I've got a 100 gallon metal container that I dump my used motor oil in. It now has a small leak in the bottom. It was an old water well pressure tank, and I guess it got weak in that area and took a while for the oil to start leaking. My question is: can it be safely welded? I'd like some opions from people who know, not speculations. I would just be welding a small patch over the leak. It is empty now, but it has had oil in it. Probably has a little accumulation on the bottom. I've got plenty welding experience, but nothing with something that could possibly be flammable. Thanks in advance.

 

I wouldn't weld it myself. What I'd do is get one of those gas tank repair kits. The one I used included a wax crayon which is used to stop the flow of material temporarily. Than you clean it well and apply this two-part epoxy. The repair seemed to work good. I would guess it would work fine on an oil tank too. Although I don't know how big the leak is. Those epoxies are pretty impressive now.

 

If you have enough oil inside and a small enough leak it can be welded.

I wouldn't do it because if the material has rusted to the point it leaking, your probably gonna blow bigger holes in it trying to weld it.

An oversized patch plate will work but you still risk finding the next thin spot. weld it like you were welding thin sheet metal.

 

Watched a guy try and braze a nipple into a 5 gallon oil can that had cutting oil previously in it,It blew the lid off the can and ruptured it.
I know of another guy (a neighbor that lived 3 1/2 miles from me) that was killed cutting the top off a 55 gallon oil barrel.
The only way I possibly would do it is to fill it up with water and weld the patch on.

 

yea, you gotta be well below the fluid line to weld it. but it can be done.

In this case, I suspect the base metal is too far rusted and gone to salvage.

 

If you need to weld a patch on a tank or vessel that has had combustible materials in it. If you don’t have fuel air, you cant have a fire. What I am getting at I have had to weld a couple fresh 500 gallon gas tanks. What I have done is put a hose in the tank and hook the other end into an exhaust of a gasoline vehicle have not had a problem, I did weld an oil pan on a G855 Cummins and did not have a problem at all, hope that helps.

 

A couple sheets of 1/4 or 3/16 plate will make you a tank that will last a long time.

 

The problem with epoxy is that I cannot get into the tank to apply it from the inside, so it would have to be done outside. I had thought that it would be better to weld it full of oil, or full of water. The metal around the leak is fairly good. It is a pin-hole sized leak. I'd say it leaked a gallon of oil in two weeks. I've got a 220 mig welder that will turn down low and weld thin stuff well. So, if I were to fill it with water, say 6 inches higher than the weld area, I would be ok?

 

I would go ahead and fill it all the way up. water is cheap.

 

If you must weld it, fill it mostly with water leaving an air pocket where you'll be welding(if you can position it that way) then purge out all oxygen with argon.
I would never weld any tank of combustibles any other way. You might get away with car exhaust 100 times but the one time that you miss it and that car is a little off it's curtains!! I personally ain't gonna take that chance. If you can get the wand of a pressure sprayer in it I'd try to wash it out as well as possible. Then I'd J-B weld the outside making sure to push some of it through the leak. If the outside is completely clean of residue it should bond well enough to stop any leakage. I would spread a really large patch around the leak.

 

We have used dry ice to purge a tank.
a couple pounds of dry ice in oil or water saves your argon tanks.

 

I'd like to try an epoxy like JB weld, but I think JB Weld breaks down in the presence of oil or fuel? Anyone else know for sure? It would be easier than filling and welding it if it'll work long-term.

 

If it is a pinhole, get a screw that is used to attach metal roofing to a steel purling (rubber washer on a tek screw) and shoot it into the hole. No danger there.
If it is a rust hole, there will be more in the future. Might be wise to replace it soon.

 

I'm going to try this first. I think i'll give washer a good blob of RTV too just to make sure. Thanks for the idea.

 

I've seen that trick work on the fuel tank of a Ford Superduty. It was a diesel tank.