Welding a gas tank safely

[aka Larry]

So I need to relocate the fill tube on a gas tank. I've read the horror stories and I'd like to do it w/o blowing myself up. What's the safest DIY way to purge the tank of the explosive fumes?

 

[royce]

Fill with water to the top, then make the cut and weld.

Royce

 

[KMScott]

I took mine to the local Radiator Repair shop and they boiled it in their tanks. A good radiator repairman knows how to prepare a gas tank for welding. Good luck.

 

[ducksface]

Fill with water to the top, then make the cut and weld.

Royce

This is how.
Horror stories? Selective and natural selection at the same time.

I bet your radiator guy will do the whole job for 80 bucks. Brazing and all.

I have no fear but I also have no want.

 

[dr_clyde]

I purge with argon. No O2, therefore no combustion. I don't like doing it. I prefer to avoid welding on gas tanks if I can help it. Sometimes, it can't be helped. I've only had to do it a handful of times, fortunately.

Argon is the quickest and the easiest. Plus then there's no water left in your fuel tank. Do the math, cubic feet of tank, cubic feet per hour out the reg, and then give it a little extra before you start.

The scariest is the guys who will cut into a 55gal drum with a cutting torch, half the time without even bothering to look what it held. Yikes.

 

[aka Larry]

I'll check with the local radiator shop to see what they will charge, but I've also heard using dry ice will work as the C02 will fill the void with inert gas while welding.

 

[rnscustom]

We used to stick exhaust from a running car by hose into it

 

[DTE]

I'll check with the local radiator shop to see what they will charge, but I've also heard using dry ice will work as the C02 will fill the void with inert gas while welding.

In years past I have been involved in removing underground storage tanks and we used dry ice to de-fume them.

 

[royce]

Bar none the safest way to move the fill nozzle is to remove the hydrocarbons, first.
The question was how to DIY purge safely.
It can be purged with any inert gas, but without a LEL/02 meter, there is always risk.
With using water there is no atmosphere to check.
I'm all for cleaning the tank first.

Royce

 

[KRB52]

The scariest is the guys who will cut into a 55gal drum with a cutting torch, half the time without even bothering to look what it held. Yikes.

But the drum is empty now, what difference does it make? Hey, what's that sizzling noise?

 

[dontlifttoshift]

My first step in welding a gas tank is checking to see if a new one is available.

They are so cheap. I had a guy in today that wanted me to repair a leaky tank in a 67 biscayne wagon. I laughed and said buy one. 10 minutes later it's on its way from RockAuto for 135 bucks.

If you have to weld on it, I wash it with dish soap and let it soak. Then I rinse it out and let is sit outside for a few days. It's usually good after that.

 

[ducksface]

If you have to weld on it, I wash it with dish soap and let it soak. Then I rinse it out and let is sit outside for a few days. It's usually good after that.

Usually can be defined as
More than occasional.
A slight advantage over 'I hope'.

How often has it occasionally('occasionally' is the balance you add to 'usually' to get 'always') not worked?

 

[Ole Slewfoot]

I know a guy alive today who would fill them with CO2, climb inside with waders and a breathing apparatus, and weld away.

 

[Lwel9226]

We used to stick exhaust from a running car by hose into it

I have done this.... works very well..... remove/open all openings, run hose from exhaust of most any gas engine, (lawnmower, auto, what ever you have handy....

Lynn W

 

[mrobins297aaa]

when I replaced the gas tank on my kia I had to take a torch to the bolts that hold that plastic canister on the tank on the right hand side, it was $150 to replace so I wanted to re-use it if at all possible.

so first I let my gas blower run air threw the tank until the smell was gone than I filled it with water before I burned off the bolts.
I was more worried about getting that plastic canister with the torch I'm sure there were enough fumes in there to ruin my day.............anyway it all worked out ok.

 

[sberry]

I am with the dr here, I don't like working on them.

 

[goldtang]

Get some professional advice I would not do it myself we are here for a short time but a Long time dead ( sorry if this offends any body)

 

[dontlifttoshift]

Usually can be defined as
More than occasional.
A slight advantage over 'I hope'.

How often has it occasionally('occasionally' is the balance you add to 'usually' to get 'always') not worked?

It has never not worked. I forget that there are many levels of common sense and many more levels of pedantry. I should have been clearer and will clarify my previous statement.

