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Post by nemesis on Nov 7, 2007 15:10:57 GMT -5
Have a alloy tank which has sprung a small leak along a seam. A friend who is a welder can repair it but needs me to make the tank clear of petrol so it is safe to weld. What is the best way to make it safe to weld?
Thanks
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Post by wotavidone on Nov 7, 2007 19:49:31 GMT -5
Mate, That's a tuff one.
Some say vent the tank, fill it up with water, drain it, vent it again, etc.
My father-in-law tried that with his boat fuel tank, but it still blew up when he welded it.
Probably got himslef a steam explosion, instead of a fuel one.
The trick is to get it dry, no fumes etc.
Apparently a bloke up here goes through all the usual stuff you hear, like drain it, fill it right up with water, drain it again, sit it in the sun till its very dry, then when he welds it, he has a hose hooked up to a car exhaust filling the tank with exhauust fumes while he welds it.
I have not tried it myself, too scary by half for me.
My tank has been patched with EPI Fill two pack marine epoxy putty reinforced with fibreglass mat. OK if you are going to sand and paint it, not much chop, if you want a polished alloy tank.
Mick
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Post by curly001 on Nov 8, 2007 1:00:08 GMT -5
Wash it out with soapy water and make sure it's dry. You will never get ride of the smell, but if there is no petrol in the tank to vapour off it can't catch fire. Make sure you leave the cap off and if your still worried just before welding it fill it with an inert gas such CO2 or some argon.
Curly
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Post by future on Nov 8, 2007 1:03:13 GMT -5
When I worked in the aircraft industry we used to weld up aircraft fuel tanks. The tanks used to come to use steam cleaned and they were fine to weld up. I would say steam cleaned a few times over first.
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lurch
Full Member
Posts: 217
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Post by lurch on Nov 12, 2007 10:08:15 GMT -5
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Post by canucksr on Nov 12, 2007 13:18:41 GMT -5
I had my stock SR tank welded years ago and like wotavidone mentioned, the tank was purged with exhaust gases from a running auto after rinsing with water, and then welded.
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Post by davedunsboro on Nov 13, 2007 5:07:42 GMT -5
Nitrogen gas is what the fridgiees use for purging & welding their gear with . It stops combustion & it also prevents oxidising . Not sure about exhaust gas as I recon it could be both explosive & toxic .Maybe you could get those donkey dudes to weld & film themselves doing it coz that'll be your problem actually getting somebody to do it for you ! Maybe get the "Mythbusters" to check it out too Cheers Dave.
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Post by aero on Nov 14, 2007 5:38:19 GMT -5
I've welded a fair few tanks in my time.
The quickest and most reliable way to make the tank safe to weld is with a steam cleaner, the heat ensures any fuel caught in the seams evapourates away and the water flushes the tank out. I guess filling the tank with boiling water from a kettle and ensuring it gets nice and hot will have the same effect if you don't have a steam cleaner
If MIG or TIG welding you already have a supply of inert gas. BUT if you have not got rid of any fuel trapped in the seems you're safe only as long as you maintain the inert atmosphere...not long then. (CO2 is a reactive gas BTW, watch out if welding, Argon is better)
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Post by marlon on Dec 2, 2007 16:46:25 GMT -5
Apparently a bloke up here goes through all the usual stuff you hear, like drain it, fill it right up with water, drain it again, sit it in the sun till its very dry, then when he welds it, he has a hose hooked up to a car exhaust filling the tank with exhauust fumes while he welds it. Mick I used to work for BOC, and strangely enough a few of the welders there recommended that procedure. |
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