Phoson 0 brazing rod

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jscarmozza
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Phoson 0 brazing rod

Post by jscarmozza » Mon Feb 04, 2019 4:01 pm

I have never used this type of brazing rod, but I understand that if used on clean copper, brazing is done without flux. My question is how is oxidation of the base metal prevented when applying heat? Is it through flame manipulation, oxidizing or reducing, or some other technique? Thanks, John

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Re: Phoson 0 brazing rod

Post by Harold_V » Mon Feb 04, 2019 4:52 pm

The title gives a clue. Such rod contains phosphorus, which has a serious affinity for oxygen. Strange as it may sound, it works quite well. My limited experience is with Sil-Fos.

H
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jscarmozza
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Re: Phoson 0 brazing rod

Post by jscarmozza » Mon Feb 04, 2019 5:05 pm

Thanks Harold, looking forward to giving this stuff a try. John

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NP317
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Re: Phoson 0 brazing rod

Post by NP317 » Mon Feb 04, 2019 9:04 pm

Just don't braze up a copper boiler with Sil-Fos rod, or similar.
I have read that Sulfur from burning fuels degrades the joints.
~RN

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10KPete
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Re: Phoson 0 brazing rod

Post by 10KPete » Mon Feb 04, 2019 11:15 pm

Absolutely correct, Russ! Makes changes causing brittleness.

I used to do a lot of fabricating with Sil-Fos, gas and tig, and it can't be beat for how handy it is compared to actually welding copper, which takes loads more heat!

Pete
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jscarmozza
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Re: Phoson 0 brazing rod

Post by jscarmozza » Tue Feb 05, 2019 9:19 am

Ok guys, you just opened an old wound...does the sulfur in coal really affect Sil-Fos and Phoson solder, I hear so many different opinions that I don't know what to believe. I've been running my LE Atlantic on charcoal (real wood charcoal that I make myself) because I suspected that the LE boiler was fabricated with Phoson-0 and would be adversely affected by burning coal in it, a lot of people think I'm nuts. A very experienced live steamer told me that he's never heard of a copper boiler failing for the aforementioned reason and that he'd be more concerned about the water that's in the boiler than the fuel that's heating it. Another told me that flaws in the soldering process and flux pockets are the culprit. Harris's web site says that they don't recommend Sil-Fos for high temp applications and I think they mention something about sulfur, but I'm not sure. Phoson joint's are said to be brittle at low temps but fine at higher temps, a good reason not to hydro a boiler with cold water. If I recall what was on the LE boiler fabrication drawings, they said to heliarc some of the components (castings) and use Phoson-0 for the rest of the joints. There has to be a lot of LE boilers out there, are there solder problems with those boilers? This coming season I was thinking about switching over to coal, the charcoal burns clean and hot but very fast...so I'd like to air this matter out beforehand. Thanks, John

jscarmozza
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Re: Phoson 0 brazing rod

Post by jscarmozza » Tue Feb 12, 2019 1:33 pm

I did some further research and found that Sil-Fos 15 is not recommended if exposed to sulfur or steam as would be the case in a copper boiler, and that phosphor/copper brazing alloys (Phoson) tend to make brittle joints. So far that's all I can find, but it's enough to resurrect my concern for how my LE boilers were fabricated.

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Bill Shields
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Re: Phoson 0 brazing rod

Post by Bill Shields » Mon May 13, 2019 6:36 am

I have personally built two new boilers to replace those originally built wit sil-phos....after time and exposure to sulphur, the joints turn into leaky sponges and are not repairable.The typical joint failure is in the firebox area (tube sheet and mudring included).

I have to say that I have not see a joint fail that was 'out in the air' and not exposed to hot gasses...like on a steam dome..
Too many things going on to bother listing them.

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Re: Phoson 0 brazing rod

Post by jscarmozza » Tue May 14, 2019 6:59 pm

Bill, what is the correct silver solder to use on a boiler?
John

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Bill Shields
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Re: Phoson 0 brazing rod

Post by Bill Shields » Tue May 14, 2019 7:50 pm

depends on that you have and how you are going to use it....and proper planning...

suggest you stay away from the stuff with chromium in it unless you KNOW you will be outdoors upwind at all times. I have quite a bit of the Cr alloy stuff that was given to me...and I always work outside.

35% silver solder is good for boilers. Folks say they like to use different alloys so that they can reheat an area without worrying if what they have already done will come loose...I have never had that problem. Silver solder melting point tends to increase a bit every time you heat it so, I don't worry.

In reality the screws and rivets we use to hold things together keep everything from moving when hot anyway, so why worry?

the biggest question is not what alloy, but what shape (size of rod) is most convenient for what you are doing.

If you are going to roll it in ringlets and wrap around tubes, or cut up little pieces and stick them along a fillet, then 1/16" is a good size...easy to wind on a mandrel in you lathe and cut off to rings for firetubes and / or staybolts.

if you have a larger gap to fill, the 1/8" is easier to work with as a long stick because it has some stiffness to it.

The straight sticks are a bit easier to work with (because they are straight) especially if you have to reach down inside of something very hot, but the solder in a long roll is more common to find....but annoying to straighten for those occasions when you need a straight section.

then there are the occasions when a flat, thin ribbon works well...but not very often with a boiler.

If you need pictures, let me know.

Most important is good flux (I like the black), a bucket of acid and plenty of heat...you would be surprised how much heat 50# of copper will suck up until you get it all up to 600 F...it's really a 3-4 handed job. I typically use at least one really big Sievert propane tip, a lazy susan to allow rotating things and most often an oxy-acetylene torch to get the heat up in a concentrated area after the entire boiler is almost to where you need it.

Also...don't plan on learning to silver solder by starting with a boiler...

Find someone that has done a couple and be an apprentice...guarantee you he will appreciate an extra pair of hands or two once it comes time to light up.
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10KPete
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Re: Phoson 0 brazing rod

Post by 10KPete » Tue May 14, 2019 10:14 pm

Bill, I think you meant Cadmium , not Chromium.

For future followers of the thread. Which is great!

Pete
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Re: Phoson 0 brazing rod

Post by Harold_V » Wed May 15, 2019 3:36 am

Yep! What Pete said. Cadmium is the devil (its purpose is to give better flow characteristics), and it can be, and often is, lethal. Avoid the fumes at all costs.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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