Jim and Becky wrote:

For some reason when two aluminum tanks were installed just three years ago,
they chose not to put fuel guage senders in.
So now I need to install them.
The tanks hold diesel fuel.
I'm concerned about the danger of an explosion as I saw the holes.
What do people do? I'd never try this with a gasoline tank but am unsure of
diesel.



You can probably do it with no issues. I have welded diesel tanks that
were emptied with no issues many times.

If you are really worried, use nitrogen or CO2 to inert the atmosphere
inside the tank. If there is no oxygen, there can be no flame.

I'd be more worried about the chips in the tanks than any fire hazard.

--
“TANSTAAFL”


“All I can say is there had better be some cheese at the end of this maze……”
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"A prudent man foresees the difficulties ahead and prepares for them;
The simpleton goes blindly on and suffers the consequences." - Proverbs 22:3