Heat insulation

I'm to start making a boiler but I need a insulation inside the copper tube.

Years ago asbestos was used, coak is a alternative but cant seem to find this.

Any other materials that can be used , would fiber glass be any good.

Thanks Bob

You could cut and shape a thermalite block? I noticed a jewellry site selling charcoal blocks as a solder base on the grounds that it reflects heat well and has reducing benefits- so perhaps BBQ charcoal? Don't do what I stupidly tried and fill it with vermiculite from the garden centre which promptly flew everywhere when i showed it the gas torch <embarrassed>. Or just stuff it full of thermal blanket.

pgk

Inside???? Is this a Smithies or equivalent?
If you are looking for a thin layer between the outside of the boiler and the cleading? A product called Kaowool I think is available from some of the ME suppliers. Several asbestos substitutes are available for direct flame contact. Look at laboratory suppliers.

Balsa wood and cork sheet are also readily available.

Not sure what you mean by " insulation inside the copper tube" but on my traction engine boiler I looked at various products, most of which I found would absorb water and cause a possible rust problem ( including fibreglass, I have a steel boiler). Instead I decided to just use an air gap between the boiler shell and the cleading. Air is an excellent insulator if trapped in a cavity. Spacers were used to separate the cleading from the boiler but as the cleading is just wrapped around the spacers, any water can leak through and not remain in any insulation. Adhesive, silicon impregrated fibreglass tape was then applied to the spacers to insulate them from the cleading. The tape is water resistant and good for 280 degrees C. (similar to the insulation tape used inside electric motors).

Paul..

Assuming you need this to insulate the boiler tube whilst silver soldering either end.

Glass fibre will melt, Rockwool whilst looking the same is OK and makes a huge difference. it's best to test it with some red hot copper scrap.

You can also use bulk Vermiculite from old fashioned garden centres, it may also be available from gas fitter suppliers, my 1988 gas fire install had half a sacks worth underneath it.

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Sorry I was a bit vague on my question.

I'm actually making the boiler and the insulation is for silver soldering to compact the heat.

I asked a question the other day on the forum if

a Map torch will give me enough heat for silver soldering,

or I was to rivet and soft solder the boiler .

I would prefer silver solder but limited to a Map torch.

Thanks Bob

Vermiculite blocks are best for making a hearth. Cup Alloys sell them or a little hearth kit.

Bigger torch is better as your Mapp one will be limited by the wattage of the small burner, about 7kw should do your 4" boiler

Hi, I've always used ceramic fibre which is available in a roll from pottery suppliers, Around £2 per sq ft. and 1 inch thick. works really well. I held it in place with iron wire.

Thanks for the advice, quite like the ceramic fiber, and Vermiculite.

I'm a bit lost now with the Map torch I have as it looks like it hasn't the burner size. I've looked on Ebay at the propane torches, will these fit a Map cylinder.

I have a large cylinder of Calor gas will this be any good, if so will a propane torch fit the cylinder.

I really haven't a clue with fittings and gas, only ever used acetylene many years ago.

Thanks Bob

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Whereabouts are you Bob? There might be a club you could join with the required kit and expertise to see you through your first boiler? or possibly one of us on the forum might live close to you willing to give a hand.

Roger

Sievert equipment is for propane not butane and they don't sell a butane compatible fitting because running on butane will not give professional level heat. Butane is for domestic caravan heating and cooking not metalworking use. Mapp is a mix of propane and butane to add a bit of oomph to hobby style torches without the expense of a stronger cylinder needed for propane. I think the original Mapp gas company went out of business but other suppliers have resurrected the product owing to demand from loads of small torch users for plumbing. etc.
Calor do propane in an orange cylinder and butane in a blue cylinder. A bunch of odd coloured cylinders are around from butane companies half of which have gone out of business. The butane cylinders have a non theaded quick connect top. Propane has a threaded top. If you have a threaded regulator on an old heater it is likely to be very old from before the quick connect came in.
You might be able to use a butane powered weed burner to provide base heat and use the small torch to provide concentrated heat at the joint. Bit of a risk of failure as silver solder definitely has to be good and hot compared to plumbing work with soft solder.

BTW your first post asked about coak which should be coke. Lots of garage forecourt and DIY shop sacks of 'coal' are coalite which is coke. In fact I doubt real coal will be available in that type of bag for home use after a few more months of Extinction Rebellion.

Thanks for the replies.

A re think needed on this.

Bob

To correct some misinformation in a previous post...

The original MAPP (sic) gas - a mixture of methylacetylene and propadiene - is no longer available. MAPP substitutes seem to be propylene. Both burn in air with a higher flame temperature than propane, which burns hotter than propane/butane mixtures, which burn considerably hotter than butane. As a self-contained, hand-held torch, a 'MAPP' torch makes a butane torch look rather silly.

In your application, you probably need to concentrate on heat output, rather than temperature, so propane feeding a larger burner will almost certainly be better than a self-contained 'MAPP' torch. Large bottles of Propylene are available (in USA, at least), but I don't know about in UK; pity us in backward NZ, where, apart from MAPP-substitute hand-held torches, the best we can get (easily) is a propane/butane mix (of no standardised proportions). It's not too bad with Sievert burners, but, for small jobs, I still go to my MAPP-subs. torch.

Thanks all,

I've ordered a torch with three different nozzles also with the propane tank and deposit came out very reasonable.

Bob