[Mercury Bullet]

We had the fuel tank on the race boat welded a few times.
No problems when done by professionals, they filled it with argon or Halon iirc.


Then one day I was at Greenwood a few years ago and there was an almighty explosion.
Bloke literally blew his double brick house, and himself up. Welding the tank.

If you don't know what you're doing, call someone who does.
It's the fumes that explode not the petrol, when they are empty they are bombs.