BS&B - Model SKR -Rupture Disk (Bursting Disc)

Safety by design:

• one disk for gas, liquid, vapor & 2 phase service
• 95% operating ratio
• certified for “UD stamp” or “CE mark”
• designed for non fragmentation
• high flow characteristics; certified relief area & Kr values
• unique damage resistant design – saf™ technology
• fail safe – damage safety ratio < 1
• paired with the industry leading SRB-7RS safety head
  

Application Recommendations:

• Primary pressure relief
• Secondary pressure relief
• Relief Valve Isolation
• Custom Engineered Assemblies
• Nominal Sizes 1”~10” / 25mm~250mm
• Burst Pressures from 15psig to 500psig / 1 bar to 34.5 bar
• Temperatures from cryogenic to 1100oF / 593oC
• Static, cyclic, vacuum or pulsating operating pressure
• Where back pressure resistance is required
• Where low cost of ownership is desired

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

Design

The SK_R 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 SK_R 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 SK_R^TM 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 SK_R 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.

Alternatively the SK_R 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 K_R may be used to determine the relieving capacity of a system according to the ASME and CEN (pending) codes. Individual K_R values have been established for both gas and liquid service for the SK_R 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 SK_R 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 -40^oF to 400^oF (-40^oC to 205^oC). PTFE -40^oF to 500^oF (-400^oC to 260^oC).

SAF Technology: Damage Safety Ratio <=1

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

K_R Values

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

(May be lower for CE marked products.)

The SKR disk installed in an SRB-7RS 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 SK_R disk may also be installed into an S90-7R Safety Head without the benefits of a pretorqueable design. The SRB-7RS Safety Head is used with other rupture disks (Types S90, JRS, RLS, FRS) 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 SK_R 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.

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