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LPG Tank - how rusty is unsafe?

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So what was meant to be a fairly quick Sunday morning job has turned into a bit more work - isn't that lways the way?!

One of my underslung LPG straps had broken so off came the tank, while it was off I thought I'd give it a clean and apply some waxoyl. There's a fair bit of surface rust however in two places it's a little more than surface rust as you can see on my pics.

Now for obvious safety reasons I have stopped all work until I'm happy I can work on the tank safely. How rusty do they have to be until there's a risk? How thick is the metal? :blink:

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How far away from me do you live?

That's not safe, I reckon. It looks like sheet rust.

G.

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Tanks are only supposed to be used until~10 years old IIRC, my guess is that is much older than that, so should be changed.

They are thick, and that is 50 times thicker than steel, but that is some serious corrosion there!

I would be looking for new replacements.

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How far away from me do you live?

That's not safe, I reckon. It looks like sheet rust.

G.

About 90 minutes away Gazzar - my parents used to live in Coleford. Why do you ask?

Tanks are only supposed to be used until~10 years old IIRC, my guess is that is much older than that, so should be changed.

They are thick, and that is 50 times thicker than steel, but that is some serious corrosion there!

I would be looking for new replacements.

Well it's back on for now, but taking into consideration what you guys say I think I'll order a new tank - appears to be only about £70. I think it's the tank that was fitted when the conversion was done by the previous owner and I've had the vehicle for about 8 years.

Cheers

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The tanks are 3mm thick

I'm in the same boat at the moment. From recent reading on the net, in the UK it is not law to replace after ten years. I'm replacing my underslung tank with a second hand tank that has been in someone's boot.There's no rust at all, but this time I'm giving it a few coats of smoothrite before installing.

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Just thinking about the explosion, and if you are far enough away in Didcot?

Please change it, carefully, as I'm visiting Oxfordshire next weekend.

G.

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On the tanks I've had, there has always been a stamped plate with a certification expiry date. It may not be law, but insurers usually want a certificate of some variety for installation and I'd have thought that periodic maintenance and inspection (even self inspection) was implied.

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LPG tanks are really save. They are tested to 30 bar (425 psi) and normal working pressure is 10 bar (145 psi) max.

But when in doubt and for only £70 I would change it.

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On the tanks I've had, there has always been a stamped plate with a certification expiry date. It may not be law, but insurers usually want a certificate of some variety for installation and I'd have thought that periodic maintenance and inspection (even self inspection) was implied.

Mine had those, but they rusted off.... Seriously, the plates rusted off but the actual tank only had very slight pitting and surface rust where moisture had seeped under the powder coating. The only way I could get the powder coat that remained off was with a blow torch, now that was a very exciting afternoon!

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Just thinking about the explosion, and if you are far enough away in Didcot?

Please change it, carefully, as I'm visiting Oxfordshire next weekend.

G.

Out of curiousity what would happen should the rust weaken the tank enough for it to 'burst'?

On the tanks I've had, there has always been a stamped plate with a certification expiry date. It may not be law, but insurers usually want a certificate of some variety for installation and I'd have thought that periodic maintenance and inspection (even self inspection) was implied.

Ahhh ok so it would appear my tank 'expired' in 2008 :mellow::ph34r: You learn something new everyday - thanks.

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Out of curiousity what would happen should the rust weaken the tank enough for it to 'burst'?

I would think to start with the tank would become porous and the gas would seep out. Only if there was a source of ignition would there be a risk of explosion but I would think given that the gas is under pressure it would be like a flame thrower.

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I would think to start with the tank would become porous and the gas would seep out. Only if there was a source of ignition would there be a risk of explosion but I would think given that the gas is under pressure it would be like a flame thrower.

My grandfather set light to a gas holder he was repairing once (yes, one of those massive things that go up and down and maintain pressure in the pipeline!!!). It was the pressure that kept the flame coming out. I dread to think what would happen if it set light to the entire contents! Probably say bye bye to part of south east london! They put it out by releasing the gas into the pipeline and lowering the gas holder sections down into the water that sealed each section (well, that's what he told me anyway!)

