A question about vertical boiler construction

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Orrin
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A question about vertical boiler construction

Post by Orrin » Sun Aug 12, 2012 12:35 pm

The following is a picture-intensive boiler construction project. The pictures and text are a cut above average and I got some good ideas from it. I'm wondering about the choice of solder, however. Would anyone care to comment?

http://www.rcdon.com/html/vertical_boiler_project.html

This page tells of the choice of solder:

http://www.rcdon.com/html/vertical_boil ... 4_17_.html
Now it is quite possible that this joint would be leak free as-is considering that I riveted the heck out of it !!! However I will have a hard time fixing any leaks should they occur when I am boiler testing. To ensure the joint is sealed I will be adding a silver solder “caulk” to simply seal the joint.
The solder I am using is a 1% Tin, 97.5% Lead and 1.5% Silver solder that has a melting temperature of 588° F. This is about a 160° hotter than a standard silver solder which will help keep this solder solid during the consecutive soldering steps needed to seal the boiler tubes and bushings. This type of silver solder has a tensile strength of about 1750 PSI @ 300° F which is suitable for caulking joints....
...and, on this page:

http://www.rcdon.com/html/vertical_boil ... 4_23_.html
To solder in the first side of the boiler tubes I will be using a high strength non-lead silver solder. This solder has a tensile strength of about 9500 PSI and is comprised of 96% Tin and 4% Silver with a melting point of 430° F. This temperature will be ideal to seal the boiler tubes without melting the end plate caulking I had soldered earlier....
Does anyone have an opinion about the choice of solder? Comments?

Orrin
So many projects, so little time.

Harold_V
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Re: A question about vertical boiler construction

Post by Harold_V » Sun Aug 12, 2012 3:10 pm

The article clearly has silver bearing soft solder confused with silver solder. (Judging from the comments posted---I did not follow the links).
It is my (less than credible) opinion that soft solder has no place in a boiler.

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

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GlennW
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Re: A question about vertical boiler construction

Post by GlennW » Sun Aug 12, 2012 4:05 pm

Orrin wrote:The following is a picture-intensive boiler construction project. The pictures and text are a cut above average and I got some good ideas from it. I'm wondering about the choice of solder, however. Would anyone care to comment?

http://www.rcdon.com/html/vertical_boiler_project.html

This page tells of the choice of solder:

http://www.rcdon.com/html/vertical_boil ... 4_17_.html
The solder I am using is a 1% Tin, 97.5% Lead and 1.5% Silver solder that has a melting temperature of 588° F.
Here it states that the 97.5% lead solder melts at 361°F, which is far more believable than the claimed 588° that he posted.

http://www.all-spec.com/products/KW44110.html

He apparently has his facts all mixed up…so there is no telling what he actually used.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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Fender
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Re: A question about vertical boiler construction

Post by Fender » Sun Aug 12, 2012 5:26 pm

It is my understanding that rivetted joints that were sealed with soft solder was a common practice in the early days of live steam (1930s or so), but that practice has long since been discontinued in favor of silver brazing. It seems incredible that anyone would revert back to a practice long abandoned due to unfavorable experiences.
Dan Watson

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Marty_Knox
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Re: A question about vertical boiler construction

Post by Marty_Knox » Sun Aug 12, 2012 6:30 pm

I didn't see what pressure he plans to operate at, or what fuel he intends to use. If he's going to burn butane and run it at 50 PSI or less, I don't see it as being a hazard. But, it is interesting that he doesn't show any calculations of a safe working pressure.

Ryker Carruthers
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Re: A question about vertical boiler construction

Post by Ryker Carruthers » Sun Aug 12, 2012 6:48 pm

Marty_Knox wrote:I didn't see what pressure he plans to operate at, or what fuel he intends to use. If he's going to burn butane and run it at 50 PSI or less, I don't see it as being a hazard. But, it is interesting that he doesn't show any calculations of a safe working pressure.
Marty, I have seen the video of the engine and boiler described here. It is fired by a pressurized colman fuel system. The working pressure is I belive he said 80 psi. the pop valve may be set higher though. here is the video


http://www.youtube.com/watch?v=8FXeYKvQ ... plpp_video

Ryker Carruthers

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Orrin
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Re: A question about vertical boiler construction

Post by Orrin » Sun Aug 12, 2012 8:31 pm

I didn't see what pressure he plans to operate at, or what fuel he intends to use. If he's going to burn butane and run it at 50 PSI or less, I don't see it as being a hazard. But, it is interesting that he doesn't show any calculations of a safe working pressure.
I'll give the fellow credit for reading KN Harris and he did some calculations. If you start at the beginning, linked above, you'll get a bigger picture than what I gave.

