U.S. patent application number 09/891195 was filed with the patent office on 2001-12-20 for rupture disk assembly.
This patent application is currently assigned to BS&B Safety Systems, Inc.. Invention is credited to Brazier, Geof, Cullinane, Donall, Daly, John, Farwell, Stephen, Klein, Greg, Lowe, Barry, Rooker, Mitch, Tomasko, John.
Application Number | 20010052358 09/891195 |
Document ID | / |
Family ID | 26977620 |
Filed Date | 2001-12-20 |
United States Patent
Application |
20010052358 |
Kind Code |
A1 |
Cullinane, Donall ; et
al. |
December 20, 2001 |
Rupture disk assembly
Abstract
An improved rupture disk assembly and methods and apparatuses
for forming a rupture disk are disclosed. The rupture disk assembly
includes a rupture disk having a flange connected to a dome-shaped
rupturable portion by a transition area. The rupturable portion
includes a structural apex formation at or near the apex of the
dome and is configured to rupture when exposed to a fluid having a
predetermined pressure. Preferably, a safety member is disposed
adjacent the rupture disk. The safety member includes a hinge about
which the disk bends when the disk ruptures. The present invention
is also directed to an apparatus and method for consistently,
accurately, and repeatably forming a structural apex formation in a
rupture disk before the formation of the rupture disk dome, during
the formation of the rupture disk dome, and after the formation of
the rupture disk dome.
Inventors: |
Cullinane, Donall; (Bray,
IE) ; Daly, John; (Cootehill, IE) ; Farwell,
Stephen; (Owasso, OK) ; Klein, Greg; (Owasso,
OK) ; Lowe, Barry; (Limerick, IE) ; Rooker,
Mitch; (Sand Springs, OK) ; Tomasko, John;
(Claremore, OK) ; Brazier, Geof; (Woodbury,
MN) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT &
DUNNER LLP
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
BS&B Safety Systems,
Inc.
|
Family ID: |
26977620 |
Appl. No.: |
09/891195 |
Filed: |
June 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09891195 |
Jun 26, 2001 |
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09568505 |
May 11, 2000 |
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09568505 |
May 11, 2000 |
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09310848 |
May 13, 1999 |
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6178983 |
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Current U.S.
Class: |
137/68.25 |
Current CPC
Class: |
F16K 17/1606 20130101;
Y10T 137/1744 20150401; Y10T 137/1729 20150401 |
Class at
Publication: |
137/68.25 |
International
Class: |
F16K 017/14 |
Claims
What is claimed is:
1. An apparatus for indenting a rupture disk including an annular
flange and a rupturable portion having a domed shape, comprising: a
first member having an opening, the first member configured to
engage a first side of the rupturable portion; and a second member
disposed on a second side of the rupturable portion and aligned
with the opening in the first member, the second member operable to
engage the rupturable portion at or near the apex of the domed
shape and to displace a section of the rupturable portion relative
to the first member, thereby creating an indentation in the
rupturable portion at or near the apex of the domed shape.
2. The apparatus of claim 1, wherein the first member is an anvil
and the second member is a punch.
3. The apparatus of claim 2, wherein the rupturable portion
includes a concave side and a corresponding convex side and the
anvil engages the concave side of the rupturable portion.
4. The apparatus of claim 2, further including a frame having an
inner wall defining a cavity configured to receive the flange of
the rupture disk.
5. The apparatus of claim 4, wherein the diameter of the cavity
closely corresponds to the diameter of the flange such that the
inner wall of the cavity ensures the rupture disk is properly
aligned on the anvil.
6. The apparatus of claim 5, wherein the annular flange includes at
least one opening and the frame includes a pin configured to engage
the opening to align the rupture disk on the anvil.
7. The apparatus of claim 2, wherein the punch includes a tip
having a circular cross section and the opening in the anvil has a
circular shape.
8. The apparatus of claim 2, wherein the outer diameter of the
punch tip has substantially the same size as the opening in the
anvil so that the section of the rupturable portion is displaced in
shear.
9. The apparatus of claim 2, wherein the punch includes a tip
having a cross-sectional shape different from the shape of the
opening in the anvil.
10. The apparatus of claim 9, wherein the cross-sectional shape of
the punch tip includes an arc connected by a chord and the anvil
opening is generally circular.
11. The apparatus of claim 9, wherein the punch tip has a tear drop
cross section and anvil opening is generally circular.
12. The apparatus of claim 2, wherein the centerline of the opening
in the anvil coincides with the apex of the domed shape and the
centerline of the punch is offset from the apex of the domed
shape.
13. The apparatus of claim 2, wherein the punch includes a tip
having a concave surface.
14. A method of forming an indentation in a rupture disk including
an annular flange and a rupturable portion having a domed shape,
comprising the steps of: supporting a first side of the rupturable
portion with a first member having an opening; and engaging a
second member aligned with the opening in the first member with a
second side of the rupturable portion at or near the apex of the
domed shape to displace a section of the rupturable portion
relative to the first member, thereby creating an indentation at or
near the apex of the rupturable portion of the rupture disk.
15. The method of claim 14, wherein the first member is an anvil
and the centerline of the opening in the anvil is aligned with the
apex of the domed shape.
16. The method of claim 15, wherein the second member is a punch
and the centerline of the punch is offset from the apex of the
domed shape.
17. The method of claim 14, wherein the second member displaces the
section of the rupturable portion in shear.
18. The method of claim 14, wherein the second member displaces the
section of the rupturable portion a predetermined distance from the
apex of the domed shape.
19. The method of claim 14, further comprising the step of
reforming the disk after the indentation is formed to reduce the
depth of the indentation.
20. A rupture disk having an indentation formed in accordance with
the process of claim 14.
21. A method of forming an indentation in a rupture disk,
comprising the steps of: supporting a first side of a rupture disk
blank with a first member having an opening; engaging a second
member aligned with the opening in the first member with a second
side of the rupture disk blank at or near the center of the rupture
disk blank to displace a section of the rupture disk blank relative
to the first member, thereby creating an indentation at or near the
center of the rupture disk blank; and subjecting a portion of the
rupture disk blank to a pressurized fluid to form said portion of
the rupture disk blank into a domed shape such that the indentation
is disposed at or near the apex of the domed shape.
22. The method of claim 21, wherein the first member is an anvil
and the centerline of the opening in the anvil is aligned with the
center of the rupture disk blank.
23. The method of claim 22, wherein the second member is a punch
and the centerline of the punch is offset from the center of the
rupture disk blank.
24. The method of claim 21, wherein the second member displaces the
section of the rupture disk blank in shear.
25. A rupture disk having an indentation formed in accordance with
the process of claim 21.
26. An apparatus for forming a rupture disk from a blank,
comprising: a clamp configured to fixably secure an outer perimeter
of the blank, the clamp having a pathway configured to direct a
pressurized fluid against the unclamped portion of the blank, the
pressurized fluid acting on the unclamped portion to displace the
unclamped portion of the blank relative to the clamp; a mold having
a concave shape configured to receive the unclamped portion of the
blank as the unclamped portion is displaced relative to the clamp
and to form the unclamped portion of the blank into a domed shape
generally corresponding to the concave shape of the mold; and a
member disposed in the mold and configured to engage the unclamped
portion of the blank as the unclamped portion is displaced relative
to the clamp to thereby form an indentation at or near the apex of
the domed shape.
27. The apparatus of claim 26, wherein the member is a punch and
the centerline of the punch is aligned with the apex of the domed
shape.
28. The apparatus of claim 27, wherein the member is a punch and
the punch has a circular cross section.
29. The apparatus of claim 26, wherein the member is a punch and
the punch includes a tip having a concave surface.
30. A method of forming a rupture disk from a blank, comprising the
steps of: clamping the outer perimeter of the blank; directing a
pressurized fluid against a central portion of the blank to
displace the central portion of the blank relative to the outer
perimeter and into a mold having a concave shape; forming the
central portion of the blank into a domed shape generally
corresponding to the concave shape of the mold; and engaging a
member with central portion of the blank as the central portion is
formed into the domed shape to form an indentation at or near the
apex of the domed shape.
31. The method of claim 30, further comprising the steps of:
removing the member from the mold; and directing a pressurized
fluid having a second pressure against the central portion to
reduce the depth of the indentation relative to the apex of the
domed shape.
32. The method of claim 30, further comprising the step of
controlling the depth of the indent relative to the apex of the
dome by adjusting the member relative to the mold.
33. A rupture disk formed in accordance with the process of claim
30.
34. A rupture disk assembly to be sealed in a pressurized system,
comprising: a rupture disk including rupturable portion configured
to reverse when exposed to a fluid having a predetermined pressure,
the rupturable portion defining an opening therethrough; and a
liner disposed between the rupture disk and the pressurized system,
the liner configured to cover and seal the opening in the
rupturable portion of the rupture disk.
35. The assembly of claim 34, wherein the rupturable portion has a
domed shape and the opening encompasses the apex of the domed
shape.
36. The assembly of claim 34, wherein the liner covers the entirety
of the rupture disk.
37. The assembly of claim 34, wherein the liner is attached to the
rupture disk with an adhesive.
38. The assembly of claim 34, wherein the liner is made from a
metallic material and the liner is welded to the rupture disk.
39. The assembly of claim 34, wherein the liner is made of a
material that has a greater flexibility than the material of the
rupture disk.
40. The assembly of claim 34, wherein the rupturable portion of the
rupture disk includes a score line.
