What are Explosives?
Apr 16, 2018

What are Explosives?

Rachel Chesterfield Rachel Chesterfield

The word explosives immediately suggests a brilliant display of fireworks or the shocking release of power in the form of a billowing mushroom cloud. If your organization has anything to do with explosives, you would be aware that it is important to store and handle them in a way that reduces the risk that they pose upon the people, property and environment of your organisation.  

In short, an explosive is a substance or combination of substances that can react violently to emit heat, light, sound and gas at speeds and pressures which can cause a lot of damage to the surroundings

The Australian Dangerous Goods Code classifies explosives as ‘Class 1’ hazardous goods, and the UN defines them as: 

‘A solid or liquid substance (or mixture of substances) which is capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings. Pyrotechnic substances are included even when they do not evolve gases;’

‘A Pyrotechnic substance is a substance or a mixture of substances designed to produce an effect by heat, light, sound, gas or smoke or a combination of these as the result of non-detonative self-sustaining exothermic chemical reactions.’

Divisions of Class 1 - Explosives

Class 1 Explosives substances are divided into six subdivisions. These subdivisions are defined below:

  • Division 1.1 – Substances and articles which have a mass explosion hazard.
  • Division 1.2 – Substances and articles which have a projectile hazard, but not a mass explosion hazard.
  • Division 1.3 – Substances and articles which have a fire hazard and a minor blast hazard or a minor projectile hazard or both.
  • Division 1.4 – Substances and articles that present no significant hazard; only a small hazard in the event of ignition or initiation during transport with any effects largely confined to the package.
  • Division 1.5 – Very intensive substances which have a mass explosion hazard.
  • Division 1.6 – Extremely insensitive articles which do not have a mass explosion hazard.

Types of Explosions

There are two general classifications of explosions according to velocity:  High order and Low order explosions.

  • High order explosions release energy instantaneously and produce shock waves faster than the speed of sound (supersonic), and tend to shatter any objects in the path of the explosions.
  • In comparison, low order explosions release energy at a slower rate and release large amounts of gas.  This reaction is known as deflagration (as opposed to detonation), and creates a slower (subsonic) blast pressure front, tending to push objects from its path.

Higher order and low order explosives are used for different applications.  Low order explosives are predominantly used as propellants and for pyrotechnics, whereas high order explosives tend to be used in demolition, mining and military applications.  These different explosives can also be further classified as primary or secondary explosives, with primary explosives often used as detonators.

Common Explosives used in Industry

When asked to name an explosive or related industry, the words Dynamite, TNT and C4 come to mind, as do large open cut mines, military operations and training exercises.

Mines and quarries use explosives such as ANFO (ammonium nitrate/fuel oil) and more traditionally black powder and dynamite for blasting or drilling processes.  Today, emulsifiers and slurries are more commonly used, majority based with ammonium nitrate. Other explosives such as shock tubes, booster, ignition charges, initiation devices and detonators with varying chemical compositions are also frequently used in mines and quarries.

Obviously, fireworks are explosives.  A fuse is lit leading to the core charge, generally consisting of black powder, composed of 75% potassium nitrate, 15% charcoal and 10% sulfur. Once in the sky, a secondary fuse ignites a number of compartments, known as stars or pellets that are filled with a mixture of explosives and other elements to enhance color and effect.

Rail companies use explosives as warning devices for bad weather to warn of an incident or construction work. Railway companies also use explosives in rail hardening. This gives the rail a shock to make it more resistant to external pressures.

Explosives are used in the oil and gas industry for a number of purposes. These include shooting oil and gas wells in order to increase flow (often nitroglycerin), and heat resistant shaped charges are used to penetrate the metal casing of the well to admit the influx of oil.

Explosives are often utilized in the marine industry as flares, and for underwater extraction. They are also used as safety devices in other industries, such as aviation and automotive. Explosives are also commonly used in forensics and science fields.  In order to prevent harm to the people in your workplace, it is extremely important to ensure that everyone in the workplace is aware of the explosives that are present and they are stored in a safe and compliant manner.

The Risk of Explosives

Failure to treat and store explosives in a safe and controlled environment can quickly escalate to harm property, people, and the environment. We will now discuss the the risks that explosives pose upon people, property and the environment in more depth.

Risks to  the environment

Explosives substance that have been released into the environment can be slow to degrade and are likely to produce dangerous by-products before fully decomposing.  Naturally, the extent of the damage depends on the composition and quantity of the explosive substance that has been released into the environment.

Risk to property

Typically, explosions release an enormous amount of heat, light and sound at an incredible rate of pressure. If you watch an explosion occur in slow motion, you will notice that the shock-wave precedes the core.  This incredible amount of force from this explosion pushes everything out of its path – crumbling walls, smashing windows and destroying anything else in its way.

Risk to people

Again, the extent of damage depends on the size and nature of the explosives in question.  Due  to the highly combustible nature of explosives, physical dangers are extensive and can result in fatalities.  Burns, both physical and chemical are common injuries received from explosions due to the extensive amount of heat emitted. Shock waves can rapture lungs and eardrums. Flying debris and missiles from property destruction can become a major hazard, and similarly the combination of various fumes and gases emitted can cause intoxication. In short, if your organisation uses explosives you should go to extensive measures to ensure that you comply with all the explosives storage regulations to reduce the hazards that explosives pose upon the people in your workplace.  

Storage of explosives

The Australian Standard that outlines the storage requirements for explosive substances is AS2187-1998 - Explosives - Storage, transport and use. Section 2.2.2 of this standards outlines the requirements for internal explosive storage cabinets. These requirements are outlined below:

  • The construction of the internal storage cabinet must be of sheet steel of 0.8mm thick or sheet aluminium of 1.1mm thick. The internals of the explosive box must be lined with wood which must be fastened to the steel or aluminium.
  • The explosive storage box must be fitted with a close-fitting lid secured with a steel hasp, steel staple and steel hinges. When the explosive box is going to be used for gunpowder the hasp, staple and hinges must be constructed from brass.
  • Fitted with a secure lockExplosive Storage Cabinets.jpg
  • Fitted with handles for lifting
  • Painted both internally and externally.

An example of a safe explosive storage device is shown below:

explosive storage device

Next steps

If your organisation uses explosives substances, it is very important that you store them in a safe and compliant manner to reduce the risks they may have upon the people, property and environment of your organisation. One factor that must be considered when storing explosive substances is ensuring that they are segregated from other incompatible classes of dangerous goods. For more information on how to safely segregate explosive substances from other incompatible classes of dangerous goods download our free eBook by clicking on the image below 👇.

How to segregate incompatible classes of dangerous goods

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