cleaning the inside of a gas tank

[tompit9]

I think I read in here once peoples opinion on how to clean the inside of a gas tank.
Looking for those opinions again. Thanks Tommy

[Joe H]

What do you mean exactly, removing the gas completely, or removing rust?

[zapster]

back away from the tank....
and get a new one...

gas tanks...i wont go there...

...zap!

[mla2ofus]

If you mean cleaning rust, etc.,put some small(1"-2") crushed rocks in it w/ a couple of gallons of diesel. Then suspend it from a rope so it is balanced and start sliding the rocks back and forth alternating directions they move. Be sure the tank doesn't have a lip where spout enters tank. if it does, you won't be able to remove rocks. In that case use a short length of chain w/ a good nylon rope attached to it so you can pull it out.
If you're thinking of welding or brazing it,fill it w/ CO 2. I've done it w/ the old garden hose hooked to car/PU exhaust. But I won't recommend it to someone else.
Mike

[halbritt]

Originally Posted by zapster

back away from the tank....
and get a new one...

gas tanks...i wont go there...

...zap!

Then why bother posting in response?

[zapster]

Originally Posted by mla2ofus

If you mean cleaning rust, etc.,put some small(1"-2") crushed rocks in it w? a couple of gallons of diesel. Then suspend it from a rope so it is balanced and start sliding the rocks back and forth alternating directions they move. Be sure the tank doesn't have a lip where spout enters tank. if it does, you won't be able to remove rocks. In that case use a short length of chain w/ a good nylon rope attached to it so you can pull it out.
If you're thinking of welding or brazing it,fill it w/ CO 2. I've done it w/ the old garden hose hooked to car/PU exhaust. But I won't recommend it to someone else.
Mike

dangerous... at best..

listen

in 1988 my cousin was in a factory..big factory that did plastic injection molding...
the owners were car nuts just like us...
they were building a dune buggy out back in the machine shop..nice tools everything you'd want..

needed a gas tank...

went out in the field and dragged a gas tank out of a vw beetle that sat for 10 yrs...
no fuel in it so it was "good to go"

they wanted to cut it in half and make it smaller...
they filled it with water a couple of times to make sure it was clean..

went to cut it with a torch?..
burned the building down...everything..
the owner was in the burn ward for 2 yrs... my cousin burnt his arm up pretty bad..he's ok now but just the thought..

the moral is that anything can happen and will if your not careful...

myself? after that i dont go near them.. never again..i get a new one and call it a day...


...zap!

[mla2ofus]

Zap, I feel for your cousin. My question is why didn't they use a sawzall to cut it in half?By using the torch,what little gas was in in there certainly had plenty of oxidizer!!!Not trying to belittle anyone or start an argument!!! I've never cut one w/ a torch. Always filled it w/ CO 2 or exhaust gases and brazed cracks since oxygen is consumed in torch flame. Maybe I'm just lucky,tho I lived in Nv. for several years and never had good gamblers luck(LOL).
Mike

[halbritt]

Originally Posted by zapster

dangerous... at best..

listen

in 1988 my cousin was in a factory..big factory that did plastic injection molding...
the owners were car nuts just like us...
they were building a dune buggy out back in the machine shop..nice tools everything you'd want..

needed a gas tank...

went out in the field and dragged a gas tank out of a vw beetle that sat for 10 yrs...
no fuel in it so it was "good to go"

they wanted to cut it in half and make it smaller...
they filled it with water a couple of times to make sure it was clean..

went to cut it with a torch?..
burned the building down...everything..
the owner was in the burn ward for 2 yrs... my cousin burnt his arm up pretty bad..he's ok now but just the thought..

the moral is that anything can happen and will if your not careful...

myself? after that i dont go near them.. never again..i get a new one and call it a day...


...zap!

Great, but how is that relevant to the topic? I'm sure I can dig up plenty of anecdotes where people have been injured or killed attempting to cut or weld a fuel tank, but that won't help the original poster who wants to know how one properly cleans a fuel tank, presumably in preparation for cutting and welding.

