Sigma™ and Sigma EXL™ Rupture Disk - Part of the Sta-Saf™ System

Enhanced Performance Reverse Buckling Disk


Performance Features

  • Designed for gas, liquid and multi-phase service
  • Suitable for operating pressure to 95% of the marked burst pressure (95% of the minimum)
  • 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% Manufacturing Design Range)
  • Pressure Equipment Directive “CE” marking and/or other International Certifications
  • BS&B proprietary technology; US Patent 9,168,619 and international patents apply

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

Sizes & Pressures

Sigma™ and Sigma EXL™ 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 316SS
in mm 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
1 25 35 500 2.41 34.47 58 500 4.00 34.47 50 500 3.45 34.47 55 500 3.79 34.47 35 500 2.41 34.47
1.5 40 30 400 2.06 27.58 45 400 3.10 27.58 45 400 3.10 27.58 45 400 3.10 27.58 30 400 2.07 27.58
2 50 25 400 1.72 27.58 30 400 2.07 27.58 30 400 2.07 27.58 30 400 2.07 27.58 25 400 1.72 27.58
3 80 20 400 1.38 27.58 22 400 1.52 27.58 22 400 1.52 27.58 25 400 1.72 27.58 20 400 1.38 27.58
4 100 16 400 1.10 27.58 18 400 1.24 27.58 18 400 1.24 27.58 20 400 1.38 27.58 16 400 1.10 27.58
6 150 15 225 1.03 15.51 15 225 1.03 15.51 15 225 1.03 15.51 20 225 1.38 15.51 15 225 1.03 15.51
8 200 15 125 1.03 8.62 15 125 1.03 8.62 15 125 1.03 8.62 20 125 1.38 8.62 15 125 1.03 8.62
10 250 15 100 1.03 6.89 15 100 1.03 6.89 15 100 1.03 6.89 20 100 1.38 6.89 10 100 0.69 6.89
12 300 15 75 1.03 5.17 15 75 1.03 5.17 15 75 1.03 5.17 20 75 1.38 5.17 10 75 0.69 5.17

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%

Accessories

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

Jackscrews

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

Sta-Saf System
Sigma™ and Sigma EXL™
Burst Alert Sensors
Saf-T-Change™ QDR Rupture Disk Replacement System
Detec Saf Alarm System - Burst Disk Monitor

Installations

Sigma EXL™, Sigma™, SKR™, and LPS™ Installation Instructions
Burst Alert Leak Dectector Installation Instruction
Burst Alert Sensor Installation Instruction

Overview

The Sigma EXL™ and Sigma™ Reverse Buckling Rupture Disk (Bursting Disc) has been developed to provide the highest operating pressure capability available from a Rupture Disk (Bursting Disc) pressure relief device. Sigma EXL™ and Sigma™ Rupture Disk (Bursting Disc) technology and the SRB-7RS™ Safety Head combine the accuracy and reliability of Reverse Buckling Disk technology with unique disk and safety head design features that enable the Sigma EXL™ and Sigma™ disk to operate to 95% of the Marked Burst Pressure (100% of Minimum Burst Pressure according to CEN ISO 4126-2 standards). The Sigma EXL™ and Sigma™ Rupture Disk (Bursting Disc) embraces SafT technology, Structural Apex Forming, the central feature on the disk dome enhancing burst pressure accuracy.

Sigma EXL™ and Sigma™ Rupture Disk (Bursting Disc) Material Options

The Sigma EXL™ and Sigma™ rupture disks (bursting discs) are available in a range of corrosion resistant materials (see table). For each material the upper temperature limit has been determined from the recommendations of material manufacturers and user experience. While Hastelloy C-276 is the standard grade used, Hastelloy B and Hastelloy C-22 may be available upon request. All standard disks are available with 0%, 5%, and 10% manufacturing ranges.

 

Testing at Temperature

The burst pressure of each lot of Sigma EXL™ or Sigma™ rupture disks (bursting discs) is tested at the users requested temperature. If the disk is requested above or below ambient temperature, burst testing for product certification will be carried out at this temperature to ensure the best product accuracy. For applications with operating temperatures that may exceed this tested burst temperature, please review with BS&B Safety Systems, Inc. or BS&B Safety Systems Ltd.

 

Installation in SRB-7RS™ Safety Head

The Sigma EXL™ and Sigma™ rupture disks (bursting discs) are installed in an SRB-7RS™ Safety Head permitting 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.