41. The assembly of claim 34, wherein the opening is circular.
42. A rupture disk to be sealingly engaged with a pressurized
system, comprising: an annular flange; and a rupturable portion
configured to rupture when exposed to a fluid having a
predetermined pressure, the rupturable portion having a domed shape
with a convex surface and a corresponding concave surface and a
structural apex formation disposed at the apex of the dome, the
structural apex formation including a crease formed in at least one
of the concave and convex surfaces.
43. The rupture disk of claim 42, wherein the structural apex
formation is an indentation.
44. The rupture disk of claim 43, wherein the indentation is
centered at the apex of the domed shape.
45. The rupture disk of claim 43, wherein the indentation is
generally circular.
46. The rupture disk of claim 42, wherein the crease is in the
concave surface.
47. The rupture disk of claim 42, wherein the crease is generally
circular and centered about the apex of the domed shape.
48. A rupture disk assembly to be sealed in a pressurized system,
comprising: a rupture disk having a dome-shaped rupturable portion
including a convex surface and a corresponding concave surface
forming a dome area, the rupturable portion including a score line
having a first and a second end, the score line creating a line of
weakness along which the rupturable portion will tear when the
rupturable portion of the rupture disk is exposed to a fluid above
a predetermined pressure; and a safety member disposed adjacent the
concave surface of the rupture disk and including a flange and a
hinge, the hinge defining first and second pockets configured to
receive the area of the rupturable portion adjacent the respective
ends of the score line when the rupture disk ruptures.
49. The rupture disk assembly of claim 48, wherein the hinge
extends into the dome area.
50. The rupture disk assembly of claim 48, wherein the hinge lies
in the same plane as the flange of the safety member.
51. The rupture disk assembly of claim 48, wherein the outer edge
of the hinge is generally straight.
52. The rupture disk assembly of claim 48, wherein the rupture disk
includes a flange and the flange of the safety member is welded to
the flange of the rupture disk.
53. The rupture disk assembly of claim 48, wherein the safety
member includes a stress riser configured to engage the rupturable
portion of the rupture disk to ensure the rupturable portion tears
when the pressure of the pressurized fluid exceeds the
predetermined level.
54. The rupture disk assembly of claim 53, wherein the stress riser
includes at least one stress concentrating point configured to
contact the score line in the rupturable portion to ensure the
rupturable portion tears along the score line.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of application
Ser. No. 09/310,848, filed on May 13, 1999 for Rupture Disk
Assembly.
BACKGROUND OF THE INVENTION
[0002] This invention relates to pressure relief systems. More
particularly, the present invention relates to an improved rupture
disk assembly for a pressure relief system and to apparatuses and
methods for forming and manufacturing rupture disks.
[0003] Pressure relief assemblies are commonly used as safety
devices in systems containing pressurized fluids in gas or liquid
form. A pressure relief assembly will vent fluid from the system
when the pressure in the system reaches an unsafe level. A number
of emergency conditions, including fire and system failure, can
create dangerous pressure levels, which require immediate relief to
preserve the safety of the system.
[0004] Generally, a pressure relief assembly includes a rupture
disk that is sealed between a pair of support members, or safety
heads. The pressure relief assembly is then typically clamped, or
otherwise sealingly disposed, between a pair of conventional pipe
flanges in the pressurized system. One of the pipes conducts
pressurized fluid to one side of the pressure relief assembly and
the other pipe provides an outlet to a safety reservoir or may be
open to the environment. The support members include a central
opening that exposes a portion of the rupture disk to the
pressurized fluid in the system. The exposed portion of the rupture
disk will rupture when the pressure of the fluid reaches a
predetermined differential pressure between the inlet and outlet
sides. The ruptured disk creates a vent path that allows fluid to
escape through the outlet to reduce the pressure in the system.
[0005] Rupture disks typically have a dome shape and can be either
forward acting or reverse acting. In a forward acting disk, the
concave side of the dome faces the pressurized fluid, placing the
material of the disk under tension. In a reverse acting disk, the
convex side of the dome faces the pressurized fluid, placing the
material of the disk under compression. In the reverse acting disk
(also known as a reverse buckling disk), when the pressure of the
fluid exceeds the predetermined level and the material of the disk
structure cannot withstand the pressure, the dome of the disk will
buckle and begin to reverse. This reversal, or buckling, will begin
at a particular point on the disk, known as the point of initial
reversal. As the disk continues to reverse, the material of the
disk is torn by an opening means to create the vent path to release
the pressurized fluid.
[0006] Both types of disks commonly include score lines (areas of
weakness) to facilitate the opening of the disk. In a reverse
buckling disk, the disk will tear along the score line when the
disk is reversing. Selected portions of the disk are usually left
unscored, acting as a hinge area, to prevent the disk from
fragmenting upon bursting and escaping along with the pressurized
fluid. Additionally, pressure relief assemblies are known that
include safety members to assist in opening the disk and to absorb
the energy created by the bursting of the disk to attempt to
prevent the disk from fragmenting.
[0007] In an emergency situation, where the system pressure becomes
unsafe, it is important to reduce the pressure as quickly as
possible. The American Society of Mechanical Engineers (ASME) code
establishes minimum performance requirements for fluid flow rates
through pressure relief systems. The size and shape of the opening
created when the disk bursts is a limiting factor on the rate at
which fluid can escape the system. A burst disk having a large,
unobstructed opening will perform better than a burst disk having a
small, obstructed opening because the velocity head loss (i.e.
pressure drop) over the large, unobstructed opening will be lower
than the velocity head loss over a smaller or obstructed opening.
The lower velocity head loss translates to a lower flow resistance
(K.sub.r) and, thus, a greater flow rate through the disk.
[0008] Adjusting different facets of the disk design, including the
size of the rupturable portion of the disk and the location of the
score line, can control the size and shape of the opening created
when the disk bursts. A larger disk has the potential to create a
larger opening.
[0009] Another factor affecting flow resistance is the nature of
the fluid in the pressurized system. It has been found that rupture
disks open differently depending on the nature of the fluid in the
system. Typically, a disk burst in a gas environment will open more
fully than a disk burst in a liquid environment. Thus, to meet
desirable flow resistance performance requirements, the design of a
disk may have to be different if the disk is being used in a liquid
application, even if the liquid is at the same pressure as a
similar gas application.
[0010] An additional factor of disk design that affects flow
resistance is the thickness of the rupturable portion of the disk.
A disk made of a thinner material will bend easier than a disk made
of a thicker material. Thus, for disks rupturing at the same fluid
pressure, a thinner disk is more likely to completely open and
create a large, unobstructed opening than a corresponding thicker
disk.
[0011] However, a disk made of a thinner material is more
susceptible to damage than a thicker disk. Any damage to the
rupture disk could alter the actual burst pressure of the disk.
This is particularly an issue in low pressure, reverse buckling
disks where the disk material must be thin to burst at the desired
low pressure. The thinner, low pressure disks are more likely to be
damaged during installation, which may compromise the structural
integrity of the disk and cause the disk to reverse at a pressure
significantly less than the desired rupture pressure. In these
situations, the material of the disk does not tear as expected and
the disk may completely reverse without tearing. The reverse
buckling disk then acts like a forward acting disk and the fluid
pressure places the material of the disk in tension. Because the
tensile strength of the disk material is greater than the
corresponding compressive strength, the disk may not tear to create
the vent path until the pressure of the system significantly
exceeds the desired rupture pressure. This over-pressure condition
could result in damage to the system that the rupture disk was
intended to prevent.
[0012] Rupture disks are rated by their performance in a damaged
condition. This rating is generally known as the damage safety
ratio of the disk and is determined by dividing the actual pressure
at which a damaged disk ruptures by the desired, or rated, rupture
pressure of the disk. A damaged disk with a damage safety ratio of
1 or less will burst at the desired rupture pressure, or before the
pressurized fluid reaches the desired pressure, thereby preventing
any damage to the system.
[0013] Another important performance rating of a rupture disk is
the burst accuracy of the disk. There are variations in materials,
manufacturing, and installation that may result in any given two
disks in a manufacturing lot of seemingly identical disks not
bursting at the same pressures. Thus, there is typically a
variation in actual burst pressure among disks having the same
rated pressure. With current rupture disk design and manufacturing
methods, rupture disks will typically burst at a pressure that is
less than 5% of the rated pressure or less than 2 psig when the
rated pressure is below 40 psig. Thus, to prevent premature disk
rupture and to provide a safety margin, the standard operating
pressure of a system should not exceed 90% of the rated pressure of
a rupture disk used in the system.
[0014] In light of the foregoing, there is a need for a pressure
relief assembly that provides a low flow resistance K.sub.r in both
liquid and gas applications. There is further a need for rupture
disks that have an accurate and repeatable burst pressure and thus
can be used in a high operating capacity. There is still further a
need for a rupture disk having a low damage safety ratio so that an
inadvertently damaged reverse buckling disk does not create a
potentially dangerous over-pressure situation in either liquid or
gas applications.
SUMMARY OF THE INVENTION
[0015] Accordingly, the present invention is directed to a pressure
relief assembly that obviates one or more of the limitations and
disadvantages of prior art pressure relief assemblies. The
advantages and purposes of the invention will be set forth in part
in the description which follows, and in part will be obvious from
the description, or may be learned by practice of the invention.
The advantages and purposes of the invention will be realized and
attained by the elements and combinations particularly pointed out
in the appended claims.
