SKr-U™ Reverse Buckling Rupture Disk

Performance Features

  • Designed for gas, liquid and multi-phase service
  • Suitable for operating pressure to 90% of the marked burst pressure (95% of the minimum burst pressure)
  • Designed for non-fragmentation, recommended for relief valve isolation
  • Damage safety ratio ≤ 1
  • Suitable for cycling service
  • Vacuum resistant
  • Available with ASME “UD” (select 0%, -5%, -10% Manufacturing Design Range)
  • Pressure Equipment Directive “CE” marking and/or other International Certifications. Patent 6321582, 6178983, 6446653, 5996605 apply/pending

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  • Sizes & Pressures
  • Burst Tolerance
  • Safety Heads & Sensors
  • Accessories
  • Documentation

Sizes & Pressures

SKr-U™ Disk Specifications Minimum/Maximum Pressure with Rating at 72° (22°C)

Disk Size Nickel Alloy 200 Monel® Alloy 400 Inconel® Alloy 600 Hastelloy® Alloy C-276 and 316 Tantalum Titanium
in mm psig barg psig barg psig barg psig barg psig barg psig barg
min max min max min max min max min max min max min max min max min max min max min max min max
0.5 15 55 500  4 35 60 500 4 35 60 500 4 35 60 500 4 35 55 500 4 35 90 500 4 35
0.75 20 55 500  4 35 60 500 4 35 60 500 4 35 60 500 4 35 55 500 4 35 90 500 4 35
1 25 55 500  4 35 60 500 4 35 60 500 4 35 60 500 4 35 55 500 4 35 90 500 4 35
Note: Hastelloy® is a trademark of Haynes International Inc. Monel® and Inconel® are registered trademarks of Special Metals Corporation and Its subsidiaries.

Burst Tolerance

Marked Burst Pressure Burst Tolerance
≤ 40 psig (2.76 barg) ± 2 psig (0.138 barg)
> 40 psig (2.76 barg) ± 5%


BS&B supplies many of the Accessories required to safely and conveniently install our overpressure relief devices and complementary products. Through our professional team and global network of sales engineers and procurement personnel, we are able to provide the highest quality accessory products to meet your installation requirements.

Saf-T-Change Quick Disk Replacement (QDR)

After activation, the replacement disk is quickly slid into place. Saving hours of lost production due to blown rupture disks.

Tell-Tale Assemblies & Excess Flow Valves/Gauges

A gauge tap in the outlet flange of the safety head may be considered when the safety head is installed in a vertical position.

Spare Safety Heads & Cap Screws


When activated, the jackscrews effectively separate the flanges, providing adequate clearance to remove or insert a safety head and external gaskets.

Lifting Lug Eye Bolts

Eye bolts are recommended when weight and/or accessibility is a factor in lifting safety heads.

Baffle Plate

When a safety head is free-vented to atmosphere, a baffle plate may be considered to disperse overpressure and absorb recoil.

Product Literature

SKr-U™ Rupture Disk
Burst Alert Sensors
Detec Saf Alarm System - Burst Disk Monitor


The SKR-U™ Rupture Disk (Bursting Disc) is partnered with the UR-2 safety head to provide high integrity reverse buckling rupture disk (bursting disc) technology in a threaded union type holder. The SKR-U™ rupture disk (bursting disc) uses Saf™ technology (structural apex forming) to accurately control its burst pressure making it insensitive to the assembly torque variations that will occur in a threaded type holder.

SKR-U™ Rupture Disk (Bursting Disc) Material Options

The SKR-U™ rupture disk (bursting disc) is available in a range of corrosion resistant materials. Standard disk materials are Nickel alloy 200, Stainless Steel grade 316, Monel® (Nickel alloy 400), Inconel® (Nickel alloy 600), Hastelloy® C-276, Titanium, & Tantalum. All standard disks are available with 0%, 5%, and 10% manufacturing ranges.


Thread Connection Options

As an option, the UR-2 safety head can be provided with a threaded connection on the outlet side to enable the connection of a ‘tell-tale’ assembly. While the standard thread connections are _", _" and 1" NPT female inlet & outlet, the following alternatives are available within the same overall dimensions.


Installation in UR-2 Safety Head

The UR-2 safety head contains 4 metal components: inlet, holdown ring, outlet, and hexagon assembly nut. The SKR-U™ rupture disk (bursting disc) is pre-assembled to the safety head between the inlet and the holdown ring using two capscrews. This locates and centers the disk, ensuring the correct direction of installation: these two capscrews and a single locating pin in the UR-2 inlet have an asymmetric layout that matches three holes in the SKR-U™ disk flange.