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Post by wdiannes on Dec 21, 2013 12:38:13 GMT
Can you elaborate Allan? What do you see may be a problem in "operation use"?
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Post by Deleted on Dec 21, 2013 17:17:51 GMT
SWAGED was the word I was looking for back there----------It's just that I've no personal experience with expanded COPPER tubes ( as opposed to steel that is)so was wondering how the rolled joint (NO! I'm not on Drugs--LoL) would react to the heating-cooling-heating cycle encountered during the locos use ??..........Or you could make them detachable by having some form of screw fitting, but that's getting a bit complicated.....Just an observation but you might want to put some small, hacksaw "nicks" across the tube plates to encourage the Silver Solder to flow through each joint to the inside ??.......Question to everybody}---- Be honest now!!...how many of you have actually checked each and every INNER tube joint (going around 360 degrees per tube) after silver soldering them .........
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Post by wdiannes on Dec 21, 2013 18:13:59 GMT
I talked to a few of the local people and they have been having success with rolled-in tubes so I decided to go that way. I got the boiler barrel, end plates, and dome soldered up this morning with the help of a 10K BTU propane hot plate to assist the oxy-acetylene torch and OMG it took a LOT of heat! (The disadvantage of 1/4" end plates and 0.130 wall tube for the barrel.) It isn't the neatest silver solder job I have done but I got nice penetration and a good inside beads. (A little generous with the silver solder and even managed to solder the boiler to the hot plate - what a job getting that apart! LOL!!!) The next step will be installing the tubes and doing a hydrostatic test.
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Post by Deleted on Dec 21, 2013 18:29:03 GMT
looks like you had a busy morning Dianne.. I also note that it looks like your rotary table must have arrived too... Pete
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Post by wdiannes on Dec 21, 2013 19:51:45 GMT
No Pete. My rotary table is somewhere in the northern Ontario wilderness. I got tired of waiting and did it the manual way - a little scary but it worked. I clamped a pivot bolt into the mill vice and an arm to the work piece and slowly rotated the work past the mill. Crude but effective
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Post by Deleted on Dec 21, 2013 20:10:16 GMT
cool.. any way that gets the job done is good enough for me... Pete
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Post by wdiannes on Dec 21, 2013 21:28:19 GMT
I got the tubes in - made an expander/beading tool for the 5/8" tube. Just the flue yet to go but I need to make another expander for 1-5/8". Not too bad a day's work .....
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steam4ian
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Post by steam4ian on Dec 21, 2013 21:39:46 GMT
Dianne
Fantastic work.
What are you going to use as an expander because for the flue it will need to be a rolling type. From your obvious ingenuity to will probably make one up before breakfast.
As for the tubes your expander could be a rubber bush type. Here you get a rubber bush which just fits though the tube, by having a threaded rod though the bush with nuts either end you compress the bush longitudinally so it expands around its circumference. BTW this has worked for me, the pressure of life has squeezed me longitudinally and my circumference has expanded; anyway that's what I tell my wife.
If all else fails, there is still Comsol.
Ian
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Post by wdiannes on Dec 21, 2013 22:30:44 GMT
....the pressure of life has squeezed me longitudinally and my circumference has expanded.... That's a good line; I think I might use that I am thinking of a rubber expander and was searching the shop for a suitable piece of rubber but haven't found one yet.
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Post by Deleted on Dec 21, 2013 23:26:41 GMT
Looking good there, DIANE !!........tickled "pink", no doubt ??---------PS, have just re-read my earlier posting and would ask that you totally ignore that tip about the hacksaw nicks to encourage solder flow around the tubes !! ( No point if you're swaging them, eh ??)..Memo to self--- LEAVE THOSE MUSHROOMS ALONE !!!!!
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Post by Jim Scott on Dec 22, 2013 0:05:30 GMT
Hi Diane I'm very interested in your idea to expand the tubes in place, after all it is common practice in full size. In answer to your query 'does rolling copper tubes into a copper tubesheet work?' the only reference I can find is from the Polish company Krais who manufacture roller expanders. In their literature they do list copper to copper, see table at krais.com/guide-to-correct-expansion/ but note the relatively large 10% tube wall reduction recommended. However, I suspect they might be talking of tubeplates upwards of 1" thick, you are certainly breaking new ground with such a thin tubesheet, especially with the larger of the tubes. Ian has mentioned comsol as a fallback position, another possibility, not that I think you will need it, is TIG welding, provided the copper is a de-oxidised type. Look forward to your conclusions following testing. Jim S
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jma1009
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Post by jma1009 on Dec 22, 2013 2:12:59 GMT
i dont like the idea of copper tubes in copper plates being expanded. if expanded that leaves one half of the end plate diameter completely un-stayed, and contrary to dianne's original design. i would strongly advise silver soldering same. comsol has no inherent strength, it is just a caulking medium. plus the end plate at one end takes all the force to and fro of the cylinder so quite unlike a typical loco boiler. this factor needs to be assessed with expanded tubes and doesnt seem to me to be a good engineering way of doing things, or sound from a safety point of view.
i think you have done a superb job so far in silver soldering up the boiler, dianne, but the remainder leaves me somewhat worried if the tubes are not silver soldered too.
cheers, julian
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Post by ejparrott on Dec 22, 2013 10:02:10 GMT
I've yet to come across copper tubes rolled in to copper tubeplates, steel plates yes, never copper. I'll be interested to see the long term results of it, I wonder about the thinning of the tube and then the repeated heated/cooling cycles.
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Post by wdiannes on Dec 22, 2013 11:04:38 GMT
Copper tubes rolled in to copper flue plates has been used locally by a few builders (in much thinner tube plates) with no problems though I am tempted to caulk with soft solder. I have not been able to find any information on "comsol".
OOPS! Just found comsol - a high lead soft solder.
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Post by Deleted on Dec 22, 2013 11:43:54 GMT
Hi DIANNE---------- Think of COMSOL more of a "Caulking" agent rather than a solder as such.......
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Post by wdiannes on Dec 22, 2013 12:22:04 GMT
Think of COMSOL more of a "Caulking" agent rather than a solder as such....... Is it 'pounded into place' cold or melted on hot?
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uuu
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Post by uuu on Dec 22, 2013 12:29:21 GMT
It's melted on. But it has to be at the end, as you'll not want to heat the boiler up to high heat afterwards.
I would try to pump the boiler up without it to start with, have faith in your expanding\rolling method. Comsol does tend to imply "I couldn't get it right fist time" although not a fair thought in this case.
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Post by Deleted on Dec 22, 2013 12:30:57 GMT
Hi DIANNE....In the past it's been used as a "Secondary layer" if you like over a weeping stay, or a "local" mechanical repair job maybe, where a temp. lower than the surrounding Silver Solder is useful..So it's melted on------- I used the phrase "Caulking agent" in that respect........I wouldn't use it as the main joining medium at this level of boiler work, though.........PS, once used then you can't re-silver solder in that area....
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steam4ian
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Post by steam4ian on Dec 22, 2013 12:33:40 GMT
Dianne
Comsol would be a last but effective resort. It is a solder and applied as such.
Copper tubes have been rolled into copper firebox tube plates for over a century and a half. Your tube plate is much thicker than most.
It needs to be remembered that the tube holes do not contribute to the stress on the tube plate from the internal pressure which is only applied to the plate in the spaces between the tubes, again your thick tube plate has a lot going for it.
Ian
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uuu
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Post by uuu on Dec 22, 2013 12:42:21 GMT
Just another thought. If you avoid Comsol, and try the expanded joints out under pressure, if you then doubt them, you could change your mind and replace with silver-soldered tubes.
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