[0016] To attain the advantages and in accordance with the purposes
of the invention, as embodied and broadly described herein, the
invention is directed to an apparatus for indenting a rupture disk
that includes an annular flange and a rupturable portion having a
domed shape. The apparatus includes a first member and a second
member. The first member has an opening and is configured to engage
a first side of the rupturable portion of the rupture disk. The
second member is disposed on a second side of the rupturable
portion of the rupture disk and is aligned with the opening in the
first member. The second member engages the rupturable portion at
or near the apex of the domed shape and displaces a section of the
rupturable portion relative to the first member to thereby create
an indentation in the rupturable portion at or near the apex of the
domed shape.
[0017] In another aspect, the present invention is directed to a
method of forming an indentation in a rupture disk that includes an
annular flange and a rupturable portion having a domed shape.
According to the method, a first side of the rupturable portion is
supported with a first member having an opening. A second member
aligned with the opening in the first member is engaged with a
second side of the rupturable portion at or near the apex of the
domed shape to displace a section of the rupturable portion
relative to the first member and thereby create an indentation at
or near the apex of the rupturable portion of the rupture disk.
[0018] In still another aspect, the present invention is directed
to a method of forming an indentation in a rupture disk. According
to the method, a first side of a rupture disk blank is supported
with a first member having an opening. A second member aligned with
the opening in the first member is engaged with a second side of
the rupture disk blank at or near the center of the rupture disk
blank to displace a section of the rupture disk blank relative to
the first member, thereby creating an indentation at or near the
center of the rupture disk blank. A portion of the rupture disk
blank is subject to a pressurized fluid to form said portion of the
rupture disk blank into a domed shape such that the indentation is
disposed at or near the apex of the domed shape.
[0019] According to another aspect, the present invention is
directed to an apparatus for forming a rupture disk from a blank.
The apparatus includes a clamp configured to fixably secure an
outer perimeter of the blank. The clamp has a pathway configured to
direct a pressurized fluid against the unclamped portion of the
blank. The pressurized fluid acts on the unclamped portion of the
blank to displace the unclamped portion of the blank relative to
the clamp. A mold having a concave shape receives the unclamped
portion of the blank as the unclamped portion is displaced relative
to the clamp and forms the unclamped portion of the blank into a
domed shape generally corresponding to the concave shape of the
mold. A member disposed in the mold engages the unclamped portion
of the blank as the unclamped portion is displaced relative to the
clamp to thereby form an indentation at or near the apex of the
domed shape.
[0020] In still another aspect, the present invention is directed
to a method of forming a rupture disk from a blank. According to
the method, the outer perimeter of the blank is clamped and a
pressurized fluid is directed against a central portion of the
blank. The pressurized fluid displaces the central portion of the
blank relative to the outer perimeter and into a mold having a
concave shape. The central portion of the blank is formed into a
domed shape that generally corresponds to the concave shape of the
mold. A member is engaged with central portion of the blank as the
central portion is formed into the domed shape to form an
indentation at or near the apex of the domed shape.
[0021] According to yet another aspect, the present invention is
directed to a rupture disk assembly to be sealed in a pressurized
system. The assembly includes a rupture disk that is configured to
reverse when exposed to a fluid having a predetermined pressure.
The rupturable portion defines an opening therethrough. A liner is
disposed between the rupture disk and the pressurized system and is
configured to cover and seal the opening in the rupturable portion
of the rupture disk.
[0022] According to still another aspect, the present invention is
directed to a rupture disk to be sealingly engaged with a
pressurized system. The rupture disk includes an annular flange and
a rupturable portion that is configured to rupture when exposed to
a fluid having a predetermined pressure. The rupturable portion has
a domed shape with a convex surface and a corresponding concave
surface and a structural apex formation disposed at the apex of the
dome. The structural apex formation includes a crease formed in at
least one of the concave and convex surfaces.
[0023] In still another aspect, the present invention is directed
to a rupture disk assembly to be sealed in a pressurized system.
The rupture disk assembly includes a rupture disk having a
dome-shaped rupturable portion that includes a convex surface and a
corresponding concave surface forming a dome area. The rupturable
portion includes a score line that has a first and a second end and
creates a line of weakness along which the rupturable portion will
tear when the rupturable portion of the rupture disk is exposed to
a fluid above a predetermined pressure. A safety member is disposed
adjacent the concave surface of the rupture disk. The safety member
includes a flange and a hinge that defines first and second pockets
configured to receive the area of the rupturable portion adjacent
the respective ends of the score line when the rupture disk
ruptures.
[0024] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate one embodiment
of the invention and together with the description, serve to
explain the principles of the invention. In the drawings,
[0026] FIG. 1 is a cross sectional view of a pair of support
members and a rupture disk according to the present invention
positioned between a pair of pipe flanges;
[0027] FIG. 2 is a top view of a rupture disk and a safety member
according to the present invention;
[0028] FIG. 3a is a cross sectional view of the rupture disk and
safety member of FIG. 2, taken along line Z-Z;
[0029] FIG. 3b is a cross sectional view of an alternative
embodiment of the rupture disk and safety member of FIG. 2, taken
along line Z-Z;
[0030] FIG. 4 is a cross sectional view of the rupture disk and
safety member of FIG. 2, taken along line Y-Y;
[0031] FIG. 5 is a cross sectional view of a pair of support
members and a rupture disk according to the present invention
positioned between a pair of pipe flanges, illustrating the rupture
disk in a burst state;
[0032] FIG. 6 is a perspective view of a rupture disk having a
central indentation according to the present invention;
[0033] FIG. 7 is a cross sectional view of the rupture disk of FIG.
6;
[0034] FIGS. 8 and 9 are top plan views of alternative embodiments
of central indentations according to the present invention;
[0035] FIG. 10 is a cross-sectional view of an apparatus for
creating an indentation in a rupture disk in accordance with the
present invention;
[0036] FIG. 11 is a cross-sectional view of another embodiment of a
punch tip for creating an indentation in a rupture disk;
[0037] FIGS. 12a-12c are end views of a punch tip according to the
present invention;
[0038] FIG. 13 is a cross-sectional view of another apparatus for
creating an indentation in a rupture disk in accordance with the
present invention;
[0039] FIG. 14 is a partial cross-sectional view of the apparatus
of FIG. 13, illustrating the punch tip engaged with the rupturable
portion of the rupture disk;
[0040] FIG. 15 is a top view of a rupture disk having an opening in
the rupturable portion in accordance with the present
invention;
[0041] FIG. 16 is a side view of a rupture disk assembly include a
rupture disk having an opening in the rupturable portion;
[0042] FIG. 17 is a top view of another embodiment of a safety
member in accordance with the present invention;
[0043] FIG. 18 is a side view of the safety member of FIG. 17;
and
[0044] FIG. 19 is a cross-sectional view of a rupture disk having
an indentation formed in accordance with an aspect of the present
invention.
DETAILED DESCRIPTION
[0045] Reference will now be made in detail to the presently
preferred embodiments of the present invention, examples of which
are illustrated in the accompanying drawings. Wherever possible,
the same reference numbers will be used throughout the drawings to
refer to the same or like parts. An exemplary embodiment of a
pressure relief assembly of the present invention is shown in FIG.
1 and is designated generally by reference number 20.
[0046] In accordance with the present invention, there is provided
a pressure relief assembly that includes an inlet support member
that defines an inlet bore for conducting a pressurized fluid, an
outlet support member that defines an outlet bore for relieving the
pressurized fluid, and a rupture disk. The rupture disk has a
rupturable portion including a convex surface and a corresponding
concave surface that defines a dome area. The rupture disk also
includes a flange for sealing engagement between the inlet and
outlet support members to align the concave surface with the outlet
bore and the convex surface with the inlet bore. In the illustrated
embodiments, the pressure relief assembly is depicted as a
pretorqued pressure relief assembly. It is contemplated, however,
that the present invention may also be used with non-pretorqued
pressure relief assemblies or as a component of a welded
assembly.
[0047] As embodied herein and as illustrated in FIG. 1, pressure
relief assembly 20 includes an inlet support member 30 and an
outlet support member 32. Inlet support member 30 defines an inlet
bore 34 and has a series of internally threaded bolt holes 43 (only
one of which is illustrated in FIG. 1) surrounding the inlet bore.
Outlet support member 32 defines an outlet bore 36 and has a series
of bolt holes 41 (only one of which is illustrated in FIG. 1) that
correspond to bolt holes 43 of inlet support member 30. It is
contemplated that the inlet and outlet support members may be
safety heads, pipe flanges, or any combination of structures
capable of sealingly engaging the rupture disk with a pressurized
system.
[0048] As also shown in FIG. 1, a rupture disk 44 is positioned
between inlet support member 30 and outlet support member 32.
Rupture disk 44 includes a flange 48 and a rupturable portion 45.
Flange 48 is connected to rupturable portion 45 by transition area
49. It is contemplated that the rupture disk and safety member of
the present invention can also be utilized in sanitary
environments, wherein well-known sanitary fittings will be utilized
to engage the rupture disk.
[0049] Rupturable portion 45 has a dome shape that includes a
concave surface 46 and a convex surface 47 that define a dome area
designated generally as 35. When flange 48 is engaged with inlet
and outlet support members 30 and 32, rupturable portion 45 aligns
with inlet bore 34 and outlet bore 36. In a preferred embodiment,
convex surface 47 extends into inlet bore 34 and concave surface
faces outlet bore 36. It is contemplated, however, that aspects of
the present invention may be utilized in forward acting disks where
the convex surface extends into the outlet bore.
