In action films when a gas tanker crashes everything goes boom. I don’t think this is entirely realistic - but I suppose it could be possible. After all gas can go boom. I think that cars because of this fact.
So does a gas tanker that crashes have any chance of exploding? Is it an action film explosion or something less dramatic?
This will have to do until an explosives expert comes along. Gas tanks and tankers can explode and usually do, if not cooled down quickly, but my guess it is not what is referred to as a “high order” explostion. That is one in which combustion is so rapid that the air can’t be moved out of the way fast enough to prevent the formation of a shock wave and a build-up to very high pressures behind it.
Usually the tanks wall are not strong enough to withstand the pressure required to get the burning rate up that the point that all of the combustibles go up more or less at once.
However, gasoline is one of the most energetic fuels and the explosion that can happen is bad enough.
It is also necessary to add that liquid gasoline doesn’t burn. It has to vaporize and mix with the proper amount of oxygen. Ergo, the whole load doesn’t burn at once. One of the design problems in fuel air explosives is giving the fuel time to vaporize and let the resulting vapors get to the right fuel-air ratio in order to get an optimum explosion.
In fact, an empty tanker that hasn’t been properly purged of vapors would probably be a better bomb than a full one.
Here’s an article that I Googled. There are a bunch more on what is called a BLEVE…Boiling Liquid Expanding Vapor Explosion.
Thanks for the initial replies. I was aware that liquid gas was not the best kaboom chemical in existence, which is why I wondered if a full tanker would actually blow up if it crashed. I suppose it depends on how full it is and how it crashes.
Good post and good information. It’s a mechanism that I hadn’t though of or heard of but it makes sense. The trick to avoid such things I guess would be to have the equivalent of a “blowout wall” in the top of the tank, a sort of “explosive fuse.” to prevent the buildup of pressure. Also, make the tank of ductile material so that it doesn’t shatter.
Back in the day, when Haz Mat training was in its infancy, I remember BLEVE’s as one of the initial courses. We saw a movie of a BLEVE in a port in Louisiana, I think, that took out the entire harbor. It was a container ship filled with fuel. Hundreds killed, as I remember. Our instructor told us that in,the event of a possible BLEVE, you were to run in the opposite direction, and not stop until you could stretch out your arm, stick up your thumb, and make sure the entire incident could visually fit on top of your thumb. Only then were you in a safe area.
What does a BLEVE have to do with a sudden mechanical blow to the side of a tank?
There was probably an ignition (heat) source somewhere to act upon all those fumes that were released when the side of the tanker was breached on I-95.
A BLEVE can occur in a pressure or non-pressure vessel. The commodity need not be hazardous. Mechanical damage prior to the application of heat can increase the likelihood of failure. When pressure rises beyond the ability of a relief valve, burst disc, or blowout plug to vent, and particularly when the application of heat is above the liquid line in the vessel (absorption of heat vs. weakening of vessel wall), failure is a matter of time unless adequate cooling is introduced.
A BLEVE should not be confused with vessel breaching/huge spill together with ignition of cargo. The latter is a huge fire, while a BLEVE propels pieces of the vessel for great distances (~1/2 mile) along with a huge fire, should the commodity be flammable or combustible.
Best viewed with binoculars, or better yet, on the evening news.
An anecdote not totally unrelated to the OP:
One stormy summer day a few years ago I was eating lunch at a fast food restaurant while idly watching a tanker filling the storage tanks at the Amoco across the street. A bolt of lightning suddenly scored a direct hit on the tanker truck. When my eyes recovered from the flash I, and everyone else in the restaurant, noticed flames shooting high from the tanker’s fume exhaust vents. Three largish employees, their faces a mask of sheer panic, simultaneously exited the front door of the convenience store and dove behind the car wash. The driver looked at them, rolled his eyes and ambled over to the tanker. He slowly, methodically closed off the three valves controlling the exhaust vents, extinguishing the flames. He then had a big time laughing at and making fun of the store employees. His attitude suggested that this happened all the time - or he was bed bug crazy.
I’ve often wondered what the chances of an explosion were in that situation and how large a hole would have been left.