[Joe H]

I've worked on motorcycle tank some.. What I always did was pour in some methanol, shake it up real good, then fill with water and flush it for half an hour or so. That should remove any gasoline. I would still shy away from cutting it with a torch though. Another thing to remember is do it outside!

Zap's right though, best thing to do is find another one.

[kbnit]

Having welded on fuel tanks, I can tell you that it's not an easy thing to do. Just go to OSHA's web site, search on industrial accidents, and look at the number of fatalities per year related to welding on tanks. If you're going to do it:

1. Go to your local motorcycle dealer, and get a Cream Coat kit. Inside are two containers, one's an acid, which will strip out the rust on the inside of the tank. The rust is what adsorbs (yes, adsorbs, not absords) the gasoline which will cause you problems and set your posterior on fire.

2. Once the tank has been properly cleaned and rinsed per the manufacturer's directions, set a nitrogen or argon purge (nitrogen's cheaper) in the inside of the tank before cutting. Purge for at least 20 minutes at about 4-5 scfh. Don't get too high a flow or turbulent flow will result, and you dont want to pressurize the inside of the tank. This is for cutting with O/F, or with a sawzall. Remember, sawzall's make sparks, too.

3. When you're ready to weld, again, purge the inside of the tank.

Finish with the cream coat, per the manufacturer's instructions.

I know how to weld tanks. If I can find a replacement at the local graveyard, rather than welding it, I'll pitch and replace in a minute. And if you're not absolutely sure what you're doing, stay away, we'd like to continue seeing you here in these forums.

[zapster]

sorry to get into it guys...
but when something as "innocent" as that happens...


i stay away..far away...

if you like playing with old / new gas tanks then have fun..

saftey first..

...zap!

i saw the results...thats enough for me

[Joe H]

You are right, Zap. If original tanks in good condition for vintage bikes were cheap and easy to find I would have never touched one.

[halbritt]

I get irritated every time I read one of these threads. Admittedly, that is my own shortcoming, but I don't see the necessity of attempting to constrain anyone from doing anything they'd like to do even if it is dangerous. It should suffice to simply inform the person of the risks involved and let them make their own decision.

Welding and cutting on fuel tanks is an inherently risky business as it is difficult to properly passivate a fuel tank that has been soaked in fuel for any length of time. If it isn't done properly, there is a strong likelihood of a fire or an explosion. When there are significant risks involved, one has to consider how much faith to invest in any advice received from strangers on the Internet or from anyone for that matter. There are a lot of myths surrounding the proper procedures.

I've never welded a fuel tank in my life, but I wouldn't hesitate to do so if I felt it were necessary. If I were going to weld a fuel tank, the very first thing I would do would be to get a copy of this publication and read it:
http://www.awspubs.com/product_info.php?products_id=232

The second thing I would do would be to purchase an LEL meter like this one:
http://www.coleparmer.com/catalog/pr...sp?sku=8194835

Then, I suspect that I would steam clean the tank, check it with an LEL meter, let it sit for a while and then check it again, maybe steam-cleaning it some more. Then I'd purge it with nitrogen, and get on with my welding and cutting. I wouldn't advise that anyone else follow this procedure or any other, but it is what I would do if I had the need.

[zapster]

Heath...

now this is exactly why your on the team..

did you enter and sign in please?

...zap!

[heavymetal_2006]

Ive filled the tank up with co2 first then did the work. Welding, cutting, etc. and I cant imagine, drowning a gas tank in water twice, blowing up. Something obviously was overlooked, what? Only he knows.

[tompit9]

I'm talking about cleaning out the dried up crap at the bottom of the tank, not torching it,( AH HELL NO ) ! Thanks

[Sober_Pollock]

tompit9:

I don't know how large the tank you are working on is, if it's a motorcycle tank or similar give this some thought:

I clean and polish (Yes polish) the insides of really, really badly rusty, gummed up, grimy motorcycle tanks by mounting them on an old grill rotisserie and letting them roll for a couple of days with a quart or two of sand in them. Sometimes I have to let them roll for a while in one direction then turn them and let them roll for a while in the other direction to get good coverage.

