whats the safest way to welf aluminum fuel tank?

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Ol Yeller
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Re: whats the safest way to welf aluminum fuel tank?

Postby Ol Yeller » Tue Feb 02, 2016 5:06 pm

The way I would do it is to wash it out with soap the best I can. Then take a 20' pvc pipe with a lit rag soaked in lighter fluid, and put that fire in the hole. Let that fire find what ever fuel vapor is remaining and then you're good to go. You could also use a long rope and tree branch to lower fire into the tank if you want to be further away.

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Re: whats the safest way to welf aluminum fuel tank?

Postby Hog Guts » Tue Feb 02, 2016 8:06 pm

Hmmmm. Thanks for all the replies. I'm glad I asked. The tank seems like it's in good shape except where the powder coat wore off and it corroded in a small spot. It's for a friend of mine not for work, one of those good friends you feel compelled to help when you can. It just seemed crazy to pay $500 plus for a new tank when a couple hours could fix it. I knew I needed to clean it out but it sounds a lot more complicated than that... Or is it? It's definitely not worth my health - he's a great friend but.... I like the reply that said it's more fun to build a new one. I agree. But I've challenged myself to fix it so, it's one of those deals... I think I'll leave it in my hot truck a week as one guy suggested, been there two days now any way. Then fill with dawn and water and rinse three times as suggested by another guy. Then fill with water and cut three holes in top to thoroughly inspect inside. If looks good and worth saving I'll fill again with water or argon and continue. That's my plan at this point but I'll be much more cautious than I would have without reading all the horror stories I sure don't need one of those. Thanks again for your time. Here is a pic... It's looks dirty and crappy but it really seems to be in good shape other than the small corrosion spot.Image



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Re: whats the safest way to welf aluminum fuel tank?

Postby JRC » Tue Feb 02, 2016 8:31 pm

I've welded several tanks with fuel still in them..NOT that I recommend it!! Plumb the tank with a inert gas...Argon works best.. Heavier than air and will displace the oxygen out of the tank thru a vent at the top of the tank that YOU must provide.... Don't get in no hurry.... Purge the tank 10 minutes or so....it depends on the size of tank and how fast your Argon flow is.... Keep a flow during welding... But not pressure... It will blow out as you weld it ... Not blow up... But scare the $hit out you... . DON'T do it if you don't understand this... A mistake can ruin your day! Like a purge hose getting pinched. Or comes off!!! I found out who trusted me when I do it..lol.. Most people leave the shop!! Lol... Which isn't a bad thing... If Not sure take it to a professional!!!!

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Re: whats the safest way to welf aluminum fuel tank?

Postby skinnypockets » Tue Feb 02, 2016 8:38 pm

If you're only dealing with one small spot I would suggest a product made by fasco, (makers of steelflex), called "epoxo 88". I recently used it to repair corrosion holes in my pontoon boat and I was very impressed with it. Sand or wire brush the spot, mix the two part epoxy and apply with a putty knife or something similar. You have to work quickly because it sets in 6 minutes. I have no doubt it will solve your problem without going through the washing and purging and it's under $20.

Check it out here; http://fiberglasssupplydepot.com/

:rebel: :florida: :old_glory:

P.S., If you still choose to weld it, video it so we can make bets on the outcome. :lol: :lol: :lol:
I'VE DONE SO MUCH WITH SO LITTLE FOR SO LONG, I CAN DO ANYTHING WITH NOTHING!

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Re: whats the safest way to welf aluminum fuel tank?

Postby JRC » Tue Feb 02, 2016 8:54 pm

Just saw your tank picture.. I'd remove the pickup tube, put a hose nipple in that fitting, attach the Argon hose with a clamp, use most quality tape and tape off your fill tube and not the vent tube,yet.. use a 1/16" dia rod a poke 8 to 10 holes thru the tape on the inlet tube...purge the hell out it.. Vent on top...when you feel good about removing all oxygen out,. Tape the vent tube off.. Lower the inlet flow of Argon down to a positive flow without pressurising the tank..... Aluminum needs to be CLEAN to weld.. I don't recommend anyone to do this... Take it to a professional..

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Re: whats the safest way to welf aluminum fuel tank?

Postby pontoon outlaw » Tue Feb 02, 2016 9:39 pm

a buddy of mine did it in cocoa welding shop he just ran a hose from the exhaust into the tank and welded away and 6 years later it's still holding

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Re: whats the safest way to welf aluminum fuel tank?

