The Fail
Safe CSI™ Reverse Buckling Disk and CSR-7RS Safety
Head
The Sure-Saf® System has been developed to provide optimal safety
using rupture disk (bursting disc) pressure relief technology. The CSI™ rupture disk (bursting disc)
combined with the CSR-7RS™ safety head provides accuracy and reliability.
This unique partnership ensures the CSI™ disk bursts at or below its
certified burst pressure in the event that the disk is installed in the
wrong direction or becomes damaged.
The CSI™ rupture disk (bursting disc) uses SafT
technology (structural apex forming), the central feature on the disk
dome, which enhances accuracy of burst pressure. At its burst pressure,
the CSI™ rupture disk (bursting disc) dome reverses and opens by shearing around a
circular score line located at the perimeter of the dome. The CSR-7RS™
safety head outlet contains an energy-absorbing hinge that aligns with an
unscored portion of the CSI™ disk perimeter that retains the CSI™ disk
upon opening, avoiding fragmentation.
CSI™ Disk
Features
- Reverse Buckling Disk in Sizes 1" / 25mm ~ 8" / 200mm
- Non-Fragmentation Design
- Designed for Gas, Liquid, or 2-phase Flow Conditions
- Fail
Safe: Reversal Safety Ratio <1
- Fail
Safe: Damage Safety Ratio <1
- High
Operating Ratio: 90% of Marked Burst Pressure
- High
Operating Ratio: 95% of Minimum Burst Pressure (ISO & European
Codes)
- SafT
Technology
- Vacuum Resistant
- Resists Product Accumulation
- Static or Cyclic Operating Conditions
- Standard 0% Manufacturing Design Range
- Optional -5% & -10% Manufacturing Design Range
Reversal
Safety Ratio < 1
Should the CSI™
rupture disk (bursting disc) in its CSR-7RS™ safety head be accidentally installed the
wrong way, it will burst at or typically below its burst pressure. This
"fail-safe" design feature is called the reversal safety ratio. With a
value of 1 or less, the CSI™ disk will relieve pressure at a reduced burst
pressure should improper installation cause pressure to be applied to the
disk's concave side.
Installed in the
wrong direction, the CSI™ rupture disk (bursting disc) interacts along its circular score
line with stress raising features in the CSR-7RS™ safety head to open at a
reduced burst pressure.
Damage Safety
Ratio <1
If the CSR™ rupture disk (bursting disc) is accidentally damaged, it will relieve pressure by bursting
at or typically below its marked burst pressure. This "fail-safe" design
feature is called the damage safety ratio. With a value of 1 or less, the
CSI™ disk will relieve pressure at a reduced burst pressure if damaged.
When the domed structure of the CSI™ rupture disk (bursting disc) is damaged, it will
reverse at a reduced pressure and interact along its circular score line
with stress raising features in the CSR-7RS™ safety head to open at a
reduced burst pressure.
Burst
Tolerance
Burst tolerance
is the +/- range of pressure over which a rupture disk (bursting disc) can be expected to
burst.
Burst tolerance is either +/-5% of burst pressure or +/-2psi
(+/-0.138 bar) for disks rated below 40 psi/2.76 bar.
Minimum Net
Flow Area / Net Relief Area
Disk
Size
in/mm |
Minimum
Net Flow Area
in square inches |
Net Relief Area
in square centimeters |
1/
25 |
0.86 |
5.55 |
1-1/2/
40 |
1.89 |
12.19 |
2/
50 |
3.36 |
21.68 |
3/
80 |
7.29 |
47.03 |
4/
100 |
11.20 |
72.26 |
6/
150 |
22.65 |
146.13 |
8/
200 |
42.72 |
275.61 |
|
In the case
of the CSI™ rupture disk (bursting disc), the MNFA & the NRA are the same. MNFA
is expressed in square inches to facilitate sizing calculations in
line with ASME practices. NRA is expressed in square centimeters for
use when sizing in line with ISO, European Standards and forthcoming
CEN practices. |
CSI™ Rupture
Disk Material Options
The CSI™ rupture
disk is available in a range of corrosion resistant materials (see table).
For each material the upper temperature limit has been determined through
the recommendations of material manufacturers and user experience. While
Hastelloy C-276 is the standard grade used, Hastelloy B & Hastelloy
C-22 may be available upon request.
Fluorocarbon film
liners are available as an additional corrosion barrier attached to the
inlet side of CSI™ rupture disks (bursting discs). FEP is the standard liner material. PFA
and PTFE are available. FEP & PFA are limited to 400 ºF/ 204 ºC
maximum recommended temperature, PTFE is limited to 500 ºF/ 260 ºC.
Teflon® materials are typically used: Teflon® is a DuPont
trademark.
