Rupture Disk
The original rupture disk (bursting disc) manufacturer shaping the growth of pressure relief devices for over 80 years.

RB-90™ Reverse Buckling Disk

Definitions
Advantages
Features
Primary Relief
RB-7R Bolted Type Safety Head
RB-90 Safety Head Specifications

 Definitions

The disk relieves overpressure by reversing and snapping against knife blades located in the Safety Head cutting the disk into four petals.

  • Sizes: 1" to 36" (25 to 900mm)
  • Marked burst Pressures: 10 to 1800psig (.69 to 124.1)
  • Temperatures: -420°F to 1000°F (-251°C to 538°C)
  • Maximum Operating Pressure: 90% of the marked burst pressure
  • Materials: Standards and Specials
  • Vacuum: Withstands full vacuum or 15 psig of back pressure without the use of supports
  • Manufacturing Ranges: 0%, 5%, 10%
  • Pressure Cycling or Pulsating Conditions: Excellent
  • Service Phase: Gas or liquid with gas pocket
  • Longer Service Life
  • Only a 10% margin between system operating pressure and the reversal pressure of disk
Advantages

Closer Margin Between System Design and Operating Pressure

The RB-90 Rupture Disk (Bursting Disc) enables systems to be operated at pressures up to 90% of the tagged burst pressure ... as compared to a maximum of 70 to 80% for tension loaded solid metal and composite disks.

Existing equipment can now operate closer to its maximum allowable working pressure (MAWP).

Cuts Costs of New Systems 

Only a 10% margin is needed between system operating pressure and the reversal pressure of an RB-90 Disk.  This means the design pressure of a vessel, protected by the RB-90, can be closer to its operating pressure than one protected by relief devices requiring a 20 to 30% margin.

Longer Service Life

The RB-90 Rupture Disk (Bursting Disc) will last ten or more times longer than conventional prebulged disks in static or positive pressure cycles... 100 or more times longer in pressure-vacuum cycling service.

Less Affected by Fatigue and Creep

RB-90 disks are installed with the convex side toward the process and have compression loading.  Conventional disks are installed with the concave side toward the process and are under tension loading.  Disk metals under compression are much less affected by fatigue and creep.

No Vacuum Supports Required

RB-90 Disk metals are thicker than those used in conventional solid disks of the same size and pressure rating, so vacuum supports are not required.  The RB-90 disk can also withstand high back pressure without damage.

Product Buildup is Reduced

RB-90 disks resist product buildup.  Only the smooth convex side is exposed to system contents.  The vacuum support under a conventional disk has an irregular surface which tends to allow a much faster product buildup.  The use of RB-90 disks therefore cut maintenance costs by greatly extending the length of time between Safety Head disassemblies for cleaning.

Designed for Minimal Fragmentation

The RB-90 Rupture Disk (Bursting Disc) has four razor sharp blades that cut the disk into four equal segments without fragmentation.  No process contamination by metal.

Features
  • Isolates Safety Relief Valves
  • Designed for Minimal Fragmentation
  • Operates up to 90% Rated Pressure
  • Can Withstand Full Vacuum without Supports
  • Available in Sizes 1" thru 36"
  • Wide Material Availability

SPECIFICATIONS FOR STANDARD RB-90 RUPTURE DISKS Min/Max Disk Pressure Rating at 72o F. (PSIG) Disk Material

DISK SIZE
ALUMINUM
NICKEL/ALLOY 200
MONEL/ALLOY 400
INCONEL/ALLOY 600
316 SS
(inches)
MIN
MAX
MIN
MAX
MIN
MAX
MIN
MAX
MIN
MAX
1

1 1/2

2

30

25

22

250

200

150

100

80

50

1600

1500

1400

100

80

50

1000

1000

1000

100

80

50

1800

1700

1600

100

80

50

1800

1700

1600
3

4

6

21

20

20

125

100

80

45

40

35

1300

1300

800

45

40

35

900

800

700

45

40

35

1500

1500

850

45

40

35

1500

1500

850

8,10,12

14,16

18,20

24,30,36

15

15

13

10

60

50

40

35

25

25

25

25

750

750

700

700

25

25

25

25

650

650

650

650

25

25

25

25

800

800

700

700

30

30

30

30

800

800

700

700

Manufacturing Design Ranges

  1. All standard disks are available with 0%, 5%, and 10% manufacturing ranges.
  2. On disks with 5% and 10% manufacturing ranges, the total range is placed on the minus side of the requested rating.
  3. Disks with 0% manufacturing range will be marked at requested rating.

EXAMPLE:
If a 100 psi burst pressure RB-90 disk is ordered with a zero manufacturing range, the disk will be tagged 100 psi burst pressure.

If a similar RB-90 Disk is ordered with a 10% manufacturing design range, it may be tagged at any pressure between 90 psi and 100 psi.

Burst Tolerances

Burst tolerances are the average variation from the above marked burst pressure.

