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Post by runner42 on Sept 4, 2021 0:25:03 GMT
Using a very large propane burner (114 kW) it was impossible to use the preferred method of applying the silver solder to foundation ring once the flux exhibited the watery appearance indicating that it was close to the required temperature, so the silver solder had to be positioned on the foundation ring at the outset and the heat applied to both the silver solder and foundation ring. The first attempt was to to lay strips of silver solder along the foundation ring but this was not that successful. The problem was two-fold, one the silver solder strips was dislodged due to the blast from the propane burner when placed at the edge of the foundation ring when trying to seal the join between the outer wrapper and foundation ring. Two the silver solder often melted before the copper reached temperature and tended to change from strips to nodules and as a consequence areas were not covered. This was overcome by producing small rings of silver solder in the same way when soldering rod stays and these were placed on the foundation ring side by side. The was possibly uneconomical in use of silver solder but I wanted a good coverage and the newly acquired 500g had to be put to use. I am not going to build another boiler. Brian Hi Brian, That worked out well in the end though, it's not the easiest of jobs. I'm not a fan of adding Silver Solder to a hot joint, you need to get it much hotter than necessary. 55% Silver Solder melts when it's hardly showing Red heat, so it's not necessary to get it all that hot. Anything that's unnecessarily hot just exhausts the flux more quickly than needed, and you end up with corrosion that you don't want. I've done a lot of jobs now with the Silver Solder being rested on the job, and there are a few things that make it work well. 1) I use a lot of thick creamy flux to completely cover the Silver Solder. 2) I form the Silver Solder to go right around the job if possible, so it stays where I put it. 3) I use a piece of Titanium wire to keep nudging errant Silver Solder in place. It always moves as the flux boils off the excess water, but it stays put once that's happened. If you do these things, you won't have the Silver Solder turn into balls because it's always submerged in flux which keeps the heat even. Hi Roger, thanks for your input. I agree with your points about flux exhaustion and placement of silver solder and the use of a prod to keep errant silver solder in place. Unfortunately putting silver solder close to the edge of the foundation ring gave little opportunity to nudge it back in place before it dropped down the side of the upturned firebox wrapper and required a more intrusive method of replacement. I am concerned about the corrosion you mentioned, I hadn't heard of this before. What type is this and how does it initiate? Brian |
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Post by Jim on Sept 4, 2021 0:43:48 GMT
Just a suggestion Brian but I found it very helpful to have a slight chamfer on the edge of the foundation ring adjascent to the fire box wrappers that way you had a rececess for the silver solder to flow along without running over the sides of the fire box.
Jim
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Post by ettingtonliam on Sept 4, 2021 2:17:44 GMT
Also it helps if the foundation ring is recessed slightly below the edges of the inner and outer firebox plates
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Post by Roger on Sept 4, 2021 7:15:23 GMT
Hi Brian, That worked out well in the end though, it's not the easiest of jobs. I'm not a fan of adding Silver Solder to a hot joint, you need to get it much hotter than necessary. 55% Silver Solder melts when it's hardly showing Red heat, so it's not necessary to get it all that hot. Anything that's unnecessarily hot just exhausts the flux more quickly than needed, and you end up with corrosion that you don't want. I've done a lot of jobs now with the Silver Solder being rested on the job, and there are a few things that make it work well. 1) I use a lot of thick creamy flux to completely cover the Silver Solder. 2) I form the Silver Solder to go right around the job if possible, so it stays where I put it. 3) I use a piece of Titanium wire to keep nudging errant Silver Solder in place. It always moves as the flux boils off the excess water, but it stays put once that's happened. If you do these things, you won't have the Silver Solder turn into balls because it's always submerged in flux which keeps the heat even. Hi Roger, thanks for your input. I agree with your points about flux exhaustion and placement of silver solder and the use of a prod to keep errant silver solder in place. Unfortunately putting silver solder close to the edge of the foundation ring gave little opportunity to nudge it back in place before it dropped down the side of the upturned firebox wrapper and required a more intrusive method of replacement. I am concerned about the corrosion you mentioned, I hadn't heard of this before. What type is this and how does it initiate? Brian Hi Brian, For that awkward placement of Silver Solder, I would probably have bent a large 'U' shaped piece that went around the edge on three sides of the joint, with a couple of small bends at the ends to hook over the edge to keep it in place. I spend quite a bit of time preparing the Silver Solder pieces if it's a tricky shape. You can use Tippex to stop that bonding to the Copper where the hooked pieces are. When I say corrosion, I just mean the Oxide tarnish you get when you head unfluxed Copper. It won't be an issue unless you exhaust the flux where you're trying to add the Silver Solder. |
