Imploding tankers, or when chemistry finally got interesting

I knew the moment that my chemistry professor showed this video in lecture, I had to post it to the blog. From looking at the tanker, you’d expect it to be built well enough to handle some brutal conditions. Instead, the poor thing got crushed like a soda can under someone’s foot. So, what caused such a dramatic end to the tanker? The simple laws of pressure. Basically, as the tanker was drained of its contents the volume decreased which caused an increase in pressure, thereby crushing the tanker (Correction:As the tanker was drained of its contents, the pressure was decreased inside the tanker, while the pressure on the outside remained the same. With the decrease in pressure on the inside, the external pressure was able to crush the tanker. With that being said, they had to be using a pump to vacuum out the contents of the tanker without air being let in. Thanks Jamie!). On a molecular level, it’s a little more complex. The air we breath is made up of molecules of oxygen, nitrogen and very small amounts of other compounds. On their own, these molecules just bounce around and their impact creates pressure. This results in a relatively modest 14.7 pounds of pressure per square inch at the earth’s surface. This is commonly referred to as 1 bar of atmosphere, or atm. To put that into context, our sister planet Venus sits at around 93 bars.

These facts were originally postulated by Robert Boyle and can be summed up in Boyle’s Law: when volume decreases, pressure increases. When the same number of molecules are squished into an area much smaller than before, the excitation increases causing an equal increase in pressure (Further edit: in the case of the tanker, the exact opposite occurred). Had the tanker from the video been properly vented prior to draining, the pressure would have remained the same and the tanker could have been used for other things than scrap metal. But had they done that, we wouldn’t have such an awesome video to show off the power of pressure.

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12 thoughts on “Imploding tankers, or when chemistry finally got interesting

  1. Nice video. But, to be honest, I didn’t understand why the tanker implode. You said that “as the tanker
    was drained of its contents the volume decreased”, but shouldn’t it be on the contrary? I mean, if we take something out of a bottle, we should expect that the empty space inside it would increase, and thus decreasing the pressure. But I’m certainly forgetting something.

    I’m waiting more blog posts 🙂

  2. I won’t pretend to fully understand the concepts, but I think it refers to the ratio of molecules to open space. If you have the same number of molecules in half the space, then that can be interpreted as a decrease in volume. As I learn more, I’m sure I’ll be editing this post.

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  4. So, I think the creation of a vacuum makes sense and it’s effect on the pressure makes more sense using the ideal gas law, PV = nRT, because of the addition of the moles variable (n.)
    The volume of the tanker remains the same, as does the temperature (and the gas constant, R.) The remaining moles (n) of gas spread out to occupy the available space, so there aren’t many molecules of gas hitting the tanker walls, thus resulting in a much decreased pressure inside the tanker. This enables the force of the atmosphere to crush the tanker.

    Boyle’s law really clicked for me when I read about the 1980 eruption of Mt. St. Helens: an earthquake shook lose the cryptodome/bulge, suddenly lowering the pressure on the rest of the magma in the conduit. The gases in the magma reacted by suddenly increasing in volume.

    That’s a great video! Awesome that you got to watch it in class.

  5. Although there was enough pressure to total the tanker, one has to realise how strong and thick it was. (obvious the soundtrack on this doesn’t help as the dude who edited it added a monstrous WHAM!) This tanker appears to be manufactured to hold liquids and powders. I haven’t done much research on this but Im sure to be able to google it, i don’t believe the tanker was super strong either. But to relay some truth in this, size and material of the tank matter when it comes to the pressure build up inside.

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