Just bought a new (old stock) tank that is made from i believe 0.5mm steel.

I want to modify the tank to add a fuel return, breather. I'm also looking at adding a small sump for fuel injection.

the problem i've got is i only have MIG and i'm worried that even on low power the mig will just add holes to the tank.

I expect TIG will be ok to weld the tank but i don't have that - what other ways are there that are low cost and easy to do in the garage? I've got a cheap blow torch from B&Q with butane? gas.

(and is there anyone closeish to Coventry who'll TIG for beer tokens if i supply the steel)

Would brazing not work? It would certainly be fuel resistant and strong enough, it's just a matter of getting everything hot enough with your B&Q torch.

Don't know about IVA and modified tanks though....

0.5mm steel???

its what the thickness is estimated at. I haven't seen it yet.

Its a commercial tank with pressed strengthening dents (i can't remember the technical term).

I just want to add in a swirl pot (thinking a 2" lump of box steel welded on the bottom with a hole drilled into the tank above it + the return and breather.

In each case a quick run over with the angle grinder and wire brush to clean the paint off and then .....?

followed by a brush up and repaint. 5.5 gallon tank, tall and thin so less chance of fuel starvation & 35 quid delivered

If i don't go swirl pot it just needs return and breather adding - which i may do via the bolt on fittings i've seen on here somewhere.

if you get all parts realy clean you can soft solder it all. bakers fluid for flux.
loads of tanks still made this way for the classic car boys. and radiators.

Don't know about .5mm
But I made my whole tank out of .9mm
Welded fine with mig.

The problem with MIG is 'cold start' you get a pin hole when you first start to weld as the material is not hot, the answer is to go back over yourself, so start, run 1/2" in one direction then return in the same welding pass and do the whole job in one go.

You should then be fine.

Regards Mark

Put the power setting on medium then do lots of overlapping spot welds, do the next before the previous has fully cooled and they will all melt together. Not suitable on structural stuff, but will seal perfectly well.

Technique is often used on bodywork and thin sheet