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Post by runner42 on Nov 15, 2021 5:36:59 GMT
I was expecting to be well passed this point in my boiler construction, but in attempting to correct small leaks I introduced more problems than I was attempting to resolve. It started with the preferred sequence of construction was to silver solder the smokebox tubeplate as the last or penultimate operation. This I did, but having completed the build I was faced with a number of small leaks in the firebox tubeplate, so instead of resolving these with the use of high melting point soft solder as a caulking medium, I persevered with silver soldering these. The rationale was it was easier to flux up and place silver solder in the position required and heat the boiler so that the silver solder flowed. Using soft solder was difficult because a soldering iron is really essential to place the solder in position but even with a 2 Kw soldering iron isn't enough to heat the large amount of copper to the required temperature. So pre-heating with a propane torch is required, but the narrow aperture of the firebox caused burnt hands when attempting to use the soldering iron in a hot firebox. The fatal mistake was re-heating the firebox and tubes and flues to silver soldering temperature when these were fixed at both the smokebox and firebox ends, without taking precautions to bring the boiler barrel also up to temperature. Working alone makes this difficult as two pair of hands are necessary. The consequence of this was the differential in temperature caused two of the flues to distort slightly. Not good workmanship but the distortion didn't prevent the super-heater from being installed. However, a leak persisted and what appeared to be a leak around the flue to tubeplate solder joint turned out to be a crack in the flue just inboard from the tubeplate. I found this out by sheer accident, when instead of having the boiler in a horizontal position I let the boiler barrel drop, which then allowed the water to run down the flue and exit at the smokebox tubeplate. The fix is going to be very difficult because the crack is at the bottom of the flue, if it had been at the top with the boiler upside down exposing the firebox it could have been a simpler operation. Having the boiler in the correct upright position and using gravity to work in your favour requires it to be strung up at a height so access to the firebox is available from below. So I am trying to think of a suitable caulking medium that is in a paste form that can applied with the boiler in an upside down position. Any suggestions are most welcome. The leak rate is one drop every two seconds when cold but increases with temperature. Brian  Boiler_full by Brian Leach, on Flickr |
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mbrown
Elder Statesman
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Post by mbrown on Nov 15, 2021 7:32:38 GMT
Bad luck Brian... when a boiler gets close to completion this sort of problem is really disheartening.
First rule, I guess, is to consult a boiler inspector before committing to anything.
But one suggestion might be to fit a ferrule. That is, turn a length of bronze or copper to enter the flue and go beyond the crack. A collar at the firebox end of the ferrule will stop it slipping down the flue. Coat it well with soft solder paste (the highest temperature you can get) and push it into place, then heat until you see a bright ring of solder around the ferrule end.
The slight reduction in tube diameter might cause difficulty fitting your superheater, perhaps, but the ferrule doesn't need to be very thick and it means the crack is sealed, not only by solder, but by the ferrule itself and a greater area of soldered joint, if you see what I mean.
Good luck.
Malcolm
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jma1009
Elder Statesman
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Post by jma1009 on Nov 15, 2021 21:35:09 GMT
Hi Brian,
That is a most unusual problem - splitting of a flue - at the tubeplate - that I have never heard of before.
I cannot think that your description caused the problem i.e. silver soldering in the smoke box tube plate.
I do the blackhead last with the last sections of the foundation ring.
I am having great difficulty in understanding how your quite thick flue tubes/tube could have split. I don't think that your explanation makes sense to me.
Given that you have had numerous issues with this boiler, I would tentatively suggest that if you adopt the solution proposed by Malcolm then you will be prevented from any further 'running after leaks' with silver solder. I have the highest regard for Malcolm and his experience, but what he has advocated is completely outside my own experience and what would be acceptable on a flue tube, and presupposes everything else is sound and leak free.
You need some expert advice on how possibly to retrieve matters, if that is possible. Personally, I think if you fix the split flue tube with a soft soldered sleeve, and then pump up, you are going to eventually have water squirting out of bits of the foundation ring probably caulked temporarily with hard deposits of flux on the inside, and I could suggest other bits of concern.
I would suggest you consult your boiler inspector before any further remedial action is attempted.
