GB2220032A

GB2220032A - Composite rupture disk assembly

Info

Publication number: GB2220032A
Application number: GB8829910A
Authority: GB
Inventors: Mitchel Rooker; Stephen Farwell
Original assignee: BS&B Safety Systems LLC
Current assignee: BS&B Safety Systems LLC
Priority date: 1988-06-24
Filing date: 1988-12-22
Publication date: 1989-12-28
Anticipated expiration: 2008-12-22
Also published as: DE3901586C2; CA1290641C; FR2633362A1; GB8829910D0; JPH0211977A; DE3901586A1; JPH0736217Y2; JPH0625677U; GB2220032B; FR2633362B1

Description

2 2 2 COMPOSITE RUPTURE DISK ASSEMBLY AND A RUPTURE MEMBER THEREFOR The

present invention relates to a composite rupture disk assembly and to a rupture disk therefor of the type which includes a resilient sealing member and a rupture member.

A variety of safety pressure relief devices of the rupturable type have been developed and used heretofore. Commonly, such devices include a rupture disk which is of a particular strength whereby it ruptures when a predetermined fluid pressure is exerted thereon. The rupture disk is most often clamped between a pair of annular supporting members positioned in a pressure relief passageway or conduit connected to a pressure vessel or system being protected by the rupture disk.

Some safety pressure relief devices include a single rupture disk supported between supporting members. In particular applications, use is made of composite rupture disk assemblies comprising of a metallic or other rigid material rupture member positioned adjacent a resilient sealing member. Such composite rupture 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 exerted on the sealing member, it is pressed against the rupture member, to which the fluid pressure is transmitted. When the pressure reaches a predetermined rupture pressure at which the rupture member is designed to fail, the rupture member and the sealing member tear open and fluid pressure is relieved through the annular supporting members.

In applications where reverse pressures can be encountered, e.g., a vacuum can be generated within the vessel or system being protected, a support member is 2 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 ruptures when the reverse pressure reaches a predetermined rupture pressure thereby relieving fluid pressure in the reverse direction.

Heretofore, the rupture member has included a plurality of elongate 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 of thereof, the slits and holes defining 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 varied. 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 tdsted. 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.

The trial and error procedure described above is tedious, time-consuming and expensive.

According to the present invention there is provided a rupture member for use in a composite rupture disk assembly which includes a resilient sealing member, said rupture member comprising a substantially circular disk 3 of thin rigid material having a plurality of elongate openings formed therein and having at least one rupture pressure determining score formed therein connecting points at or adjacent the ends of two or more of said elongate 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, determined by said scores.

With such a construction the holes at the ends of the slits can optionally be eliminated and, more importantly, instead of controlling the rupture pressure by means of the distance between adjacent holes or the thickness of the material forming the rupture member, one or more scores are formed in the rupture member between at least two of the elongate 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.

In a preferred embodiment, the elongate openings extend outwardly from a central portion defining a plurality of sector shapes in the rupture member. Alternatively the elongate openings lie on a line defining a substantially circular shape in the rupture member.

According to another aspect of the invention there is provided a composite rupture disk assembly adapted to be supported between inlet and outlet supporting members, said assembly including a resilient sealing member and a rupture member having a plurality of elongate 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, wherein 4 said rupture member is constructed according to the invention. in order that the present invention may more readily be identified the following description is given, merely by way of example, reference being made is the 5 accompanying drawings, in which:-

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 2A is a top plan view of another form of rupture member of the present invention which can be utilized in the assembly of Figure 1.

Figure 2B is a top plan view of a further form of rupture member of the present invention which can be utilized in the assembly of Figure 1.

Figure 3 is a vertical cross-sectional view of the composite 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.

Referring now to Figure 1 the illustrated composite rupture disk assembly 10 includes an annular positioning member 12, a rupture member 14 located 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 positioning member 12 with the assembly 10 is optional, but when included it functions to position the assembly in annular 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 section of thin rigid material having a concave-convex portion 24 connected to an annular flat flange portion 26. A plurality of elongate 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 form illustrated in Figures 1 4, the elongate 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 1A, the rupture member 14A including the slits 28 extending outwardly from the solid portion 25, is shown flat. While the elongate openings 28 are preferably slits as shown, it will be understood that other forms of elongate 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 elongate openings 28 can be slots, Also as shown in Figure 2A, the elongate 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" is used herein to mean a circle, ellipse or a series of straight lines defining a polygonal shape. Generally, the elongate openings 28 can be straight, curved or other configuration, and can be in the form of slits, slots, a series of connected openings or individual shape or shapes, or very deep scores connecting or positioned adjacent openings.

As shown in Figure,2B, and as has heretofore been the practice, the rupture member 14C can have elongate openings 28 which terminate in enlarged circular openings 30 at the inner and outer ends of each slit 28. The openings 6 can be located at only the inner ends of the elongate openings 28 and can take other shapes such as square, triangular, etc.

In order to control and predetermine the rupture pressure of the rupture member 14, at least one rupture pressure determining score connecting the inner ends of two or more of the elongate openings 28 are formed 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 pressure 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 or the rupture member having the effect of forming lines of weakness in the rupture 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 tern "connecting the ends" is used herein to mean that the rupture pressure determining score or scores either intersect the end portions of two or more elongate openings or terminate in close proximity thereto.

