got a couple of diesel tanks,about 500 gallon jobbies,they have been "empty" for a few years though you can still smell fuel vapours,can they be made safe to cut and weld and if so how?

just weld they will be ok you dont need to wash them out.as long as theres nothing in them.
adam

dont leave the cap on take it off.

[Edited on 26/9/07 by oadamo]

They don't fume like petrol but they may still catch fire. You could fill them with exhaust gas to get the oxygen content down.

ive welding about 50 this year alone and not one have gone bang.
adam

ok cheers peeps,ive done petrol ones before and know how to sort them but never diesel

The proper HSE approved way, according to what Ive read on the web, is to pump inert gas into the vessel whilst measuring the HC concentration with a meter at an exit hole e.g filler. A certain level of HC ppm is deemed safe, its online somewhere...

I dont know whether diesel is as much of an issue but over time apparently the HCs in some fuel can actually solidify in the weld seams and corners of the tank. Under the heat of the weld these deposits can vapourise and cause problems.

After I read all of this I was very reluctant to weld it at all but after several very thorough washes with very hot water and an overnight dry I chanced it....

...and I think I got away with it?!

Dont knw if id do it again though, it took years off me!

Run it on a car exhaust for about 20 mins.
Done it this way for 10 years, even with petrol tanks.
I always use a lit bit of newspaper on a pole as a final test.
I've also welded lots of aluminium lorry tanks (empty) as they tend to split on the seams.
Never had a problem, not even burning locally to the welding, but they stink though!