It's usually good after that.

What I should have typed there is that it usually no longer smells of gasoline at that point and would be fume free and ready to cut and weld. In the rare instance that the tank does still have fumes present, wash, rinse, repeat again with the dish soap and copious amounts of water.

 

[Samh]

I fill with water.

First gas tank I ever welded, filled with water and started welding. While welding, there was a piece of tube standing on the welding table that happened to fall over mid-weld. The loud bang just about made me **** my pants.

 

[Ign]

We used to stick exhaust from a running car by hose into it

This. Exhaust fumes have already combusted.

 

[ovrrdrive]

Filling it with water is the only surefire way to make sure its safe. Why experiment with it?

if they're as cheap as mentioned above why not buy a new one and weld on it instead of the old one?

With this **** gas we have now you might as well just use this as an opportunity to start the clock over on it.

 

[dontlifttoshift]

What is the application?

 

[NUTTSGT]

I had a guy braze a small spot on the sump of my tank once. He had me fill it with running water and let it flush out for about 10 minutes prior brazing.

 

[hotrodrandy]

We have a steam cleaner at work, I steam the hell out of it. If i have time i let it sit outside for a few days. No smells ready to go. I once turned a square gas tank into a round gas tank from the explosion, i did not get hurt but scared the **** out of me. be carefull.

 

[skrap metal]

buy a new one

 

[ilovevocs]

Clean then back purge with argon while welding.


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[ilovevocs]

buy a new one

Do you work for the dealership?

 

[Firebrick43]

Dad and I used to repair aluminum gasoline tankers. We used liquid nitrogen to purge them before cutting. Argon or co2/dry ice, would work as well. I have used water wash out before on small tanks several times but I have had a puff of ignition before but the space was small so no damage.

When I was an aircraft mech we had an electronic sniffer and all tanks had to be gas free engineered before hot work. We washed/flushed them for days before they would "pass". Some never would. Most of the time repair was soldering wires for wires in the tank. I would grab an argon tank and disappear for an hour in a secluded corner and get it done.

 

[toplessHO]

done a few with the double wash and plumbing exhaust from running car into it,let run for a while and tape off all outlets but one

 

[Slackerzinc]

I argon purge an use my purge meter to monitor oxygen level.

 

[JCQuick]

when I was in the petroleum biz we use to cut up large tanks (1000+ gal) they would put dry ice in them then stick the big air nozzle in the tank and run air thru the tank for about 10 hours. then test for fumes and start cutting

 

[aka Larry]

Finally got this done so I wanted to post an update.

I had friend come over who'd done a few tank mods before. He washed the tank and rinsed it a couple of times, and then filled it with water to just below the opening to be welded. Took him about and hour total and no drama.

Thanks to all who responded for your input and suggestions.

 

[skrap metal]

cool.

 

[bgarrett]

We used to stick exhaust from a running car by hose into it

I've done it this way many times. A simpler way is to remove all plugs, then 'burp' the tank with the torch

 

[Farmall 1066]

This. Exhaust fumes have already combusted.

Not always!
Worked at Massey Ferguson / Allis Chalmers dealer back in early 90's. 750-760 MF combines had a mechanical fuel gauge on side of tank, and tanks were notorious for cracking around the mounting boss stamped on the side.

Our welder was one of the most functional alcoholics I've ever met, and Shawboy came in one morning, hooked up exhaust from his welding truck (old 70's Chevy 292 6 cyl) and proceeded to prep the weld area.
He lit the torch up, started brazing, and we heard a muffled "whoomp"
He'd only drained diesel down a few inches below where he was welding, and the 292 was running fat!
Backfired that tank and blew #2 diesel up into the ceiling!
Lucky he didn't burn the whole shop to the ground, but the diesel didn't light.

 

[arkieguide]

Caution - one of my employees, said i am going home and weld my gas tank. I offered him the correct way to do it. He went home and the minute he struck an arc the tank blew up and unrolled the take. Luckily he did not get hurt bad. Listen to people that have been there.

 

[Rick B.]

I've probably welded on 50 motorcycle tanks and haven't blown one up yet. I wash them out with Tide Liquid Laundry detergent. It's a great degreaser and it gets the smell out fast. I pour some in the tank, fill it half way with water and shake it for about a minute. Then rinse. No reason why it won't on a car tank. Just use more Tide and water.