the annular supporting members 40 and 41 during installation.
In operation of the assembly 10, fluid pressure from the vessel or system being protected is exerted on the sealing member 16 of the assembly 10 by way of the conduit 46, the annular supporting member ~0 and the slots 34 of the support member 18. As a result, the resilient sealing member 16 deforms into contact with the concave surface of the rupture member 14. Upon pressure reversal, e.g., the temporary existence of a vacuum in the pressure system or vessel being protected or the reverse exertion of pressure by way of the conduit 48, the annular supporting member 41 and the slits 28 of the rupture member 14 against the sealing member 16, the sealing member 16 deforms into contact with the support member 18. The slots 34 of the support member 18 are posi-tioned such that the support member 18 can support the resi-lient sealing member 16 under a predetermined reverse pressure, but readily ruptures and opens upon the rupture of the rupture member 14 and sealing member 16 in the opposite direction.
As indicated above, the fluid pressure exerted on the assembly 10 from the pressure vessel or system being pro-~2~
tected is transmi-tted to the concave surface of the rupture member 14 thereby placing it in tension. Upon reaching the rup-ture pressure of the scores 32, i.e., exceeding the ten-sile strengths of the solid portions of the rupture member 14 beneath the scores 32 between the inner ends of the slits 28, the rupture member 14 ruptures by tearing along the scores 32. Because of manufacturing variances in the lengths of material portions between the inner ends of the slits 28, all of the portions of the rupture member 14 be-tween the inner ends of the slits 28 tear except for one such portion (having the greatest length) to which the cen-tral portion 25 thereof remains connected. When the rupture member 14 ruptures, the resilient sealing member 16 also ruptures causing pressure to be relieved through the assem-bly 10. The force of the pressure release, i.e., the flow of pressurized fluid through the assembly 10, causes the support member 18 to also open. That is, the tensile strength of the portions of the support member 18 lying be-tween the inner ends of the slots 34 is exceeded by the force of pressurized fluid passing through the slots 34 thereby causing the support member 18 to tear between the inner ends of the slots 34. However, as in the case of the rupture member 14, one portion of the support member 18 be-tween -two of the inner ends of the slots 34 remains intact to which the central portion 36 remains attached. As illus-trated in FIGURE 4, after rupture and initial pressure release, the composite rupture disk assembly 10 is opened with the sector shaped portions 27 of the rupture member 14 and the sector shaped portions 38 of the support member 18 bent upwardly providing full pressure relief to the pressure vessel or system being protected. The central portion 25 of the rupture member 14 remains attached to one of the sector shaped portions 27 thereof and the central portion 36 of the support member 18 remains attached to one of the sec-tor shaped portions 38 thereof. As indicated, upon rupture, the resilient sealing member 16 also ruptures in sector shaped portions substantially similar to the sector shaped portions 27 of the rupture member 14.
The composite rupture disk assembly of this invention can omit the positioning member 12 and/or the support member _~_ 129(~i4~

18 of the assembly 10, and can be comprised only of the rup-ture member 14 and the sealing member 16 as illustrated in FIGURE la. Optionally, the assembly can be comprised of a pair of rupture members 14, either flat or including a concave-convex portion with the resilient sealing member 16 positioned therebetween. The use of one or more rupture pressure determining scores formed in the rupture member and connecting the ends of two or more of the elongated openings to control the predetermined rupture pressure of the rupture member simplifies the manufacturing procedure described above and allows a single thickness of material to be used for forming the rupture member over a wide rupture pressure range. This results in a less expensive composite rup-ture disk assembly product as well as the more accurate control of the rupture pressure of such product.
The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those inherent therein. While pre-sently preferred embodiments of the invention are given for the purpose of this disclosure, numerous changes in the details of construction and arrangement of parts can be made which will readily suggest themselves to those skilled in the art.
What is claimed is:

. .
:

Claims

1. In a composite rupture disk assembly adapted to be supported between inlet and outlet supporting members which includes a resilient sealing member and a rupture member having a plurality of elongated openings formed therein, the rupture member being positioned adjacent the sealing member whereby rupture takes place when pressure exerted on the sealing member and transmitted to the rupture member reaches a predetermined rupture pressure, the improvement which com-prises said rupture member having at least one rupture pressure determining score formed therein connecting the ends of two or more of said elongated openings.

2. The rupture disk assembly of claim 1 wherein said elongated openings extend outwardy from a central portion of said rupture member and said rupture pressure determining score connects the inner ends of said elongated openings.

3. The rupture disk assembly of claim 1 wherein said elongated openings are arcuate and are positioned on a line defining a substantially circular shape in said rupture member.

4. The rupture disk assembly of claim 1 wherein said elongated openings are slits which radiate outwardly from said central portion defining a plurality of sector shapes in said rupture member.

5. The rupture disk assembly of claim 1 wherein said elongated openings are slits with enlarged openings at the ends thereof.

6. The rupture disk assemblies as defined in claim 4 or claim 5 wherein said rupture member includes a plurality of rupture pressure determining scores connecting the inner ends of all of said slits.

7. The rupture disk assembly of claim 1 wherein said rupture member has a concave-convex portion connected to an annular flat flange portion and is positioned with the concave side adjacent said sealing member.

8. The rupture disk assembly of claim 7 wherein said elongated openings are slits formed in said concave-convex portion of said rupture member.

9. The rupture disk assembly of claim 8 wherein said slits radiate outwardly from said central portion to near said annular flat flange portion defining a plurality of sector shapes in said concave-convex portion of said rupture member.

10. The rupture disk assembly of claim 3 wherein said slits include enlarged openings at the ends thereof.

11. The rupture disk assemblies as defined in claims 9 or 10 wherein said rupture member includes a plurality of rupture determining scores connecting the inner ends of all of said slits.

12. A rupture member for use in a composite rupture disk assembly which includes a resilient sealing member comprising a substantially circular section of thin rigid material having a plurality of elongated openings formed therein and having at least one rupture pressure determining score formed therein connecting the ends of two or more of said elongated openings so that rupture of said rupture member occurs when pressure transmitted to said rupture member reaches a level equal to or exceeding said rupture pressure.

13. The rupture member of claim 12 wherein said elongated openings extend outwardly from a central portion of said rupture member and said rupture pressure determining score connects the inner ends of said elongated openings.

14. The rupture member of claim 12 wherein said elongated openings are arcuate and are positioned on a line defining a substantially circular shape in said rupture member .

15. The rupture member of claims 13 or 14 wherein said elongated openings are slits.

16. The rupture member of claim 12 which is further characterized to include a concave-convex portion connected to an annular flat flange portion.

17. The rupture member of claim 16 wherein said elon-gated openings are slits and are formed in said concave-convex portion of said rupture member.

18. The rupture member of claim 17 wherein said slits radiate outwardly from said central portion to near said annular flat flange portion defining a plurality of sector shapes in said concave-convex portion of said rupture member.

19. The rupture member of claim 18 wherein said slits include enlarged openings at the ends thereof.

20. The rupture members as defined in claims 18 or 19 wherein a plurality of rupture determining scores connect the inner ends of all of said slits.