Thread: brazing fuel tank?

G,day there fellers ,
The petrol tank in my 30year old landcruiser is leaking again .Patched it 8 or 9 years ago with some sort of epoxy .But I've been getting wiffs of petrol fumes for a few years and now its totally pouring out .

So I should be able to get it full sealed if I braze it but anyone got any tips for getting the braze totally nonporous?

{before anyone says DONT DO IT not fixing it is not an option nor is buying a new one for a 30 year car as far as I know }
.Whenever I cut or weld etc petrol tanks or LPG gassbottles etc the bit I,m welding I put at the highest point and then just fill it like 95%+ full of water to just below the weld point .No air means no chance of explosion ,that,s easy -- getting the braze nonporous is my only concern .

Thanks blokes----Mat

I'd try the wrecking yards first, might get a good one cheap.....

Have you tried fibreglassing ,no problems with fumes otherwise it has to be steam cleaned.

Mat,
Valley Radiator Repairs in Brisbane's Fortitude Valley specialise in fuel tank repairs.
Give them a call - might save your life.
Cheers
SG

In these tough times, I am the last to try and dissuade any one from saving a dollar.

What I will try and change your mind on, is the means of repair.
I too have tried to braze a fuel tank,suitably degreased, washed out, steam cleaned,filled with water and tied to a stout fence.

The tank, a motor cycle tank jobbie , had little inlets for the riders knees. Not so when we finished,After the ensuing explosion that took out the tank shape,the fence and a good part of my hearing,we discover the the folded lap joints contain just enough residual fuel for a good bang.

Further inquiries revealed that a really decent electric soldering iron in combo with a good solder,cleaning and a flux was a better and safer solution.

I have completed further 3 subsequent fuel tank repairs with out a single explosion.

Your choice?

regards

Grahame

I used to weld steel tanks frequently - don't ask! All you need to do is rinse the tank out thoroughly with soapy water and when dry, purge the tank with co2. The easy way to do it is hold the neck of the tank over the end of the exhaust of a car and then run the engine for a few minutes. After that, you're safe to weld away with oxy, MIG or TIG or whatever fakes your tancy.

Please consider very,very carefully the implications of putting a naked arc near a fuel tank.People want to help and mean well.But advice is not fool proof.

I can do no more than re iterate my above post .I have found out by personal experience welding processes on tanks that have had fuel in them are dangerous.

My experiences and training as Tafe instructor indicate that current safety practices do not recommend purging or substitution or tanks that may have had gas.

Some exhaust gases in poorly tuned vehicles may still be combustible. people commit suicide via the carbon monoxide emitted from car exhausts.

Also please read the following, a cut and paste from a yank hot rod site. I have provided the link so you can check it out.

<I hope I am not out of line by bringing up a subject that was being discussed in general rodding tech about welding on gas tanks but this one hits a nerve with me because I had a friend die a terrible death and every time someone mentions welding on a gas tank those visions of that terrible day come back. Seems this fellow was using the common and VERY misguided trick of purging a tank with exhaust gas from a gasoline engine to make it "safe" to weld on! This was a diesel fuel tank that in all probability would not have exploded if he had not purged it at all but he did and the exhaust fumes exploded and killed him, he lived for several hours but eventually died from the burns. Being in the welding and mine machinery repair business for many years I personally know of three accidents that have occurred from doing this including the one that killed my friend, the other two guys were luckier and only received injuries although one of these was quite serious. The IMSHA investigator that investigated the fatal accident I mentioned at the mine said that he had seen several accidents caused by purging with exhaust gas including another fatality and that it happens more often than you might think, more so in the auto repair business than at a mine. This all too common myth still persists because some people think that exhaust gas is "dead air" (whatever that means ) and is an inert gas but nothing could be farther from the truth and exhaust gas is quite explosive when mixed with the right amount of Oxygen from the air. I have attempted to argue this point with several welders, one of which was later injured doing it, but usually with little success and it simply amazes me how common this dangerous and just plain stupid myth is. DON'T DO THIS! It can and does kill people!>

"http://www.hotrodders.com/forum/welding-gas-tank-119062.html"

Please be careful


GRAHAME

Hi Matt
Having put the thumbs down to the unsafe way to fix yer tank it would not be fair not to describe how it can be fixed

Hopefully having changed your mind on this,there is a a really good tool going on E bay for this at the moment.
It is an old Birko 400 watt iron.



Its on bid at $13 at the moment.I have soldered 150mm long splits with one of these.