As shown in Figures 1A and 2B, the scores 32 can connect between less than all of the inner ends of the elongate openings 28, or a single score 32 can connect between two of the inner ends of adjacent elongate openings 28. As shown in Figure 2A, the scores 32 can be arcuate and connect between the ends of arcuate elongate openings 28, whereby the scores 32 and the elongate openings 28 lie on a line defining 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, 7 and because the individual scores 32 form a circle, a single circular die can be used 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 portions defined by the slits 28, the score configuration illustrated in Figure 1A can be utilized; as no score connects 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 applications involving high pressures, a single score connecting between the inner ends of two adjacent scores can be utilized. Upon rupture, tearing takes place at the score which causes one sector shaped portion to open. The force of the pressurized 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 ull opening occurs with the central portion 25 remaining connected to one of the sector shaped portions.

Positioned adjacent the rupture member 14 on the opposite side thereof from the positioning member 12 is the resilient sealing member 16, which is generally formed of a resilient corrosion resistant plastic material and is of a peripheral size and shape corresponding to those 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, 14 and 16, so that a peripheral portion can be folded upwardly forming an annular lip 33, which 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 flat circular portion of the support member 18 includes a plurality of slots 34 radiating outwardly from a central 8 portion 36 and terminating near the periphery thereof forming a plurality of sector shaped portions 38 therein. As indicated above, the support member 18 functions to support the sealing member 16 when a reverse pressure such 5 as a short-term vacuum is exerted across the assembly 10. In applications where it is desired positively to relieve fluid pressure in both directions through the assembly 10, the support member 18 can itself be a rupture member and function in the same manner as the rupture member 14.

Referring now to Figures 3 and 4, the assembled composite rupture disk assembly 10 is illustrated clamped between a pai-r 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 clanped and sealed engagement with the assembly 10, so that fluids under pressure contained within the conduit 46 connected to the annular supporting member 40 and to a pressure vessel or system (not shown), are prevented from passing into the annular supporting member 41 and a conduit 48 connected thereto. A conventional gasket 45 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 portions of the assembly 10. The upstanding frusto-conical portion 20 of the positioning member 12 extends within the annular supporting member 41 thereby automatically positioning 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 40 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 9 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 positioned such that the support member 18 can support the resilient 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.

Fluid pressure exerted on the assembly 10 from the pressure vessel or system being protected is transmitted to the concave surface of the rupture member 14 thereby placing it in tension. Upon reaching the rupture pressure of the scores 32, i.e., exceeding the tensile 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 variations in the lengths of material portions between the inner ends of the slits 28, all of the portions of the rupture member 14 between the inner ends of the slits 28 tear, except for one such portion (having the greatest length) to which the central portion 25 thereof remains connected. When the rupture member 14 ruptures, the resilient sealing member 16 also ruptures in sector shaped portions, causing pressure to be relieved through the assembly 10. The force of the pressure release, i.e., the flow of pressurized fluid through the assembly 10, causes the support member 18 also to open, the tensile strength of the portions of the support member 18 lying between the inner ends of the slots 34 being 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. As with the rupture member 14, one portion of the support member 18 between two of the inner ends of the slots 34 remains intact to which the central portion 36 remains attached. As illustrated 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 sector shaped portions 38 thereof.

The composite rupture disk assembly of this invention can omit the positioning member 12 and/or the support member 18 of the assembly 10, and can comprise only the rupture member 14 and the sealing member 16 as illustrated in Figure 1A. Optionally, the assembly can comprise 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 elongate 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 rupture disk assembly product as well as the more accurate control of the rupture pressure of such product.

Claims

1. A rupture member for use in a composite rupture disk assembly which includes a resilient sealing member, said rupture member comprising a substantially circular disk of thin rigid material having a plurality of elongate openings formed therein and having at least one rupture pressure determining score formed therein connecting points at or adjacent the ends of two or more of said elongate 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, determined by said scores

2. A rupture member according to claim 1, wherein said elongate openings extend outwardly from a central portion of said rupture member and said at least one, rupture pressure determining score connects the inner ends of said elongate openings.

3. A rupture member according to any preceding claim, wherein a plurality of rupture determining scores connect the inner ends of all of said elongate openings.

4. A rupture member according to claim 1, wherein said elongate openings are arcuate and are positioned on a line defining a substantially circular shape in said rupture member.

5. A rupture member according to any preceding claim, wherein said elongate openings are slits.

6. A rupture member according to claim 5, wherein said disk includes a concave-convex portion connected to an annular flat flange portion and wherein said slits are formed in said concave-convex portion of said rupture member.

7. A rupture member according to claim 6, wherein said concave-convex portion to near said annular flat flange 12 portion defining a plurality of sector shapes in said concave-convex portion of said rupture member.

8. A rupture member according to any preceding claim, wherein said slits include enlarged openings at the ends thereof.

9. A rupture member for use in a composite rupture disk assembly, said rupture member being substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings.

10. A rupture member for use in a composite rupture disk assembly, said rupture member being substantially as hereinbefore described with reference to and as illustrated in Figure 1A.

11. A rupture member for use in a composite rupture 15 disk assembly, said rupture member being substantially as hereinbefore described with reference to and as illustrated in Figure 2A.

12. A rupture member for use in a composite rupture disk assembly, said rupture member being substantially as hereinbefore described with reference to and as illustrated in Figure 2B.

13. A composite rupture disk assembly adapted to be supported between inlet and outlet supporting members, said assembly including a resilient sealing member and a rupture member having a plurality of elongate 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, wherein said rupture member is constructed according to any one of the preceding claims.

13

14. A rupture disk assembly substantially as hereinbefore described with reference to the accompanying drawings.

Published 1989 atThe Patent Office,State House.6671 High HoIbornLondonWC1R4TP.Furtner c3pies maybe obtainedfromThePatent Office. Wes Branch, St Mary Cray, Orpington, Rent BR,5 3RD. Printed by MWtiplex technique. Itd, St Mary Cray, Kent, Con. 1/87