Yeah nah, that’s not the way. Sure people can get away with it, but it’s really not eliminating the hazards.

fnqsafetygroup.org.au/…/cutting-empty-drums.pdf …gov.au/…/explosions-when-cutting-used-fuel-tanks…

There’s a bunch of non-obvious hazards which exist around cutting into containers which have held fuels, including but not limited to:

• An empty propane container could have an gas+air mixture inside it in proportions which could explode.
• Any liquid residue in an empty fuel container can be vapourised by the heat of the cutting, creating a fuel+air mix which can spontaneously explode from the pressure and heat, even without sparks (think: diesel engine but instead of a 0.25L cylinder but a 200L cylinder).
• An empty gas canister can be contaminated with heavier oils/waxes that could build up over the years of refilling cycles, creating the same hazard as noted for empty liquid fuel containers.

Methods to reduce the hazard include:

• Thoroughly washing the inside of the container before cutting (access can be difficult though).
• Filling with water and cutting while full of water. (Container musn’t be sealed, and the cutting method must be safe to use in a wet environment, and further hazards such as introducing oxygen into the container need to be considered).