Postby Lwells » Tue Feb 02, 2016 11:03 pm

They make a fuel tank repair kit that you can clean the area good and apply it to the leaking area and it work for I have used it before but been so long don't remember what it was but bought it at parts house. At that time it couldn't be wet so I used a bar of so on the cracked seem to stop the leak and then applied the repair but I think that you can buy a stuff now that will repair them while leaking so you don't have to rub the soap in. Hope this helps. Ive welded fuel and gas tanks too back when I was crazier but its like taking an empty gun and holding it to your head and betting it is empty and pulling the trigger.

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Re: whats the safest way to welf aluminum fuel tank?

Postby Lwells » Tue Feb 02, 2016 11:05 pm

I used a bar of soap was what was suppose to be in my post

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Re: whats the safest way to welf aluminum fuel tank?

Postby crazycoonass » Tue Feb 02, 2016 11:24 pm

Welding on any tank that has had fuel in it is dangerous. I've done it but very cautiously and reluctantly. I wash and rinse the tank repeatedly. Then I steam it out for a few hours. Steam heats up the metal and opens the pores and releases any residual fuel left in there. Yes aluminum has pores in it. They may be microscopic but they are there. Next I get a certified and tested LEL portable gas detector. (We had them at work as well as a steam source) I don't trust my nose or anyone else's nose. Once I was satisfied it was gas free then I would make the repair. I have a friend that added water to his tank and then put it on a crawfish burner and boiled the water in it making steam. You have to be really careful and not boil the water out of it. No water equals a melted tank and possibly an explosion. I have another friend that washed his tank and used the nose method of sniffing for fumes and blew the tank up. Luckily he wasn't hurt. Just my two cents.

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Re: whats the safest way to welf aluminum fuel tank?

Postby Lwells » Wed Feb 03, 2016 8:07 pm

I'm sure no ones going to believe this but you can put a match out by sticking it into a pan, can, or whatever of gas but the can, pan or whatever that the gas is in had better be full for what ignites the gas is the fumes on top of the gas in the empty space. I watched a guy bet another guy he could put a lit match out in a five gallon jug of gas. He won money off the guy 4 times for the guy betting him couldn't believe it.

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Re: whats the safest way to welf aluminum fuel tank?

Postby Gary S » Thu Feb 04, 2016 8:27 am

I don't think I would risk 3rd degree burns to win a bar bet.

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Re: whats the safest way to welf aluminum fuel tank?

Postby InSight » Thu Feb 04, 2016 12:38 pm

JB Weld?
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Re: whats the safest way to welf aluminum fuel tank?

Postby CactusJack » Thu Feb 04, 2016 12:38 pm

I don't like the idea of putting any water or soap into a gas tank... you don't know what residue soap will leave in the tank.... and trying to get the water out of the tank when it is finished would be a pain....

just let it air out for a few days, then blow it out with compressed air and purge with inert gas.... bobs your uncle :wink:
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Re: whats the safest way to welf aluminum fuel tank?

Postby timmmyy » Thu Feb 04, 2016 6:04 pm

Rick close this please
Olways on the furst date

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Re: whats the safest way to welf aluminum fuel tank?

Postby airboat233 » Fri Feb 05, 2016 2:10 am

Hoddy yall, here is the lo down, there is no safe way known to an airboater (maybe nasa), when you think you have a safe way you will not know till you strike the arc. What I did was do all that cleaning crap, let it dry, then take a long light stick (bamboo pole) treat it like a big match, (tape a small butane tourch to end of stick) insert into tank. It may blow but you will still have all yer hair,,, but it still is not safe.This is the so called backyard, do it yourself-er, yea I saw my uncle zeke do it one time,,,(1)Take it to a professional,,He charges a few bucks,(2) scrap it, make or buy a new tank. It dosnt take but just a very, very little bit of fuel that some have said "will cause death or de limb you". One could get away with it a hundred times, it all boils down to nothing but russian roulette ...........Oh yea, the long match,, well I lost my fishing pole..j renney
Just trying to get things together to make another slide and last ride,,,airboat233

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Re: whats the safest way to welf aluminum fuel tank?

Postby CactusJack » Fri Feb 05, 2016 5:11 am

Here.... hold my beer.... I'll show you... :lol: what a bunch of nannies :roll: :wink:

Now, I have to get back to making concrete.... my kid is driving the front end loader.... he might need a nappy change :wink:

I was told I was wrong, once (not sure I believe it though)
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whats the safest way to welf aluminum fuel tank?

Postby Hog Guts » Fri Feb 05, 2016 9:25 pm

I don't feel like typing it over, but here is what I sent the last guy who sent me a long pm about aluminum coatings and the fuel tank answer.... Just so my current thoughts are shared with you guys....
Image

Since his info to me was so informative I'll repeat it here for those who can learn something from it....

