Welding Drain Port in Old 700 Gallon Diesel Storage Tank

[LanceH]

I came across a heck of a deal on a 750 gallon fuel storage tank. Doesn't have legs or a skid nor does it have a drain plug. It does have four 4" bungs on top. It's empty but there is some crud so i was going to clean it out. Before i dump a few gallons of gas in it, i wanted to weld the 3/4" weld in flange and my skid contraption. For those welders out there, or those who have done this, what kind of advice can you offer? It did have diesel in it and there is only a diesel dirt grime in it.

Thanks,
Lance

 

[dex3361]

I came across a heck of a deal on a 750 gallon fuel storage tank. Doesn't have legs or a skid nor does it have a drain plug. It does have four 4" bungs on top. It's empty but there is some crud so i was going to clean it out. Before i dump a few gallons of gas in it, i wanted to weld the 3/4" weld in flange and my skid contraption. For those welders out there, or those who have done this, what kind of advice can you offer? It did have diesel in it and there is only a diesel dirt grime in it.

Thanks,
Lance

Highly dangerous to be welding on an unknown tank. There have been a few guys killed around here doing just that and the tanks had a false bottom in them. Really not worth the risk.

 

[tgunr]

I was going to try to do something similar to my 250 gal gas tank, I researched extensively and came to the conclusion it was just too risky. There is a ton of info on the net along with many killed/injured attempting to weld these kinds of tanks. My 2 cents would be to get an water/fuel seperator on your pump if that is why you to put in a drain.

 

[Bigkrank]

Buddy's shop burnt down two weeks ago welding on a diesel tank.

 

[20 20]

I have to agree with the others, DANGEROUS! I have done work on tanks, welding, cutting, BUT I also made sure they were cleaned out.

 

[mwb]

As stated, very dangerous. If you absolutely have to weld you need to purge air (oxygen) out of the tank; pipe exhaust from car/truck/tractor to flush it out. Unfortunately there is only one way to know its purged :shocked:

Can you add a solvent or cleaner, agitate it with a loader, then invert the tank to dump it out? Doesn't help you with a skid plate or legs but maybe you can make a cradle separately to set the tank on.

 

[flyerdan]

Another good way to purge the tank is if you can get some dry ice. It won't cost a fortune, sublimates into CO2 which is heavier than air and will settle to the bottom. You can have the tank in whatever position is most easiest to weld; the gas spilling out of the hole won't hurt the weld, since most steel mix shielding gas for mig welding contains 10-25% CO2.
I wouldn't stick weld it, just because it would be very hard to get it fluid tight. I'd mig weld it with a good clean fit up.
A good sump with a drain will save a lot of grief when water or crud starts showing up in the outlet filter bowl.

 

[LanceH]

Thanks for the advice guys...The drain isn't 100% necessary and I guess if there's a chance of me dying, then the skid could be separate like the cradle that was suggested. Now that i think about it, i could always fill the tank with water and do my skid welding. I dont plan on burning any holes through the tank when welding the skid on. Sound practical?

Maybe drain immediately after welding, rinse with diesel and drain, repeatedly.

 

[MrWinkey]

Don't fill it with water either........bad bad idea.

Bro-inlaw blew out the windows of his shop and launched himself into the neighbor's yard doing just that.....

Apparently something got hot or some vapors exploded from the hot mig torch. He dosent remember now and there was too little of the tank left to tell exactly what happened.

Should you even attempt it you'll need to backflow it w/ a non flammable gas as others have suggested.

Good luck!

 

[greasemonkeyok]

There are lots of old oil tanks in Oklahoma, and over the years lots of dead fellas who had the same idea. Seems like every six months or so there will be an article in the paper about someone killed welding or cutting a fuel tank.

You also need to remember that storing diesel for long periods of time requires monitoring the moisture and bacteria in the tank. Diesel is different from gasoline in that regard.