Most welders will not weld any tank that has ever held gasoline. Could be a
big clue here!
"terry" wrote in message
...
washing and letting it vent will probably not work.

BE SURE TO INFORM SERVICE PERSONAL OF THE FORMER PRESENCE OF GASOLINE.
Otherwise you may face a costly lawsuit for wrongful death.

Only way to weld it is to leave it filled with water which will displace
any
air needed to create an explosion.