# Propane tank struck by lightning?
**URL:** https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382
**Category:** Factual Questions
**Created:** [July 28, 2006, 11:58am UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382 "2006-07-28T11:58:50Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@solkoe](https://boards.straightdope.com/u/solkoe)
#### Post date: [July 28, 2006, 11:58am UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/1 "2006-07-28T11:58:50Z")
My family and I were in a tent during a fierce lightning storm. All I could think about was the propane tank sitting on top of the picnic table next to the tent. If that got struck by lightning, I thought, we’d be toast.
After the storm, I reasoned that probably nothing would have happened. The metal can is a good conductor and would simply carry the charge to the ground without heating up too much.
Ignoring the fact the the trees were much better targets anyway, what would have happened if the propane tank if it had been struck by lightning?
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### Author:  [@VunderBob](https://boards.straightdope.com/u/VunderBob)
#### Post date: [July 28, 2006, 12:02pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/2 "2006-07-28T12:02:28Z")
Unless it was leaking significantly when struck, nothing.
The integrity of the tank will keep the propane from mixing with the air, and prevent an explosion.
If it was leaking, you’d have a blowtorch, not a bomb.
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### Author:  [@spingears](https://boards.straightdope.com/u/spingears)
#### Post date: [July 28, 2006, 1:12pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/3 "2006-07-28T13:12:32Z")
> [@solkoe](#):
>
> My family and I were in a tent during a fierce lightning storm. All I could think about was the propane tank sitting on top of the picnic table next to the tent. If that got struck by lightning, I thought, we’d be toast.
> After the storm, I reasoned that probably nothing would have happened. The metal can is a good conductor and would simply carry the charge to the ground without heating up too much.
> Ignoring the fact the the trees were much better targets anyway, what would have happened if the propane tank if it had been struck by lightning?
Trees being taller than their surrounding are usually the first to be hit by lightning.
> [@VunderBob](#):
>
> Unless it was leaking significantly when struck, nothing.
> The integrity of the tank will keep the propane from mixing with the air, and prevent an explosion.
> If it was leaking, you’d have a blowtorch, not a bomb.
Don’t bet you life on it!
Lightning is inpredictable and capricious. A direct hit on a propane take could cause it to rupture and result in an explosion, and fire.
Being shielded by the surrounding trees would make it less likely.
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### Author:  [@VunderBob](https://boards.straightdope.com/u/VunderBob)
#### Post date: [July 28, 2006, 1:36pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/4 "2006-07-28T13:36:20Z")
> [@spingears](#):
>
> Trees being taller than their surrounding are usually the first to be hit by lightning.
> Don’t bet you life on it!
> Lightning is inpredictable and capricious. A direct hit on a propane take could cause it to rupture and result in an explosion, and fire.
> Being shielded by the surrounding trees would make it less likely.
:dubious:
By what mechanism will the tank fail? The heating is too instantaneous to melt the metal. There is no layer of water to heat up and cause a vapor explosion, such as what happens to trees and the sap layer in the bark. There is not enough free O[sub]2[/sub] inside to spark combustion. The tank itself forms a Faraday shell.
If there _WAS_ a significant explosion hazard with a properly maintained propane tank WRT lightning, then the rural propane dealers would be out of business in a heartbeat.
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### Author:  [@Turek](https://boards.straightdope.com/u/Turek)
#### Post date: [July 28, 2006, 3:11pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/5 "2006-07-28T15:11:07Z")
A datapoint of which I don’t know the relevance: the commercial propane tanks I’ve seen seem to have a tall, narrow pipe attached to them for, I presume, venting. Surely lighting would find such a protruberance attractive?
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### Author:  [@Fir\_na\_tine](https://boards.straightdope.com/u/Fir_na_tine)
#### Post date: [July 28, 2006, 4:25pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/6 "2006-07-28T16:25:24Z")
> [@VunderBob](#):
>
> :dubious:
>
> By what mechanism will the tank fail? The heating is too instantaneous to melt the metal.
I’ve seen reports of lightning strikes that burned off clothing and jewelry. ASSUMING those stories are valid and that heat from a strike can be transferred that quickly, there is the theoretical possibility of a BLEVE.
Ever seen photos of a RR tank car or gasoline tanker burning fiercely and then exploding? The liquid inside the tank is being heated by a fire (or a lightning strike). The boiling liquid is expanding rapidly. Propane expands at about 270 to 1 if I recall correctly. So when the pressure inside the tank exceeds the capacity of the container, you have a BLEVE (Boiling Liquid - Expanding Vapor Explosion).
It’s impressive and deadly. And quite statistically unlikely.
But you asked.
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### Author:  [@VunderBob](https://boards.straightdope.com/u/VunderBob)
#### Post date: [July 28, 2006, 4:40pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/7 "2006-07-28T16:40:39Z")
> [@Fir na tine](#):
>
> Ever seen photos of a RR tank car or gasoline tanker burning fiercely and then exploding? The liquid inside the tank is being heated by a fire (or a lightning strike). The boiling liquid is expanding rapidly. Propane expands at about 270 to 1 if I recall correctly. So when the pressure inside the tank exceeds the capacity of the container, you have a BLEVE (Boiling Liquid - Expanding Vapor Explosion).
BLEVEs occur after hours of heating by an external fire leading to the the structural failure of the tank, or an external puncture via some kind of mishap followed by a spark.
FWIW, just about any liquid passing the boiling point into the vapor phase expands about 270 to 1.
> [@](#):
>
> It’s impressive and deadly. And quite statistically unlikely.
Exactly.
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [July 28, 2006, 4:43pm UTC](https://boards.straightdope.com/t/propane-tank-struck-by-lightning/366382/8 "2006-07-28T16:43:26Z")
> [@Fir na tine](#):
>
> I’ve seen reports of lightning strikes that burned off clothing and jewelry. ASSUMING those stories are valid and that heat from a strike can be transferred that quickly, there is the theoretical possibility of a BLEVE.
Well, at least in the case of jewelry, you have a conductor with a small cross-sectional area. If you manage to have an electrical path where a large amount of the lightning energy is going through the metal of the jewelry, it will vaporize almost instantly. However, the cross-sectional area of the tank is much, much larger. The lightning energy passes through all of it at once, and the resulting current density at any one point is too low to significantly heat the metal. It would have to go through a low-resistance path with a relatively small cross section to do that, but that still wouldn’t affect the contents any.
> [@VunderBob](#):
>
> If there _WAS_ a significant explosion hazard with a properly maintained propane tank WRT lightning, then the rural propane dealers would be out of business in a heartbeat.
Indeed, it never would have gotten started to begin with.