High Temperature Sealant?

[Kev888]

I'm looking for a high temperature sealant to seal gaps around a stainless shroud for a gas burner (and boil kettle). Something thats specified up to about 600c or more and is suitable for resisting flames (which I think rules out the high temperature silicone sealants).

There are exhaust and fire/flue sealants about that could well do the job, but I'm unsure if any would cope with the (thin) metal flexing. Most of the gaps would need the sealant to adhere to the metal under its own strength, rather than being clamped in place like a gasket - if it were too weak or brittle (e.g. like traditional fireplace cement) it would be likely to crack or crumble away.

Has anyone seen anything that would do this?

Cheers
Kev

[BenB]

Mapei Mapeflex Firestop 1200°C High Temperature Sealant Grey 300ml from screwfix?

[BenB]

Super flexible and 600,c just ain't gonna happen!

[Kev888]

Thanks, yes that Mapeflex looks very good indeed heat and flame-wise, I was just put off by it being described as a rigid seal and also by some of the reviews which suggest brittleness and cracking. I wasn't expecting super flexible, but it may be that all (reasonably priced) high temperature sealants are very rigid and brittle, and if so I'll need a plan 'b' - but I thought it worth asking in case anyone knows otherwise.

Cheers
kev

[Fil]

If you seal it tight where is the hot gas going to escape?

im probably just not on the same page, but if you circle the pot and burner with a shroud and seal the top against the pot wall, the exhaust gasses will end up flooding out the air in vents, and could end up choking the flame? lift it too high up to give the burner access to more air and you risk loosing wind proofing a lower dipping shroud would offer.

a shroud that fits close to the pot but not sealed tight would contain the heat while allowing the exhaust to rise out?

tho im probably not picturing your proposal correctly..

[Kev888]

Hi Fil, I'm going to have a specific hole (or holes) for the gas to escape at the top - partly so that I could connect a chimney for waste gases and partly so that I could close it (when not heating much) to help keep the warm air blanket in during BIAB mashes. So I just want to seal any unneeded gaps in the construction to help manage where the gasses escape.

The shroud will be a bit more enveloping than some, as it will have an under-tray - which will be sealed to the sides of the shroud and to the top of a short wind shield around the burner (though I may need a small hole or flap to light and monitor the flames). The sealant is intended to fill/bridge any small gaps between the joins within reach of the burner flames - I think the top seal between shroud and rim of the pot would be cool enough for silicone.

So it doesn't need to be hugely flexible, just capable of adhering well to metal and resisting cracking/flaking with slight flexing of the shroud walls.

Cheers
Kev

[Fil]

OK im slowly catching up.. just my preconceptions getting in the way..

im looking forward to the build post ..

[Kev888]

I will post a build thread at some point yep, its the first thing I've built in ages! Progress is very slow though so I'm waiting until theres something much to show; so far I just have the stand for the pot with no shroud at all yet so its not very helpful

Cheers
Kev

[Kev888]

I had a chat with a local company who supply and fit wood/coal burners and flues etc. They recommended Fortafix ceramix TC; it says rigid bond, but they tell me its their preferred choice for metal flue joints where some flex and expansion occurs, apparently it sticks really firmly. It says on the tube that it works for both caulking/beads and gasket-type joints which sounds ideal, so I got a tube to try. Time will no doubt tell if this was a good choice or not!



Cheers
Kev

[alix101]

Might be to late but AG300 is food grade high temperature sealent I've purchased before you just ring up and they'll send a tube postage was a ripoff but the product is excellent.http://www.intek-uk.com/

[Kev888]

Looks good, thanks. The silicone types don't go hot enough unfortunately, but it could well be useful for sealing further from the burner - their much greater flexibility could be very useful.

Cheers
Kev