Welding on Diesel Storage Tank Steel

[gmason]

Hello, I've come upon a nice old 200gal steel storage tank. I'm trying to drain all the old diesel out of it, and the drain plug on the bottom is a 5/8 square nut, but in the process of trying to get it out I broke the square nut almost off.

I was wondering if i could weld another nut to the plug with diesel in the tank. It's probably still has 30-50 gals in it. So I'm sure that some light welding on the bottom wouldn't cause the diesel to explode. The diesel is where i would weld the nut on and all the open fittings are way above the bad nut. So i wouldn't have any sparks close to any open diesel fumes.

what do you think?

thanks
gary

 

[mahlers]

I think I definitely wouldn't do it... There are more fun ways to endager myself than that.

 

[Eagleview]

I'd drain the fuel and drill out the plug , clean the threads out with a tap and install a new plug . The plug is obviously very tight for you to have twisted the square off , i doubt the welded nut could handle it anyway . There will be time enough for you to meet your maker , do'nt take the chance .

 

[Treemonkey1000]

I am with the others. If you cut through accidently and have the fuel spilling out.. Even though it's not nearly as volatile as gas.. Might singe the whiskers a little.

 

[MrJimi]

Don'T DO IT!!!!!

 

[patrick_g]

1. Drain the tank, flash point of diesel makes it safer but not safe.
2. Refill with water before drilling, grinding etc.
3. Turn the tank so the part you are working on is at the top and with only a small air bubble below the part you want to weld on and proceed to weld.

The actual metal being welded should have air behind it, not water but the total amount of air should only be as much as required to keep water from touching it.

The water won't explode. A few spoons full of air will not support a dangerous explosion. Arc welding, stick or MIG, is the best approach. Don't use O-A. You may have to run a little more heat than normal for the thickness of the metal due to the cooling effect of the nearby metal being in contact with water.

Do not attempt welding an old fuel tank with fuel in it or even if empty. You don't want to be at ground zero of an explosion.

I have welded gas tanks and diesel tanks with the almost full of water method with no problem except my mediocre welding skills.

Pat

 

[calbrown]

a lil trick i learned from the old timers dont know if it will work in your situation but its to fill the tank with car exhaust. it pushes out all oxygen. no oxygen no explosion. been told dont have to worry about the water causing rust. it has always worked for me and dont have to worry bout the water cooling weld to fast and crystalizing it. just my 2 cents

 

[Arc Angel]

You can weld it if there is a large amount of fuel in the tank. An empty tank will kill you! We did it often at work with no problems. If welding a leak I would bend a welding rod so the fuel wouldn't run down the stinger and get on my arm. Always had a helper with a CO2 bottle handy to give it a snort if stuff (or me)caught on fire.

The deal is fuel does not burn, the fumes do.

Mark

 

[Matt_Jr]

I have been able to get rusted/frozen nuts and bolts off a different way. Use a very sharp air chisel and only use the corner or edge of the chisel ponting at the angle you want it to turn. Kinda like using your finger to turn it. Use the chisel to turn the bolt NOT cut the bolt. You can even guide the chisel using the hand not holding the air hammer. The shaking wont hurt. Wear gloves if you're worried. I've used this technique for years fixing cars, trucks, tractors, old motorcylcles and removing heating elements on hot water heaters. The vibration from the chisel causes the bolts/nuts to come loose and turn. It is so simple and effective it's hard to believe it works. If you don't have an air hammer use a sharp chisel and hammer. Just as effective but requires slightly more finesse. Be sure the chisel you're using is sharp so that it "bites". Dull ones won't work, just slide off.

 

[shvl73]

I have no idea about the flash point of diesel and the safety aspect but, here is what I witnessed. I drove an older IH delivery truck that one of the tanks started to rust where the data plate is tacked on. I called the local weld shop and they told me where the boss was working. I drove over to see him so he could check it out. He took the cap off the tank to vent it and stick welded a bead right around the plate. We didn't drain the tank, though I cannot remember weather the level of fuel was above or below the weld. I had never seen anything like it and would not try that for myself, nor would I recommend it.