Patching Fuel Tanks

bill r

This new forum is withering on the vine, so here goes: Does anyone know how to be really safe when working with a fuel tank? Does anyone have a fool-proof technique that they have come to rely on? There are so many horror stories; I've never been willing to risk it...

SmithBuilt

What kind of fuel are you referring to?

I have welded on diesel fuel tanks, but I don't know that I would a gas tank.

I have a piece of flexible metal exhaust pipe that I connect to a small engine's exhaust (my generator). Then connect the other end to an opening on the fuel tank or just stick it in the tank where it won't come out. Open another hole in the tank for exhaust to escape. Idle the engine while your welding and the exhaust gas will displace the oxygen in the tank. Run the engine till the weld cools.

If it is a small leak take a punch and hit right where it is leaking, will sometimes work.

bill r

Gas; petroleum in general. Hydraulic tanks, etc. Methinks it all gets volatile when it gets hot. The point is, you've done it and lived to tell about it. I've heard of filling with fuel, filling with water, etc. I can't patch holes with a liquid involved. Your approach is to displace fumes with spent exhaust gas... that's excellent. I guess with a gas tank, you'd need to be careful of the hot exhaust itself...

I would caution the casual reader that this is a very dangerous area and they should be extremely cautious. These are not OSHA sanctioned discussions!

I was raised in Salisbury NC, by the way.

Teetorbilt

We used to fill them with Tide and water to clean and then flood them with an inert gas to weld. You should have Argon on site, Helium is also cheap and readily available.

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skyhook

Dry ice.
www.dryiceinfo.com

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bill r

I guess I'll have to screw up my courage and JUST DO IT. I've heard of dry ice, never tried it. Its hard to find locally. I'll probably try the exhaust gas technique. If I survive, I'll report in. This salt water is eating my barge hydraulic system alive!

Thanks again for the valuable input.

If I can help anyone else, I've done lots of stainless/TIG, lots of hydraulics (all homemade), tons of stick welding. PM if I can ever help.

skyhook

An old timer told me to use dry ice. Some grocery outlets carry a food grade, catering companies use it. I get it from an old ice house, $.99 lb. Keeps in an ice chest for 3 days.

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SmithBuilt

I have heard of using argon. The tank I was welding on was large and I was concerned with flooding the tank with enough argon to make it safe. But felt more comfortable with exhaust gas, plenty of volume.

I'm in Kernersville. Salisbury is a nice area. Both are growing too fast.

I may take you up on the welding advise sometime. I've found a large used mig welder, if I can figure out how to power it I'll have questions.

Mocopperhead

I have used water before. You fill the tank all the way up to just below the point of where you're welding. Leaving a very small bubble exactly where you intend to weld. By all means clean the tank with A LOT of soap an water BEFORE you even start. The exhaust trick works too and is usually less trouble. Hydraulic oil needs to be pre-heated before it will flash so regardless if you use the Water techinque or the Exhaust technique. ALWAYS CLEAN THE TANK FIRST!
I had a buddy of mine who was cutting an old hitch off of a car and burned through the gas tank. Fortunately the gas tank was full and when the gas came out it put his torch out and that's the ONLY thing that kept him from being fried to a crisp.

boatbuilder

The only way to be sure is to have the tank steam cleaned(amount of time steaming depends on size of tank). Once it is steamed cleaned out then use a L.E.L. monitor to test the tank to make sure it is safe to weld on.

I welder was once asked to fix a gas tank and he said no problem. I just need you to sit on it while I weld it up. The customer asked why he had to sit on it. The welder told him that when it blows up he doesn't want it going through his roof. The customer refused to sit on it so the welder refused to weld it.

Michaeljp86

Ive heard of people welding up tanks with gasosline in them by filling them with argon. Ive welded up alot of tanks but I aways drained them and filled them with water.

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boatbuilder

Yes, a lot of people do this and get away with it. I hope nobody ever gets blown up again. I know of a story about a welder that was doing this and the tank exploded on him and he caught fire. He was lucky(???) his best friend was there and drug him through a water pit and saved his life. The guy ended up with only holes in his head where his eyes and nose were once. He is unrecognizable to all that knew him. I have been told that he has never talked to his best friend(the fellow that saved his life) since the accident.

Michaeljp86

I know of a guy who welded on a gas tank on a car. The welder burned a hole in it and flaming gas ran across the floor and in about 2 seconds the entire garage was a huge fireball.

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I am just a vessel from which genius flows -Homer Simpson

Global warming is a myth, like evolution and the metric system.

piercekiltoff

My father has done it by filling tank with exhaust from an engine, and I've heard of the water fill before. We're getting ready to do it to a hydraulic tank on one of our rigs - if I remember, I'll clue you in on how the shop guys decided to do it.

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rustyjames

Unlike gas tanks, welding up a hydraulic tank isn't really a big deal other than the weld metal getting contaminated if you don't get the area really clean.

TRM

10 years ago i worked in a shop where we did a ton of fuel tank repairs, both gas and diesel, large and small. We did the same process for all. We would steam the tanks (we had a large steam rack built outside and powered by a small boiler). Once the tank had some dwell time on the rack (varied by size etc) we would take it from the rack, drain any water and let cool for a few minutes, then test it with an meter. If the tank passes, we would bring it in to the shop, we would open or remove any plugs on the tank, and would stick at least 1 air hose inside the tank open full blast. We would let that purge for several minutes (usually the time it would take to get the welder and patch ready). This would help purge any remaining vapor and fumes. We would keep the air on the entire time of the repair!

In all the years we did them, we only had 1 tank blow up ( only ), it was a diesel tank, it was an unusually shaped tank and i don't believe it had a long stay on the steam rack.

In any event, fuel take repairs should not be taken lightly! Just my 2 cents....

bojack467

Stay away from welding or cutting on tanks of any kind!! Use JB Weld or some of that miracle putty you mix together. Check with auto supply store. I have been a welder for 38 years and would not risk it. Even though it can be done its just not worth it.

Michaeljp86

I need to weld a fitting on a diesel transfer tank, I may do that today.

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I am just a vessel from which genius flows -Homer Simpson

Global warming is a myth, like evolution and the metric system.

Willy is

I've welded quite a few tanks, even a fuel tanker truck.

There are a number of people who have no business doing this type of repair, and so I am reluctant to tell someone green how to do it, anymore than you would hand your 7 year old a circle saw and tell them to go play.

The best description in this thread is from TRM a few posts back, IMHO.

I will add that there is information from the American Welding Society on this subject, cleaning and welding protocols.

Keep in mind that certain solvents, if used to clean a tank can kill you if they remain in a tank. (think nerve gas)

One other thing that served me well was the notion of what makes a internal combustion engines work; you need fuel, oxygen, and heat/spark for an explosion.

The notion of co2 or argon speaks to limiting the amount of available oxygen. Cleaning procedures deal with removing the fuel. Keep in mind that oil is more difficult to wash out than gasoline.

Not for amateurs. Very risky and you can't get adequate training via internet instruction, IMHO. (particularly since some of the info could kill/injure you)
It isn't even the info that's always bad, but the thought;well, now i know how to do this

willy