Removing insulation from a copper boiler

[Jim]

I'm after some copper sheet to use in some sculpture work I'm having a go at. Looked at a couple of suppliers and prices for new sheet are just stupid so was thinking about buying an old hot water cylinder and cutting that up. However all of the secondhand ones I've seen locally are covered with the hard insulation a bit like this

(this is an ebay link)

Can anyone let me know

1. When these cylinders are described as copper is that what they are or is it more of a generic description
2. Is it possible to separate the copper form the insulation on these tanks ie could I just cut it open and peel them apart
3. How thick is the copper

Sorry I know this isn't really DIY but thought this group would have the most experience of the cylinders

Thanks

Jim

[Peter Andrews]

Yes you can cut and peel open but when I tried to remove the insulation I used a wire brush on a power drill - after about 1sq ft I gave up! Finish was poor and still not clean enough - good luck.

Peter

[Gib Bogle]

I'd go to a metal scrap buyer and ask.

[Gib Bogle]

Propane torch?

[Dave Baker]

Yes they're copper.

It's spray-on foam on modern tanks the bulk of which cuts away easily but the final residue will stick to the copper like **** to a blanket.

It depends on the quality grade which determines how much head of water pressure it can resist but on normal sized modern domestic tanks up to about

25 gallons it will be about as follows.

Grade 3 for heads up to 10m (the usual spec for a house) the base will be

1.6mm and the rest 0.7mm

Grade 2 for heads up to 15m the base will be 1.6mm and the rest 0.9mm to

1.0mm

Grade 1 for heads up to 25m the base will be 1.6mm to 2.0mm depending on size and the rest 1.2mm to 1.6mm similarly.

Your chances of finding anything other than grade 3 are minimal.

Bigger commercial tanks will be made of thicker material. You could have a

3mm base and 2mm shell on a 100 gallon tank.

The base is your best bet if that's large enough because it won't be insulated and if you can beat it flat (they are made concave for strength) you'll get a piece about 450mm diameter of a decent thickness. You'll go mental trying to get the foam cleaned up from the rest of the shell and it'll probably be horribly corroded and covered in limescale inside on an old one and near as dammit paper thin everywhere anyway. These things generally get chucked because they're already leaking and when they leak in one place you can bet they'll be close to corroded through everywhere else.

[Harry Bloomfield]

Jim expressed precisely :

So far as I am aware, they are all copper if they look like copper.

Could you acquire one from a scrap yard which is old enough not to have the insulation? Otherwise I would be thinking in terms of burning it off with a gas torch. Others have mentioned internal scale - not much scale or any forms on tanks around here, but ours is a soft water area. Could you get one from a soft water area?

[R]

Carve off as much as poss with a good sharp long bladed knife. Either Nitromors or Cellulose thinners should remove the rest.