They literally come out polished inside!

[prop-doctor]

the CREAM product is some good stuff have used on many motorcycle tanks
but you might also try VINEGAR to clean it out, it is cheaper and will remove rust. but it takes a day or two of soaking... try a rusty bolt or some thing soak for a couple a days then wash off

[chopper5]

i have welded fuel tanks it's not hard 'there is a safe way to do it and im not telling but rinsing with water an't it

[halbritt]

Originally Posted by chopper5

i have welded fuel tanks it's not hard 'there is a safe way to do it and im not telling but rinsing with water an't it

That has to be the most irrational thing that I've read all day. If there is a safe way to do it, why wouldn't you share it? If you weren't inclined to be forthright with that knowledge, why bother posting?

[chopper5]

well heres the thing if i tell you and you dont do it right and get nuked it will be my fault
so do this at your owne risk
you fill the air space with argon or co2 fule wont burn with out air
the fule can not be washed out you will still have some in the tank but the air can be displaced

[gnm109]

I use phosphoric acid with about a half pound of nuts and bolts with the tank sealed to clean up rust. You can purchase 70% phosphoric acid from a chemical warehouse. The usual safety rules apply...long-sleeve shirt, eye protection, gloves, don't pour water into acid to diulte, etc.

I've welded Harley fuel tanks numerous times after doing the phosphoric wash. I never feel good about it, however. The acid will remove the petrochemicals after about a half hour. It leaves a nice patina.

As to the chemical tank liners like Kreem, they can work but only if the tank is surgically clean. If there is any rust at all, the Kreem will come off and clog the fuel tap.

In general, if you can't get the fuel tank completely clean inside, it's best to just scrap it and get another one.

[ulav8r]

Cutting a tank with oxy fuel could be extremely dangerous, per Zapster's story. The oxygen jet used for cutting is not fully consumed, so you are pumping oxygen into an enclosed container that may also contain fuel and introducing a little heat at the same time.

[gnm109]

Originally Posted by ulav8r

Cutting a tank with oxy fuel could be extremely dangerous, per Zapster's story. The oxygen jet used for cutting is not fully consumed, so you are pumping oxygen into an enclosed container that may also contain fuel and introducing a little heat at the same time.

That's absolutely correct! I was thinking more about welding something like a motorcycle fuel tank. Personally, I really don't ever think that they are perfectly safe even after cleaning. I've welded Harley fuel tanks after mush cleaning and acid washes, etc. but I try to avoid it and I would never ever feel good about it.

I know that some on this list frown on horror stories but I've got a good one. I had a 1948 Matchless motorcycle when I was a kid. It developed a leak on one seam at the rear. I took the tank to a local repair shop and the owner agreed to weld it for me.

His approach was to attempt to neitralize the fuel inside. He first washed the inside out with water. Then he started his car and put the exhaust pipe right in the fuel filler which was in the center of the top of the tank. He let the car run for about 15 minutes to attempt to neutralize the gasoline.

When he was finished with that, he filled the tank up with water. The cap was left off and the tank was slightly angled on his work table so that he could get to the leaky area on the right rear. He was going to braze the seam. He had no sooner touched the seam with the torch than it went off with a huge bang.

A flame shot out of the filler hole and went about 20 feet in the air. It looked and sounded like a lightning bolt! After he took a short break to calm down, he finished brazing the leak with no further explosions. He didn't even charge me extra as I recall!

It was a good example of how unstable a fuel tank can be. Of course they can be welded, but it's always a crap-shoot as far as I'm concerned. Got to be careful.

[billie_]

years ago we used to steam them for an hour and then weld right away...but now a-days i think new ones are cheaper..at least for most cars and light trucks...if you were to steam one now for an hour , and then add your min. labor i am certain you would be well over the cost of a new jobber tank