There are other problems I see, such as using brass instead of bronze for bushings; but, the thing that bothered me the most was the use of soft solder.

Orrin
So many projects, so little time.

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ken572
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Re: A question about vertical boiler construction

Post by ken572 » Sun Aug 12, 2012 9:56 pm

Orrin,

I agree with Harold 100% in not to use soft solder.
I would use the highest grade silver solder I could find.

My personal Choice would be SSF-6 by Muggy Weld. :wink:
http://www.muggyweld.com/?view=copperbrassbronze

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

James Powell
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Re: A question about vertical boiler construction

Post by James Powell » Sun Aug 12, 2012 10:48 pm

There is nothing inherently wrong with using soft solder as a calking material in a riveted boiler.

It is not, of necessity, the easiest, or fastest way to make a boiler. It requries more mechanical means of connection be added (rivets) to take the loads, and then the boiler being soft soldered together.

It is cheaper _in material_, but likely more expensive _in time_ to get a proper job of it.

80 PSI is about the highest I have seen this system used at, and mine runs at a more sedate 40 lb or so. Dad had at least one boiler that was made up this way, with a club certificate, in the last few years.

I'd hard solder (silver solder) the boiler together myself, I think...but there is nothing inherently wrong with a riveted & calked boiler.

James

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Bill Shields
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Re: A question about vertical boiler construction

Post by Bill Shields » Mon Aug 13, 2012 9:13 am

I would suggest that anyone building a copper boiler look at the BIG, long-term picture, not just the 'here and now'.

Anything soft-soldered is going to have a finite life - it may be a 40 year life, but will have a limit, because of degradation of the solder.

A proper silver soldered boiler will have joints (and a total structure) that out-live most builders, and probably their children.

Considering the small size of this thing, how much heat is it going to take to silver solder it properly to begin with - and then forget?
Too many things going on to bother listing them.

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gwrdriver
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Re: A question about vertical boiler construction

Post by gwrdriver » Mon Aug 13, 2012 10:47 am

James Powell wrote:There is nothing inherently wrong with using soft solder as a calking material in a riveted boiler.
I generally agree with everything which has been said so far, and in a quick look at the photos it appears he has done a good workmanlike job of the copper, . . . he certainly riveted it to death. The problem I have is the old slippery slope . . . . there are going to be a number of people who are looking for the cheapest & quickest way out, who see this article and then say all those kill-joys who insist we use silver solder are full of it - the evidence shows soft solder is perfectly OK. The problem with this will be, will they consistently do as good a job of the copper work as this man has, or will they cut corners there too? I don't know if the guy confused his solders or not, but the tensile strengths he quotes are almost certainly at room temperature and what potential builders will be unaware of is how sharply the tensile strength curve drops off for soft solders after they reach 175degrF. One little change to soft solder here, a little cutting of material corners there, and misjudgement of how much strength there is yon, and next thing you know you have a whole generation of "live steamers" who are building dangerous boilers and don't know why.
GWRdriver
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James Powell
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Re: A question about vertical boiler construction

Post by James Powell » Mon Aug 13, 2012 9:46 pm

Corporate Knowledge, passed from club members, especially for any "certified" boiler, would ensure that any club boiler should be safe, be it mechanically held together, or welded, or silver soldered, or glued with prestoglue PU239 in the year 2246.

Lone wolves are going to occasionally do something stupid, usually when they say "here, hold my Labatt Blue and watch this" (or words to that effect). There is nothing in the world which will stop them from that, other than banning people.


As regards soft solder having a life, while it will crystalize, the soft solder has the simple fix of remelting it, and it will return to its previous state...which you can't do with silver solder.

Cyclic loadings are a possible concern, note the concerns expressed with Duplex steel in NZ/Aus, but do not appear to be a substantial concern during the typical model boiler lifespan. Most engines which get worked are worn out before the boiler needs replacing, and become mantlepieces, at least in our experience.

James

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