Burst
Pressure Capability
Disk Size
in/mm
|
Nickel 200
psig/barg
Min/Max
|
316
Stainless
Steel
psig/barg
Min/Max
|
Inconel 600
psig/barg
Min/Max
|
Monel 400
psig/barg
Min/Max
|
Hastelloy-C276
psig/barg
Min/Max
|
1 /
25
|
70/
4.83
|
500/
34.48
|
90/
6.21
|
500/
34.48
|
80/
5.52
|
500/
34.48
|
70/
4.83
|
500/
34.48
|
90/
6.21
|
500/
34.48
|
1-1/2/
40 |
50/
3.45 |
500/
34.48 |
80/
5.52 |
500/
34.48 |
50/
3.45 |
500/
34.48 |
50/
3.45 |
500/
34.48 |
80/
5.52 |
500/
34.48 |
2/
50 |
50/
3.45 |
500/
34.48 |
75/
5.17 |
500/
34.48 |
50/
3.45 |
500/
34.48 |
50/
3.45 |
500/
34.48 |
75/
5.17 |
500/
34.48 |
3/
80 |
45/
3.10 |
500/
34.48 |
70/
4.83 |
500/
34.48 |
45/
3.10 |
500/
34.48 |
45/
3.10 |
500/
34.48 |
70/
4.83 |
500/
34.48 |
4/
100 |
45/
3.10 |
500/
34.48 |
65/
4.48 |
500/
34.48 |
45/
3.10 |
500/
34.48 |
45/
3.10 |
500/
34.48 |
65/
4.48 |
500/
34.48 |
6/
150 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
8/
200 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
30/
2.07 |
500/
34.48 |
Temperature
The burst
pressure of each lot of CSI™ rupture disks (bursting discs) is tested at the user indicated
temperature condition: should the disk be rated above or below ambient
temperature, burst testing for product certification shall be conducted at
this coincident burst temperature to ensure the best product accuracy. For
applications that have operating temperatures that may exceed the burst
temperature, please review with BS&B Safety Systems, Inc.
Maximum
Recommended Temperature
| Disk
Material |
Maximum
Temperature
in degrees Fahrenheit |
Maximum Temperature
in degrees
Centigrade
|
| Nickel
alloy 200 |
750 |
399 |
| 316
Stainless Steel |
900 |
482 |
| Inconel
Alloy 600 * |
900 |
482 |
| Monel alloy
400 |
800 |
427 |
| Hastelloy
Alloy C-276 |
900 |
482 |
| Fluorocarbon Liner (FEP) |
400 |
204 |
| Fluorocarbon Liner (PFA) |
400 |
204 |
| Fluorocarbon Liner (PTFE) |
500 |
260 |
| *Inconel
CSI™ disks can be specially fabricated at temperatures of up to 1100
deg F / 593 deg C. Hastelloy
is a trademark of Haynes International Inc., Monel and Inconel are
trademarks of Inco Alloys International. Teflon is a trademark of
DuPont. BS&B may use equivalent materials from other
sources. |
Operating
Pressure Ratio
CSI™ Reverse
Buckling Disks can be operated to 90% of their marked burst pressure,
which equates to 95% of their minimum burst pressure. (For disks certified
with a European / ISO 'Performance Tolerance', the CSI™ disk can be
operated to 95% of the burst pressure less the negative performance
tolerance.)
Manufacturing
Design Range
Manufacturing
design range (MDR) is a range of pressure, always applied to the minus
side of the user requested burst pressure for CSI™ rupture disks (bursting discs), that
simplifies disk fabrication testing and provides economic benefit to the
user where such an added tolerance can be accommodated by the
application.
The CSI™ rupture disk (bursting disc) is available with a standard "0"
MDR, and the options of "-5%" and "-10%". The standard "0" range provides
the user with the tightest margin between normal service pressure and
burst pressure.
