What’s a magazine ? And why ?

By Ken Price

What is the purpose of an explosives magazine ? Safety or security ?

Australia is currently reviewing its requirements as written in Australian Standard 2187, for the storage of explosives, particularly the construction requirements for magazines. We have a variety of confusing terms and descriptors for magazines that have evolved from the days when there were two basic types: a fixed permanent construction, usually a wood lined corrugated iron shed, or a smaller portable steel box.

The fixed magazine was for nitroglycerine-based explosives and typically had a smaller shed nearby for storing detonators. Both would be wood lined, no exposed steel, and an annex in front with a broom and a mat, perhaps also galoshes or overshoes, to restrict the potential for intrusion of abrasive or incendive materials like stones. Security was typically a hasp and staple or a bolt with a sound steel lock, typically a Chubb Battleship lock, with protected shackle and keyed mechanism though mortice deadlocks were also used.

Portable magazines were limited to sound steel constructions suitable for up to 250 kg. The sides and lid were 5 mm steel, and the lids had a return, so they overlapped the sides to prevent direct access to the inside. Of course, they were all wood lined; typically, 12 mm plywood. The lids were so heavy one risked death or serious injury if they fell onto any part of your anatomy. Some had a bolt protruding from the base so they could be bolted to a concrete foundation to deter theft.

Due to batch processes where acid levels weren't managed well, nitroglycerine had a nasty habit of occasionally exploding spontaneously so magazines were located far enough away from any occupied areas so the chances of anyone being affected by a magazine exploding was practically zero. This improved with mechanical production and the Abel Heat Test also enabled reliable monitoring of stability. However, the isolation meant they were usually well out of sight – ideally placed so criminals could work on them at leisure.

These magazines were widely used for civil construction and larger mining operations but less so on smaller mines.

In Western Australia, through the 1970’s explosives theft was very rare, but redistribution of wealth was quite common. Typical event was for a part time miner/prospector to come back to his “show” to find his cache of explosives tucked away in his shed or off the side of his exploratory shaft had gone missing. No doubt off to a better home at some other small prospect. This was duly reported to the authorities and some more purchased for the job. But it was an indication that security issues become more critical.

Through the 1980’s explosives and the associated storage facilities in Australia underwent significant development, not always in harmony. For example:

• Nitroglycerine based explosives practically disappeared from the scene.
• Many magazines were used to store ANFO, or other ammonium nitrate based products.
• Magazines were constructed for storage of 50 or 100 tonnes.
• Globally, rather that break bulk, freight containers became the preferred method of transport. With this development, modification of the transport unit was seen as ideal for the storage of explosives.
• Unfortunately, security for transport was inadequate for storage so industry began to modify freight containers to store explosives.
• Heavy lifting equipment became more readily available and now 10 and 20 tonne magazines are described as portable magazines.

With the disappearance of NG and similar friction sensitive explosives and the storage of ANFO in single filament plastics bags, wood lining on floors and walls suddenly seems contrary to good safety practice. Ammonium nitrate impregnated wood is very combustible and not so hard to ignite. Instances were reported of softwood pallets igniting in transport and of small, localized explosions around nail heads on pallets. None the less, it took years to remove the requirement for wood lining.
Why do we need such good ventilation in magazines storing emulsion-based explosives and detonators provided temperature cycling (eg good insulation) can be managed. Could we remove the vents and thereby simplify the design?

Mortice deadlocks and flush panel doors are still good for security, but why have mechanical lever based locking systems. My car and garage can be unlocked remotely, electronically – why not allow the same for magazines? Biometrics (ie face and finger recognition) could now be used to open doors and to monitor who has entered a magazine.
Why do I need a high security fence around a magazine if I can achieve the same result with a lightweight barrier to deter stray animals and an electronic detection system to alarm should anything else intrude. This could be as simple as a trembler alarm on the walls.

Now, moving through the first quarter of the 21st century, explosives storage is increasingly limited to boosters, in smaller magazines, and detonators in the larger structures. The issue of concern is less about safety of people exposed to an unintended explosion from product in storage and more towards security, to prevent access by terrorists or criminals.

Some more questions around this paradigm.

The worldwide shift to bulk explosives has made significant contributions to safety, productivity and economics of using explosives.

• When was the last time you heard of a magazine exploding? (and the time before that?)
• What is the point of the quantity/distance tables if, by following them, it facilitates illegal entry to magazines? Modern battery operated and portable equipment has certainly made entry to any magazine quite easy.
• If a high security standard can be achieved with light construction materials (less chance of flying debris) and modern technology, would not safety also be enhanced?

Perhaps you could put some of these questions to your local explosives regulator.

Acknowledgement: For me, the hardest part about drafting an article for SAFEX is identifying a topic. Thanks to Leslie Williams for the inspiration and Paul Harrison for the theme development.