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There's not enough oxygen in the tank to cause explosion, and any severely ruptured tank would likely be just a very fast burning rfireball rather than a true explosion...

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My grandfather set light to a gas holder he was repairing once (yes, one of those massive things that go up and down and maintain pressure in the pipeline!!!). It was the pressure that kept the flame coming out. I dread to think what would happen if it set light to the entire contents! Probably say bye bye to part of south east london! They put it out by releasing the gas into the pipeline and lowering the gas holder sections down into the water that sealed each section (well, that's what he told me anyway!)

There were several of these large 'gasometers' on the site next to British Gas's London Research Station where I worked in the late 1980's. There was a map on the wall inside LRS which showed what the expected affected zones would be if a plane were to crash into the site. I seem to remember the staff referred to the different colours as the 'frizzle zone' and the 'fry zone'.

To the OP, if you really want to frighten yourself, look up 'BLEVE' although I agree with Simon_CSK that the more likely scenario is for the tank to develop pinhole leaks rather than a catastrophic rupture. In any event the tank shown in the pictures is knackered and should be decommissioned ASAP.

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It'll go psssht and nothing much will happen. Stay away from enclosed spaces until it's replaced. That's a pretty bad tank though, never seen one that bad.

Over here tanks need to be tested every 10 years, and it's ridiculously expensive (€400 when I last asked). You can almost fit a new tank for that price, but wait, you're not allowed to do that yourself! Stupid country.

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Theres a lot of armchair pressure vessel structural engineers in this thread. From my experience of dive cylinder inspection, even pinhole corrosion can cause cracks and catastrophic failure. Ok the pressure is not as much as a dive cylinder but the mode would likely be the same.

Plus something nobody has mentioned - the tanks are designed to be crash proof, this corrosion has compromised that totally. In a crash it could fail in a big way.

Can you imagine how long you would spend in jail having knowingly driven something in that state and then caused a fireball in a public place?

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Theres a lot of armchair pressure vessel structural engineers in this thread. From my experience of dive cylinder inspection, even pinhole corrosion can cause cracks and catastrophic failure. Ok the pressure is not as much as a dive cylinder but the mode would likely be the same.

Plus something nobody has mentioned - the tanks are designed to be crash proof, this corrosion has compromised that totally. In a crash it could fail in a big way.

Can you imagine how long you would spend in jail having knowingly driven something in that state and then caused a fireball in a public place?

...Not to mention living with that on your conscience!

I hear you both, and now totally understand what I am dealing with here and it's quite clear what I should (and shouldn't do) from this juncture.

I thank you all for your input... Just stay away from Oxfordshire for the next few days! ;)

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Theres a lot of armchair pressure vessel structural engineers in this thread. From my experience of dive cylinder inspection, even pinhole corrosion can cause cracks and catastrophic failure. Ok the pressure is not as much as a dive cylinder but the mode would likely be the same.

Plus something nobody has mentioned - the tanks are designed to be crash proof, this corrosion has compromised that totally. In a crash it could fail in a big way.

Can you imagine how long you would spend in jail having knowingly driven something in that state and then caused a fireball in a public place?

Fair enough, my comment was mostly aimed at the LPG bit not being the dangerous part. A tank actually fragmenting under pressure would indeed be a very bad thing.

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Empty the thing and get rid of it NOW !

Drive it empty - really empty - and treat the reservoir as a potential bomb because the vapour inside will explode if a spark comes by. Have been using LPG in vehicles for 35 years, fitted many systems and this is dangerous - and not just for you.

Tanks need to be tested every 10 years and that one would not be allowed near a testing station.

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This is surprising - and long - and cool!

https://www.youtube.com/embed/fsppNOHdQII

Yeah saw that when i searched for BLEME. Love the silver car guy who just leaves it there and then only runs 10m back from it, until the big bangs. Also the rocket bottle that jets over the woods.

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Hi Could I have permission to use your images of the Underslung LPG tank in a new LPG guide?

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