Safex Newsletter No.82 May 2025

In alignment with our previous newsletters, we commence our articles with a safety message from Gilles de Preux, the CEO of the SEE Group, headquartered in Switzerland.

We are pleased to announce the introduction of a new member to our Board of Governors. Christo Peltz from AECI Mining will be succeeding Neil Franklin, who has stepped down due to work commitments.

Progress on our website is being prioritized under the leadership of Andy Begg, Paulo Siquera, and Ludovic Turlin. A Basis of Safety section is now operational, and significant advancements have been made on the Safety Management System. Articles regarding both initiatives are presented by Andy and Paulo.

Johanne dela Rovere from EPC presents an article on the reinforcement of windows to withstand overpressure. An assessment of the resistance of installations to blast waves typically indicates that glazed joinery and glazing are prevalent weak points in infrastructure.

Diane Ginnane elaborates on a Safety Management System developed by Dyno Nobel. Dyno Nobel has introduced an innovative Explosives Management System (ExMS) that emphasizes the identification and management of critical activities, while establishing standards and procedures that define minimum requirements for all operations related to explosives and the security of sensitive hazardous substances.

From South Africa, BME’s Dr. Ramesh Dhoorgapersadh addresses risk management in reactive ground. Reactive ground refers to soil containing high concentrations of sulfides (typically iron or copper) that have the potential to react exothermically with ammonium nitrate-based explosives.

Johanne recently delivered a presentation at a technical conference in Belgium focused on SAFEX and the associated database. In her preparation, she identified key areas for improvement, which were subsequently communicated to the webmaster.

NIXT, a Corporate Associate Member in South Africa, successfully hosted a conference in April, during which they agreed to feature two presentations in our Newsletter. One presentation will cover the Track and Trace of Explosives by Rob Penny from Synertech, while the other will discuss the application of fungi in environmental cleanup, presented by Northwest University in collaboration with Dyno Nobel and Sasol.

The current list of Board Initiatives is accessible on the homepage of the website. Should any member wish to contribute to these work groups, please feel free to reach out to me.

We are pleased to announce that our upcoming Newsletter will be published at the end of October 2025. A reminder will be distributed to solicit contributions from industry professionals.

Additionally, we would like to remind you of our triannual Congress taking place in Lisbon in April 2026. The organization of this significant event in our calendar is progressing well. We are currently seeking a few more papers on incidents for discussion during our Member Day. Please reach out to me if you are interested in representing your company.

Until we meet again, please remain vigilant and prioritize your safety.

Reinforcing windows in overpressure zones

B Johanne Della Rovere

Assessing the resistance of installations to a blast wave generally reveals that glazed joinery and glazing are common weak points in infrastructure. In the event of breakage, the resulting splinters (Figure 1) pose a risk to personnel. The protection of workers from this risk must therefore be taken into account in risk analyses.

Figure 1: rupture of a standard glazed surface subjected to an overpressure wave.
Multiple splinters generated behind the glazing

In order to provide practical solutions, Ineris (Institut national de l'environnement industriel et des risques) has drawn up a practical guide on the protection of windows and glazing in buildings against the effects of overpressure in the 20-50 mbar and 50-140 mbar ranges.
Based on a large number of full-scale tests, this guide can be very useful in our businesses for assessing whether or not it is necessary to reinforce the protection of windows in buildings housing personnel at our facilities.

Carrying out an assessment

To determine whether or not it is necessary to reinforce the windows, a preliminary assessment is required. It is essential to identify the type of windows installed in the building, pinpoint any weak points, and determine necessary reinforcement work.
The following factors should be taken into consideration:

1. The characteristics of the overpressure wave (detonation or deflagration),

2. The intensity zone (20 to 35 mbar or 35 to 50 mbar)

3. The orientation of the windows relative to the explosion source. The proposed methodology is as follows: each building is oriented in relation to the centre of the potential explosion, with each face assigned a number, ranging from 1 (most exposed face) to 4 (least exposed face). Depending on their orientation, the facades and therefore the windows are more or less exposed to the effects of the explosion. This means that the maximum dimensions of the glazed panels that make up the windows can be differentiated according to face, to help in the decision whether or not to reinforce them (Figure 2).

Figure 2: orientation of the building façades
in relation to the centre of the explosion


4. The type of glazing involved, its dimensions, as well as the material of the frame (PVC, wood, aluminium), the method of opening, the locking system (espagnolette, rod, metal or plastic striker plate, etc.) and the window installation system should also be taken into account to identify precisely the weak points of each window in question.

5. Depending on the level of stress, and knowing the nature of the explosion, the zone in which the building is located and the face number of the building, the guide proposes tables giving, as a function of the ratio L/l varying from 1 to 4 (1, 1.5, 2, 3 and 4), the maximum permissible width (l) of the glazed pane to either withstand the blast or break safely without causing injury (example table I).

Table I: Maximum width (w) of a double-glazed insulating glass pane 4/16/4 for a shock wave (zone 35-50mbar) depending on the face of the building considered and the ratio L/w

Depending on all the factors analysed, reinforcement work may be required, such as applying blast-resistant film to the glass panels, replacing the plastic strike plate with a metal one, or increasing the number of fixings for the frame in the wall.

Summary of the diagnostic assessment of the risk of damage to windows in a building subjected to an overpressure wave of between 20 and 50 mbar:

Installing explosion-proof safety film

Blast-resistant films provide an effective method of reinforcing glazing (Figure 3):

  • They increase the strength of the glazing (the glass fragments stick to the film, which absorbs a large proportion of the energy through elastic and plastic deformation)
  • They significantly reduce fragment formation upon breakage,
  • They reduce the speed of the projected fragments,
  • They also decrease the projection distance of fragments.

Figure 3: Effects of overpressure on Class ER1 glazing without and with anti-explosion film in accordance with standard EN 13541

However, their effectiveness depends in particular on their characteristics (resistance to breakage and elongation, etc.), their thickness and the way they are laid.
These films are applied to the interior side of the window glazing. They can be installed by simple adhesion, chemical fixing or mechanical fixing.

  • Mechanically fixed installation: This type of installation mechanically fixes the film to the glass frame using a system of metal strips screwed to the existing glass frame (figure 4).

Figure 4: Mechanically fastening the blast protection film

  • Chemical fixing: This method of installation allows the safety film to be fixed to the glass frame using a structural coating or silicone adhesive (Figure 5).

Figure 5: Chemical bonding of blast-resistant film

Conclusion

Appropriate glazing in a pyrotechnic environment can play a crucial role in protecting people and structures. The recommendations in the Ineris Guide Pratique Fenêtres dans la zone 20-50 mbar - Effets de surpression, diagnostic et mesures de renforcement, DRA-11-117437-05120C can help you decide whether or not to carry out reinforcement work on our facilities, in order to guarantee increased safety and optimum resistance to the risks of explosion.

Acknowledgements :

Vitroconcept company www.vitroconcept.com

Bibliography :

  • IPE Newsletter n°44 - January 2020 Access to the document
  • Guide pratique Fenêtres dans la zone 20-50 mbar - Effets de surpression, diagnostic et mesures de renforcement, DRA-11-117437-05120C, Ineris (2011) Access to the document