BS&B Safety Systems
Rupture Disks Explosion Protection Wireless Instrumentation Buckling Pin Valves
Ruputure Disks, Bursting Disks Safety Heads and other Pressure Safety Devices
The original rupture disk (bursting disc) manufacturer shaping the growth of pressure relief devices for over 75-years.
Products > Rupture Disks > Reverse Buckling Disks
SKrTM Rupture Disk (Bursting Disc)

SKrTM Rupture Disk (Bursting Disc)


SKRTM - the first rupture disk specifically developed and performance flow tested* for use in all service conditions:

  • One disk design for gas and liquid service
  • Low to high burst pressures
  • Available in standard or exotic materials
  • Long Service life in pressure cycling or pulsating conditions.
  • Suitable for operating pressures up to 95% of the Minimum Burst Pressure.
  • Fail-safe design - Damage-Safety ratio <= 1.
  • Designed for non-fragmentation.
  • Standard Manufacturing Design Range, zero%, optional -5%, -10%.
  • Withstands full vacuum.
  • Ideal for relief valve isolation.
  • Info-Tag, 3-dimensional tag indicates correct orientation and ASME or CE requirements
  • World wide patents pending.

*ASME Code Section VIII Div. 1, according to the test method of PTC-25

SKR™ DISK SPECIFICATIONS Min/Max Pressure Rating at 72ºF (22ºC) PSIG (Bar)

Specifications

Design

The SKRTM reverse buckling disk is designed with a circular score line located at the edge of the domed area, on the downstream side of the disk. At the marked burst pressure, the disk's dome reverses and opens by shearing around the circular score line. The SKRTM uses SAF- technology (Structural Apex Forming) enabling very low burst pressures to be achieved with excellent opening characteristics. An integral energy absorbing hinge located on the downstream side of the disk enables the SKRTM to perform in gas or liquid service with superior flow performance. The hinge design interacts with the Safety Head bore to retain the SKR disk on opening, avoiding fragmentation

Marked Burst Pressure

The ASME Code requires that the marked burst pressure is within the manufacturing design range and is determined such that the sample burst test pressures are within the specified tolerance (+/- 2 psig at or below 40 psig or +/-5% above 40 psig). BS&B Safety Systems, Inc. and BS&B Safety Systems Ltd. will exceed ASME code requirements by continuing to use the average of the burst test values as the marked burst pressure (for -5% and -10% Manufacturing Design Range) and requiring this average to fall within the manufacturing design range.

This is in accordance with previous editions of the code and will maintain consistency in burst pressure marking for the user.

Manufacturing Design Range

The standard Manufacturing Design Range for the SKRTM disk is 0%. The user's requested burst pressure will be the Marked Burst Pressure. Optional Manufacturing Design Ranges of -5% and -10% may be selected as operating conditions permit. The Manufacturing Design Range is applied to the minus side only of the requested burst pressure.

Example:

Requested Burst Pressure 100 psig (6.89 bar).
Agreed Manufacturing Design Range - 10%.
Therefore the Marked Burst Pressure shall be between 90 psig (6.21 bar) and 100 psig (6.89 bar).

The ASME code requires also that the Marked Burst Pressure will not exceed the Maximum Allowable Working Pressure of the vessel to be protected.

**The ASME Code defines the "Manufacturing Design Range as a range of pressures within which the marked burst pressure must fall to be acceptable for a particular requirement as agreed upon between the Rupture Disk (Bursting Disc) Manufacturer and the user or his agent".
Burst Tolerance
Marked Burst Pressure Burst Tolerance
Less or euqal to 40 psig (2.76 bar)
Above 40 pisg (2.76 bar)		 +/- 2 psig (0.138 bar)
+/- 5%

Alternatively the SKRTM disk may be marked with a minimum-maximum burst pressure in which case burst test values must be within the min-max burst range. This minimum-maximum includes the manufacturing Design Range. Such marking is recommended for CE compliant disks.

Flow Performance

The SKR Reverse Buckling Disk has been specifically developed to produce superior flow performance at all burst pressures in gas or liquid service. The circular score on the disk's dome, coupled with the non-restrictive hinge on the outlet side of the disk, ensures an excellent pressure relief opening.

Flow Resistance Factor KR may be used to determine the relieving capacity of a system according to the ASME and CEN (pending) codes. Individual KR values have been established for both gas and liquid service for the SKR disk. Minimum Net Flow Area (MNFA) for each disk size is provided to assist with ASME sizing calculations. Net Relief Area (NRA) for each size disk is provided to assist with European code sizing calculations.

Materials

The SKRTM disk is available in 316SS, Nickel Alloy 200, Monel Alloy 400, lnconel Alloy 600, Hastelloy Alloy C276, Titanium and Tantalum. A competent person should select the disk material that is chenmically resistant to the application. Corrosion of the disk material will affect its performance and may result in premature bursting or leakage through the disk. For assistance in disk material selection contact BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd.

Liners

Liners are available in all sizes as optional on the process side of the disk. Teflon® is generally used, other appropriate fluorocarbon film may be supplied.
Temperature Range FEP -40oF to 400oF (-40oC to 205oC). PTFE -40oF to 500oF (-400oC to 260oC).