[0050] As illustrated in FIG. 2, rupturable portion 45 includes a
score line 80 that has a first end 84 and a second end 86.
Preferably, score line 80 transcribes an arc of approximately
300.degree. in the concave surface of the dome-shaped rupturable
portion. The present invention can be utilized with score lines of
various configurations, such as, for example, an intermittent score
line where the score generally transcribes an arc, but includes a
series of gaps of unscored material. The score line may also
completely circumscribe the rupturable portion of the disk, but
include a section where the depth of the score line is shallower
than the remainder of the score line. For purposes of the present
invention, the points at which the depth of the score line changes
would be considered to be the first and second ends of the score
line.
[0051] As described in greater detail below, score line 80 creates
a line of weakness in the rupturable portion along which the disk
material will tear when exposed to a fluid having a predetermined
pressure. While the presently preferred embodiment provides the
score line on the dome itself, the score line may be provided in
other locations, such as, for example, the transition area between
the dome and the flange of the disk or on the flange itself.
[0052] Referring again to FIG. 1, a positioning pin 68 preferably
extends between inlet support member 30 and outlet support member
32 and through flange 48 of rupture disk 44. Positioning pin 68
ensures that inlet support member 30 is properly aligned with
outlet support member 32 and that rupture disk 44 is properly
positioned between support members 30 and 32. When the assembly is
properly positioned, inlet bore 34 aligns with outlet bore 36 to
create a fluid passageway that is blocked by rupturable portion 45
of rupture disk 44. Additional positioning pins may be placed in a
symmetrical or asymmetrical pattern around the support members to
further control the relative positions of the rupture disk and
support members.
[0053] A series of cap screws 40 (only one of which is illustrated
in FIG. 1) are disposed through bolt holes 41 to engage internally
threaded bolt holes 43. Preferably, bolt holes 41 in outlet support
member 32 include a counter bore 42 to receive the head of cap
screw 40. The engagement of cap screws 40 with bolt holes 41 and 43
draws outlet support member 32 towards inlet support member 30 to
sealingly engage flange 48 of rupture disk 44.
[0054] Preferably, inlet support member 30 includes a raised
seating surface 78 and outlet support member 32 includes a
corresponding seating surface 79 to engage flange 48 of rupture
disk 44. It is contemplated that seating surface 78 may include a
bite seal, or other similar sealing device, to create a seal with
the flange. Alternatively, an o-ring or gasket may be positioned
between inlet support member 30 and flange 48 to create the
seal.
[0055] As is shown in FIG. 1, pressure relief assembly 20 is
positioned between a circular inlet pipe 22 and a circular outlet
pipe 28. Inlet pipe 22 includes an inlet fluid pathway 64 and an
inlet pipe flange 24. Outlet pipe 28 includes an outlet fluid
pathway 66 and an outlet pipe flange 26.
[0056] Preferably, inlet pipe flange 24 includes a raised surface
74 that engages a corresponding surface 75 on inlet support member
30 and outlet pipe flange 26 includes a raised surface 76 that
engages a corresponding surface 77 on outlet support member 26. A
series of bolt members 60 draw inlet pipe flange 24 towards outlet
pipe flange 26 to create a seal with the pressure relief assembly
20.
[0057] Preferably, a U-shaped positioning fixture 38 extending from
inlet support member 30 engages an opening 58 in inlet pipe flange
24 to ensure pressure relief assembly 20 is properly oriented
between the pipe flanges. U-shaped positioning fixture 38 also
ensures that inlet support member 30 is placed adjacent inlet pipe
flange 24 and, thus, prevents pressure relief assembly 20 from
being installed upside down in the pipe flanges. Pressure relief
assembly 20 is properly positioned between inlet pipe flange 24 and
outlet pipe flange 26 when inlet fluid pathway 64 aligns with inlet
bore 34, outlet bore 36, and outlet fluid pathway 66 to create a
fluid passageway that is blocked by rupturable portion 45 of
rupture disk 44.
[0058] Inlet pipe 22 is connected to a system or vessel (not shown)
that contains a pressurized fluid. The fluid may be in either gas
or liquid form. Inlet pipe 22 conducts the pressurized fluid to
pressure relief assembly 20 and the exposed rupturable portion 45
of rupture disk 44. Rupturable portion 45 is configured to burst
when the pressure of the fluid reaches a predetermined level that
is indicative of an over-pressurization in the system or vessel.
The burst pressure of the disk may be controlled by varying
different parameters of the disk design, including, but not limited
to, the height of the domed section, the thickness of the disk, and
the depth and location of the score line.
[0059] When the disk bursts and tears along score line 80, an
opening through the disk is created. The opening allows the fluid
to flow from inlet bore 34 to outlet bore 36 and into outlet fluid
pathway 66, thereby reducing the pressure in the system or vessel.
Outlet fluid pathway 66 may release the fluid to the environment or
to a safety reservoir (not shown) depending upon the nature of the
fluid in the system or vessel.
[0060] In accordance with the present invention, the pressure
relief assembly includes a safety member disposed adjacent the
concave surface of the rupture disk. The safety member includes a
hinge having a knuckle that extends downwardly into the dome area
created by the rupturable portion of the disk and extends laterally
across the dome area to a point that is inside the area
circumscribed by the score line or inside the area circumscribed by
an arc connecting the two ends of the score line. A tongue extends
away from the knuckle and into the outlet bore of the outlet
support member in a direction generally perpendicular to the flange
of the safety member. Preferably, the tongue extends past the
flange of the safety member, although the end of the tongue may
generally align with plane created by the flange. The present
invention contemplates that the hinge may be angled with respect to
the flange, such that the hinge extends into the outlet bore and
towards the outlet support member. It is further contemplated that
the hinge may have a generally flat configuration.
[0061] As illustrated in FIG. 1, a safety member 50 is positioned
between rupture disk 44 and outlet support member 32 and generally
supports the transition area of the rupture disk. Preferably,
safety member 50 is a separate structure from rupture disk 44 and
from outlet support member 32. It is contemplated, however, that
safety member 50 may be integral with or connected to either
rupture disk 44 or outlet support member 32 with spot welds or in
any other manner to keep the structures together.
[0062] Safety member 50 includes a flange 62 and a hinge 52. Flange
62 of safety member 50 has substantially the same general shape as
flange 48 of rupture disk 44 and is sealed in pressure relief
assembly 20 between the rupture disk flange and outlet support
member 32. Preferably, as shown in FIG. 2, flange 62 includes a
series of holes 82 that may be engaged by positioning pin 68
(referring to FIG. 1).
[0063] As shown in FIG. 3a, hinge 52 includes a knuckle 53 and a
tongue 54. Knuckle 53 extends from flange 62 into dome area 35. In
the illustrated embodiment, knuckle 53 is linear in cross-section.
It is contemplated, however, that knuckle 53 may have other
cross-sections, such as, for example, a curved cross-section that
generally follows the contour of the rupturable portion.
Preferably, knuckle 53 does not contact rupturable portion 45 and,
thus, leaves a gap 51 between the knuckle and the rupturable
portion. It is contemplated, however, that knuckle 53 may contact
rupturable portion 45 when the rupture disk is in an unruptured
state.
[0064] Referring to FIGS. 1 and 2, the outer edge of knuckle 53
extends downwardly into dome area 35. Outer edge 53 also extends
laterally across dome area 35 to a point that is inside the area
circumscribed by score line 80 or inside the area circumscribed by
an arc connecting the ends 84 and 86 of score line 80. The outer
edge of knuckle 53 forms a generally straight line about which the
rupturable portion will bend when the rupture disk ruptures. In a
presently preferred embodiment, the outer edge 53 extends to a
point inside, but directly adjacent to the area circumscribed by
the score line 80 or the area circumscribed by an arc 85 connecting
the two ends of the score line. This embodiment of the hinge
prevents fragmentation, yet maximizes the size of the opening
created when the disk ruptures, thereby minimizing the pressure
drop, or velocity head loss, over the ruptured disk and achieving a
low flow resistance, K.sub.r.
[0065] As shown in FIG. 4, hinge 52 is formed with a first pocket
90 and a second pocket 92. First and second pockets preferably have
a concave shape that faces gap 51 (referring to FIG. 3b) between
knuckle 53 and rupturable portion 45 of rupture disk 44.
Preferably, first and second pockets 90 and 92 are positioned
adjacent first and second ends 84 and 86 of score line 80,
respectively. It is contemplated that first and second ends 84 and
86 of score line 80 may terminate at a point directly below first
and second pockets 90 and 92, respectively (as illustrated in FIG.
2). Alternatively, first and second ends 84 and 86 of score line
may terminate at a point that is directly aligned with or just
short of first and second pockets 90 and 92, respectively.
[0066] As illustrated in FIGS. 1-4, tongue 54 extends away from
knuckle 53 and into outlet bore 36. Preferably, as shown in FIG. 2,
tongue 54 includes a main linear section 55 with two substantially
straight side flaps 56 that project from the main linear section 55
towards the outlet safety member 32. Preferably, as shown in FIG.
2, the angle 87 between side flaps 56 and main linear section 55 is
obtuse, although the present invention contemplates that angle 87
may be a right angle or an acute angle. More preferably, angle 87
is greater than the angle between main linear section 55 and a line
of radius 89 extending through the corresponding end of main linear
section 55. Still more preferably, angle 87 is within the range of
about 130.degree. to 160.degree..
[0067] In the embodiment illustrated in FIG. 1, side flaps 56
extend towards outlet safety member 32. Preferably, side flaps 56
are in close proximity to, but do not contact outlet safety member
32 when the disk is in an unruptured state.
