Welding Tips and Tricks

A client of mine wants to k ow if I want to weld on his transport tank in the back of his truck. Should I be purging with co2 or argon? The tank can be empty i just dont want to put water in it.
Thanks Jake

First, always consider your and others safety. Always do what you feel is safe, even if its overkill.
With that said, I have repaired many diesel fuel tanks and have never purged or filled a tank with water. You better be sure your customer is ok with you putting water in his tank before you do it, will be real fun to clean out.
What type of "weld" are you doing to this tank? This will also help determine recommendations. Diesel is not explosive like gasoline and when the container is open to allow venting you should be fine.
-Jonathan

For a "quick and dirty", you can purge the tank with the truck's exhaust. The oxygen level in the exhaust will be so low that the fuel residue in the tank won't even be flammable.

For comfort, or you're new to this, CO2 is just fine, and inexpensive.

If this were a gasoline tank, I'd take a more cautious approach.

Steve S

Thanks for the replys there is a couple of pin holes in the tank the tank isn't 2 yes old. I'll be might welding them. Thanks jake

If you are filling pin holes you will have a fun time pulling the diesel into the weld pool.
Now, I have received private criticism for this but I still find nothing wrong with it and still do it. I use the tig torch to light up on nasty sections or holes to burn out some impurities, draw/burn what diesel is there and to pre-heat (which you don't need).
Prep it as good as you can and go to town. Do you have any pics for our curiosity?
-Jonathan

I would suggest if it's a tank mounted in the bed of a truck, if I'm reading that right, I would remove it from the truck. Much easier and cheaper to put out a tank fire than a truck fire. If it has a pump monted in it remove it also and leave every port open so the hot fumes can escape.

I clean the area that I need to weld off with acetone to get the fuel out of the pin holes and purge with Nitrogen but I have 850 tons of liquid N2 at my disposal, it's what we make. Co2 will work fine for what you doing though as will exhaust, I just hate smelling the exhaust. Just remember that the acetone is flammable.

Len

If you want to purge, pressurization purge is what I do.

Section 4.1.1 of this document:
https://hssestorage.blob.core.windows.n ... urging.pdf

You would use less pressure though.

Otto Nobedder wrote:For a "quick and dirty", you can purge the tank with the truck's exhaust. The oxygen level in the exhaust will be so low that the fuel residue in the tank won't even be flammable.

For comfort, or you're new to this, CO2 is just fine, and inexpensive.

If this were a gasoline tank, I'd take a more cautious approach.

Steve S

Have used exhaust many times in past 30 yrs,both diesel and gasoline engines as a purge,even on Top Fuel Dragster nitro tanks, purge and vent while welding. Be careful as all exhaust fumes not good for breathing,do in ventilated area.
Practical safty first

easy clean up no water/chemical contamination of tank

Old family friend mechanic was in the army or navy (can't remember) he said there was a truck (think it was a deuce) that had a leaking tank, he said he filled it up, put the bubble gum over the hole that he was chewing, then either welded it or brazed it (can't remember which also)

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Superiorwelding wrote:First, always consider your and others safety. Always do what you feel is safe, even if its overkill.
With that said, I have repaired many diesel fuel tanks and have never purged or filled a tank with water. You better be sure your customer is ok with you putting water in his tank before you do it, will be real fun to clean out.
What type of "weld" are you doing to this tank? This will also help determine recommendations. Diesel is not explosive like gasoline and when the container is open to allow venting you should be fine.
-Jonathan

Same here. A year or two ago I welded 10, 300 gallon diesel tanks that were cracked and needed reinforcement added. 60 something feet of weld per. Some still had a gallon or three of fuel in them.

Thanks for the replys y'all the tank will be out of the truck. I haven't got the tanks yet!!! So I'm not even for sure what is wrong. They might be pin holes or cracks. I guess will find out from what I have read open the vents clean the shit off and weld it up? I can Tig it which I think will be better.

I'd strongly prefer TIG.

Some or most of this has been suggested, I think...

After cleaning the metal, wire wheel, flap disc, whatever, I'd "weld" the crack or pinhole without filler... Bring it to welding temperature (carefully, so you don't blow a hole in it, of course) and let it puke whatever it wants to spit back at you. Then grind and prep for weld, and weld it with the filler.

Steve S

I sometimes cut fuel oil tanks, and clean them afterward. I capitalize on the scientific fact that combustion requires combustible vapor. Number two and diesel aren't very volatile. I can throw a match or hot sparks into liquid fuel and they are instantly quenched by the liquid. Precautions must be taken. Once I laid a tank (275 gallon household fuel) on forks, it contained maybe 10 gallons of dirty #2. I got interrupted, and had to move it. Motion caused a bit of fuel to slosh out the slot I was cutting, on to the ground. Rather than risk ground water pollution, I set fire to the spill. It flared up, and wind drove it toward the garage causing scorch marks on the siding!

I once decommissioned a 10000? gallon tank for a friend. I cut a 4' square hole in the end. A small amount of fuel remained. Splashing some up the wall of the tank, I set fire to it deliberately with the cutting torch. In seconds the fire grew, reaching terrifying scale! I was certain I would be arrested! A number of citizens came to investigate, but evidently none reported me to the authorities! It eventually burned itself out.

Water and light diesel fuel cohabitate. .That is why you have pin holes in bottom of tanks. Remove tanks, fill with water and rotate them upside down, then TIG up the pinholes....Then roll them over and drain the water....Just drain it, and reinstall...you ain't gotta dry them out beyond that.

I maintain 60,000 gallons of #2 diesel oil in my underground tanks ,Same diesel fuel as you pump into your tractor or diesel pickup except it ain't dyed red) and another 8K gallons in my above ground day tank...My day tank was constructed back in 1929 and is of riveted construction.,,,It has experienced many pinhole leaks this last century and all have been safely welded once filled with water.

You will discover that the pinholes form at the water line tween the fuel and water...near bottom of tank.

Same thing occurs on older industrial air compressor tanks where water is allowed to accumulate in bottom of tanks that do not have auto blow downs.....Pin holes first appear, then unless addressed-high pressure rupture.

I'm also a little concerned that where you have a couple of pin holes, you've got many more just waiting to happen. If that's the case, then you'll be chasing one after another and perhaps a patch is going to be the best approach. If the pin holes are caused by internal corrosion, there might be many.

There's a good item on the forum from Jonathan about patching Diesel Tanks here.

Do let us know how you get on.

Cheers
Trevor

You can neutralize the Diesel in the tank with bleach. Pour in the bleach, slosh it around.

Here is a Diesel tank that was converted to a hydraulic tank. Use the bleach trick and tiged in a bung.





Also used that same technique to repair strap rot on those tanks.

Shannon