[modeleng] Re: Solder Qestion
- From: Allen Messer <al_messer@xxxxxxxxx>
- To: modeleng@xxxxxxxxxxxxx
- Date: Thu, 27 Jul 2006 05:09:07 -0700 (PDT)
Glad you were successful with the repair job, as they
are always more trouble than new construction. Thanks
for sharing the details with the rest of us as we can
profit by your methods.
Al Messer
--- Bede McCormack <bede@xxxxxxx> wrote:
> Well I've finally managed to seal up the old Conway
> boiler thanks to
> advice from the list group and want to report back.
>
> The short version is that, as we know, repairs like
> this require a
> thorough cleaning and opening up of the offending
> gap, then ample high
> temperature fluxing, then closing up the gap as much
> as possible (shim
> or tap the gap closed), then more flux and then very
> high heat to flow
> the comsol (296C, 564F) to a smooth finish over the
> leak. I used a
> scratch rod to help flow the comsol and add more
> flux while heating.
>
> Materials used: Comsol high temperature soft solder,
> and "Bridgit"
> burn-resistant soldering flux, both of which I got
> through Reeves. I
> guess the comsol is from Johnson Matthey in the UK
> <http://www.jm-metaljoining.com/index.htm>, but the
> flux is actually
> sold by a US company, J.W. Harris in Mason, Ohio,
> though its actually
> made in Mexico... <http://www.jwharris.com/home/>
> I tried other
> fluxes (Oatey), but they blackened before the solder
> melted and made a
> mess. The Bridgit stuff stayed clear throughout the
> heating and seemed
> to have worked fine, it contains Zinc Chloride, so
> presumably etched
> into the metal a bit.
>
> Here're a few details- In the end there were three
> places where it
> leaked- the known leak where boiler barrel meets the
> throat tube along
> the lower left quadrant, an expected and later
> realized leak around the
> firehole ring, and a completely unexpected leak
> around the lower half
> of the smokebox end of the superheater tube...
>
> The superheater tube was a tiny pinhole and sealed
> right up with flux
> and comsol after a thorough cleaning and picking at
> the approximate
> position of the hole (couldn't really see it even
> with a magnifying
> glass).
>
> The same with the firehole ring- clean, clean clean,
> and pick away at
> the hole itself to give the comsol a clean
> "purchase". The leak was
> along backhead side of the upper half of the ring,
> so after I'd cleaned
> up and fluxed the gap, I flipped the boiler onto its
> back and took a
> bit of 3/4" round bar and gently banged the ring
> back up against the
> opening in the backhead to seal up the gap as much
> as possible, then
> stood the boiler on its front/smokebox end and
> soldered immediately so
> the comsol flowed into the gap.
>
> The barrel/throatplate hole was another story. I
> figured I wouldn't be
> able to pick away any solid silver solder, so I
> picked away at the
> debris/caulk with a bit of sharpened 1/8" steel rod.
> As I cleaned and
> picked away at the hole, it gradually opened up into
> a real gaper- a
> long, thin crescent-shaped thing almost 2 inches
> long, 2 cm high at its
> midpoint, tapering to paper- thin at the edges. It
> seems the silver
> solder along this seam never "took" properly, and
> the gap was a result
> of the the silver solder coming away, and the barrel
> end being slightly
> deformed inward, partly, perhaps as a result of my
> cleaning efforts.
>
> I then made a copper shim/bung. This had to lay
> "flat" along the curve
> of the barrel and have the correct varying height
> along its length
> (i.e., 2cm in the middle, tapering to paper
> thickness at the ends). In
> addition, it had to be "shim-like" so that the
> leading edge slipped
> easily into the gap and then angled up to close the
> gap. 'This took a
> few tries, but in the end I managed to cut and file
> the shim so that it
> was a very tight fit and just about closed up the
> hole completely. I
> tapped it almost all the way home, but held back the
> final taps 'til I
> was actually ready to solder. Then I removed the
> shim and cleaned the
> hole and surrounding area very thoroughly, running
> we/dry sandpaper
> inside it, steel wool all along the barrel and
> throatplate, etc., 'til
> it was all nice and shiny. Then I heated it a bit
> and plunged it into
> the acid bath for a good soak. Then I cleaned it
> all over again 'til
> it was nice and shiny.
>
> Finally I was ready to solder. I upended the boiler
> onto its backhead
> with a slight list to starboard (just two or three
> degrees) so the
> solder would run up against the barrel (the leak was
> on the left side).
> Then I fluxed the gap inside and out, including
> the area all along the
> barrel and throatplate adjacent to the hole, then
> fluxed the shim
> itself, and then banged it into the gap 'til it was
> just proud of flush
> with the forward edge of the throatplate. then I
> hit it with my
> Sievert torch plus two hand-held plumbers torches
> (BernzOmatic). I
> rigged cradles out of bricks to hold the two
> handheld torches. This was
> a lot of heat, but it brought the copper to
> temperature quickly until
> the comsol flowed into the area, covering the length
> of the shim and
> about 3/4" beyond with a thick, smooth layer an
> eighth of an inch or so
> thick. Let cool and quench with water (no acid).
>
> I plugged up all the bushes and tested the thing to
> 180 pounds which is
> double working pressure. It held for a good half
> hour without any
> signs of leaking, so I was happy with it. I later
> put all the fittings
> back on and fired it using two propane torches held
> in the firebox and
> it seems to hold fine.
>
> One note- I fixed the superheater tube leak first,
> then the
> barrel/throatplate leak, and lastly the firehole
> leak. Not sure why
> in hindsight, guess I felt I wanted to keep the
> heatings as far from
> each other as possible, both in distance, and with
> length of heating
> required, though I imagine the whole boiler was
> equally heated during
> each repair job.
>
> Okay, sorry to go on, just wanted to to let anyone
> interested know that
> repairs like this are possible, and also because I
> now have another
> question (on lubricators) and don't want to appear
> ungrateful for the
> advice I got for this last project!
>
> Regards,
> Bede McCormack
> Brooklyn, NY
>
> On Jun 14, 2006, at 3:50 PM, Clif Walker wrote:
>
> > HI,
> >
> > I would be inclined top make up a shim and solder
> it in with Comsol.
> > Perhaps
> > a brass screw in through the side just to hold the
> shim in place
> > whilst you
> > solder
> > The main problem is getting a Flux which is
> aggressive enough to run
> > in and
> > clean out the slot to ensure that the solder
> takes.
> > In the old days Reeves used to sell a flux called
> Fluxall, this stuff
> > would
> > eat any muck in the area but the Manufacturers had
> to stop making it
> > because
> > of Health and Safety.
> > I think that the best stuff that you could use now
> is
=== message truncated ===
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