smoke box seal

[Andy G]

Hi Folks,
Can anybody suggest a good brand of sealant to use for the seal where the smoke box meets the boiler barrel ?
I suppose I could use silicone sealant. I wondered if there was a sealant that would do the job which would stay supple, making it easy to remove the smoke box in the future,as apposed to silicone which would become like glue.
Thanks
Andy G.

[Scrat]

Hi Andy,

I use stuff called FIREGUM. This is normally used for exhaust pipes. Worked well for me so far. After putting it on and putting the parts together, this stuff stays flexible until you heat it. To avoid cracking I hest the boiler slowly the rfirst time. After that it becomes solid as rock. Even after years of service there were no cracks. I had to remove the boiler of my LBSC Minx lately. I used a small chisel and a small hammer to crack the layer of firegum. After removing the boiler the remaining firegum easily came off using the wire brush.

Hope this helps.

Holger

(currently in Tianjin)

[Ballan Baker]

Hi Andy,
I have found Purimanchos, a fire cement that is like gray putty to use but sets firmly, works well. Buy from plumber/builders merchants Regards Ballan..

[Eddyg]

Andy,

Silicone sealants are fine. I've just lifted a boiler that has been in service for eleven years. The ordinary silicone sealant I used for the smokebox around the main steam pipework and the exhaust was still flexible and was easily removed. Also where the ashpan was fitted to the firebox there was a run of silicone sealant and that was also still flexible and easily removed once the ashpan joint was broken. I first used silicone more than twenty years ago when I tried some material marketed for car engine joints. I ran out of this when getting a loco ready for an event and used bathroom sealer instead, and I have used this ever since (it's much cheaper). You can get a general purpose silicone sealant in a range of colours and I use black or brown if I can find it. Be careful to get the old acetic acid curing material. The latest water curing stuff doesn't do.

Regards

Eddie

[Andy G]

Thanks to all three of you for your replies and suggestions.
I think I will go with the general purpose silicone Eddy, (thanks for confirming that it lasts a long time without adverse effect under high temperature).
Best Wishes to all.
Andy G.