What are we using to seal smokeboxes these days?

[Boadicea]

I want to re-seal a hole in the bottom of my smokebox where the blast pipe enters and the superheated steam exits.

Good old Martin Evans says a compound should be made by "kneading some asbestos sheet with water". I cannot think this is a good idea! We must have something better by now, or at least safer. I have seen tile cement advertised under the name Firebrand which purports to be OK to 1400 degrees C and asbestos-free - like this....

cgi.ebay.co.uk/FIRE-CEMENT-BLACK-500G-TEMPERATURE-RESISTANT-TO-1400C_W0QQitemZ330133935289QQihZ014QQcategoryZ20564QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Has anyone had success with the above type of compound or similar?

Additionally, for the boiler barrel/smokebox seal, good old Martin Evans and LBSC said to use plumbers jointing compound. I assume they meant boss white (now should be called boss khaki). Is there something better than that now?

Thank you in advance.

Regards, Bo.

[stantheman]

I have used, along with others within our own club, ordinary silicon bath sealant.

Surprisingly easy to 'squirt' into the gaps, maybe more difficult to remove, although not impossible, and even more surprising it withstands the heat in that area. Ideally of course the sealing faces would be better clean, but I have found it does work even on slightly dirty surfaces.
Lets not go down the route about colours, what is wrong with good old fashioned 'White', you can obtain bath sealant in a variety of colours now in DIY stores.
Stan.

[Steve M. W]

I used plumbers clear silicon soon went black after the first steam.

Steve

[Malcolm]

Gun-Gum, or the Halfords equivalent, as used for sealing leaky exhausts, works very well.

[havoc]

There is some sealant for hearths and so. Would stand up to the heat and adhere to metal.

[SteveW]

Bo,

I second Malcolm's gun-gum suggestion. I used it around the boiler barrel/smoke box joint when I re-built our club loco earlier this year.

I think originally some sort of fire cement was used but over the twenty or so years it sort-of crumbled. The good thing about gun-gum is that it has some form of fibre in it which make it tougher and it sticks like the proverbial.

One point I did find is I should have cleaned off my finger prints better. I left the smoke box with a few wet marks but they dried grey on the matt black finish.

[3405jimmy]

You can buy at B&Q small tubs of fire brick cement which worked fine in my Burrell Surprisingly it sticks very well to the steel and has never come loose.

Jim

[Shawki Shlemon]

Hi all
I must be eccentric as I use nothing between s/box and boiler & front plate, just good fit . for pipe holes ,I cut a thin sheet of brass/ bronze with a neat hole for the pipe and covers the bigger hole and apply any silicon sealant to keep it there and seal whatever gap left .

[Nexuas]

You can get a High temperature silicone sealant, which I had used to seal round my new fireplace in the house, I used this on my boiler/smokebox joint, when the loco was reassembled, however I had to remove the boiler a few weeks ago to fix an ashpan problem, and did not want to remove the cladding, so it was impossible to reseal the joint, although as it is a tight fit I had not experienced any real problems with the joint...