[QUOTE=Kevin Morin;6841341]hog, I will give some tank and aluminum corrosion facts to encourage a new tank build. I have built plural hundreds of welded aluminum boats, more tanks than I have any idea and countless masts, booms, davits, cleats, and rigging so if there are mistakes in aluminum to make- you can count on the fact that I've made them at least once or ten times. (think my photo confirms at least one big error?)

Metals corrode in general areas or in small sites called pits by the same basic chemical action. I’m not going to get too techie, too far into chemical engineering here- but there are three main ways aluminum corrodes and they are: #1 by different metals contact when both are wet; #2 by acids or bases that are too strong; #3 and by electrical energy that results in the same basic chemical activity at the molecular level. All three methods result in the same basic metal chemistry, the original alloy of aluminum is reduced to non-alloy and the molecules of metal are removed from the parent material.

All three are different paths to corrosion- but they result in the deterioration of aluminum alloys. #1 Metal to Metal corrosion is called Galvanic corrosion; #2 Acids and bases can corrode due to strong Chemical bonds robbing aluminum of its protective oxide (aluminum and oxygen combined) film and if aluminum is allowed to have a charge from a battery, for example, and get wet… then aluminum molecules can go into the water or whatever is wetting the metal from #3 Stray (electrical) Currents.

So Galvanic, Chemical and Stray Current corrosion are all types of aluminum corrosion but when you research and explore you’ll find they all amount to the (molecular level) same event: aluminum molecules are removed from the parent metal into the wetting agent (salt water) or electrolyte. An electrolyte is just a conductive liquid that allows metal molecules to move from one metal structure to another, or to decompose as metal into non-metallic compounds.

What does this have to do with aluminum tanks? All three variations of metal corrosion can happen to an aluminum tank and all three can be avoided or mitigated to such a degree as not to affect a tank.

Let’s take the chemical or acid attack first, because 99.999% of people don’t seem to get this aspect of aluminum maintenance. Very strong acids or very strong bases (https://en.wikipedia.org/wiki/PH) are chemicals that have what we usually call ‘reactivity’; these chemicals will react with metals and aluminum is no exception. Strong acid or base will react with aluminum and ‘seize’ the molecules of the metal and convert them to other molecules hence the description reactivity – this could be called ‘UN-refining metal’ since the strong chemicals’ actions on the aluminum do not leave the original alloy when the reaction is done.

hog, this is what happened to the tank you're involved with on this thread but the owner doesn't know it.

Now, this acid to aluminum reaction may be very fast due to “strong” (read article on Ph) or very mild and slow acting due to ‘mild’ or less active acids: BUTTTTTT the acid or base beyond certain ph limits will remove aluminum’s healing oxide layer and then ‘react’ down into the metal in a pit. This action is called pitting but the term is not limited to acid or chemical corrosion. Further; this reaction, especially the slow version can happen as a ‘wetting cycle’ over and over again, once started.

While we’re exploring acids let’s look at water, yep plain ole everyday tap water. Tap water is more or less neutral ph, like sea water is in terms of acidic or basic ph. (The symbol ph stands for the amount of acid or base on the ph scale. ) However, if water loses its naturally occurring (entrained or mixed in) oxygen – then it becomes deaerated- where deaerated is “oxygen starved” water and ends up acting as acidic. Where does this happen? When water is trapped between two pieces of metal, like two pieces of aluminum- the water initially gives up its oxygen to the aluminum to form more oxide!

This is called thin film stagnation which essentially means the thickness of the layer of water is thinner than a hair, and once in that thin film, the stagnation or chemical changes happen much easier, faster and results in a stronger metal reaction than in a bucket full of the same water.

Wait! Hey! aluminum oxide is good stuff, it heals aluminum so that’s all good right? Well- it’s fine for a while- but the acidic action of that water then takes back the oxygen and the aluminum oxide is dismantled. There goes the protective film. As a result, pure aluminum is exposed to water that is slightly acidic-acting and with the oxide is stripped off the parent metal begins to corrode! This event – called crevice corrosion or poultice corrosion begins a cycle that will corrode aluminum which can’t get "Free Oxygen" to form aluminum oxide to ‘heal’ the surface and protect the base metal from corrosion!!!

