The dangers of explosives are clear. And yet many people are injured or die in explosions each year. There are various precautions required to deal with explosives but serious incidents still happen.
The quality of explosives and safety regulations regarding their use are significantly better than they used to be. But the hazards are still present, and improper storage methods or improper use can lead to serious incidents.
There are safe practices designed for working with explosives and they must be followed to protect workers and the general public.
Explosives should be kept in proper storage facilities to protect them from the elements and possible degradation. Magazines have very clear design specifications that must be adhered to in order to ensure proper and safe storage, to minimize the possibility of inadvertent ignition and to protect employees and others.
For example, heating a magazine has to be done in such a way as to not direct the heat onto the explosives but to keep their temperature constant. OSHA’s regulations are very specific (e.g., “The electric fan or pump used in the heating system for a magazine shall be mounted outside and separate from the wall of the magazine and shall be grounded.”), but the basic requirements are that the explosives must be:
- dry and well ventilated;
- as cool as possible and not exposed to serious changes of temperature;
- protected from direct sunlight and flooding;
- not exposed to excessive or constant vibration,
- stored separately from blasting caps, electric blasting caps, detonating primers, and primed cartridges; and
- accessible only to authorized workers who are competent, trained and use extreme care.
Magazines storing explosives (whether they’re buildings or containers) must adhere to a number of requirements:
- Magazines are to be kept clean and orderly.
- All explosives must be accounted for at all times through the use of records and logbooks. The oldest explosives must be used first because the quality of explosives can degrade over time; a rotation system that allows for this must be in place.
- When opening or closing wood packages of explosives, a wood wedge and a fiber, rubber, or wood mallet must be used.
- Magazine floors must be regularly swept (the sweepings must be properly disposed of) and kept clean and dry. Brooms and other cleaning utensils mustn’t have any spark-producing metal parts.
- In the event of a fire breaking out and being in imminent danger of contact with explosives, no firefighting actions should be taken. Instead, all employees must be removed to a safe area. In addition, the fire area must be guarded to prevent anyone from entering it by accident or on purpose.
- Smoking and open flames mustn’t be present within 50 feet of explosives and detonator storage magazines. This should be well understood by everyone, but sometimes people need reminding.
Transportation of explosives needs to follow regulations regardless of whether it’s long or short distance. Employers must develop procedures in accordance with the regulations to protect workers and bystanders.
- Vehicles carrying explosives must always have the right of way.
- Ensure that motor vehicles transporting explosives, or explosives themselves, are never left unattended.
- If transporting vehicles do not have a closed body then, in order to protect the explosives against moisture and sparks, they must be covered with a flameproof and moistureproof cover or other effective protection.
- Explosives mustn’t be transported with other materials or blasting caps.
- The drivers transporting explosives must be licensed, physically fit and be familiar with the transportation of explosives regulations.
- Vehicles used for transporting explosives must be in good mechanical condition and be the right size for the load.
- Any exposed spark-producing metal on the inside of the transport vehicles must be covered with non-sparking materials (like wood).
- Signs, markings or placards with the word “Explosives” must be placed on all sides of the transport vehicles. The signal word must be written over white background and in red letters that are at least four inches in height.
- A red flag, visible from all directions, may also be used in addition to the signs.
- Fully charged and working fire extinguishers in good condition must be placed in each vehicle. They must have a minimum rating of 10-ABC.
- The drivers must be trained in the use of the extinguisher.
Handling and blasting
The use, delivery and handling of explosives must be performed by competent workers with the right training and experience. Not only must they always use extreme care, but they also have to know and follow all the procedures and regulations to ensure everyone’s safety. Such regulations cover all aspects of the use of explosives from packaging to weather conditions.
- Boxes and packing materials that contained high explosives mustn’t be reused. Instead, they should be safely burned.
- Explosives (and supplies related to their use) that are deteriorated or damaged must not be used but, instead, safely disposed of in accordance with written procedures.
- Moving detonators and other explosives to a blasting area must be done in their original containers, or class II magazines.
- When preparing for blasting, before the detonators are wired into the blasting circuit they must be short-circuited in holes that have been primed and shunted.
- Accidental discharge of electric blasting caps must be prevented through appropriate precautions. These must consider situations such as a current induced by radar, radio transmitters, lightning, power lines or dust storms.
- In the event of an approaching electrical storm, all blasting operations must be suspended.
- If overhead power lines, communication lines and utility structures are present near the blasting operations, owners and operators of these structures and equipment must be notified and the operations can only be carried out when control measures are in place.
- Special precautions must be taken to control each blast and the resulting throw of fragments. These precautions should include visual and audible warning signals, flags, barricades or woven wire mats.
For the safety of employees and the general public, all workers handling, using or affected by the use of explosives must be trained in all the relevant safety procedures. This is to ensure that all workers are familiar with the various explosive materials they may work with and with the procedures they have to follow if they’re faced with out-of-the-ordinary situations (such as explosives found in an incorrect place). But even proper use of explosives could lead to dangerous situations such as:
- fly-rocks: workers or others can be struck by a rock if they stand too close to the blast or the rock travels farther than predicted;
- premature blast: as the name suggests, this is an explosion that happens earlier than planned. This could be caused by a faulty fuse, degraded explosives, carelessness, environmental conditions or other issues;
- misfires: this happens when a charge fails to explode completely or partially. The remains of the explosives could now be triggered by any environmental condition or mechanical force like digging, so recovering operations of these explosives can be extremely dangerous;
- mine-induced seismicity: this is very dangerous in underground mining areas and can be triggered by the use of explosives, resulting in earthquake-like events that can collapse the mine, flood it or even cause damage on the surface.
With all the risks involved, a thorough, comprehensive safety training plan is vital. It should aim to prepare workers not only for predictable situations but also for unusual ones. In addition, regular refreshers are always needed as they help keep safety information fresh and relevant.
When handling explosives, every opportunity to mitigate any potential errors must be considered, so adding human factors to the training program is also critically important. This type of training prepares the workers to recognize and address states of mind (such as rushing or fatigue) that can easily influence decision-making and lead to errors. A deep understanding of human factors is also needed for the development of effective engineering solutions, procedures and checklists.
Knowing the rules and regulations is not always enough. People handling explosives need to be well-trained and mindful of the risks and of their own states of mind. For example, a sleep-deprived employee is much more likely to forget or miss something vital, exposing themselves and others to greater risks. And when handling explosives, increased risk is not an option.