Disk marked above 40 psig ± 5%
Disks marked 40 psig
and below ± 2psi

Service Conditions 

Recommended for gas service only. For longer service life and lower maintenance, the STA-SAF® System (Type S-90, JRS and RLS) or SURE-SAFTM (Type CSR) is recommended. Refer to Catalogs 77-4001 and 77-4009

Specifications for RB-90® Reverse Buckling Rupture Disks

BS&B reverse buckling rupture disks (bursting discs) listed on the following chart are standard.  Disks with higher or lower bursting pressures than those listed and in other materials may be available on special order.  Consult factory with your application details.

Maximum temperature ratings have two sets of figures.  Temperatures shown in black are °F., those in red are °C.  

Disk Material
Un-lined Disks
Fluoropolymer Lined Disks
Aluminum
250o
250o F
 

 

121o
121o C
Nickel/Alloy 200
750
400
 

 

399
204
Monel/Alloy 400
900
400
 

 

482
204
Inconel/Alloy 600
1100
400
 

 

593
204
316 S.S.
900
400
 

 

482
204
Tantalum
500
400
 

 

255
204

Hastelloy C-276/

Alloy C-276

900
400
482
204

Non-Standard Materials PSIG

DISK
VENEERS**
SIZE
TANTALUM

HAST C-276

ALLOY C-276

TANTALUM

HAST C-276

ALLOY C-276

(inches) 
MIN 
MAX 
MIN 
MAX 
MIN 
MAX 
MIN 
MAX
1
110
1000
120
1000
180
1000
165
1000
1 1/2
85
1000
90
1000
140
1000
130
1000
2
60
1000
65
1000
100
1000
90
1000
3
48
900
48
900
80
900
70
900
4
42
850
42
850
70
850
60
850
6
34
700
34
800
60
850
55
850
8,10,12 
30
500
-
-
45
800
-
-
14,16
-
500
-
-
45
800
-
-
18
-
-
-
-
35
700
N/A
N/A
20,24,30
-
-
-
-
-
-
N/A
N/A
36
-
-
-
-
N/A
N/A
N/A
N/A

Primary Relief

The RB-90 Rupture Disk (Bursting Disc) is ideal for primary relief either by itself or installed at the inlet of a safety relief valve.  The RB-90 complies with Section VIII Division 1, Paragraphs UG 125 through 134 of ASME Code.

RB-90 Reverse Buckling Disk. Pressure on CONVEX side of disk and patented seating design puts compression loading on disk metal.  Four razor-sharp knife blades cut metal into four equal sections when reverse buckling occurs, providing complete opening without fragmentation.
To control accurate reversals, the RB-7R Safety Head utilizes a patented offset shoulder, machined radius and bite-type seal.

Guides to RB-90 Applications in a Wide Range of Services

Acceptable
1.Where the RB-90 is located in gas phase,

  • Gaseous pressurized systems, or Liquid systems pressurized by gas.
  • Liquid systems with viscosity similar to water, where a large volume of liquid will be released immediately should overpressure occur. 

Non Acceptable Applications
1.Where the RB-90 is located in an all liquid system (except
those involving the release of a large volume of liquid immediately should overpressure occur).

Advantages of Installing Rupture Disks Under Safety Relief Valves

. Zero process leakage to the atmosphere 
. Longer periods between major overhauls 
. Valves can be tested in place 
. Less expensive trim material can be used 
. Valve life is extended by isolating corrosive fluids from internal valve parts. 

RB-90 Reverse Buckling Safety Head mounted at inlet of a safety relief valve.  This arrangement permits testing of a valve as shown without disassembly or process shutdown. 

On all RB-90 disks, except aluminum, a system pressure of 50% or more of disk rating should be held on the convex side of the disk during valve testing to allow a testing pressure of 110% of disk rating to be applied. 

CAUTION!  If these conditions on differential pressure are not followed closely, laboratory tests indicate that performance rating of disk may be progressively reduced up to a maximum of 10% when disk is required to function.  

RB-7R Bolted Type Safety Heads with RB-90 Reverse Buckling Disks

Type RB-7R QUIK-SERT SAFETY HEAD with side-mounted screws and bars.
RB-90 Rupture Disks can only be used in BS&B RB Type Safety Heads to guarantee correct burst pressures.
RB-90 Safety Heads require preassembly of reverse buckling disk in RB-90 flanges to assure proper seating.  Standard RB-90 inlet and outlet flanges are flatfaced.  Ring joint, raised face and tongue-and-groove facings are available.
Standard knife blade material is heat treated stainless steel.

Bolting Torque is Critical in the RB-90® Design
If bolting torque is too low in an RB-90 assembly, or if the compression load slacks off over a period of time because of a cold flowing gasket, a low pressure reversal can occur.  So, select a gasket material that has a minimum tendency to relax in service. 

Follow the torque values included in the installation instructions packed with each disk.

If the RB-90 Safety Head is located on a glass-lined outlet nozzle and minimum torque specified can damage lining, use the RB-7FS assembly.  This condition requires only enough torque on bolting of mating flange to seal and hold gaskets on one or both sides of assembly.  The RB-7FS assembly has enough capscrew bolting to provide the required holding force.

