By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Smokebox to Boiler joint

All Topics | Latest Posts

Search for:  in Thread Title in  
Baz25/08/2015 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 Lousick25/08/2015 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 Youldon25/08/2015 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

Baz25/08/2015 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
avatar
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 atkins25/08/2015 23:10:21
avatar
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

Baz26/08/2015 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 atkins26/08/2015 16:36:22
avatar
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 Wyatt26/08/2015 17:43:51
avatar
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 Lousick27/08/2015 00:08:17
2276 forum posts
801 photos

Car accessory stores sell high temperature silicon gasket material for use on car engines.

Speedy Builder509/07/2017 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 ?
BobH

JasonB09/07/2017 07:51:27
avatar
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

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate