A question about vertical boiler construction

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Bill Shields
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Re: A question about vertical boiler construction

Post by Bill Shields » Tue Aug 14, 2012 6:10 am

soft solder, once it has gotten very old and OXIDIZED / been contaminated internally and on the joining surfaces, is very difficult to get to seal up again. Simply remelting doesn't always get it to adhere in a non-porous manner.

I have 50# of scrap boiler here in my shop that is a testament to that problem.

I cannot say that I have ever seen an old, properly done silver solder joint fail..
Too many things going on to bother listing them.

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steamin10
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Re: A question about vertical boiler construction

Post by steamin10 » Wed Aug 15, 2012 4:25 am

I have seen two such silvered boilers fail at the fireside stays. During construction they were not adequately heated, so the silver solder only capped the nuts to teh sheet, without flowing throughout the joint. Burning coal, produces a hot flame and considerable sulfur, that oxidize the silver away. Once the capping was gone, a leak developed, as the stay was not bonded through the joint, only the surface.

One boiler was scrapped because of other issues, (Dry fired crown sheet) but the newer leaky firbox, had the stays removed and oversized for the succesful repair. It ran at Heston when they had the elevated line there for 3/4, now long gone.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
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Bill Shields
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Re: A question about vertical boiler construction

Post by Bill Shields » Wed Aug 15, 2012 4:50 am

Dave:

As I said, "PROPERLY SILVER SOLDERED" failure.

I have (like you) seen MANY improperly silver soldered joints fail.
Too many things going on to bother listing them.

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ken572
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Re: A question about vertical boiler construction

Post by ken572 » Wed Aug 15, 2012 10:57 am

Guy's

Bill Shields is correct when he say's "PROPERLY SILVER SOLDERED" the joint
will last a very long time.

Copper is very touchy to, Silver Solder, Stick Weld, Tig Weld, etc.

This is because many people burn, oxidize, and ruin the joint when the application
is being done.

This is because the mass of copper around the joint you are trying to repair is
stealing all the heat from the joint you are trying to make, and then TO MUCH
heat is applied at the joint, trying to get it to melt and flow.
You can tell because it will turn dark and sometimes crusty and impure. "BURNT"
"OXIDIZSED" and will fail early.

A slow and gentle continuous preheat on the copper around the joint you are
working on will prevent this.

Sometimes it can take one or two extra people around you to apply the preheat,
while you make your silver solder melt and flow into where it needs to be.

It takes lots of practice to get your technique down right.

NOTE: Each and every time you reheat solder and or silver solder to get it to melt
and flow, it require's a HIGHER TEMP to do so.

Ken. :)
One must remember.
The best learning experiences come
from working with the older Masters.
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Bill Shields
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Re: A question about vertical boiler construction

Post by Bill Shields » Wed Aug 15, 2012 11:40 am

I think that the 'burnt / oxidized' condition is more of a flux condition than that of the copper.

Use of the black flux instead of the white flux (forget names), can really help in this area.

I use a #12 rosebud to 'warm' the entire boiler before switching to a smaller tip for actual soldering.

This eliminates the need for helpers and greatly speeds the process to something tolerable. 8)
Too many things going on to bother listing them.

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ken572
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Re: A question about vertical boiler construction

Post by ken572 » Wed Aug 15, 2012 1:07 pm

Bill Shields wrote:I think that the 'burnt / oxidized' condition is more of a flux condition than that of the copper.
I think you might have misunderstood what I meant to say. If the major mass of
copper around the area that is to be repaired is not held at a proper preheat temp
while you are trying to silver solder, it will cause you to put too much heat into the
area that you are trying to melt and flow solder to, which will burn the flux away and
allow the area to oxidize and contaminate.
With that said, we are saying the same thing.
Bill Shields wrote:Use of the black flux instead of the white flux (forget names), can really help in this area.)
I agree with you that there are fluxes better then other's, but if you burn any flux
away the area will oxidize and contaminate.
Bill Shields wrote:I use a #12 rosebud to 'warm' the entire boiler before switching to a smaller tip for actual soldering.

This eliminates the need for helpers and greatly speeds the process to something tolerable. 8)
I've used rose buds many times. They are life savers when you need alot of preheat.

Ken. :)
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

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steamin10
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Re: A question about vertical boiler construction

Post by steamin10 » Thu Aug 16, 2012 9:14 am

Oh, OK. I can relent on the 'properly soldered' statement. Most often it is insufficient heat on the joint, which goes to a minor (mistake) lack of experience to see the joint flow in. Not everyone builds a boiler often, so the skills may be off a bit.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

hammermill
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Re: A question about vertical boiler construction

Post by hammermill » Thu Aug 16, 2012 9:25 am

iwill observe that many the refrigeration tech has trouble silver brazing when pipe size goes beyond a few inches in diameter
also the quality// grade of fluxes call play a big factor in sucess

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Bill Shields
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Re: A question about vertical boiler construction

Post by Bill Shields » Thu Aug 16, 2012 9:42 am

totally agree.

flux i have most success with is Stay Silv Black Flux.

White stuff is OK, but a pain to do an entire boiler with. I have made several with it (white) but the black is easier on the nerves.
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hammermill
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Re: A question about vertical boiler construction

Post by hammermill » Thu Aug 16, 2012 4:10 pm

i have used the purfied black fulx kind of a milky brown and was taught to keep it in a airtight contained so it doesn,t absorb oxygen and protect it from contamination.
several saw filers swear by this stuff.

James Powell
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Re: A question about vertical boiler construction

Post by James Powell » Thu Aug 16, 2012 6:29 pm

So, to take the words from the collective wisdom:

""Bill Shields is correct when he say's "PROPERLY SILVER SOLDERED" the joint
will last a very long time.

Copper is very touchy to, Silver Solder, Stick Weld, Tig Weld, etc.
""

and yet most on here are advocating in favor of silver solder vs riveted/calked soft solder boilers...

My opinion of it is that a mechanically connected, soft solder calked boiler is _easier_ for the neophite to get right, but it will take more time to build than a silver soldered boiler, and has other noticeable deficiencies.

I'm not advocating building boilers with soft solder & rivets for all, just that it is a still valid construction technique, and not one which poses any greater or lessor risk than a silver soldered boiler, or a welded boiler. (Different risks, yes, but not particularly greater/lesser)

James

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Fender
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Re: A question about vertical boiler construction

Post by Fender » Thu Aug 16, 2012 9:53 pm

One thing I haven't seen discussed is what alloys of bronze components are suitable in a silver-soldered boiler. Some bronzes are very difficult or impossible to SS, like aluminum bronze. Silicon bronze should be OK. What about leaded bronze like C93200? I know brass is bad because of the de-zincification problem.
Dan Watson

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