Baz | 25/08/2015 12:25:51 |
1033 forum posts 2 photos | Please can I call on you all again for some assistance, I am trying to fit a smokebox to a boiler, the front of the boiler is out of round, as you would expect it to be, by about 15 thou. I am boring the smokebox rear ring to fit the high spots but I will be left with gaps which I assume need to be sealed. I have read lots of construction articles by Evans, Young and LBSC and none cover the fitting and sealing, Jack Buckler in the Sweet Pea book says to bore it a relatively easy fit on the front of the boiler barrel, not a word about any subsequent sealing. How do you all do yours? |
Paul Lousick | 25/08/2015 12:50:14 |
2276 forum posts 801 photos | 15 thou out of round at the smokebox is what I would call very accurate. It is not a pressure joint and can easily be sealed with heat resistant gasket sealant, graphite type or similar. Full size riveted seam boilers had gaps bigger than this and were sealed by peening the plates with a chisel to seal the gap. These had to seal against the full boiler pressure. Paul. |
Bob Youldon | 25/08/2015 14:18:21 |
183 forum posts 20 photos | Hello Baz, I wouldn't worry about the 15 thou gap when fitting the smokebox to the boiler; if you intend fixing the smokebox to the barrel, e.g. bolting it or fitting a few screws then most of any gap will disappear. I'd recommend a smear of gasket sealant, Heldtite or similar to both surfaces prior to assembly and that'll do the trick. Some folks will also put a bead of silicon sealant around the joint at the rear of the smokebox as an additional seal, but with only .015" gap I think it is a bit superfluous. I've used the foregoing method for many years with complete success. Regards, Bob |
Baz | 25/08/2015 20:05:11 |
1033 forum posts 2 photos | Thank you Paul and Bob for your replies, I have located a stockist of Heldtite so I will be purchasing some this week. |
Mark P. | 25/08/2015 21:03:04 |
![]() 634 forum posts 9 photos | Hello Baz, to seal smokebox to boiler wet assemble with fire cement, then seal round all pipe fittings in the smokebox with the same. Available from most DIY shops. Mark P. |
julian atkins | 25/08/2015 23:10:21 |
![]() 1285 forum posts 353 photos | hi Baz, silicon sealant if perfectly ok. it will fill a 15 thou gap. car gasket sealant is also ok. you can always tap the copper to get it to fit. it wont do the boiler any harm. dont ever use fire cement as advocated by Mark P. it will crack and leak. i always make mechanically sound joints around pipes in the smokebox. cheers, julian |
Baz | 26/08/2015 16:22:44 |
1033 forum posts 2 photos | Julian, Silicon sealant as in the stuff the local DIY shop sells for sealing the bath etc? I was not sure if it would take the heat but if you recommend it I am sure there is half a tube of it in the shed, left over from domestic duties. Thanks
Barry |
julian atkins | 26/08/2015 16:36:22 |
![]() 1285 forum posts 353 photos | hi barry, yes ordinary silicon sealant is perfectly ok. however there is a high temp version available from Screwfix for sealing fireplaces. cheers, julian |
Neil Wyatt | 26/08/2015 17:43:51 |
![]() 19226 forum posts 749 photos 86 articles | Posted by Baz on 26/08/2015 16:22:44: I am sure there is half a tube of it in the shed, left over from domestic duties. If there's 'half a tube' of silicon sealant anywhere on the planet, I've never found it Neil |
Paul Lousick | 27/08/2015 00:08:17 |
2276 forum posts 801 photos | Car accessory stores sell high temperature silicon gasket material for use on car engines. |
Speedy Builder5 | 09/07/2017 07:29:50 |
2878 forum posts 248 photos | Old thread, but I will prolong it. I want to add dummy rivets around the smokebox joint of a 5" SPEEDY. Do I drill for the rivet, lightly countersink inside and set the rivet, or use soft solder and then clean up afterwards or use some sort of glue ? |
JasonB | 09/07/2017 07:51:27 |
![]() 25215 forum posts 3105 photos 1 articles | Why not screw it on with slotless roundheads, look like rivits but don't need hammering home. When I have done dummy rivits I just deburred the back of the hole, cut rivit so length equals metal thickness and then one punch mark in the rivit has been enough to expand it in the hole. Taper reamer can also be used from the inside rather than a csk |
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