Ok, here me out… wait wait just listen. This absolutely violates every Osha regulation in the book, no body is arguing that, but what I am about to argue is this is actually pretty safe.

1. Those sparks cool through the air fast enough that they won’t burn skin let alone solid steel.
2. any melted metal is under the tanks so it will drop safely to the ground.
3. If any melted metal did land on the tank it would not be enough to melt through. It would simply solidify and leave a clump of metal.
4. even if he aimed the torch directly at the tank it would still take 3-5 Minutes to burn through way more than enough time to realize what he is doing.
5. even if he did somehow Pierce the tank they would not explode they don’t have oxygen in them they would only burn a small torch like flame out the hole you put in it.
6. if one of them for some reason exploded(once again not going to happen) it would not set up a chain reaction, these tanks are made like….Tanks they will not explode from so little force.