Advice please on welding repair to oil tank

Hi all

I know this isn't a landrover issue but I was wondering if anyone technical could help please. I have a steel 1000l domestic oil tank which has developed a slow leak due to rust. The cost & sheer hassle of swapping it out has caused me to think about running it dry, turning it over and welding some repair plates on the base where it sit on slabs.

My question is regarding the risk of fire/explosion caused from the heat of welding given that although the tank will be drained it will have vapour in it. Has anyone any experience/ideas on the matter?

Cheers

Tony

Reply to
Tony
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You have mail.

Welding on tanks as you describe is a major hazard. What I've sent will provide the basic guidance(fill with Carbon Dioxide or water for the rest of you).

As far as washing out afterwards, that's probably unnecessary in your case provided that you have a drainable 'sludge' volume below the offtake. Close the offtake valve, refill the tank and allow to settle before re-opening the offtake valve. Drain the 'sludge' when convenient

- or before re-opening the offtake valve if there's lots of water left behind.

Reply to
Dougal

Hi all

Apart from the potential dangers, unless your welding skills are well above average, dump it, and install a new plastic tank. More costly yes, but I would say a lot less hassle. If you do decide to go ahead with welding be prepared to seal all apertures so that you can pressurise the tank with an airline and test all welds with soapy water before risking re-filling with oil.

Also check all round above the oil line as condensation often leads to rust from inside up the sides of the tank as well as external rust at the base.

Mike

Reply to
Muddymike

Plastic is definitely a lot less hassle and you won't be repeating the patching operation regularly for years to come!

Be very careful to limit the air pressure (no more than 5psi, if asked to pull a figure from the sky) if following this suggestion. A tank of this volume at any significant pressure is a serious hazard in itself should something 'let go' suddenly.

Reply to
Dougal

I would also expect to find that it's not just a couple of pinholes, but large slabs of steel that will turn to powder when you start chipping back to find good metal to weld to. The corrosion will be from outside and inside, as the oil will have contained water when delivered as well as the condensation while it's sitting, which gathers in the bottom of the tank unless you're scrupulous in draining it out every few months. As others have said, a new tank is a better solution, especially if you value your time.

Reply to
John Williamson

The flashpoint of heating oil is significantly higher than that of petrol so it is more difficult to ignite. None the less before chancing it, fill it with water, it is awfully difficult to ignite water, however, the water will form a rather excellent heatsink making the welding pretty much impossible. I'd certainly feel safer tossing the tank and replacing it with a plastic one. I'm sure Lee might have a definitive view on the subject?

Reply to
GbH

3 PSI is enough, and this is from experience on big tanks.

Mike

Reply to
Muddymike

Yeah, leave it till the Summer when I'm likely to be out of the country and out of range of the resulting spectacular.

Go Plastic, you know it makes sense.

Lee D

Reply to
Lee_D

Yes - JUST DON'T! Cut it up to remove it if needs be and put a plastic one in. You'll only end up flogging the same dead horse again - sooner than you might think. With the corrosion eating into the steel at a granular level, you'll never ever get a really good weld that will remain fuel-tight unless you come about 18" up the tank - and to be honest, if you have the space and facilities to attempt this as a repair, then you have the space and facilities to just replace it. Badger.

Reply to
Badger

And a plastic replacement will have a built in bund as well, so should eliminate all chance of the very expensive bill (thousands) from the Enviroment Agency should 1000l if kerosene find it's way out of the repaired steel and into the ground one without you noticing...

Reply to
Dave Liquorice

I thought it was legal for domestic heating tanks to be un-bunded up to

1250L, only over that figure or commercial having to be bunded by law? Maybe that's another piece of legisalation that differs north of the border, I don't know? Anyways, you'd have to be able to prove beyond any reasonable doubt that you had taken all possible care to prevent any spillage if you wanted them to go easy on you - and D.I.Y. welding wouldn't fit that classification. Badger.
Reply to
Badger

Pikeys love all plastic tanks, hot pipe melts through both walls silently ;-)

AJH

Reply to
andrew

One would hope the clean up bill and new tank would be covered by ones house insurance. A leak from a DIY repaired steel tank almost certainly wouldn't be...

Reply to
Dave Liquorice

You could be right, 1250 might be the break point for a bund on a domestic tank but even so clearing up 1250l of kerosene isn't going to be cheap. And you can bet that it will leak just after a delivery when there is most strain on the tank.

Personally 1250l is far too small a quanity. You get a better price at 2000l/delivery and 1250l would only last a couple of months in the winter here. With it being a fairly cold winter we are getting through the best part of 200l/week...

Reply to
Dave Liquorice

Tell me about it! We might not have had as much snow as some parts of the UK up here in Moray (at close proximity to the coast, at least) but by heck we've had some low temps. My heating's been working overtime! Badger.

Reply to
Badger

I wasn't commenting on the subject, rather pointing out that all plastic tanks seem to attract theft. I'd quite like a plastic bunded steel tank.

Because ours is a commercial installation we have a 2500l plastic bunded tank but have had to build a concrete block bund around it too, because it gravity feeds the boiler. The smaller plastic bunded red diesel tank is pumped and sits in a shipping container for security. When full at current prices there's about GBP2000 invested in the contents.

AJH

Reply to
andrew

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