Stagnate water will continue this corrosion cycle but fresh water rinses, with the free oxygen will often stop this cycle!

what do you suppose happens to tank water bottoms under fuel? The condensation of the air's humidity will leave water bottoms in all marine tanks. The day is warm and humid, the tank heats up and expands- the vent allows the air on the fuel/gas to vent out as it expands. The sun goes down... the tank cools the expanded air contracts, the air on top of the fuel/gas 'pulls' or vacuums in the surround humid air and it cools on the tanks sides; inside the tank.

The condensed water runs down the tank sides to the tank bottoms, it lays there and becomes robbed of oxygen, it deareates and becomes acidic: the tank bottom is attacked. The tank is junk due to lack of maintenance by the skipper.

To fully grasp this series of events chemically, you’ll have to spend some serious reading time, a little head scratching time and some review time… but the result is this; unless aluminum can get oxygen to renew its oxide film- the metal can corrode from chemical agents.

A Solution? Give aluminum oxygen and it will heal itself- starve aluminum of oxygen and it can lose its oxide film and begin to corrode.

Next will be my rant portion of this post.

The fact is that aluminum mill scale, if not removed from the material will promote this type of corrosion. I realize that hundreds of tanks, just as many whole boats and countless other welded aluminum products do NOT HAVE the mill scale removed(!) but that doesn’t change the fact that this film will retain water, the water will become acidic and the metal will corrode if the mill scale is not removed. Mill scale, that shiny chrome looking film is porous, retains water VAPOR and is not galvanically the same as the underlying aluminum!!! How’s that for a built-in problem?

But then anyone who’s worked in steel knows the same is true of steel mill scale coatings. Steel mill scale will promote rust by holding water film and vapor, aluminum isn't much different except that if the mill scale is removed the metal will 'heal' but steel will continue to oxidize, but not as fast as if the scale were left on.

First step to protecting a tank, clean the mill scale, inside an out with an acid wash (that is diluted and neutralized when the etch is done) or mechanical abrasion so the aluminum has the best chance to form its aluminum oxide, self-healing film to protect from at least a couple of the corrosion's sources that may deteriorate your tank. Even a dry tank with mill scale has a layer of ambient water vapor retained in the porous film- therefore what may appear as a dry tank installation can begin to corrode due to the water held in the mill scale. That is what the tiny white ‘flowers’ are in the inside of boats, on tanks, and even on exposed topsides of some aluminum boats are. The beginning of mill scale supported crevice corrosion pit sites, from a vapor film of deaerated water's action working on the oxide film under the mill scale.

Water on the bottom of an aluminum fuel or gas tank will become deareated and acidic, and it will begin to corrode the tank bottom unless it is removed. If the tank's plates were not cleaned using acid etch or buffers of mill scale this entire process is sped up, and the entire tank bottom will be pitted.

Done ranting about aluminum mill scale, but if an aluminum tank is pitted through in some places; as has been stated above lots of times; its toast.

Tool rental stores will rent color video borescopes for a few bucks- they're not all that expensive to buy: take out the fuel level sender and go in for a look; I'll wager there will be an entire 'mine field' of pits in different areas over the bottom of this tank.

Hog, I've been there, done that, and as you can see, I've skipped the T-shirt but kept the trophy. Be careful of used tanks.

by the way, nice air sled and great bench frame!

Cheers,
Kevin Morin
Kenai, AK[/QUOTE]

And a bit more. Couldn't copy the text from...
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CactusJack
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Re: whats the safest way to welf aluminum fuel tank?

Postby CactusJack » Sat Feb 06, 2016 12:20 am

So, pull it out, empty it and coat it with goo If the goo wants to come out where it is leaking.... bond on a patch ... she'll be right mate :)
I was told I was wrong, once (not sure I believe it though)
If you can't blind 'em with brilliance, baffle 'em with BS
Airboat experience so far, limited to having bolted a gyrocopter to a flat bottom punt.... but THAT.... is about to change, bigtime :-)

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Re: whats the safest way to welf aluminum fuel tank?

Postby P.Vento » Sun Feb 07, 2016 2:45 pm

just bring it to someone who knows how(like me) drop it off , pick it up done pay your money, keep your self safe.

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Re: whats the safest way to welf aluminum fuel tank?

Postby Hog Guts » Tue Feb 09, 2016 11:35 pm

pete no doubt you can tackle it but you have too many cool new airboats to make and i need the practice so ill handle this but i may need some sheet bent....

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Re: whats the safest way to welf aluminum fuel tank?

Postby swamper2 » Wed Feb 10, 2016 8:17 am

Hey Hog I was looking for the electrical corrosion process and how to reduce it. Thanks
16ft alumitech/406sbc/2.38w/3-80in.R's


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