In physics, an explosion is a quick increase in volume coupled with an exceptionally rapid inflow of energy, typically accompanied by high temperatures and the sudden release of high-pressure gasses.
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Chemical, mechanical, and nuclear explosions are just a few examples of the multiple types of explosions. Moreover, not all explosions happen with fire. Since the causes of these many explosions vary, this article will explore the many types of explosions and the elements that lead to them.
Soon, you’ll also learn more about explosions without fire, how they work, what causes them, and some famous examples.
What’s A Fire Triangle?
Three ingredients must be present to start and maintain a fire, known as the combustion triangle. The only thing you need with this triangle is a tiny ignite. Fuel, oxygen, and heat are the three necessary ingredients for the reaction in a combustion triangle.
The combustion triangle will collapse, and you can extinguish the flames if only one of these components is removed. Let’s review these factors in more detail.
Heat
Any material that may ignite must have an external ignition source, and different combustibles have varied ignition temperatures (also known as “flashpoints”).
Unfortunately, combustion processes generate heat as they burn, raising the temperature of the combustible material even more. You can use water to cool the heat produced by various forms of fire.
Flammable Material
There shouldn’t be a fire where there is no ignition source. Paper, oil, wood, and textiles are ignition sources found in residential and commercial buildings that can initiate a fire.
Note that some self-heating ignition sources are more prone to burning than others. Because fuels are the most challenging side of the combustion triangle to remove, it’s best to store them properly to avoid fire danger.
Oxygen
Because oxygen (or an oxidizing agent) combines with the burning fuel to generate heat and CO2, it’s necessary to keep the combustion process going. In addition, because oxygen makes up 21% of the air in the atmosphere, there are sufficient levels available to start a fire if the other two components are present.
Suffocation is caused by fire blankets and some fire extinguishers, which remove or dispense the oxygen side of the triangle, producing suffocation and stopping the combustion reaction.
Types of Explosion
To keep yourself and your staff safe, it’s essential to understand the distinctions among different explosions and how they occur.
Chemical Explosions
Chemical explosions are created by either decomposition or combination processes that induce massive volumes of scorching gas. These chemicals expand fast and increase the pressure in the surrounding area.
The high volume of hot gas effectively creates shock waves, creating an explosion able to cause widespread destruction potentially.
For example, gunpowder was one of the first chemical explosives to be utilized, and it’s still in use today. The chemical explosive dynamite is another example of a chemical explosive. When dynamite is ignited, it’ll burn fast, releasing scorching gas and causing an explosion.
Chemical explosions are one of the most prevalent forms of explosions. Thus, chemical manufacturing businesses must always look for potential fire and explosion build-up and follow emergency procedures.
Electrical & Magnetic Explosions
An electrical arc is a high current electrical fault that can generate tremendous energy levels and cause an ‘electrical explosion.’ These explosions rapidly vaporize metal and insulating material.
Likewise, a magnetic explosion might occur within an ultra-strong electromagnet due to high magnetic pressure within the magnet. In addition, static electricity can generate a tiny spark, resulting in the combustible material igniting.
Combustible Dust Explosions (Dust Accumulation)
A dust explosion occurs within a confined space when tiny particles in the air spontaneously ignite. Dust explosions can occur when any distributed combustible dust is present in high enough quantities in the atmosphere or another oxidizing gaseous media, such as pure oxygen.
A fuel-air explosion occurs when fuel is the explosive ingredient in a blast resulting in dust clouds.
Coal mines, grain elevators, and other industrial sites are all at risk of dust fire. Special effects artists, filmmakers, and pyrotechnicians also frequently employ them because of their magnificent looks and ability to be securely confined under carefully-regulated situations.
When readily combustible dust is quickly applied to an area, it ignites to provide explosive force through thermobaric weaponry. Dust explosions are the most potent ignition sources for non-nuclear weaponry.
Astronomical Explosions
Supernovae, which happen when certain types of stars reach the end of their lives, are among the most massive explosions ever recorded in the cosmos.
Solar flares are an example of a typical, considerably less energetic explosion that may happen on the Sun and, presumably, on most other planets, including Earth. When there’s solar conductive plasma build-up, it causes tangling of magnetic field lines, which produces solar flare activity.
This tangling generates the spark that powers solar flare activity. Another type of massive astronomical explosion happens when a very large meteorite or asteroid collides with the surface of another object, like a planet. For example, the Tunguska event in 1908 is thought to have been caused by a meteor airburst.
In the form of a gravitational wave, black hole mergers, which usually involve binary black hole systems, can emit multiple solar masses of energy into the cosmos in a fraction of a second. As a result, it can deliver conventional energy and destructive forces to adjacent objects.
However, they’re usually rare in the expanse of space nearby.
