What are Explosives?

The word explosives may evoke thoughts of a brilliant display of fireworks or the shocking release of power in the form of a billowing mushroom cloud. However, many workplaces – from mines to construction sites – use explosive substances in their daily operations.  If your workplace is one that relies on explosives, it’s crucial that the risk to people, property and the environment is effectively controlled. In this post, we’ll be looking at explosive materials and their various subdivisions. We’ll also be highlighting the specific risks that they pose, as well as how they should be stored according to the Australian Standards.   

What is an Explosive? 

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 immense 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.’ 

Explosive Substances 

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). These explosions tend to shatter any objects in their path. 

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), which 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. 

Explosive materials are used across a diverse range of industries.

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 classed as explosive materials.  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. The pyrotechnic substance produces these effects through non-detonative self-sustaining exothermic chemical reactions. 

Pyrotechnic substances are used to produce firework displays.

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, which gives the rail a shock to make it more resistant to external pressures. 

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

Explosives may be used in the marine industry as flares and for underwater extractions.  

Explosive compounds may also be used in other industries, such as aviation, construction, automotive, science and forensics. 

REMEMBER: It’s vital that everyone in the workplace is trained to understand the hazards associated with explosive materials, as well as how they should be stored and handled.  

The Risk of Explosives 

Failure to treat and store explosive compounds in a safe and controlled environment can quickly escalate to harm property, people, and the environment. We will now discuss the risks that explosive materials pose when they’re used in the workplace. 

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.   

Risks to the environment 

If explosive substances have been released into the environment, they can be slow to degrade. The explosive compounds 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. 

If explosive materials aren’t handled or stored in the correct way, the explosive can decimate an area far exceeding your workplace, creating extreme damage to your local environment and community. 

Storage of Explosives 

The Australian Standard that outlines the storage requirements for explosive substances is AS 2187 - 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 lock 
• Fitted with handles for lifting 
• Painted both internally and externally 

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

Storemasta manufactures a range of explosive storage equipment that’s made to meet the Australian Standards.

REMEMBER: Your choice of storage is only the first step in maintaining a safe environment when handling and storing dangerous goods. Read our blog on explosive magazine management to learn more about the requirements relating to Class 1 storage. 

Storing Explosive Material Safely 

If your organisation uses chemical explosives, you must handle and store them in a careful, precise and compliant way. One factor that must be considered when storing explosive compounds 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, you can access our FREE eBook here.