[0068] In an alternative embodiment, and as illustrated in FIG. 3b,
tongue 54 includes a tongue support 57 that projects from the end
of the tongue towards outlet support member 32. Preferably, tongue
support 57 extends to a point that is in close proximity to, but
not in contact with, outlet support member 32. It is contemplated
that other embodiments of the support structure will be readily
apparent to one skilled in the art.
[0069] Referring to FIG. 2, safety member 50 preferably includes a
series of stress risers 88. Each stress riser 88 extends away from
flange 62 and into dome area 35 of rupturable portion 45 of the
rupture disk. Each stress riser 88 terminates in one or more stress
concentrating points. Preferably, the stress concentrating points
of at least two of the stress risers are aligned with score line 80
in rupturable portion 45 of the rupture disk. The stress
concentrating points, as explained in greater detail below, contact
the rupturable portion of the rupture disk when the rupture disk
reverses to ensure the rupturable portion tears to create a flow
path for fluid to escape.
[0070] The safety member may include recessed, or "scalloped out,"
areas between each stress riser. These "scalloped out" areas create
gaps in the support of the transition area of the rupture disk. As
also explained in greater detail below, the gaps in the support of
the rupture disk also help ensure that the rupturable portion tears
to create a flow path for fluid to escape. These scalloped out
areas may be located at a few selected locations around the safety
member annulus or may alternatively be regularly spaced around the
entire annulus or substantially the entire annulus (e.g. exclusive
of the hinge area).
[0071] As described above and referring to FIG. 1, inlet fluid
pathway 64 conducts pressurized fluid, in either gas or liquid
form, to inlet bore 34 and to rupturable portion 45 of rupture disk
44. In the illustrated embodiment, the pressurized fluid contacts
convex surface 47 of rupture disk 44, thereby placing the material
of the disk under a compressive force. The magnitude of the
compressive force corresponds to the pressure of the fluid. When
the pressure of the fluid reaches a predetermined level and the
compressive force exceeds the structural and material strength of
the rupturable portion of the rupture disk, the dome-shaped section
will begin to buckle, or reverse.
[0072] As illustrated in FIG. 5, the reversal of the disk will
cause the disk to tear along score line 80 to form a disk petal 103
that has a shape defined by score line 80 and a disk hinge 102 that
connects disk petal 103 to flange 48 to prevent the disk from
fragmenting. Under the continued fluid pressure, disk hinge 102
will bend, with respect to the flange, through gap 51 towards
safety member 50. Because knuckle 53 of safety member 50 is close
to disk hinge 102, the momentum gained by the disk hinge will be
relatively small and will be arrested by the eventual contact with
the knuckle before the disk petal gains enough momentum to tear
away from the disk hinge.
[0073] If the disk does not tear along the score line during the
initial buckling of the disk, the disk will continue to buckle and
reverse under the pressure of the fluid until the disk contacts the
stress concentrating points of stress risers 88. The stress
concentrating points will increase the stress in the score line 80
to facilitate opening of the disk. In addition, the unsupported
gaps of the transition area, as defined by the shape of the
"scalloped out" areas of the safety member, create additional
forces in the rupturable portion of the disk to ensure the disk
opens to create a vent path for the fluid.
[0074] After the rupturable portion tears and the disk hinge 102 is
supported by knuckle 53, the force of the fluid pressure and the
momentum of disk petal 103 will cause the disk to bend around the
outer edge of knuckle 53. The petal will continue to bend around
knuckle 53 until contacting tongue 54 of hinge 50. The contact of
disk petal 103 with tongue 54 will bend the tongue until side flaps
56 contact outlet safety member 32. The portions of disk petal 103
that extend on either side of tongue 54 will wrap around the tongue
and contact side flaps 56.
[0075] Depending upon the pressure in the system and the momentum
with which the petal is moving, tongue 54 and side flaps 56 may
further bend and deform with the contact of disk petal 103 to
absorb the kinetic energy of the moving disk petal and stop the
movement of the disk petal. Preferably, side flaps 56 are angled
with respect to the outlet support member so that they may bend
outwardly, or inwardly depending upon angle 87, if the force of
contact with the moving petal is great enough. By absorbing the
kinetic energy of the moving disk petal, the tongue reduces the
overall force on the disk petal, thereby preventing the disk petal
from fragmenting. The dimensions of the hinge and, in particular,
the dimensions of the knuckle and tongue, are selected so that the
hinge will effectively absorb the kinetic energy of the disk petal,
while achieving a large and unobstructed flow path through which
the pressurized fluid may vent.
[0076] In the illustrated embodiment, the portions of the disk
petal surrounding the end of the score line will fold into pockets
90 and 92 of hinge 50. Pockets 90 and 92 extend generally away from
the flange 62 of the safety member and in the direction of the
outlet bore. Pockets 90 and 92 have curved surfaces and are
configured to receive the portions of the rupture disk adjacent the
respective ends 84 and 86 of score line 80 without creating any
additional stress concentrating points. The pockets provide support
for the rupture disk material adjacent the ends of the score line.
This reduces the tensile forces acting on the ends of score line to
prevent the tear in the rupture disk from continuing past the ends
of the score line. Thus, the pockets help in preventing the petal
from completely separating from the disk. In a preferred
embodiment, the disk reverses symmetrically and the disk will wrap
around the opposing pockets at the same time thereby preventing the
creation of any uneven stresses in either side of the disk
hinge.
[0077] The opening created by the rupture of the disk will be
defined by the shape and location of the score line and by the
shape and location of the hinge. In the preferred embodiment, the
score line and hinge are configured to maximize the size of the
opening. It is contemplated that the shape of the hinge, as defined
by the first pocket, the second pocket, and the outer edge of the
knuckle, may be a generally straight line Alternatively, as
illustrated in FIG. 2, the outer edge of the knuckle may be
generally straight and the pockets, disposed on either side of the
knuckle, may angle towards the flange of the safety member.
[0078] In the preferred embodiment and as illustrated in FIG. 4,
the outer edge of the knuckle 53 includes a generally straight
section that is located at a point minimally inside the ends of the
score line 80. The straight section may be inside, but directly
adjacent to the area 83 circumscribed by the score line 80.
Alternatively, the straight section may be inside, but directly
adjacent to the area transcribed by an arc 85 connecting the ends
84 and 86 of score line 80. The line 85 appears for purposes of
illustration in the drawings and does not actually appear on the
disk.
[0079] When disk petal 103 bends around the outer edge 53 of hinge
50, the bending portion of the petal will preferably form a
generally straight line between the ends 84 and 86 of score line
80. Thus, a maximal portion of disk petal 103 will bend out of the
fluid passageway. In this manner, the size of the opening created
when the disk ruptures is maximized.
[0080] In another embodiment and as illustrated in FIGS. 17 and 18,
safety member 50 is generally flat. In certain applications, such
as, for example, electrical switchgear, the space available for the
pressure relief assembly necessitates that the outlet safety head
and hinge be replaced with a flat plate that can be bolted or
otherwise directly attached to the system. To help prevent a
rupture disk from fragmenting in these situations, a hinge may be
defined in the flat plate.
[0081] As illustrated in FIG. 17, safety member 50 includes a hinge
52. Hinge 52 includes a tongue 53 that defines a generally straight
outer section and a pocket 190 and 192 on either side of the hinge.
In the illustrated embodiment, hinge 52 lies in the same plane as
flange 62. The present invention contemplates, however, that hinge
52 may be bent to extend downwardly into the dome of the rupture
disk or upwardly away from the concave side of the disk dome. In
addition, the outer edge of the hinge may have a curved shape.
[0082] Preferably, flange 62 includes a series of bolt holes (not
shown) to allow safety member 50 to be directly connected to the
pressurized system. The flange of the rupture disk may be attached
to flange 62 of the rupture disk with an adhesive or through
welding.
[0083] Pockets 190 and 192 are positioned adjacent first and second
ends 84 and 86 of score line 80 (referring to FIG. 2). It is
contemplated that first and second ends 84 and 86 of score line 80
may terminate at a point directly below first and second pockets
190 and 192. Alternatively, first and second ends 84 and 86 of
score line may terminate at a point that is directly below the edge
of hinge 53 that defines first and second pockets 190 and 192.
[0084] As described in greater detail above, when the rupture disk
opens, petal 103 of the rupture disk will bend around hinge 52 to
absorb the energy of the disk opening. Hinge 52 may bend with petal
103 as the rupture disk opens to further absorb the energy of the
disk opening. Preferably, safety member 50 also includes stress
risers 88 that, as also described above, ensure the rupture disk
fully opens along the score line.
[0085] The portions of the disk petal surrounding the ends of the
score line will fold into pockets 190 and 192. This will reduce the
magnitude of the stresses acting on the ends of the score line to
prevent the tear in the rupture disk from continuing past the ends
of the score line and ultimately causing the disk petal to
fragment.
[0086] Another factor in obtaining a large and unobstructed opening
in all service conditions is controlling the initial reversal point
of the disk. The initial reversal point of the disk is the point at
which the disk initially buckles under the force of the pressurized
fluid. In one preferred embodiment, the initial reversal point is
positioned at the apex of the dome shaped rupturable portion. This
is a central position on the rupture disk and also the position on
the rupturable portion that is the furthest from the transition
area of the disk. Initiating reversal at this point ensures that
the disk reverses in a symmetrical fashion.