An alternate to this if yer miss out is an old plumbers iron which you will have to flame heat well away from the tank.

Rust holes, which I suspect you have in abundance in the base of your cruiser tank, can be treated by wire brushing with a big stiff rotary brush.This area has to go back to a shiny surface.

The entire area is then tinned using solder and then another patch of galv sheet also tinned and then the two tinned faces are sweated together.Here a block of solid sal ammoniac available for glass supplies (from memory) is the go to clean your iron face up.A stick or two of 60/40 solder is necessary too.

On top of that there is a treatment the yank use to coat the innards of the tank to kill and seal the rust pittings. I believe it is now available out here in Australia.
I'll hunt it up after teatime. Here tis http://www.ppc.au.com/kits3.htm

found this as well

http://www.ratwell.com/technical/Fue...storation.html

Grahame

Originally Posted by Pheonix

Have you tried fibreglassing ,no problems with fumes otherwise it has to be steam cleaned.

i did make a couple of fiberglass tanks for motorbikes [about 35 years ago] that worked fine , but apparently ethanol in petrol dissolves fiberglass these days Although that may be polyester ,maybe epoxy is ok..

Soldering sounds interesting ,I have got an 80w iron ,wonder if that would do it and I did have a big old copper one u put in the fire somewhere ..That should definitely do it.Easier than trying to braze super thin rusted steel.

Hi found some more stuff

Some similar stuff as the PQR

http://www.ftrs.com.au/fueltanks/red-kote_dry.pdf

Grahame

Have alook here http://media.iinet.net.au/index.cgi?id=cruizin several of the episodes take you through repairing a fuel tank

There's some ambiguity here. I can't for the life of me remember the source (I'm still searching for it), but purging fuel tanks with car exhausts was the recommended means in some government technical manual on welding.

I can understand how one might believe the exhaust fumes from an overly rich-running engine may contain sufficient unburnt fuel to further ignite when combined with oxygen, but I can't see it happening in reality in the circumstances discussed.

Car/motorcycle mechanics have been repairing fuel tanks in this manner since the inception of the internal combustion engine. I myself have repaired several tanks thus and never experienced a 'pop' let alone anything more deadly.

In the case of your friend, I respectfully suggest he perhaps didn't properly clean out the fuel residue or purge the tank for long enough before commencing welding.

Having sailed on fuel tankers for some years and understanding the upper and lower explosive limits and the ratios of fuel to air mix , (at this point I would add that not all car exhausts are below 4% oxygen and that pumping car exhaust will push out all the oxygen to a level below 4% unless you have an entry and exit point ), if you intend to braze up a hole in a fuel tank with oxy then you may well get away with it but I think you should change the name of the tank to fool tank
Full of water up to the point you are brazing will suck the heat away and as it is a thin shell you have a good chance of enlarging the hole
Brazing an empty tank regardless the precautions you take ,( and why whould soapy water be better than plain water ), is why it should be a fool tank
If you have to, take all the precautions and follow grahame's advice and solder it up

This is NOT a recommendation and I will not be responsible if you try it. When i lived overseas I had some Nigerian friends who told me (very seriously) they welded up fuel tanks all the time back in Lagos. "Sure. no problem if the fuel tank is full (of fuel)". A full tank would mean no gases, and it is the gas that explodes and not the petrol. ...No I won't stand next to you with the fire extinguisher.

Guys ,We are playing with uncertainties here.How the hell can any of you who advocate a flame method, be absolutely certain you are 100% safe.
Without the use of some very sophisticated and expensive vapour monitoring gear you can,t be positive you don't have explosive vapours.

I thought after the degrease and steam clean and water,that I was ok.The fuel was trapped between 2 overlapped seams and there could have only been a tiny little bit.

Don't rely on what someones mates' friend says. Go to the local Govt work health and safety crowd or maybe the Fire Brigade and see what they tell you about fuel tank welding and flame.

I have some ambulance friends who have clued me in on burns.

They tell he type of burn typically suffered from a fuel explosion can be very serious More than 10% of the body surface area have the potential to be fatal.To give perspective they said guess whats 5%.Oh! that!!!

Its not a quick painless death either but involves high pain levels shock and infection and disfigurement if you survive .

If anyone freely chooses to go the welding route after this your probably not able to be saved anyway.Do your self a bloody favour, read some safety reports and coroners reports and talk to some doctors nurses, ambulance people and firefighters on this subject.Talk to them.

Grahame