Example: Requested burst pressure 100 %
User
selected manufacturing design range -10%
Applicable burst tolerance
+/-5%
Then following the two different code approaches to these
tolerances:
| ASME /
North American Codes & Standards |
European / PED & International / ISO
Standards |
| Marked
Burst Pressure lies between 90~100 % |
Burst Pressure is 100% |
| Lowest
possible burst pressure is 90 less 5%burst tolerance =
85.5% |
Minimum burst pressure is 100 less 10% MDR less 5% burst
tolerance = 85.5% |
| Highest
possible burst pressure is 100 plus 5% burst tolerance =
105% |
Maximum burst pressure is 100 plus 5% burst tolerance =
105% |
| - |
Alternatively the tolerances may be expressed as a +5% / -15%
Performance Tolerance on 100%. |
| If Marked
Burst Pressure is 95%, lowest burst pressure is 90.25%, highest is
99.75% |
Marked Burst Pressure is always either Min/Max or 100% with a
Performance Tolerance |
| By
providing this example in percentage terms, real pressures can be
input using any units. Effectively the ASME and CEN approaches could
deliver the same product, although generally the ASME approach will
not consume the whole of the manufacturing design
range. |
CSR-7RS™
Safety Head Specifications
|
Nominal
Size |
Safety Head Flange Rating |
Safety Head Flange Thickness |
Dimensions |
| X |
Y |
| IN |
MM |
ANSI |
DIN |
JIS |
IN |
MM |
IN |
MM |
IN |
MM |
| 1 |
25 |
150 |
- |
- |
1-1/2 |
38.0 |
2-5/8 |
66.7 |
2-5/8 |
66.7 |
| 1 |
25 |
300/600 |
10/16/25/40 |
10/16/20/30/40 |
1-1/2 |
38.0 |
2-7/8 |
73.0 |
2-7/8 |
73.0 |
| 1.5 |
40 |
150 |
- |
10/16/20 |
1-5/8 |
43.0 |
3-3/8 |
85.7 |
3-3/8 |
85.7 |
| 1.5 |
40 |
300/600 |
10/16/25/40 |
30/40 |
1-5/8 |
43.0 |
3-3/4 |
95.2 |
3-3/4 |
95.2 |
| 2 |
50 |
150/300/600 |
10/16/25/40 |
10/16/20/30/40 |
1-3/4 |
47.5 |
4-1/8 |
104.8 |
4-1/8 |
104.8 |
| 3 |
80 |
150/300/600 |
10/16/25/40 |
16/20/30/40 |
2-1/8 |
55.0 |
5-1/4 |
133.3 |
5-1/4 |
133.3 |
| 3 |
80 |
- |
- |
10 |
2-5/8 |
66.7 |
4-3/4 |
120.6 |
4-3/4 |
120.6 |
| 4 |
100 |
150/300 |
10/16/25/40 |
16/20/30/40 |
2-7/8 |
73.0 |
6-1/4 |
158.7 |
6-1/4 |
158.7 |
| 4 |
100 |
- |
- |
10 |
2-3/4 |
69.9 |
Flower Petal |
| 4 |
100 |
600 |
- |
- |
2-5/8 |
66.7 |
7-5/8
|
OD/193.7 MM OD |
| 6 |
150 |
150/300 |
10/16/25/40 |
10/30/40 |
3-11/16 |
93.7 |
Flower Petal |
| 6 |
150 |
- |
- |
16/20 |
4-1/5 |
106.7 |
Flower Petal |
| 6 |
150 |
600 |
- |
- |
3-1/8 |
79.4 |
10-3/8" |
OD/263.5 MM OD |
| 8 |
200 |
150/300 |
10 |
- |
3-3/4 |
95.3 |
Flower Petal |
Flow
Performance - KR Values - Rupture
Disk Sizing
Flow resistance
factor "KR" may be used to determine the relieving capacity of a system when
using techniques such as those described in Crane Technical Paper No. 410.
Individual KR values have been established for both Gas & Liquid
service for the CSI™ disk. These are experimentally determined at the
BS&B Safety Systems Inc. flow laboratory following ASME procedures and
witnessed by ASME representatives. Care must be taken to use the correct
value for sizing purposes. When KR values are
marked on the CSI™ disk tag, those for gas service are shown as
"KRG", and those for liquid service are shown as "KRL". The KRg value is 0.62 and the KRI value is 6.92.
When using
KR value for sizing calculations, the nominal pipe size (assuming
schedule 40 pipe) of the vent system is used. When using 'coefficient of
discharge' sizing techniques, the Minimum Net Flow Area or Net Relief Area
of the rupture disk (bursting disc) device is used. This information is shown with the
CSR-7RS™ safety head details.
CSR-7RS™
Safety Head
- Asymmetric locating pins center the disk in the safety head
eliminating disk slippage and ensuring correct installation.
- The
CSR-7RS™ can be pretorqued in the workshop for exact calibration
permitting simple and correct installation.
- For
further installation assurance, a J-bolt is fitted which mates with a
hole drilled in the inlet companion flange.
- The
CSR-7RS™ fits multiple international flanges ratings including ANSI,
DIN, BS and JIS, thus reducing unwanted inventory.
- Metal
to metal bite-type seal 2 inches and above.
- Unique stress raising features in the bore of the CSR-7RS™
interact with the CSI™ disk circular score line to provide a Reversal
Safety Ratio & Damage Safety Ratio of 1 or less.
- Materials available: 316SS, Carbon Steel, Inconel Alloy 600,
Monel Alloy 400 and Hastelloy-C276/Alloy C-276.
Patent Information
CSI™ rupture disk (bursting disc):
Worldwide patents
& US 5167337.
US and worldwide patents pending.
CSR-7RS™
safety head:
Worldwide patents and US 4751938 &
5005722.
Products, specifications and all data in this
literature are subject to change without notice. Questions regarding
product selection and specifications for specific applications should be
directed to BS&B Safety Systems, Inc. or BS&B Safety Systems
Ltd.
All sales are subject to BS&B Safety
Systems, Inc. or BS&B Safety Systems Ltd. standard terms and
conditions of sale. |
ENG
DE
RUS
FR
ITA
