17 replies to this topic

[crazicarl]

Has anyone made/ fabricated a fuel tank?
Would you butt weld or lap weld/ joggle the edges to be welded?
Mig or tig weld the tank?
Last question, how would you test the tank, is it pressure tested or is there another way of ensuring that there are no leaks etc.?

Thanks in advance :)

[Scoop77]

I made one for my kit car out of 1.6mm Ali. Formed it with a metal folder and then had a very experienced friend tig weld it. I had to hold it with a 1mm gap between the edges whilst he did it. Cut the holes for the filler, sender and breather (and return injection) before the welding.

[crazicarl]

How did you test it?

[Scoop77]

It's been a while now but I think it's only about 6 to 8 psi and he did it at work. I leak tested it as well but his welding was sublime and seamless so no issues. I did that by putting a can of fuel in it and letting it sit in various positions for a couple of hours at a time. Made it for a couple of quid and a box of beer ;)

[ibrooks]

Commercially they are pressurised and dunked in a bath of soapy water - bubbles means leaks.

 

It's possible to do it with MIG but you will have leaks that you need to go back to (how many and how bad depends on the skill/experience of the welder). Once you've got them all down to pinholes Frost (and no doubt others) do a kit to repair tanks that consists of a resin coating that you pour into the tank and then roll the tank around to ensure it's coated all over. Usually designed for older tanks which are hard to replace but no problems doing it to seal a brand new tank so long as the welding is structurally sound and you really are just using it to seal pinholes in the welds.

 

Iain

Edited by ibrooks, 04 October 2013 - 09:13 AM.

[Scoop77]

Easily done with a bike pump and a wheelie bin ;)

[crazicarl]

Ok thanks for the tips on pressure testing.

 

Any suggestions with regards whether or not to butt weld or lap/joggle the edges together? 

 

I am looking at fabricating a tank out of steel.

[Yoda]

But weld, with oxy-acetylene torch,(old school) or Tig if you have access, laps/joggles are harder to get a good seal and if not done correctly can promote distortion and later on, corrosion.

 

Others may have a different opinion, but this is how I would go about it.

[welderman]

Alloy and tig weld, fabricated many fuel, water, oil tanks for kit cars, boats and buggies. Pressure test and also fill test.

[mattiek]

The company next door to me used to make fuel cells/tanks for Naval and Air Force use. The did a couple of different types of testing, non-destructive and destructive (destructive is great fun, lol!).

 

To test the tank for leaks etc. it needs to be pressure tested. DO NOT try pressurising the tank with compressed air, this makes for a very dangerous explosion similar to that of a Frag Grenade if the tanks splits/fails. Instead, fill a large vessel with water with a little washing liquid and then submerge the tank. Next, seal the all fuel hose outlets except one. Fill the tank with water to the top of the filler neck and then seal that too. NOW you can add a little air pressure to the tank via the remaining fuel hose. You only need to be just above atmospheric pressure, since the tank should never be under any internal pressure anyway. If the tank has any leaks, the pressure will drop. Bubbles may form. If the tank does rupture, the water inside and the water outside in the tank will contain the pressure change and stop the "explosion". It's a bit of a bugger getting all the water out afterwards but much safer than trying to pump straight air in to the tank!

 

This way is very similar to how the test scuba diving cylinders (hydrostatic testing).

Edited by mattiek, 04 October 2013 - 12:00 PM.

[LM36]

For my grasser (micra) i use RSM in manchester. He does mainly motorsport stuff but if you ask sure he will sort something out

 

Link to his ebay items.

http://www.ebay.co.u...utograss&_sop=7

[crazicarl]

Thanks, that gives me a good idea of how to approach my little side line project :)

[ibrooks]

Just pressurise with air - you only need to go to 5psi or so and that's not going to give you a catastrophic failure or shrapnel even if it does split a seam. Scuba tanks are tested to thousands of psi so a different kettle of fish altogether.

 

Iain

[jmmini]

Don't forget some baffles or simular if it's going to be a flat type one for racing purposes etc

Imo TIG welding is far easier than oxy welding (and is a bit outdated to weld with) apart from round the filler neck etc were you would probably need to use the torch.

Edit- didn't realise you didn't state what metal, I responded as to you using aluminium which would be the best choice

Edited by jmmini, 08 October 2013 - 12:56 AM.

[Yoda]

For aluminium, yes Tig is the way to go. but as it was stated that he was using steel, My preference would be for Oxy as it is easier.

 

But then, this describes me perfectly " (and is a bit outdated ) "

Edited by Yoda, 08 October 2013 - 05:55 AM.