We all woke up to the news of the explosion that occurred in Abule Ado, an area in the Festac side of Lagos State, which led to the death of over 17 people and left many injured. According to the report from Al Jazeera, the explosion was triggered by a truck that ran into gas bottles stacked up in a gas processing plant near a pipeline. The impact of the explosion was felt as far as fifteen kilometers away. Houses in the immediate environment of the explosion were pulled down by the force of the blast, while houses farther away lost their windows and ceiling as shock waves ripped through them.
What we experienced alongside the pipeline explosion is technically called a Boiling Point Expanding Vapour Explosion or BLEVE (pronounced blee-vee). BLEVE is an explosion caused by the damage or rupture of a vessel containing a pressurized liquid (e.g. methane and propane, our regular cooking gas) that has attained temperatures above its boiling point. Because the boiling point of a liquid rises with pressure, the contents of the pressurized vessel can remain liquid so long the vessel is intact. Once the vessel’s integrity is compromised, the loss of pressure and dropping boiling point can cause the liquid to rapidly convert to gas and expand rapidly. If the gas is then combustible, as is the case with the gas processing plant in Abule Ado, further damage can be caused by an ensuing fire.
BLEVEs can emit shock-waves that pushe the surrounding atmosphere with exponential pressure fronts, travelling at supersonic speed. This phenomenon explains the sonic boom heard around Lagos due to the explosion. According to Dr. Davidson Olusesan, A geologist and hydraulics engineer, a BLEVE can cause a shock-wave pressure of about approx. 250 psi, when just a pressure of 5 psi can rupture the ear drum. The shock-wave pressure concentrated at the center of the explosion was responsible for the collapse of buildings closest to the gas processing plant, and most deaths. It is also responsible for the effect (caving in of ceilings, breaking of glasses, etc.) felt by houses and cars farther away.
For a BLEVE to occur there must be:
- Liquid Cargo: Vapour alone cannot lead to a BLEVE. A liquid cargo must be present inside the tank to make it happen. Even water can lead to a BLEVE. However, there will be no fire as it is not flammable.
- Pressurized container: The liquid cargo must be inside a tightly closed container or hold. A ventilated container may lead to a BLEVE only if the vent mechanism becomes faulty, leading to pressure development inside the tank or hold.
- Above Boiling Temperature: The temperature of the enclosed liquid cargo must be above its boiling point at atmospheric pressure to contribute to Boiling Liquid Expanding Vapor Explosion. When a pressurized cargo hold or tank is heated, the vapour pressure will increase. An elevated boiling point accompanies the increased vapour pressure.
- Structural Failure: The liquid needs a path to escape from the pressurized tank and convert into vapour, which can only happen when there is a structural failure of the tank or hold.
To prevent a re-occurrence of such events, we have to probe ourselves and ask the tough questions. Are we ready to develop at a rate that won’t put us in harm’s way? Do we truly take the safety of our lives and properties seriously?
By all standards, building residences around or close to a pipeline, gas station, tank farms or power-line is wrong, but do we really care? When all of these happen, blames are thrown in the air and arguments surround who should take responsibility for the events. With an introspection, everyone knows where they have gone wrong and must be willing to take responsibility moving forward. We should be more proactive than reactive.
There is a reason we have urban planners, surveyors, building engineers, environmental health officers. These are professionals that would advise you properly when making decisions around the development of landed properties. Why must we have building that pose a hazard to us? Why build a house at all costs just for the sake of whatever is the driving force?