SRI-7RS™ Safety Heads (Holders)

Performance Features

  • Insert type safety head that fits inside the bolt circle of companion flanges to allow for easy installation and removal
  • Hexagonal head pre-torqued capscrews allow installation and in service re-torquing using standard workshop tools. High quality stainless steel capscrews prevent galling with safety head.
  • The unique geometry of the safety head ensures concentricity with the pipe optimizing fluid flow in line with certified Kr values
  • Increased rupture disk seating area allows for high companion flange stud torques compatible with spiral wound type gaskets
  • A J-bolt ensures the safety head is fitted in the required direction between companion flanges by engaging a blind hole drilled on the inlet companion flange perimeter
  • Asymmetric alignment pins in the safety head mate with locating holes in the rupture disk, ensuring centering and correct orientation of the rupture disk within the safety head
  • Flow arrows on the side of the safety head indicate correct directional installation with process flow
  • Proprietary ‘bite seal’ on flat seating surface to optimize sealing between rupture disk and safety head process side allowing leak tightness of 10^-6cc/s He or greater
  • Can be equipped with pressure tapping in either inlet or outlet to allow installation of monitoring devices and sensors
  • For use with flanged piping connections; Raised face, Ring joint and tongue and groove flange facings. Designed for multi flange ratings and piping standards
  • The rupture disk dome fully protected within safety head inlet to avoid damage when installed into piping system

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  • Sizes & Pressures
  • Disks & Sensors
  • Materials & Option
  • Accessories
  • Documentation

Sizes & Pressures

Disk Size Safety Head Flange Rating Safety Head Flange Thickness
in mm ASME / ANSI EN JIS in mm
1 25 150/300/600 10/16/25/40 10/16/20/30/40 1.5 38
1.5 40 150/300/600 10/16/25/40 10/16/20/30/40 1.7 43
2 50 150/300/600 10/16/25/40 10/16/20/30/40 1.9 48
3 80 150/300/600 10/16/25/40 16/20/30/40 2.2 55
4 100 150/300* 10/16/25/40 16/20/30/40 2.9 73
6 150 150/300* 10/16/25/40 10/16/20/30 3.6 92
8 200 150/300* 10/16/25/40 16/20/30 3.8 95
* Available for ANSI 600# with adapter ring. Consult BS&B or your local representative.

Standard Materials

316 stainless steel and carbon steel.

Also available Monel® alloy 400, Inconel® alloy 600, Hastelloy® alloy C and C-276, aluminum, and titanium.

Torque Resistant Safety Head Option

The Type TR™ Series torque resistant safety head option offers the identical performance and flow characteristics valued from standard BS&B safety heads. The only difference – the TR Series Safety Heads are designed with a wider seating surface to be used with metal spiral wound gaskets at the flange. This distinct safety feature protects rupture disks from situations where plant personnel may overtorque rupture disks within piping systems.

Because of the wider seating surface of the TR Series Safety Head, the load is distributed over a much broader area reducing the influence of excessive torque transmitted to the disk.


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

Sta-Saf System
SRI-7RS™ Safety Head Brochure
Burst Alert Sensors
Detec Saf Alarm System - Burst Disk Monitor


Sta-Saf™ System Installation Instructions

Flange Bolt Patterns

ANSI / ASME B16.5 150lb configurations shown.

1” (DN 25) NFI-7RS
1.5” (DN 40) NFI-7RS
2” (DN 50) NFI-7RS
3” (DN 80) NFI-7RS
4” (DN 100) NFI-7RS
6” (DN 150) NFI-7RS
8” (DN 150) NFI-7RS