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Sept 24, 2020 14:59:33 GMT
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Probably a daft question, but any risks, like fuel tanks?
It's got a load of thick black gloopy oil in the bottom of it.
Not really sure if I should clean it first or after, but can't think how to clean it apart from washing it out with petrol!
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Last Edit: Oct 5, 2020 16:58:06 GMT by VW
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Sept 24, 2020 18:50:05 GMT
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It will come in handy even if you never use it
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Sept 24, 2020 19:11:15 GMT
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It will come in handy even if you never use it
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Sept 25, 2020 6:57:47 GMT
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Ah.
And what if you have no choice as you need the oil tank and a new one isn't available?
On the plus side, what I need to weld is a bracket which is on the oil tank, rather than the tank itself. The bracket is maybe 2" away from the opening though.
It's a small oil tank, holds maybe 2 litres of engine oil.
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Sept 25, 2020 6:58:43 GMT
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Glad I asked now, didn't really think this would have the same dangers as fuel tanks!
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Sept 25, 2020 11:08:57 GMT
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Good job you asked we don’t always know how dangerous some things can be. A new tank can always be made what about gluing the bracket on?
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It will come in handy even if you never use it
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Sept 25, 2020 15:09:27 GMT
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Good job you asked we don’t always know how dangerous some things can be. A new tank can always be made what about gluing the bracket on? It's a pressed steel tank. Making one would be very expensive, if I could even find someone to do it! The bracket is still on the tank, it's just cracked. I guess it's not vital that it's fixed, it will still mount up ok. The tank is going to my local engine reconditioners to be cleaned, stripped and de rusted. I'll then see what my coded welder friend makes of the situation, he may be happy to seal the tank and tack the bracket. If not, I'll leave it cracked. |
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Sept 25, 2020 16:19:03 GMT
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If you clean it out properly then fill it or set up a backing purge with argon or co2 when welding then it can be done.
If you don't fancy it then try a radiator reconditioning place, they usually do fuel tanks so will sort it.
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Sept 25, 2020 16:54:50 GMT
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Good idea, people do weld them safely, but it can be overlooked as whilst its not as flammable as petrol oil will still give a good explosion.
I am sure some one will be doing them day in day out and it wont be an issue for them
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It will come in handy even if you never use it
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Sept 26, 2020 10:08:20 GMT
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Could you fill it with water, maybe wash out the oil with water and washing up liquid?
If it's full of water it shouldn't be a problem but leave the cap off to let any steam generated by the welding escape.
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Sept 27, 2020 7:04:06 GMT
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Iv'e welded petrol tanks filling them with water but it only really works around thd filler neck where you can completely fill the tank and be sure to have no vapour trapped.
Oil does burn well, I was welding.a breather (with the gauze removed) recently and the residues in there were enough to have a flame like blowlamp coming out of it and vast amounts of choking smoke.
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Darkspeed
Club Retro Rides Member
Posts: 4,669
Club RR Member Number: 39
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Sept 27, 2020 8:47:14 GMT
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Its been covered plenty in this thread but to confirm
Oil is a fuel
Its not oil or petrol that burns in its liquid phase - they ignite in their vapour phase - the only difference between the different hydrocarbon fuels Oil Diesel Kerosene Petrol Parafin etc. etc. is the flash point - the temperature where they change phase from liquid to a vapour.
Petrol flash point (minus)-43C
SAE 30 mineral Oil flash point 135C
Diesel 54C
And oil for its weight has more energy stored than Petrol ! so when you warm it up to 135C look out.
You need 3 things for combustion - Fuel an ignition source and oxygen - its called the combustion triangle - take one away and there is no combustion. - you also need a minimum amount of oxygen.
So to safely weld a fuel tank - you remove as much of the fuel as possible leaving as little energy in the tank as possible - steam clean / wash it out to within an inch of its life - you then purge all the oxygen from the inside - inert gas.
I have welded a tank once - not something I fancied doing - washed out thoroughly and then purged further on the end of a car exhaust. Then filled with CO2
Welding fuel tanks is not something I do
Steam cleaning - steam is at a temperature over the flash point of most fuels so it cleans very effectively.
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Sept 28, 2020 8:32:28 GMT
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Wash it out well and purge. But yeh, oil will vaporise and burn just like petrol once at welding temperatures.
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Sept 28, 2020 20:59:40 GMT
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When I was little I used to put old engine oil into a litre paint tin with a hole in the lid. Sitting it in the bonfire you could hear the oil boiling then you would get a decent jet of flame it of the hole. Occasionally it would go with a whump...
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Sept 29, 2020 14:08:52 GMT
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When I was little I used to put old engine oil into a litre paint tin with a hole in the lid. Sitting it in the bonfire you could hear the oil boiling then you would get a decent jet of flame it of the hole. Occasionally it would go with a whump... Sounds like fun! |
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Sept 29, 2020 17:17:08 GMT
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When I was little I used to put old engine oil into a litre paint tin with a hole in the lid. Sitting it in the bonfire you could hear the oil boiling then you would get a decent jet of flame it of the hole. Occasionally it would go with a whump... Sounds like fun! A few years later when I got taught about fractional distillation in school I always used to wonder if I could get a burnable fuel from it in a similar manner. |
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Got the oil tank back from the engine shop. They put it (and a load of other stuff) in their tank. It is now free of oil.  Still needs a little 're rusting. This is what needs welding  Seems pretty safe to me now, but then I didn't realise it was dangerous in the first place! On a very similar note, I might need to weld the fuel tank. It hasn't had fuel in for 40 years. It has also gone through the engine shops tanks (don't know what's in the tanks but it removes anything organic, so paint, oil etc but not rust). Any further thoughts? |
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Darkspeed
Club Retro Rides Member
Posts: 4,669
Club RR Member Number: 39
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If its the crack that needs welding - that's a bracket not an oil tank and if mine would have been welded and back on the car the same morning - no need to clean anything out to weld that.
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If its the crack that needs welding - that's a bracket not an oil tank and if mine would have been welded and back on the car the same morning - no need to clean anything out to weld that. It is very close to an opening at the bottom of the tank (1 inch away from a 2 inch diameter hole), and it had a good layer of sludge inside before hand. It was getting cleaned anyway. I'll weld it up then 😂 |
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