Accessories take the work out of installing RB-90 Safety Heads.  See Union/Bolted/QUIK-SERT Safety Heads catalog for illustration of jack screws, eye bolts, baffle plate, gauge tap, full diameter preassembly.

Jack Screw specifications for RB-90 Safety Head Assembly RB-7R are the same as for QUICK-SERT Assembly FA-7R.

Standard RB-90 Safety Head Assemblies

Assembly RB-7R

Easiest to install and remove from service.  For services allowing the use of reduced diameter Safety Head flanges.  Disk is installed between two reduced-diameter flanges and preassembled with recessed cap screws or side-mounted screws and bars.  Safety Head assembly nests between studs of the ANSI companion flanges. 

Assembly RB-7FFTM 
For services where released product can be vented to atmosphere harmlessly.  Disk is installed between two full-diameter flanges and preassembled with recessed cap screws.  Safety Head assembly bolts to ANSI flange.  Outlet is free vented.  

Assembly RB-7FSTM 
For applications where product buildup requires periodic cleaning and Safety Head assembly must be removed without breaking disk seal or disturbing the bolting torque.  Disk is installed between two full diameter flanges and torqued with recessed cap screws

RB-90 Safety Head Specifications

OVERALL HEIGHT BY ASSEMBLY NO. Dim. "C"
 

 

Outside Dia. Dim. "A"
Nom. Pipe & Disk Size in.
RB-7R in.
RB-7FF in.
RB-7FS in.
STANDARD MATERIALS AVAILABLE
Assy. RB-7R in.
Assy. RB-7FF RB-7FS in.

150# ANSI (275# Max. at -20o F to + 100o F)

1
1 1/2
1 5/8
1 1/2
 

Carbon Steel

Stainless Steel (316, 304)

Monel/Alloy 400

Inconel/Alloy 600

Nickel/Alloy 200

Hastelloy C-276/Alloy C-276

(inlet and outlet

materials need not

be same. Specify

each.)

2 1/2
4 1/4
1 1/2
1 9/16
1 13/16
1 9/16
3 1/4
5
2
1 11/16
1 7/8
1 11/16
4
6
3
2 1/8
2 5/16
2 1/8
5 1/4
7 1/2
4
2 11/16
2 3/4
2 3/4
6 3/4
9
6
3 7/16
3 9/16
3 7/16
8 5/8
11
8
4 7/16
4 7/16
4 7/16
10 15/16
13 1/2
10
5 1/8
5 1/8
5 1/8
13 1/4
16
12
5 7/8
5 7/8
5 7/8
16
19
14
6 7/16
6 7/16
-
17 5/8
21
16
7 3/16
7 3/16
-
20 1/8
23 1/2
18
7 15/16
7 15/16
-
21 1/2
25
20
8 3/4
8 3 /4
-
23 3/4
27 1/2

300# ANSI (720 Psi Max. @ -20o F to + 100o F)

1 " through 3" - Same as 600# ANSI Group  

4
2 11/16
3 5/16
2 3/4
Carbon Steel

Stainless Steel (316, 304)

Monel/Alloy 400

Inconel/Alloy 600

200

Nickel/Alloy 

Hastelloy C-276/Alloy C-276

(Inlet and outlet

materials need not

be same. Specify

each.)

7
10
3 7/16
4 1/8
3 7/16
9 3/4
12 1/2
4 7/16
5 1/16
4 7/16
12
15
10 
5 1/8
5 13/16
-
14 1/8
17 1/2
12
5 7/8
6 9/16
-
16 1/2
20 1/2
14
6 7/16
7 1/16
-
19
23
16
7 3/16
7 15/16
-
21 1/8
25 1/2
18
7 15/16
8 11/16
-
23 3/8
28
20
8 3/4
9 9/16
-
25 5/8
30 1/2

600# ANSI (1440 Psi Max. at - 20o F to + 100o F)

1
1 1/2
2 5/16
1 1/2
Carbon Steel

Stainless Steel (316, 304)

Monel/Alloy 400

Inconel/Alloy 600

Nickel/Alloy 200

Hastelloy C-276/Alloy C-276

(Inlet and outlet

materials need not

be same. Specify each.)

2 3/4
4 7/8
1 1/2
1 9/16
2 3/8
2 1/4
3 5/8
6 1/8
2
1 11/16
2 11/16
2 3/16
4 1/4
6 1/2
3
2 1/8
3 1/4
2 3/16
5 3/4
8 1/4
4
2 11/16
4 3/16
-
7 1/2
10 3/4
6
3 7/16
5 1/16
-
10 3/8
14
8
4 7/16
5 3/4
-
12 1/2
16 1/2
10
5 1/8
6 11/16
-
15 5/8
20
12
5 7/8
7 7/16
-
17 7/8
22
14
6 7/16
7 7/8
-
19 1/4
23 3/4
16
7 3/16
9
-
22 1/8
27

NOTE: For dimensions of larger units not shown, consult Factory.

NOTE: 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, Attn: Customer Service Dept.