[0087] A symmetrical disk reversal will result in an enhanced disk
opening for both scored and unscored disks. In a scored disk, the
symmetrical reversal ensures that an equal force is distributed
along the entirety of the score line so that the disk material will
tear completely along the score line and fully open. In an unscored
disk, where a secondary cutting mechanism, such as perimeter teeth,
are used to puncture and open the disk, the symmetrical reversal
ensures that the disk material will fold evenly over the secondary
cutting mechanism. The secondary cutting mechanism will then cause
the disk to fully open and allow the disk petal to bend around the
disk hinge and maximize the size of the opening.
[0088] In accordance with the present invention, the dome of the
rupturable portion includes a structural apex formation. A
structural apex formation of the present invention will introduce a
structural weakness, such as, for example, a thinning or stretching
of the disk material, into the rupturable portion of the rupture
disk. The thinning or stretching of the disk material compromises
the structural integrity of the disk dome. It has been found that
when the disk is subject to a fluid having a certain pressure, the
rupture disk will initiate its reversal at the structural weakness.
Thus, a properly configured structural apex formation will control
the initial reversal point of the disk.
[0089] It should also be noted that a structural apex formation
will reduce the expected burst pressure of the rupture disk. In
other words, a disk that has a structural apex formation will burst
at a lower pressure than a similar disk without a structural apex
formation. This is noteworthy in that a disk without a structural
apex formation must be made from a thinner material in order to
achieve the same burst pressure as a disk with a structural apex
formation. It has also been found that a correlation exists between
the size and shape of the structural apex formation and the amount
of reduction in the burst pressure. In general, a larger structural
apex formation will result in a greater reduction in burst
pressure.
[0090] The concept of the structural apex formation offers the
potential for great improvement in the reliability and accuracy of
rupture disks, particularly those disks configured to rupture at
low pressures. The low pressure disks must typically be made from a
thin material, which is easily damaged. Any damage to the disk
prior to or during installation can dramatically alter the burst
pressure of the disk. In addition, any irregularities in the
installation, such as mis-alignment of safety heads or of the disk
itself, heat induced irregularities, and bolt or flange
insensitivity, can further alter the burst pressure of the disk.
Since a disk with a structural apex formation can be made from a
thicker material that is less susceptible to these types of
problems, the introduction of a structural apex formation will
improve the reliability of the rupture disks.
[0091] In addition, it has been found that the size and shape of
the structural apex formation will be the determining factor in
determining the burst pressure of the rupture disk. In other words,
the configuration of the structural apex formation will override
other design factors, such as, for example, the depth and location
of the score line, that previously affected the burst pressure of
the rupture disk.
[0092] As shown in FIGS. 6 and 7, the structural apex formation is
preferably an indentation 140 located at the apex of the domed
shape of the rupturable portion. Preferably, as shown in FIG. 7,
indentation 140 is formed in convex surface 47 of the dome,
creating a cavity 143 in the convex surface 47 and a corresponding
nipple-shaped protrusion/dimple 144 in the concave surface 46.
Alternatively, indentation 140 may be formed in the concave surface
46 of the dome, creating a cavity in the concave surface 46 and a
corresponding nipple-shaped protrusion in the convex surface
47.
[0093] As shown in FIG. 7, indentation 140 includes a circular
outer edge 142. Preferably, the distance from the outer edge 142 to
transition area 49 is the same at all points along outer edge 142
of indentation 140.
[0094] As shown in FIGS. 8 and 9, the indentation may have a
variety of shapes. For example, as illustrated in FIG. 8,
indentation 140 may be a straight line having a midpoint coinciding
with the apex of the dome. In addition, as shown in FIG. 9,
indentation 140 may include two straight lines that intersect at
the apex of the dome.
[0095] It is contemplated that changing the size and shape of the
structural apex formation can produce wide variations in the
pressure at which a disk of given size and material will burst. For
example, a 1" disk made of 0.003" thick material having a small
indentation will burst at a higher pressure than a similar disk
with a larger indentation. Thus, altering the configuration of the
structural apex formation allows a particular size and thickness
rupture disk to be adapted to the particular pressure relief needs
of a variety of different commercial applications.
[0096] It should be noted, however, that to produce a rupture disk
that will accurately burst at the desired pressure, the
indentation, or other structural apex formation, must be formed in
a manner that ensures that the configuration of the structural apex
formation is consistent between disks. One method of forming an
indentation in a rupture disk is described in U.S. Pat. No.
6,006,938 to Mozely. In the method described therein, the
indentation is "free-formed" in that a tool is impacted with the
disk as the disk is being formed, without any additional support
for the rupture disk. As shown in the test data set forth below,
the rupture disks formed according to this method will not
consistently burst at a desired pressure. This method, therefore,
will not produce a disk with the high level of burst pressure
accuracy that is demanded by many commercial applications.
[0097] In accordance with the present invention, an apparatus for
forming an indentation in the dome of a rupture disk is provided.
It is contemplated that the indentation may be formed at any stage
in the manufacture of the disk. Accordingly, the present invention
is directed to an apparatus for forming an indentation in a formed
rupture disk or a rupture disk blank and to an apparatus for
forming an indentation in a rupture disk as the dome of the disk is
being formed. The indent forming apparatuses allow indentations to
be formed in rupture disks in a reliable and consistent manner,
which, as set forth in the test data below, results in an
improvement in the burst accuracy of the rupture disks.
[0098] As illustrated in FIG. 10, an indent forming apparatus 148
includes a first member, which is preferably an anvil 154. Anvil
154 includes a support surface 155 that defines and opening 164.
Preferably, opening 164 is circular, although it is contemplated
that opening 164 may have other shapes.
[0099] Support surface 155 is configured to engage one side of
rupturable portion 45 at the apex of the domed shape such that
opening 164 encompasses the apex. It is contemplated that support
surface 155 may have a small width such that only a selected
portion of rupturable portion 45 is supported. Alternatively,
support surface 155 may have a shape that conforms to the contour
of the rupture disk dome and extends to the transition area of the
disk, such that the entire rupturable portion 45, outside of
opening 164, is supported.
[0100] Preferably, support surface 155 engages the concave side of
the domed shape, although the support surface may engage the convex
side of the domed shape. Alternatively, the anvil may engage one
side of a rupture disk blank that, as described in greater detail
below, will eventually be formed into a rupture disk.
[0101] In the illustrated embodiment, the centerline 162 of anvil
154 is aligned with the apex of the domed shape of rupturable
portion 45. It is contemplated, however, that centerline 162 may be
offset from the apex of the dome shape.
[0102] A frame 156 surrounds anvil 154. Frame 156 includes an inner
wall 158 that defines a cavity configured to receive flange 48 of
the rupture disk. Preferably, the height of inner wall 158 is
chosen to ensure that flange 48 does not contact the bottom surface
159 of the cavity so that anvil 154 is the only source of support
for the rupture disk. In addition, the diameter of inner wall 158
closely corresponds to the diameter of flange 48. In this manner,
inner wall 158 ensures that the rupture disk is correctly aligned
on anvil 154.
[0103] Frame 156 may include one or more pins 160 (only one pin
illustrated in FIG. 10). Pins 160 are configured to engage holes 88
in flange 48 (referring to FIG. 6). The engagement of pins 160 with
holes 88 further ensures that the rupture disk is correctly aligned
on anvil 154.
[0104] The indent forming apparatus 148 also includes a second
member, which is preferably a punch 150 that is generally aligned
with opening 164 in anvil 154. In the illustrated embodiment, the
centerline 166 of punch 150 is directly aligned with the centerline
162 of the anvil. The present invention contemplates, however, that
the punch 150 may be offset with respect to the apex and/or the
anvil, provided that the punch tip is within the area circumscribed
by anvil opening 164.
[0105] Punch 150 includes a tip 152 that engages the second side of
rupturable portion 45. As punch 150 moves relative to anvil 154,
the material of the rupturable portion corresponding to opening 164
is displaced relative to the anvil 154. This forced and controlled
displacement causes the disk material along the edge and
downsloping section of the indentation to deform, by stretching,
thinning, or shearing, relative to the surrounding disk
material.
[0106] The supporting force of the anvil, which opposes the force
of the punch, will create a permanent deformation, such as a crease
200 (referring to FIG. 19) in the surface of rupturable portion 45.
This permanent deformation is created as the punch forces a
displacement of the material of the rupturable portion relative to
the material that is supported by the anvil. Preferably, the
concave surface of the disk is supported by the anvil and, thus,
the deformation will be formed in at least the concave surface. It
is contemplated that the deformation may also be formed in the
convex surface or in both the concave and convex surfaces.
[0107] The deformation, stretching, thinning, or shearing of the
disk material creates the structural weakness in the disk dome. By
precisely controlling the movement and location of the punch and
anvil, similar amounts of thinning, stretching, or shearing may be
induced in successive disks. In this manner, the reliability and
accuracy of a series of rupture disks may be maintained at a level
required for commercial application.
[0108] Preferably, the motion of punch 150 is precisely controlled.
In the preferred embodiment, the allowable range of motion of punch
tip 152 is governed by a micrometer, which allows for adjustments
of 0.0001". In this manner, the depth of the indent, with respect
to the apex of the dome, that is created in the rupture disk may be
accurately and precisely controlled.
[0109] Alternatively, punch tip 152 and anvil opening 164 may be
closely sized so that the disk material is displaced in shear. As
illustrated in FIG. 19, indentation 140 formed by shearing
rupturable portion 45 results in outer edge 142 having a sharp
corner. In addition, a crease 200 is formed on the opposite side of
rupturable portion 45, which in the illustrated embodiment is the
concave surface. The shearing action of the punch also creates a
well-defined thinned area 202 in the rupturable portion 45. This
thinned area represents the structural weakness that will coincide
with the point of initial reversal.
