Repairing a boiler

[jamesdblack]

HI,
I have a project that was abandoned by the builder because the boiler tubes slipped during silver soldering the firebox stays. Actually rather than slipped it looks as if the tube ends silver solder re melted and the tube plate distorted enough for the tubes to not protrude properly through the plate any more. To see if I can save an otherwise good and expensive boiler (a 5" King) I have machined out the tubes. Has anyone ever replaced tubes in an otherwise assembled boiler, remembering that a King has a narrow fire box? I have new tubes ready and a good sliding fit but am looking for advice on re-silver soldering them given that access is not brilliant in the fire box.
James

[brozier]

Hi James,

How many tubes have fallen out? All of them?

I guess your main issue is to solder them without disturbing the other joints.

I'd aim to lightly swage each end of the tubes so they cant fall out again (both ends), make up rings of Easy Flo 2 for each joint. I'd do one end per heating. Try and find someone capable with Oxy-Acetylene or oxy propane to do the fire box end or use a cyclone burner. Aim for one heat and caulk any pin holes with comsol. Make sure the preheat with propane is even.

Best of luck
Bryan

[maninshed]

I seem to remember an article in the ME covering changing tubes in situ on a boiler which was for a Maid of Kent. The boiler they did it on was old and conciderable time was spent cleaning up the tube plates both internally and externally. The tubes were then soldered in with high temperature soft solder. Now this I think was done during the 80s, whether a boiler inspector would allow this procedure now i'm not sure. The engine was owned by Percy Wood one time IMLEC winner and the article was written by Ted Joliff one time editor of the ME.

[Shawki Shlemon]

Hi James
It is a great experience , all you have to lose is the tubes and some silver solder if failed .Hopefully you succeed .
First consult a boiler inspector ,no point of doing something that will not be passed if successful .
If all the tubes are removed and the fire box tube plate is 100% clean , flare the tubes and enter them from the back in the holes , flux properly ( plenty ) and put rings of silver solder as mentioned above , warm the boiler all over and use oxy- acetylene to do the job , check for penetration from the front , if OK ( if suspect faults , fix before next operation ) do the front with new tube plate .
It is a big boiler and narrow long fire box , I built one but it is possible to fix.I am assuming everything else is OK .