Longitudinal stay ends

[chiptim]

I need to make the longitudinal stay ends from 3/8" AF Hex Pb. The closest I can find is 10mm Hex in Colphos 90. Is this a suitable material for stay ends?
Also I am right in thinking I can solder the firebox end directly without stay ends and just fit them to the smokebox end? (I'm assuming they prevent distortion when you solder the stays so that they end up straight and prevent bulging under pressure).

Regards Tim

[chiptim]

Thanks Paul,
I think I've found some Pb102 in the right size but it wasn't easy!
Regards Tim.

[Shawki Shlemon]

Hi Tim
I don't know what are the rules where you are but I would be talking to the boiler inspector before making or soldering the longitudinal stays . For example here in OZ they must be secured by threaded fittings on both sides .

[GWRdriver]

Shawki,
What, if anything, do you use as a thread sealant, especially on the smokebox ends?

[Shawki Shlemon]

I use loctite thread sealant ,I think it is no 567 . it comes in a tube like toothpaste . Never leaked or gave any problems .

[chiptim]

Hi Shawki,
having sourced the hex Pb102 I'm going to thread both ends as per the drawings. I believe these ends are silver soldered the same as any other bushes?
Regards Tim

[Shawki Shlemon]

That is exactly how they should be done Paul .

[chiptim]

Thanks Paul, Shawki
let me check I'm getting this right. The "nuts" are threaded on the inside to screw onto the end of the stay, and threaded on the outside to screw into the tubeplate(smoke box end) or backhead (firebox end). Where they screw into the boiler there's no bush, they screw directly into the copper and you're saying it is this joint that gets the loctite?
No copper washer unnder the heads?
Regards Tim

PS sorry for the delayed response, my PC at home has locked me out somehow...

[redmog]

Stay Nut and a Bush.

Sept 14, 2009 11:34:46 GMT chiptim said:

Thanks Paul, Shawki
let me check I'm getting this right. The "nuts" are threaded on the inside to screw onto the end of the stay, and threaded on the outside to screw into the tubeplate(smoke box end) or backhead (firebox end). Where they screw into the boiler there's no bush, they screw directly into the copper and you're saying it is this joint that gets the loctite?
No copper washer unnder the heads?
Regards Tim

PS sorry for the delayed response, my PC at home has locked me out somehow...

Yes Tim. Just as you have said - like in this drawing,
but without the wedge washer which is for sloping backhead only.
But - try and fit a bush as well if you can.
Like in the next photo.
It's always better than screwing into copper.
Stay thread and bush thread MUST be the same pitch!
A thin string of rolled up ptfe under the nut shoulder will seal if required.
Chris

[simonwass]

Something I've always thought possible given adequate care in fitting.
I wonder if rather than using the same pitch threads you use say 40 on the bush and 32 on the stay you could get a bit of preload on the stay?
I fully silversolder stays so could be getting compression on the stays which is the opposite we really require.

[Shawki Shlemon]

In our code if the copper is 1/8" or more , then bush is not mandatory but recommended ,if the metal is less than 1/8" thick the bush is mandatory. The choice is yours .The sealant is applied between the nut and the plate ( or the bush ) . I always fit bushes and play it safe .

[chiptim]

Many thanks everyone esp. for taking the time to post the pictures. The plate is about 10 SWG and my boiler inspector advised that bushes weren't required so problem solved. I've got the threads nice and tight. Apparently if they leak Camsol is the normal route.
Regards Tim.