Nuclear Explosions
When it comes to nuclear weapons, both fusion and fission processes are utilized in their manufacture. A nuclear explosion happens due to either a fusion or a fission reaction, instantaneously releasing a tremendous quantity of heat and gas.
The energy released warms the air around it, resulting in a blast wave. Nuclear explosions generate radiation and radioactive debris, incredibly damaging to individuals in the explosion’s direct proximity. Therefore, it is possible to plan atomic explosions to cause injury and destruction to those in direct proximity.
Mechanical & Vapour Explosions
When the pressure inside a sealed or partially sealed container causes it to burst, it’s commonly referred to as an explosion, even though it’s purely physical rather than chemical or nuclear.
The rupture of a vessel carrying pressurized liquid, resulting in the fast expansion of the liquid’s volume (first explosion), is one sort of mechanical explosion that can occur. Boiling liquid expanding vapor (BLEVE) explosions is another type of mechanical explosion.
However, it’s important to remember that the contents of the container might cause a secondary explosion, which could be even more catastrophic, such as a propane tank engulfed in flames.
Mechanical explosions are compounded by the escape of gaseous propane from a ruptured tank, which results in secondary dust explosions when an ignition source ignites it. As a result, emergency personnel frequently distinguish between the two situations.
What is BLEVE?
An explosion of vapor caused by an explosive breakdown of a tank structure storing a cargo liquid over the boiling point at nominal air pressure is known as a BLEVE explosion.
The gas carrier’s tanks contain a mixture of liquid and gas in a normal state. However, a collapsed tank structure causes a reduction in pressure inside the tank because the vapor attempts to leave or seep through the hole.
When the pressure within the cargo tank is drastically reduced, it causes the liquid to boil quickly and create vapor. A shock wave or explosion is caused by the pressure of the escaping vapor, which destroys the tank’s structural integrity and the surrounding environment.
For a BLEVE explosion to completely cover a container or hold, you must consider the cargo’s size, volume, and weight. Therefore, liquid cargo in the tank at the BLEVE moment directly connects with explosion intensity.
Please keep in mind that the BLEVE might develop even without an explosive chemical. BLEVE can happen under the exact circumstances for liquid cargo held in freezing temperatures, such as liquid helium or other refrigerants or cryogens.
If the material or cargo used in BLEVE is poisonous, it will pollute a vast region. However, they are not often considered chemical explosions. If the material in question is combustible, it will produce a fireball cloud during BLEVE, akin to self-ignition, also known as a vapor cloud explosion (VCE).
BLEVE Explosions Extreme Example: Feyzin Explosion
Before the Flixborough catastrophe in 1974, the Feyzin tragedy was the most severe accident in Western Europe’s petroleum and petrochemical industries. As a result, many pressurized tanks holding liquid gasses have BLEVE’d since then.
The risks are now better-known, and the new designs protect storage spheres from fire engulfment. This large-scale fire and explosion accident first saw the BLEVE phenomenon.
On January 4, 1966, an effort was made to drain an aqueous layer from a propane storage sphere. First, the workers opened two valves in sequence on the bottom of the sphere. The top valve was closed and reopened when the process was virtually finished.
Then, the workers opened the valve even more because no flow was coming out of the fractured valve. The ice or hydrate obstruction was removed, and propane began to flow freely. Unfortunately, the operator could not close the top valve, which had frozen open when he attempted to close the lower valve.
The staff sounded a loud alarm, and the traffic stopped on the adjacent highway. An automobile around 525 feet (160 meters) away is believed to have ignited the cloud of vapor. The storage sphere was engulfed in flames, and as gas lifted the relief valve, a stream of escaping vapor ignited.
The sphere broke 90 minutes after the initial spill, killing everyone nearby.
BLEVE Explosions Extreme Example: The Texas City Explosion of 1947
On April 16, 1947, an industrial catastrophe in Texas City was started by the fire and explosion of the SS Grandcamp. The explosion also triggered a 15-foot (4.5-metre) tidal surge. The injuries were between 4,000 and 6,000, with 400 to 600 deaths.
French-owned Grandcamp was about to complete loading an ammonium-nitrate fertilizer consignment at Texas City’s port near Galveston on the morning of April 16. Then, around 8:00 a.m Members of the flight crew detected smoke coming from the cargo hold, which had already been loaded with 2,300 tonnes of fertilizer.
The team chose not to use water to put out the fire but instead attempted to extinguish the flames themselves. By 9:00 a.mThe cargo area’s temperature had increased so much that a large explosion could be heard 150 miles (240 kilometers) away.
The dock area was damaged, and the Monsanto Chemical Company factory was engulfed in flames due to the blaze.
A mushroom cloud smashed two tiny planes flying overhead that soared to 600 meters (2,000 feet). A great deal of burning shrapnel was hurled into the air, and most of it fell on industrial districts, where it caused fires and severe destruction.