SAF Technology: Damage Safety Ratio <=1

Structural Apex Forming, the central 'dimple' present in all SKRTM Rupture Disks, combined with the unique energy absorbing hinge design ensures that a damaged SKRTM disk will rupture at or below the marked burst pressure

KR Values

The KR Value for the SKRTM disk for gas service is 0.37, contact BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd. for liquid service KR values. When sizing per the ASME code use these KR values for service with schedule 40 piping, for alternate pipe schedule contact BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd.

Minimum Net Flow Area (MNFA) / Net Relief Area (NRA)

Disk Size
in mm		 1 25 1.5 40 2 50 3 80 4 100 6 150 8 200 10 250
in2 0.86 1.93 3.36 7.39 12.74 28.89 50.0 78.8
cm2 4.8 11.3 19.7 40.8 69.7 158.6 275.6 433.6

Recommended Maximum Temperatures

(May be lower for CE marked products.)

Nickel Alloy 200 750oF 399oC
Monel Allow 400 900oF 482oC
Inconel Alloy 600 1100oF 593oC
316SS 900oF 482oC
Hastelloy Alloy C-276 900oF 482oC
Titanium 572oF 300oC
Tantalum 500oF 260oC

SRB-7RSTM 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 1/2 40 150 - 10/16/20 1 5/8 43.0 3 3/8 85.7 3 3/8 85.7
1 1/2 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 in 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 in OD, 263.5 mm OD
8 200 150/300 - - 3 13/16 96.8 Flower Petal
10 250 150/300 - - 4 3/8 111.1 Flower Petal

Installation in SRB-7RSTM Safety Head

The SKR disk installed in an SRB-7RSTM Safety Head permits the correct torque to be applied in the workshop before installation into the process. The asymmetric locating pins ensure centering and orientation of the disk within the Safety Head. The performance-proven metal-to-metal 'bite type' seal in the Safety Head (2"/50mm size and above) assures a leak tight assembly. When installed properly into the SRB-7RS Safety Head, the assembly can be removed, inspected, cleaned carefully then reinstalled without replacing the disk as the pretorque capscrews maintain the clamp load on the disk.

The SKRTM disk may also be installed into an S90-7RTM Safety Head without the benefits of a pretorqueable design. The SRB-7RSTM Safety Head is used with other rupture disks (Types S90TM, JRSTM, RLSTM, FRSTM) of the STA-SAF® System, Catalog 77-4001. The use of a common Safety Head facilitates upgrading from these rupture disks to the superior technology of the SKRTM Rupture Disk.

US patent No 4,751,938 and other international patents.

Teflon® is a registered trademark of DuPont. Inconel® and Monel® are registered trademarks of lnco Alloys international. Hastelloy® is a registered trademark of Haynes International, Inc.

S90-7RTM Dimensions

NOMINAL SIZE SAFETY HEAD FLANGE RATING OUTSIDE DIAMETER OVERALL HEIGHT
IN MM IN MM IN MM
1 25 150 2.50 63.5 1.69 43.0
300/600 2.75 69.9 1.25 32.0
DIN PN 10/16/25/40 2.80 71.0 1.77 45.0
1.5 40 150 3.25 82.8 1.25 32.0
300/600 3.62 91.9 1.25 32.0
DIN PN 10/16/25/40 3.62 91.9 1.50 38.0
2 50 150 4.00 101.6 1.25 32.0
300/600 4.25 108.0 1.25 32.0
DIN PN 10/16/25/40 4.21 107.0 1.50 38.0
3 80 150 5.25 133.4 1.50 38.0
300/600 5.75 146.0 1.50 38.0
DIN PN 10/16/25/40 5.59 142.0 1.73 44.0
4 100 150 6.75 171.5 1.72 43.6
300 7.00 177.8 1.72 43.6
600 7.50 190.5 1.72 43.6
DIN PN 10/16 6.38 162.0 1.77 45.0
DIN PN 25/40 6.58 167.0 1.88 48.0
6 150 150 8.62 218.9 2.50 64.0
300 9.75 248.0 2.50 64.0
600 10.38 263.6 2.62 66.5
DIN PN 10/16 8.54 217.0 2.50 64.0
DIN PN 25/40 8.78 223.0 2.50 64.0
8 200 150 10.88 276.1 3.38 86.0
300 12.00 304.8 3.38 86.0
600 12.50 317.5 3.75 95.3
DIN PN 10/16 10.71 272.0 3.46 88.0
DIN PN 25 11.14 283.0 3.38 86.0
DIN PN 40 11.42 290.0 3.38 86.0
10 250 150 13.25 336.6 6.02 153.0
300 14.13 358.9 6.02 153.0
600 15.62 396.7 - -
DIN PN 10/16 12.91 328.0 6.02 153.0
DIN PN 25 13.39 340.0 - -
DIN PN 40 13.86 352.0 - -

SKRTM The all service Rupture Disk (Bursting Disc)

Manufactured in conformance with the requirements of the following international codes and standards:

  • ASME (UD Stamped)
  • CEN (pending)
  • BS 2915
  • ISO 6718
  • TUV AD Merkblatt A1
  • SVTI
  • Stoomwezen
  • ISO 9001 Quality System Certification


Further Information

Related Products