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Boiler rivets soldering question

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gordini

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Discussion starter · #1 ·
Ok here is the second question, i am thinking to put some rivets to my Ruby's boiler. Scale hardware has many sizes available. If i soft solder them will they handle the heat or i need to silver solder them. Is it possible to silver solder such small rivets? Problem is that i'm not expert in silver soldering

Thomas
 
#2 ·
Number 1... DONT mess with the boiler if you don't know what you are doing!
Number 2... Unless the rivets are a PERFECT fit and seal perfectly, then when the soft solder melts you will have leaks. Whether the solf solder will melt or not depends on the specific solder alloy and where on the boiler it is and whether you run the boiler low on water by accident and a dozen other criteria. In general, don't use anything but high silver content solder on a boiler. The cheap stuff at the hardware store that has only a few percent silver in it is NOT good enough for boiler work. You need HIGH silver content solder.
 
#3 ·
Thomas,
an easy way is to use a 0.01" brass boiler wrapper and punch fake rivets with e.g. a NWSL riveter. I did this on my scratch built locos and it looks pretty good:




Regards
 
Discussion starter · #4 ·
Well i forgot to mention that i will wrap my boiler with brass sheet and between the boiler and brass i will put some heat blanket also.
Your boiler even with fake rivets looks very nice is just that i prefer real ones, Ofcourse if this is not possible and If i finally use rivets i might try the riveter.

Thomas.
 
#5 ·
Your boiler even with fake rivets looks very nice is just that i prefer real ones
Thomas,

If you are putting the rivets on a boiler 'wrapper' over a heat blanket then regular solder will work.

Is it possible to silver solder such small rivets? Problem is that i'm not expert in silver soldering

Yes. The 'cheap stuff' that Semper Vaporo mentions will work. (I got mine from Micromark - it melts at about 500 degrees. I also have some proper stuff that needs 1,400 degrees!)

Silver soldering (with the cheap stuff) is quite easy, but needs a blowtorch instead of an iron. I have a small butane torch which I use on regular solder jobs that need plenty of heat. Practice soldering with the torch on ordinary solder before you play with silver solder.

Now, soldering your rivets is probably best done from the back. I would drill the boiler wrapper, put the rivets through the holes, hold them in place with tape while I got the job supported on a piece of wood (firebrick would be better) then play the torch over the back while spreading solder and soldering paste where needed. Then chop/cut off the excess length of rivet at the back.

Drilling holes in straight lines is easy if you have a drill press and an X-Y table. Another option is to print/draw a row of rivets where you want them, tape the paper onto the brass wrapper, center-punch there the holes go, and then drill through the paper.

You might want to make up a dummy of paper first, so you aren't drilling and soldering a curved wrapper. Get the paper version right, then flatten it out and lay it on the brass and make the brass version.
 
#6 ·
It is very difficult to get consistent solder joints. There are always some rivets, where the solder wicks to the front and this is very difficult to remove. In the end the "fake" rivets are easier to make and look better, especially after painting. At least this is my experience.

Regards
 
#8 ·
http://www.stoodyind.com/Catalogs/FISC/05catpg372.pdf is illuminating with regard to the two Stay-Brite silver bearing solders readily available on the box store market. Both the original and the -8 variety share the identical melting points of 430F which means they will completely fail at that temperature even though the -8 product advertises 1,000 psi more in cold tensile testing. Just for reference: steam at 30 psig is 250F and steam at 60 psi is 300F. Dash8 also is more conductive to electricity [I suspect temperature transmission too] because it "has a higher silver content than regular Stay-Brite, .....". In years past Stay-Brite published the exact amount of silver contained in their products [used to be only one] in the 5% area; as I remember.
The tin and silver mix is used now because the EPA got-the-lead out of common plumbers solder, and the cadmium "wetting agent' was killing folks that worked the old solders in enclosed spaces [I think that I got a snoot full too; back in the olden times]. Tin soldering does not work well, but add some silver to the mix and the alloy will flow with low temperature fluxes [rosin/rosin acid] like water, and tensile strength will go way up.
These products should never be confused with brazing fillers that have silver contents in the 50% to 60% ranges [I use Sil-Braze 56 x 3/32" dia.]. Soldering is just that; like high temperature gluing. Brazing is a eutectic process that co-mingles molecules to produce a "progressive" alloy. A cross section of a solder joint will show parent materiel on each side of the joint with a marked and definite separation line. A cross section of a brazed joint will show no marked nor definite line, but rather the parent material on the first side is molecularly mixed in with the brazing filler materiel, which in turn repeats the molecular mixture in the brazing filler on the other side.
As a general rule soldered joints will fail at the solder line in cold tension tests. Under the same proviso brazed joints will fail on the parent material side of the joint. Every leaky silver brazed boiler that I have examined [brass, copper, monel] failed, under pressure, in the parent material close to the braze joint, but not in the joint itself.
 
Discussion starter · #9 ·
pre-made rivet strips is a good idea and maybe i order some but if the temperature at 60psi is 350f or 176c, that means that i can solder them without problems.
How do you calculate temperature related to pressure?

Thomas
 
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