One of the ships that caught fire and detonated was carrying a large amount of sulfur, while crude oil tankers near the site were in flames for days, burning enormous amounts of petroleum.
In addition to the loss of life and property, the original explosion destroyed the town’s firefighting apparatus, further adding to the catastrophe.
Different Phases of BLEVE
It’s been noted that BLEVE won’t suddenly occur if any of the elements previously discussed are lacking. Listed below are the procedures that can lead to BLEVE:
- Failure of the tank/hold: Tank failure can be caused by various factors, all of which can result in a rise in internal pressure and failure of the tank’s weakest portion, depending on the circumstance.
- Phase transition: An abrupt depressurization of the liquified gas will happen when the tank construction breaks. The superheated mixture of liquid and vapor will be in a thermodynamically saturated state with a greater temperature than its boiling point in milliseconds.
- Splashing of liquid vapor mixture: Due to the high temperature, rapid bubble nucleation will begin inside the tank, resulting in a forceful splashing of the liquid/vapor combination into the atmosphere.
- Explosion: The boiling of the liquid, followed by bubble nucleation, will lead to an explosion when depressurization happens, combined with a violent phase transition in the superheated state.
Common Causes of BLEVE
BLEVE will not come instantly. However, it will happen under specific circumstances, in other words, if warning indicators are ignored. The following are the requirements for a Boiling Liquid Expanding Vapor Explosion:
- Liquid Cargo: No amount of vapor can get you to BLEVE. The tank must contain liquid cargo for this to happen. There is a risk of BLEVE even in water. There will be no fire, however, because it is not flammable.
- Pressurized container: Containers and holds used to transport liquid goods must be airtight. Only if the vent system malfunctions and pressure builds up inside the tank or hold can lead to BLEVE.
- Above Boiling Temperature: Atmospheric pressure must be above the boiling point of the liquid cargo to contribute to the explosion of Boiling Liquid Expanding Vapor. The vapor pressure rises as the temperature rises in a pressurized cargo hold or tank. As the vapor pressure increases, the boiling point increases as well.
- Structure Failure: The liquid can only leave the pressurized tank and become vapor if the tank or hold structurally fails.
Beware of BLEVE Causes & Signs
Heat near tanks storing gas cargo, such as propane, is the most prevalent cause of BLEVE. The temperature of the tanks begins to rise due to the high ambient temperature, and the inside of the tanks becomes too pressurized.
The relief valve will usually discharge the excessive pressure inside the tank. However, suppose the surrounding temperature and pace of heating allow the pressure to rise quickly. In that event, the tank will collapse at the weakest spot, exposing pressurized and combustible material that will result in a vapor explosion caused by boiling liquid.
Failure of tank structure could happen because of the following reasons.
- Tanks that have not been adequately maintained
- The tank structure is corroding.
- The tank’s relief valve is malfunctioning or jammed.
- Damage to the tank’s mechanical systems
- Heat-damaged tank construction
BLEVE warning signs include the following.
- Discoloration of the tank structure’s metal shell
- Small metal fragments flaking
- A bubble or bulge on the tank surface
- A metal shell that makes a ringing tone
Fire prevention precautions to avoid BLEVE include the following.
- Regular maintenance of the cargo tank
- Correct installation of the tank
- Proper installation of ventilation systems and other process equipment
- A fully operational relief valve at all times
- Follow the International Gas Code and national fire protection association health and safety guidelines regarding the relief valve size
- Prepared crew members in the event of an emergency and fire prevention.
- Avoiding general cargo, storage, and compressed gas operations in the area of the gas cargo activity during the gas cargo transfer
- No oil or gasoline bunkering shall be carried out during or before the cargo operation.
- Checking the mooring lines to ensure the ship is securely attached to the pier or dock.
- A readily available LP-Gas detector at the berth
- Any cargo transfer at night or during the dark hours should be done in a well-lit and safe handling environment, both in port and on the ship.
- While the cargo transfer is taking place, the connection area stops valves and should be marked and visible without obstructing their path.
- During the operation, firefighting apparatus should always be present and accessible.
- There should be enough warning signs to ensure that all workers (shore and ship crew) are aware of the cargo transfer operation and that the measures are taken.
Conclusion
Even though BLEVE incidents seldom occur, their catastrophic impact on buildings, equipment, workers, and the economy can’t be overstated. Unfortunately, you cannot reduce the chances of BELVE to zero, but you can cut down its likelihood by essential and straightforward precautions.
We hope this article can help you understand the importance of BELVE precautions more. If you believe you have conditions that might lead to a BELVE occurrence, Roar Engineering can provide fire and explosion investigation services and risk assessment.
Although, fire and explosion investigation and disaster reconstruction are just a few areas in which we specialize in environmental cleanup. We’ve built a name for ourselves as experts in forensic engineering and Explosion investigation that can survive a rigorous court examination.
