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Aug 23, 2013 20:29:04 GMT
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Hi folks,
don't think of me as mad just yet.
I need to weld my fuel tank. I'm going modify the exhaust on the dolomite to be center exit, but that means it fouls the (rubber) fuel outlet. Which would mean instantaneous fire.
I can feasibly run it the other side, but that means cutting the outlet off and welding it the other side. This is doable, but the problem is, while its empty now, and has been venting for a couple of weeks, i cant guarantee there is no fuel/vapour in there and i do not want to be killed by a huge fuel vapour related explosion.
What getting at is, is there such a thing out there i could use to sterilise the fuel so its no longer flammable? sounds stupid, but its what i need!
I mean you could burn the fuel off, but that A) means a lot of carbon in the tank, and B) could run the risk of warping the tank or an explosion anyway.
Anyway, what are my options? i cant leave it venting forever because i need to get it done soon!
Cheers for reading...
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Aug 23, 2013 20:35:35 GMT
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Brim the tank with water, drop the water out and you're golden to do with it as you please.
Even as it is, empty and venting for weeks the worst you'll get is a "whoomph" if there is sufficient vapours inside to ignite. At atmospheric pressure, petrol vapours aren't really all that explosive really.
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Aug 23, 2013 20:37:12 GMT
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Petrol evaporates pretty quickly.
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1958 Hillman Minx
1988 Saab 900 T16
1989 Renault Trafic camper van
2003 Mazda 323F diesel
1994 Volvo 850 T5
1988 Saab 900i 4-door auto: breaking - anyone need parts?
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Aug 23, 2013 20:57:45 GMT
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When I've flushed tanks through with water before they still smell of petrol after I've let the water out.
I believe a better way is to get the bit you want to fab pointing upwards and fill the rest of the tank with water to a point slightly below where you are going to work, that minimises the volume likely to contain any vapour and reduces the risk of a little excitement.
Rob
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'55 Austin A30
'71 MGB GT
'72 Datsun 240 shed
'72 Mercedes 240D
'79 Firebird
'86 Austin Maestro Van
'91 Mercedes 250D
'91 BMW e34 535i Sport
'92 Mazda MX-5
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MrSpeedy
East Midlands
www.vintagediesels.co.uk
Posts: 4,786 
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Aug 23, 2013 20:59:53 GMT
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Can you not route the exhaust from the original back box along the rear of the rear valance to the centre? I can't remember the exact layout of the dolly 'zorst
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Aug 23, 2013 21:00:56 GMT
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Well the outlet is on the bottom of the tank so to do that i'd have to turn it upside down which i cant due to filler holes  Though general consensus so far is that i'll be fine if i flush it thoroughly with water, so i may just do that. |
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Aug 23, 2013 21:02:54 GMT
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Can you not route the exhaust from the original back box along the rear of the rear valance to the centre? I can't remember the exact layout of the dolly 'zorst You could, but you'd see it. It will be far easier, and more aesthetically pleasing to delete the second silencer box and move the pipe along, but like i say that means it fouls the outlet, but now i can move it its not a problem. |
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MrSpeedy
East Midlands
www.vintagediesels.co.uk
Posts: 4,786
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Aug 23, 2013 21:19:42 GMT
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Well. if you're gonna move the actual fittings on the tank, the only 99% safe way of doing it, is to either fill the tank with water or inert gas whilst you weld it, or use a large soldering iron (electric, not gas)
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Midas
Part of things
Posts: 505
Club RR Member Number: 14
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Welding a fuel tank....Midas
@midas
Club Retro Rides Member 14
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Aug 23, 2013 23:43:42 GMT
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On the few occasions I've welded tanks they have been pressure washed out, brimmed with water several times and then given a good dose of caustic soda before being dried out with a hot air gun.
When welding the tank is filled with whatever I'm welding with, these days Argoshield, in the past CO2. It's a good reason to keep the crappy mini-bottle regulator so you can have the purge running from a small non refillable bottle.
When you've done all that, seal the damn thing. MIG weld can weep petrol like you wouldn't believe. I've had good results with the Frost stuff but others are available. Allow two weeks for it to dry properly before putting fuel in though.
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Aug 24, 2013 11:02:54 GMT
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Take the tank into an open space, stand a little back and put a candle lighter near the opening. The fumes will only light the once so try and light it in a controlled way and then you know you're good to go
as already mentioned if it does light its not going to explode anyway
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jikovron
Part of things
mechanical chaos
Posts: 633
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Aug 24, 2013 11:13:34 GMT
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On my dolomite i unscrewed the 7/16 unc brake pipe style outlet fitting and forced a 1/4bsp brass compact 90 degree bend and 8mm hosetail in it with some pez resistant loctite so that the fuel pipe ran inside the boot rather than underneath, then the hole can be welded shut in the boot floor too
HTH
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Aug 24, 2013 13:13:18 GMT
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On my dolomite I unscrewed the 7/16 unc brake pipe style outlet fitting and forced a 1/4bsp brass compact 90 degree bend and 8mm hosetail in it with some pez resistant loctite so that the fuel pipe ran inside the boot rather than underneath, then the hole can be welded shut in the boot floor too HTH Thats a good shout actually.Then i can just move the pipe rather than the whole outlet, any photos at all? |
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Aug 25, 2013 19:13:23 GMT
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purge the tank with the exhaust fumes from another car first
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Aug 25, 2013 19:33:42 GMT
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That sounds remarkably dangerous...
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Aug 25, 2013 19:44:10 GMT
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I must have welded over 50 fuel tanks this way. Just offering my experience / opinions.
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Darkspeed
Club Retro Rides Member
Posts: 4,710
Club RR Member Number: 39
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Welding a fuel tank....Darkspeed
@darkspeed
Club Retro Rides Member 39
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Aug 27, 2013 20:06:23 GMT
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I must have welded over 50 fuel tanks this way. Just offering my experience / opinions. + 1 ^ - empty - rinse out and then connect a hose from the exhaust of another car and weld away - no oxygen present = no possibility of a fire. |
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Aug 27, 2013 21:54:43 GMT
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Its alright I'm going to do what jikovron said anyway, much less sketchy!
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Aug 27, 2013 22:10:17 GMT
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Lots of dodginess in this thread!
I washed and aired my Dolly sprint tank for about two months and it still caught light several times when i welded it.
If i was gonna do it again, I'd fill the tank with CO2 from an old extinguisher first.
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Koos
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Aug 30, 2013 17:45:29 GMT
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Simple answer. DON'T! I knew a chap who was scarred from head to foot by welding a DIESEL tank that had been washed out, purged etc. There must be another way. If in doubt, pop along to your local fire station!
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Life without spanners is no life!
Rover 414 SLI
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Aug 30, 2013 18:58:11 GMT
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It would help if you read some of the previous comments. Decided against it a while back.
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