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

GCR-S™ Reverse Buckling Disk

GCR-STM Reverse Buckling Disk

The type GR-CTM outlet fitting with industry standard connections provides quick and easy installation of the GCR-STM reverse buckling disk onto existing standard sanitary inlet ferrule. The uniquely designed gasket helps eliminate inverted installation of the rupture disk.

Innovative design using SAFTM (Structural Apex Forming) technology offering a wide range of burst pressures for sanitary/aseptic applications in the pharmaceutical, biotechnology and food industries.

Features and Benefits

  • One disk design for gas and liquid service
  • "Fail-safe" design - Damage-Safety Ratio <=1
  • Low to high burst pressures
  • Ideal for CIP/SIP Service*
  • Installed with integral sanitary/aseptic gaskets
  • 8 to 16 micro-inch typical disk surface finish
  • Minimum dead space between process fluid and the disk
  • Suitable for operating pressures up to 90% of Marked Burst Pressure** or 95% of the specified minimum burst pressure (EN 4126-2)
  • Designed for non-fragmentation
  • O% Standard Manufacturing Design Range, optional - 5%, -10%
  • Withstands full vacuum at all burst pressures
  • SASTM (Sanitary Alert Sensor) with leak sensing option available
  • Integral burst disk sensor option
  • Worldwide patents pending

*Clean/Steam in Place
**At marked burst pressures of 40 psig (2.76 barg) and below, the recommended maximum operating pressure is 90% of the marked burst pressure, less 2 psig (0.138 barg) tolerance.

GCR-STM Disk Specification Min/Max Burst Pressure at 72o F (22o) Psig (BAR)

Sanitary Fitting Burst Pressure Overall Height
(with outlet fitting)
(sanitary connection)

Nominal Disk Size





in mm psi bar psi bar in
1.5 40 10 0.69 300 20.7 1.62 41 1.98 50.3
2 50 10 0.69 300 20.7 1.62 41 2.52 64
3 80 10  0.69 175  12.1 1.81 46 3.58 90.9
4 100 10  0.69 75  5.2 1.81 46 4.68 118.9

Other Burst Pressures may be available, consult BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd.


The GCR-STM family of reverse buckling disks is designed with a circular score line located at the edge of the domed area. At the marked burst pressure the disk's dome reverses and opens by shearing around the circular score line. The GCR-STM uses SAFTM technology 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 disk to perform in gas or liquid service with superior flow performance. The hinge design interacts with the holder outlet bore to retain the disk on opening, avoiding fragmentation.

Optional SASTM (Sanitary Alert Sensor)

The Sanitary Alert Sensor is for use between standard sanitary /aseptic fittings to provide warning of a burst rupture disk (bursting disc). Leaking disk detection is also available; consult BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd. for details.


The GCR-STM and GCR-SMTM disks are also available with integral sensors to provide warning of a burst rupture disk, specify types GCR-SSTM and GCR-SMSTM.

Manufacturing Design Range    

The standard Manufacturing Design Range for the GCR-STM 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.

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

 Manufacturing Design Range is 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

<= 40 psig (2.76 bar)

± 2 psig (0.14 bar)

> 40 psig (2.76 bar)

± 5%

Alternatively the GCR-STM disks may be marked with a minimum - maximum burst pressure in which case the burst test values must be within the min-max burst range (as per CEN standard pending).

Flow Performance

The GCR-STM Reverse Buckling Disk has been specifically developed to produce superior flow performance at all bust 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 disk. Minimum Net Flow Area (MNFA) for each disk size is provided to assist with ASME sizing calculations. Net Relief Area has been provided for sizing according to European and International standards.


The GCR-STM is supplied with FDA approved Silicone, Viton® (white or black), EPDM (white or black) and Tef-Steel® gaskets ensuring correct and leak-tight installations with type GR-CTM fitting or FM-CTM /FT-CTM disk holders.

Gasket Service Temperature


Service Temperature



Silicone -67oF (-55oC) 450oF (232oC)
Viton® -40oF (-40oC) 400oF (204oC)
EPDM -67oF (-55oC) 300oF (149oC)
Tef-Steel® -20oF (-29oC) 450oF (232oC)


The disk is available in 316 SS and 316L SS as standard. Alternative materials are available on request.


Liners are available in all sizes as optional on the process side of the disk. FEP or PFA are generally used.

Temperature Range FEP -40 oF to 400 oF (-40 oC to 204 oC)
PFA -40 oF to 500 oF (-40 oC to 260 oC)



Minimum Burst Pressure
for lined disks at 72 oF (220 oC)

in mm psi bar
1.5 40 36 2.48
2 50 36 2.48
3 80 16 1.10
4 100 12 0.83

SAFTM Technology: Damage Safety Ratio <= 1

Structural Apex Forming, the central "dimple", present in all GCR-S rupture disks (bursting discs), combined with the unique energy absorbing hinge design ensures that a damaged disk will rupture at or below the marked burst pressure.


Disk Size 1 1/2" 40 mm 2" 50 mm 3" 80 mm 4" 100 mm
KR 1.95 1.25 1.95 1.95
*MNFA in2 1.5 2.7 5.29 9.78
**NRA cm2 9.67 17.4 34.1 63.09

*Use MNFA in2 when sizing according to ASME Code, para UG-127(a)(2)(a)
**Use NRA cm2 (Net Relief/Area) when sizing according to European standards

The KR values indicated are for gas service. The GCR-STM disks have been performance tested for both gas and liquid, contact BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd. for liquid service KR values. CE marking of bursting disks will be offered on completion of validation to the European Code.

GCR-STM Disk Types

GCR-STM and GCR-SSTM with uniquely designed FDA approved gaskets are installed between a standard inlet ferrule and the GR-CTM outlet fitting ensuring correct direction of disk and leak tight installation.

The GCR-SMTM and GCR-SMSTM have a symmetric gasket configuration on both sides of the disk and fit between standard Tri-Clamp® (or equivalent) ferrules.

The GCR-SETM is installed in a FM-CTM Safety Head. The inlet of the FM-CTM Safety Head is welded to the vessel wall and permits the rupture disk (bursting disc) to be installed flush with the interior wall of the vessel. The space between the process fluid and the disk is minimized. Similar flush installation is achieved with GCR-NTM and GCR-NSTM (integral sensor) type disks when installed with NA-Connect® fittings.

GCR-SWTM is a welded ferrule assembly, the disk is welded between standard ferrules.


The GR-CTM outlet fittings and FM-CTM or FT-CTM holder designs ensure correct direction and leak tight rupture disk (bursting disc) installation. We recommend the assembly of GCR-STM rupture disks (bursting discs) into their respective holders using a Tri-Clamp® 13 MHHS Clamp (or equivalent) with a hexagonal nut enabling control of installation torque. 

The GCR-STM disk range, using SAFTM technology, exhibits minimum sensitivity to changes in clamp loading on the disk induced by service temperature variations. However an adequate clamping load to maintain leak tightness must be maintained.

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.

Viton® is a trademark of DuPont Dow Elastomers LLC.
Tri-Clamp® is a registered trademark of Tri Clover Inc.
Tef-Steel® is a registered trademark of Rubber Fab Molding and Gasket
NA-Connect® is a registered trademark of NovAseptic Equipment AB