Blockhead Posted May 12, 2009 Share Posted May 12, 2009 After tracking down a 'good' injection fuel tank, I noticed that patches of paint were sagging and rippled. After pulling the paint off I find a dodgy leaking repair with what looks like solder and mig welding wire . This was all covered over with what seems like ordinary body filler. As well as this there are 5 or 6 other pin holes in the tank, all on the bottom where the straps go- no surprise there then. Anyway, having bought another tank to avoid welding mine it seems it's rather been forced upon me Not much worries me but to be honest sparks on an empty fuel tank do concern me slightly What is the best way to *safely* weld a tank? Fill it with water, block any open pipes to stop the water coming out and turn it over to weld? Any tips welcome! Quote Link to comment Share on other sites More sharing options...
Snowy Posted May 12, 2009 Share Posted May 12, 2009 After tracking down a 'good' injection fuel tank, I noticed that patches of paint were sagging and rippled. After pulling the paint off I find a dodgy leaking repair with what looks like solder and mig welding wire . This was all covered over with what seems like ordinary body filler. As well as this there are 5 or 6 other pin holes in the tank, all on the bottom where the straps go- no surprise there then. Anyway, having bought another tank to avoid welding mine it seems it's rather been forced upon me Not much worries me but to be honest sparks on an empty fuel tank do concern me slightly What is the best way to *safely* weld a tank? Fill it with water, block any open pipes to stop the water coming out and turn it over to weld? Any tips welcome! I have welded hatch tanks before by putting a garden hose into the filler and turning the water on. Once full start welding. Just do not turn the water off. Saying that the last tank i did still exploded. I think the experts wash the tanks then fill them with inert gas during the welding process. Quote Link to comment Share on other sites More sharing options...
greg Posted May 12, 2009 Share Posted May 12, 2009 Give it a good rinse out 2 or 3 times with water and leave to soak overnight filled with water and caustic soda, which will help get the petrol out of the porous metal and seams. rinse out again. Make sure you where some fire retardant clothing (not your best shell suit!) and cover you hands, arms and head. I personally prefer to weld the tank without water in as if it does flashover you could get soaked in boiling water/steam. *This is just how I've done it in the past and I accept no responsibility should you do it and cause injury or damage, if in any doubt leave it to a professional* Quote Link to comment Share on other sites More sharing options...
manta400john Posted May 12, 2009 Share Posted May 12, 2009 Greg; "if in any doubt leave it to a professional" Yup, Bodie and Doyle will do a crackin' job but better still leave it to George Cowlie,he'll do the best job in exchange for a nice bottle of malt! Filling the tank with sand is supposed to be a safe bet. I had a swirl pot welded into an A series tank a few years back, the guy that did it was into stock-car racing and had done a few before. Maybe the stocky boys do a bit o' tank welding for a reason.....? John. Quote Link to comment Share on other sites More sharing options...
Blockhead Posted May 12, 2009 Author Share Posted May 12, 2009 Thanks for your replies. I've also heard of a bloke at a garage who "lights the breather pipe and waits for it to burn off". Personally I don't think I'll be doing that! I do know a banger racer but I don't know if he's ever welded fuel tanks because he uses a small ally competition tank. I've also heard the sand method but am dubious about getting every grain of sand out again... Points taken about not your fault if I blow the tank up in front of me, I'll accept that you're not liable- nobody can guarantee anything. Quote Link to comment Share on other sites More sharing options...
paul1393 Posted May 12, 2009 Share Posted May 12, 2009 Before welding my petrol tank I removed the sender and inserted an air line hose set at 30psi, I left it venting the tank for around 8 hours. this removed all traces of petrol. There was no smell remaining when I came to weld it or no drama either! Quote Link to comment Share on other sites More sharing options...
Blockhead Posted May 12, 2009 Author Share Posted May 12, 2009 Just to help me find out where it's leaking, I've filled it with water expecting plenty of vapour to come out as it was filling. I think because it's been stood for some time most of the vapour has already escaped, working in my favour. A couple of repairs have been done with solder and these seem to be holding fine- has anybody had any success soldering up pinholes before? I would trust myself more with a big 'battery terminal soldering iron' we have than a welder on this stuff. With a good clean, plenty of flux and good tin/ lead solder I've soldered steel fine before. What is the maximum pressure I should expect in a working fuel tank- Hot day, maximum fuel being returned to the tank etc. etc. - surely can't be much? Quote Link to comment Share on other sites More sharing options...
greg Posted May 12, 2009 Share Posted May 12, 2009 Pressure in tank won't be much above atmosphere, provided the vents/breathers aren't blocked. Quote Link to comment Share on other sites More sharing options...
mantasrme Posted May 12, 2009 Share Posted May 12, 2009 The vapour is the worst thing for exploding, but there will likely be a thin layer of enamely petrol residue on the inside of the tank which can also go pop If you've got a couple of pin holes the metal around them will also be thin and rotting, so better to do a patch than solder each hole as it'll just go through next to it. Last one i did i washed out with solvent remover detergent like THIS then vented for a week before cutting out the rotten section and welding in a patch Didn't put too much weld in any one spot to keep from burning through with a big hot bit of molton metal and sparking anything off. Worked really well for me However first time i did it i washed out with just water (and possibley some washing up liquid ) didn't bother venting it, infact i think i left some water in it Then tacked the corners of the patch before starting a seam run up one side, about half way up there was a low deep boom and the welding spark stopped I flipped up my old crappy welding helmet only to find the tank had shot 3foot sideways But once i dragged it back into place i welded the rest without further problem. Quote Link to comment Share on other sites More sharing options...
pat Posted May 12, 2009 Share Posted May 12, 2009 not tried it myself but was once told to rinse well and run a tube from a running car exhaust to the tank , leave for 30 mins before starting work , dunno but may work Quote Link to comment Share on other sites More sharing options...
Shug Posted May 12, 2009 Share Posted May 12, 2009 I asked someone about welding a petrol tank. He said its not a problem, and very easy. His advice? Get someone to start the weld then take over if they are still alive Quote Link to comment Share on other sites More sharing options...
Blockhead Posted May 12, 2009 Author Share Posted May 12, 2009 not tried it myself but was once told to rinse well and run a tube from a running car exhaust to the tank , leave for 30 mins before starting work , dunno but may work Ha ha, I could try that with the Manta and turn it into an oil tank Get someone to start the weld then take over Think that's the best advice yet!! Quote Link to comment Share on other sites More sharing options...
Snowy Posted May 12, 2009 Share Posted May 12, 2009 Just because you cannot smell petrol doesn't mean it's not there. The tank that blew apart on me had been standing for nearly two years with all the pipe work off and cap off. Quote Link to comment Share on other sites More sharing options...
mikemanta Posted May 12, 2009 Share Posted May 12, 2009 rinse it well then connect up to an exhaust of a running car then weld it up, the gas given out by the car whilst running is inert so it will not allow the vapour to ignite ive done a few bike tanks this way and it works Quote Link to comment Share on other sites More sharing options...
MANTAMAN Posted May 13, 2009 Share Posted May 13, 2009 I've got a GTE Hatch tank that needs weldig, as its for a Manta thats at the back of a long que i dont need it in a rush so it spent most of last summer outside the workshop, so on every sunny day (yes we do have them) the tank got heated by the sun,sometimes to the point of being almost too hot to touch, this got rid of the last of he petrol vapor. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.