Yes, after washing the tank with water, - we run a exhaust hose from a running vehicle into the filler tube hole or gauge sender hole with the other hole as vent.
Exhaust gas is an extinguisher, ( if all cylinders are firing, that's another story) so we run exhaust thru the tank for several minutes to purge it with hot extinguisher, then weld away , - while continuing to pump exhaust thru tank.
I was plenty scared when my mentor did it, but back then it was not uncommon.
I finally got comfortable doing it .
If you fill a bag with exhaust gas, try to light a Bic inside the bag.