The Home Machinist!

I have a copper locomotive boiler with some small pin hole leaks that I want to attempt to plug with sodium silicate. How much is required per gallon of water? I can't find any application instructions on the Net.

I wouldn't do that...not with sodium silicate...

Where are the leaks?
Can you caulk them closed?

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Dan Watson
Building IC mikado in 1.5" scale

Absolutely NOT use sodium silicate in any model boiler. If done it will forever block any future repairs with soldering methods, and require a complete disassembly for cleanup and rebuild. ( That is nearly impossible by itself.)

Leave the sealing compound for bad radiators and cracked motor blocks. Use oversoldering techniques described in some of the old construction manuals. (Martin Evens?) Which one was it, described repairs of weeps?

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Big Dave

Be Alert! The world needs more Lerts.

The leaks are on the side of the firebox. I would like to be able to fire up the loco for running for a couple of days at the end of the month. After that boiler will be scrapped and a new steel one with copper flues will be built and installed. I was under the impression that sodium silicate or water glass was an exceptable fix.

Stays are notorious for getting weeps, because in a coal burner, the sulfer has a tendacy to strip the silver from the joint. it weeps B/C a pinhole was allowed in the joint, and stripping the cap openend it up, so it was a weak/incomplete job at the begining.

For repair, scrubbing with a SS brush and muratic or dilute sulfuric will clean the surface, (or sand blast in a dificult corner) and with a good torch use some Silver Bearing solder, that is lower temp than high silver content and overflow a layer of metal on the leaker. (Not soft solder).

While not for the faint of heart, a good torch , some thought and laying the solder on the flux, where the repair is, all helps to get things done, a scratch tool kept handy is also a help.

It is known to me, that a copper boiler is pretty much bulletproof, except for the erosion of the silver with coal. More boilers have been detroyed by dry fire than any other cause tho, as far as I know..

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Big Dave

Be Alert! The world needs more Lerts.

depends on what it was soldered with.

if done with sil-fos or phos-copper and in coal service, leaks are going to happen and are really un-repairable.

If you are going to junk it, then dump in some ginger powder.

Bill, do you have any idea what Blackgates (UK) uses for solder?

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Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com

no idea.

why do you ask?

my copper boiler is from them and i fire coal. i'm just curious.

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Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com

OK, Bill that begs the question of why it would be unrepairable with the Sil-fos? Many small boilers were made with this handy compound, but as I remember is prone to cracks on the fireside.

Is there more you can expound on?

I am working on a 3/4 Raretan boiler.

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Big Dave

Be Alert! The world needs more Lerts.

not cracks, really - leaks.

the joints become porous and unrepairable after exposure to high temp sulfur (after time).

to fix, you have to diasssemble boiler / joints, grind all the stuff out and resolder with silver solder - which is not possible.

hence - a new boiler.

Fred:

don't worry about it. They would use silver solder, nothing else.