[0110] As illustrated in FIG. 11, a punch tip 152 for shearing the
material of rupturable portion 45 preferably includes a concave
surface 168. When punch tip 152 is engaged with rupturable portion
45, edge 167 first engages the curving surface of the rupturable
portion. This ensures that each indentation formed in subsequent
rupture disks will have essentially the same shape. A flat punch
tip will wear down with use and may eventually result in uneven and
inconsistent indentations.
[0111] The profile of punch tip 152 may have any shape or size. For
example, as illustrated in FIGS. 12a-12c, punch tip 152 may have a
circular profile (referring to FIG. 12a), a D-shaped profile
(referring to FIG. 12b), or a tear drop profile (referring to FIG.
12c). The shape of anvil opening 164 may or may not be configured
to correspond to the profile of punch tip 152. For example, a tear
drop shaped punch profile may be used in conjunction with either a
circular anvil opening or a tear drop shaped anvil opening.
[0112] The present invention contemplates that the configuration of
indentation 140 may be varied through any number of variances in
the indent forming apparatus. For example, the size and shape of
punch tip 152 and anvil opening 164 may be varied alone or in
combination to alter the resulting shape of the indentation. In
addition, one or both of punch tip 152 and anvil opening 164 may be
offset from the apex of the dome shape to further vary the
configuration of the indentation. It is expected that continued
experimentation with differently shaped and sized punch tips and
anvil openings will result in an indentation configuration that
provides optimal performance characteristics.
[0113] An apparatus 160 for forming an indentation in the
rupturable portion as the rupture disk is formed is illustrated in
FIGS. 13 and 14. As is known in the art, rupture disks are
typically manufactured from a flat, circular sheet of material
known as a rupture disk blank. A portion of the flat sheet of
material is subject to a pneumatic or hydraulic pressure to form
the dome-shaped rupturable portion.
[0114] Apparatus 160 includes a clamp 161 that securely holds the
perimeter of a disk blank (identified as dashed line 172). Clamp
161 includes a support 162 and a mold 164. Support 162 includes a
central passageway 168 connected to a source of pressurized fluid.
When the disk blank is securely fastened in clamp 161, passageway
directs the pressurized fluid (as indicated by arrows 170) against
the central, unclamped portion of the disk blank. The force of the
fluid acts on the unclamped material of the disk blank to displace
the unclamped material relative to the clamp and into mold 164.
[0115] Mold 164 includes a concave surface 176 that faces the disk
blank. As the unclamped material is displaced relative to the
clamp, the material engages concave surface 176. The shape of
concave surface 176 defines the resulting shape of rupturable
portion 45.
[0116] Mold 164 includes an opening 150 that houses a member, which
is preferably a punch 150. Punch 150 includes a tip 152 that
projects from concave surface 176 at or near a point that
corresponds to the apex of the domed shape. Preferably, punch 150
is moveable with respect to mold 164 to vary the distance by which
punch tip 152 projects from concave surface 176. Mold 164 also
includes a vent 174 to allow the pressurized fluid to escape if any
problems occur during the formation of the rupture disk.
[0117] As illustrated in FIG. 14, punch tip 152 engages the
material of the disk blank as it is displaced by the pressurized
fluid. The continued force of the fluid on the blank material
causes the material to deflect around the punch tip, resulting in
the formation of indentation 140. The shape of indentation 140 and
of indentation edge 142 may be altered by varying the pressure of
the forming fluid. A higher fluid pressure will result in a sharper
radius of curvature in indentation edge 142. Conversely, a lower
fluid pressure will result in a greater radius of curvature in
indentation edge.
[0118] By forming the rupture disk into the mold and punch
combination, the resulting configuration of the indentation can be
precisely controlled. In particular, the depth of the indentation,
with respect to the apex of the dome, can be precisely controlled.
In addition, the height of the dome with respect to the disk
flange, which is another factor that has a significant impact on
the burst pressure of the disk, can be precisely controlled. Thus,
the reliability and accuracy of the rupture disks can be maintained
at a level required for commercial applications.
[0119] The present invention contemplates that punch tip 152 may
have a cross-sectional shape as illustrated in FIG. 11, and any
profile, including, for example, those profiles illustrated in
FIGS. 12a-12c. It is further contemplated that the punch tip may be
offset from the apex of the domed shape.
[0120] The configuration of indentation 140 may also be varied by
moving the punch tip and reforming the disk dome. After the disk is
formed with a fluid at a first pressure, punch tip 152 may be
retracted, partially or fully, with respect to the concave shape of
the mold. The rupture disk is then subject to pressurized fluid at
a second pressure, which is preferably less than the original
forming pressure. The pressurized fluid will again act on the disk
to reform the dome. Since the punch tip is no longer engaged with
the rupturable portion, the fluid will act to decrease the depth of
the indentation relative to the apex of the domed shape. In this
manner, the configuration of the indentation may be altered.
[0121] The present invention further contemplates that a rupture
disk dome having an indentation may be hard stamped from a rupture
disk blank. This would be achieved by tooling that is configured to
create the desired shape of the rupture disk dome from the rupture
disk blank. In this embodiment, the punch is slidably disposed in
the tooling. This would allow the depth of the indent, relative to
the apex of the dome, to be changed between disks having similar
dome heights and shapes. As discussed above, the configuration of
the indentation determines the burst pressure of the rupture disk.
Thus, the burst pressure of otherwise similar disks may be easily
modified to meet the needs of different commercial
applications.
[0122] Alternatively, as illustrated in FIGS. 15 and 16, the
structural apex formation may be an opening 180 in rupturable
portion 45 of the rupture disk. As shown in FIG. 15, opening 180 is
preferably centered at the apex of the domed shape of rupturable
portion 45. It is contemplated, however, that opening 180 may be
offset from the apex of the domed shape.
[0123] As illustrated in FIG. 15, opening 180 is preferably
circular. The present invention contemplates, however, that opening
180 may have other shapes, such as, for example, a triangle,
square, pentagon, hexagon, or oval.
[0124] As illustrated in FIG. 16, a liner 182 covers and seals
opening 182. Preferably, liner 182 is made of a material that is
lighter and more flexible that the material of the rupture disk.
Preferably, liner 182 covers the entire rupture disk, although
liner 182 may only extend a short distance past opening 182. Liner
182 may be attached with an adhesive material or through welding to
any part of the rupture disk, including the rupturable portion
and/or the flange.
[0125] It has been found, as evidenced in the examples below, that
indenting the dome of the disk at the apex in accordance with the
methods and apparatus of the present invention improves the burst
accuracy of the rupture disk. Rupture disks are manufactured in
lots of a given number (typically 5-10 pieces) and all disks within
a lot receive a rated rupture pressure based on a statistical
sampling of test disks from the same manufacturing lot. Typically,
all of the disks within the lot will rupture within 5% of the rated
rupture pressure. Thus, to prevent premature rupture of the disk,
the operating pressure of the system should not exceed 90% of the
rated rupture pressure of the disk. Increasing the accuracy and
repeatability of the disk will allow the system to be operated at
higher than 90% of the rated pressure of the rupture disk and still
achieve an acceptable safety margin.
[0126] Rupture disks according to the present invention are
considerably more consistent in their actual rupture pressure. The
following burst accuracy test data represents comparative testing
done on rupture disks having an indentation formed in one of three
different methods: (1) free formed indent, (2) mold formed indent;
and (3) anvil formed indent.
[0127] Burst Accuracy Test 1--Disks with Free Formed
Indentation:
[0128] This burst accuracy testing was performed on 1.5" disks
having an indentation formed with a "free form" method where a tool
was engaged with the disk dome during formation, without the use of
a mold or other support. Several configurations of disks having
various thicknesses, dome heights, and indent depths were burst to
determine the actual burst pressure of each disk. The actual burst
pressures for each configuration of disk were then compared to
determine the burst accuracy for that disk configuration.
1 Dome Indent Avg. Burst Test Disk Size Thickness Height Depth Nbr.
of Pressure Burst Pressure No. (inches) (inches) (.001") (.001")
Samples (psi) Accuracy* 1 1.5 0.003 126 14.2 10 15.4 5.6 2 1.5
0.003 152 5.2 8 18.1 2.3 3 1.5 0.007 251 14.3 6 150 1.0 4 1.5 0.007
150 11 7 95 5.0 5 1.5 0.007 142 1 8 122 4.7 6 1.5 0.007 256 17 10
155 2.8 7 1.5 0.01 207 3.7 5 318 2.0 8 1.5 0.01 274 5.1 7 401 4.7 9
1.5 0.01 234 8 10 353 3.1 10 1.5 0.01 207 3.7 5 305 5.2 11 1.5
0.0025 152 12.5 4 10.2 5.1 12 1.5 0.004 155 12 8 28.4 5.9 13 1.5
0.004 145 3 8 35.2 7 *Represents three times the standard deviation
in actual burst pressures as a percentage of the average rated
burst pressure.
[0129] Burst Accuracy Test 2--Disks with Mold Formed
Indentation:
[0130] This burst accuracy testing was performed on 1.5" disks
having an indentation formed with a mold as described in greater
detail above. Several configurations of disks having various
thicknesses, dome heights, and indent depths were burst to
determine the actual burst pressure of each disk. The actual burst
pressures for each configuration of disk were then compared to
determine the burst accuracy for that disk configuration.
2 Disk Dome Indent Avg. Burst Test Size Thickness Height Depth Nbr.
of Pressure Burst Pressure No. (inches) (inches) (.001") (.001")
Samples (psi) Accuracy* 1 1.5 0.003 289 8.9 12 38.2 2.8 2 1.5 .003
136 10.4 20 15.1 2.6 3 1.5 .006 140 6.7 20 75.7 2.9 4 1.5 0.007 144
10.7 10 114 1.9 5 1.5 0.007 268 2.7 5 215 1.3 6 1.5 0.0025 143 1.2
5 14.7 4.6 7 1.5 0.003 289 8.9 12 38.8 2.2 8 1.5 0.003 289 9.3 8
38.3 2.9 9 1.5 0.003 289 8.8 7 38.5 2.9 10 1.5 0.003 291 3.7 7 46.4
2.4 11 1.5 0.003 291 2.8 6 58.1 2.7 12 1.5 0.003 291 9.1 5 37.6 3.3
13 1.5 0.003 287 7.1 10 51.3 2.1 *Represents three times the
standard deviation in actual burst pressures as a percentage of the
average rated burst pressure.
[0131] Burst Accuracy Test 3--Disks with Anvil Formed
Indentation:
[0132] This burst accuracy testing was performed on 1" disks having
an indentation formed with an anvil after formation of the disk
dome, as described in greater detail above. Several configurations
of disks having various thicknesses, dome heights, and indent
depths were burst to determine the actual burst pressure of each
disk. The actual burst pressures for each configuration of disk
were then compared to determine the burst accuracy for that disk
configuration.
3 Disk Dome Indent Avg. Burst Test Size Thickness Height Depth Nbr.
of Pressure Burst Pressure No. (inches) (inches) (.001") (.001")
Samples (psi) Accuracy* 1 1 0.003 190 23.6 9 22.56 2.59 2 1 0003
190 25.5 9 22.43 2.5 3 1 0.003 190 27.6 9 22.40 2.92 4 1 0.003 190
29.5 9 22.39 1.95 5 1 0.003 190 29.5 9 22.26 2.79 6 1 0.003 190
31.4 9 21.79 2.79 7 1 0.004 190 n/a 10 50.63 2.20 8 1 0.003 250 n/a
5 35.24 4.3 9 1 0.011 190 n/a 5 310.1 3.8 10 1 0.011 250 n/a 5
460.3 1.0 11 1 0.007 220 n/a 5 151.4 3.9 *Represents three times
the standard deviation in actual burst pressures as a percentage of
the average rated burst pressure.
[0133] Burst Accuracy Summary
[0134] The following table summarizes the foregoing test data. This
table presents the average of burst accuracies for the different
methods of forming an indentation in the dome of the rupture
disk.
4 Indent Forming Method Average Burst Accuracy* Free Formed Indent
4.18 Mold Formed 2.66 Anvil Formed 2.79 *Represents an average of
the burst accuracies as determined in the above testing.
[0135] As shown in the above testing and summarized in the
preceding table, rupture disks having an indentation formed in
accordance with the present invention have a far greater burst
accuracy than disks having indentations formed with other
methods.
[0136] Adjusting other design parameters of the disk, such as, for
example, the location of the score line, may provide additional
improvements upon the burst accuracy of the disk. The present
invention contemplates that a rupture disk having a structural apex
formation consistent with the present invention and a score line in
the transition area of the disk will also have greatly improved
burst accuracy characteristics when compared to the burst accuracy
characteristics of conventional rupture disks.
[0137] Another benefit of the present invention is a reduced damage
safety ratio. The damage safety ratio of a disk is determined by
dividing the actual burst pressure of a damaged disk by the rated
pressure of the disk. The following data represents the damage
ratio of rupture disks made according to the present invention with
different types of damage:
[0138] Damage Test:
[0139] The following damage testing was performed on 1" rupture
disks according to the present invention. These rupture disks were
made from 0.004" Ni formed at 275 psig with a resulting 0.190"
crown height. The average burst pressure of the disk batch tested
in an undamaged state was 50.6 psig. According to ASME standards,
an acceptable burst pressure tolerance is .+-.5 psig of the rated
burst pressure. Thus, for the rupture disks of this test, the
minimum acceptable burst pressure is 48.1 psig and the maximum
acceptable burst pressure is 53.1 psig.
5 Average Burst Actual Burst Damage Damage Type* Pressure (psig)
Pressure (psig) Ratio None 50.6 50.5 1.00 None 50.6 50.5 1.00 Blunt
damage** to disk dome 50.6 51.0 1.01 behind hinge, so that disk
dome contacts midpoint of the knuckle Blunt damage to disk dome
50.6 51.0 1.01 behind hinge, so that disk dome does not contact the
knuckle Blunt damage to the transition 50.6 51.0 1.01 area behind
the hinge Blunt damage to the transition 50.6 51.0 1.01 area
opposite the hinge Sharp damage*** to the 50.6 49.7 0.98 transition
area behind the hinge Sharp damage to the transition 50.6 50.5 1 00
area opposite the hinge Sharp damage to the transition 50.6 51.0
1.01 area over one of the stress risers Sharp damage on score line
50.6 51.0 1.01 opposite the hinge Blunt damage across score 50.6
42.5 0.84 line opposite the hinge Blunt damage across 50.6 25.0
0.49 center of dome Sharp damage to dome 50.6 35.0 0.69 3.75 mm
from central indentation Sharp damage to dome 50.6 45.0 0.89 7.5 mm
from central indentation *A disk is considered damaged when the
dome of the disk is physically altered to include a feature that is
visible on both sides of the rupturable portion of the disk.
**Blunt damage to the disk was inflicted using a generally flat
object with a circular profile, for example a hammer with a
diameter of approximately 0.75". ***Sharp damage to the disk was
inflicted using a tool having a rectangular profiled tip, for
example a screw driver with dimensions 0.200" .times. 0.040".
[0140] As shown in the above testing, a rupture disk made in
accordance with the present invention has a damage safety ratio of
less than about 1. Thus, if a rupture disk according to the present
invention is damaged prior to or after installation, the disk will
still rupture at a pressure that is no greater than the maximum
acceptable burst pressure of the disk (which, in this example, is
the rated burst pressure plus 5%).
[0141] As mentioned previously, the disclosed pressure relief
assembly may be used in a pressurized system containing either a
pressurized gas or a pressurized liquid. In accordance with the
present invention, a rupture disk is provided that, when burst, has
a low flow resistance, K.sub.r, in both a liquid application and a
gas application.
[0142] The flow resistance, K.sub.r, of a rupture disk determines
the rate at which the rupture disk will relieve fluid to reduce the
pressure of a system. The flow resistance is a function of the
pressure drop, or velocity head loss, over the burst rupture disk.
A large velocity head loss results in a large K.sub.r and, thus, a
lower fluid release rate. The American Society of Mechanical
Engineers (ASME), standard ASME PTC 25, have established
performance testing requirements for fluid relief rates of a
rupture disk.
[0143] Rupture disks made in accordance with the present invention
have a low K.sub.r in both liquid and gas environments. The K.sub.r
rating of a rupture disk is determined through a standardized
procedure. In one method, the K.sub.r rating of a particular disk
design is determined by bursting three samples of three different
sizes of the rupture disk at the minimum pressure rating for the
disk. The K.sub.r value for each of the nine burst disks is then
determined. Next, the average and the standard deviation of the
nine K.sub.r values is determined. The K.sub.r rating for the
rupture disk is equal to the average of the nine K.sub.r values
plus three times the standard deviation of the nine K.sub.r values.
The following test data represents testing done on disks made in
accordance with the present invention in a gas environment
according to ASME standards:
6 Disk Size Test No. K.sub.r Value 1.0" 1 0.256 1.0" 2 0.266 1.0" 3
0.271 1.5" 1 0.329 1.5" 2 0.321 1.5" 3 0.285 2.0" 1 0.314 2.0" 2
0.270 2.0" 3 0.282 Average 0.288222 Standard Deviation 0.022074
K.sub.r Rating 0.354444
[0144] As shown in the above testing, a rupture disk according to
the present invention has a low K.sub.r in a gas environment. While
the K.sub.r for a liquid environment may be slightly higher, the
present invention nonetheless provides for a low K.sub.r value
under liquid conditions. Preferably, the K.sub.r of the rupture
disk according to the present invention is less than about 1.6 in
both gas and liquid applications. More preferably, the K.sub.r of
the rupture disk according to the present invention is less than
about 1.0 in both gas and liquid applications. Even more
preferably, the K.sub.r of the rupture disk according to the
present invention is less than about 0.7 in gas and/or liquid
applications.
[0145] An additional benefit of the present invention is a rupture
disk design that provides low rupture pressures in a liquid
application. Conventional non-fragmenting rupture disks are
unsuited for low pressure liquid applications since the disks will
not open fully in such an application. The rupture disk of the
present invention, however, will meet ASME performance standards in
liquid applications having operating pressures of under 100
psig.
[0146] It will be apparent to those skilled in the art that various
modifications and variations can be made in the rupture disk
assembly of the present invention without departing from the scope
or spirit of the invention. Other embodiments of the invention will
be apparent to those skilled in the art from consideration of the
specification and practice of the invention disclosed herein. It is
intended that the specification and examples be considered as
exemplary only, with a true scope and spirit of the invention being
indicated by the following claims.
* * * * *