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Post by runner42 on Nov 15, 2021 22:20:42 GMT
Bad luck Brian... when a boiler gets close to completion this sort of problem is really disheartening. First rule, I guess, is to consult a boiler inspector before committing to anything. But one suggestion might be to fit a ferrule. That is, turn a length of bronze or copper to enter the flue and go beyond the crack. A collar at the firebox end of the ferrule will stop it slipping down the flue. Coat it well with soft solder paste (the highest temperature you can get) and push it into place, then heat until you see a bright ring of solder around the ferrule end. The slight reduction in tube diameter might cause difficulty fitting your superheater, perhaps, but the ferrule doesn't need to be very thick and it means the crack is sealed, not only by solder, but by the ferrule itself and a greater area of soldered joint, if you see what I mean. Good luck. Malcolm Hi Malcolm, an excellent suggestion. Just one point on the use of solder paste, I EBay'd solder paste and the returns were exclusively for a paste (read flux) for silver soldering. I assume you mean a paste that contains soft solder particles in a binding medium. Do you have a link for the type of product you are advocating? Brian |
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Post by runner42 on Nov 15, 2021 22:39:58 GMT
Hi Brian, That is a most unusual problem - splitting of a flue - at the tubeplate - that I have never heard of before. I cannot think that your description caused the problem i.e. silver soldering in the smoke box tube plate. I do the blackhead last with the last sections of the foundation ring. I am having great difficulty in understanding how your quite thick flue tubes/tube could have split. I don't think that your explanation makes sense to me. Given that you have had numerous issues with this boiler, I would tentatively suggest that if you adopt the solution proposed by Malcolm then you will be prevented from any further 'running after leaks' with silver solder. I have the highest regard for Malcolm and his experience, but what he has advocated is completely outside my own experience and what would be acceptable on a flue tube, and presupposes everything else is sound and leak free. You need some expert advice on how possibly to retrieve matters, if that is possible. Personally, I think if you fix the split flue tube with a soft soldered sleeve, and then pump up, you are going to eventually have water squirting out of bits of the foundation ring probably caulked temporarily with hard deposits of flux on the inside, and I could suggest other bits of concern. I would suggest you consult your boiler inspector before any further remedial action is attempted. Hi Jullian, that is a rather negative response and somewhat disheartening even for you. The results of the leak testing shows that it is in the position that I mentioned although a visual inspection does not show signs of a crack and the leak rate indicates that the split is not great. I don't know how you came to the conclusion that pressurising the boiler would result in water squirting out of the foundation ring caulked temporarily with hard deposits of flux and other unmentioned bits of concern. Do you have X-Ray vision that extends over the vast distance from Wales to South Australia? A closeted Superman. Brian |
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Post by coniston on Nov 15, 2021 22:42:06 GMT
I think this is the sort of thing Malcolm is talking about, really useful for assembling brass water tanks etc. www.cromwell.co.uk/shop/welding-brazing-and-soldering/flux/standard-fryolux-paint-40-60-500gm/p/FRY8756026SLike Julian, I would consult your BI before doing anything else. A professional boiler maker (a decent one anyway) would probably remove the failed tube and replace with a new one. I am not sue I would want to trust a repair of that sort one a new build boiler, you just won't know long before it could fail again. Chris |
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mbrown
Elder Statesman
Posts: 1,795
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Post by mbrown on Nov 15, 2021 23:49:31 GMT
Yes, I had Fryolux soft solder paint in mind, although my pot of it is old and looks rather different (a little goes a long way, so it lasts ages).
But the key thing is to use something a fair way below silver soldering temperature, whatever its constitution.
I haven't used the ferrule method on anything as big as a superheater flue. But my Burma Mines boiler has a 1/4" dia pipe running from the backhead to the tubeplate to take the exhaust from the vacuum ejector. On the first test, it was clear that the joint with the bush in the backhead was letting a drip through about 1/2" in from the backhead. I did exactly what I suggested to Brian and the BI passed it on test with no leaks at a steady 180 psi.
But I certainly agree, check the plan with the BI first. I do agree with Julian that the fault in Brian's boiler is a bit hard to visualise, so I am quite prepared to be told my approach wouldn't work in his case.
Malcolm
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Post by Cro on Nov 16, 2021 8:24:24 GMT
I personally think if it were me I would cut the tube out and put a new one in, its a brand new boiler I wouldn't want to start its life with a "fix" in what you have already proven is a difficult area. I don't see a reason for Malcolm's fix to not work just if I was the BI I think I would rather see a new boiler with a new flue in if possible - what's to stop that crack from growing with the boiler expanding and contracting and as you say you can't see the crack how do you know fitting a ferrule will cover it all, then you are really stuck once its in place! Certainly not easy but worth getting right in the end.
I think what Julian is trying to say is that once this leak is fixed you may find others when able to fully clean and pressurise it for a period of time for its official tests. It's not uncommon for flux and residue to plug holes in things like the foundation ring if not thoroughly cleaned which later show up during testing so I don't think his comments are that unfair if I have understood him correctly and he has far more experience in building boilers than some of us.
Just my thoughts that's all.
Adam
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Post by ettingtonliam on Nov 16, 2021 9:02:54 GMT
Could I suggest temporarily plugging the offending flue tube, and taking the boiler up to test pressure to make sure that the rest of it is sound? Not much point in expending a lot of effort into fixing this problem if there are other weak areas. After all, if one flue tube has cracked (and I don't understand the reason why it has cracked), how do you know the others haven't?
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Post by runner42 on Nov 16, 2021 22:42:04 GMT
I personally think if it were me I would cut the tube out and put a new one in, its a brand new boiler I wouldn't want to start its life with a "fix" in what you have already proven is a difficult area. I don't see a reason for Malcolm's fix to not work just if I was the BI I think I would rather see a new boiler with a new flue in if possible - what's to stop that crack from growing with the boiler expanding and contracting and as you say you can't see the crack how do you know fitting a ferrule will cover it all, then you are really stuck once its in place! Certainly not easy but worth getting right in the end. I think what Julian is trying to say is that once this leak is fixed you may find others when able to fully clean and pressurise it for a period of time for its official tests. It's not uncommon for flux and residue to plug holes in things like the foundation ring if not thoroughly cleaned which later show up during testing so I don't think his comments are that unfair if I have understood him correctly and he has far more experience in building boilers than some of us. Just my thoughts that's all. Adam Hi Adam, I am coming round to your suggestion to replace the flue in question, it will be a surer way of satisfying myself and others that it is a sound boiler that will last. The problem that I have to resolve is how to do it. I think that it requires oxy-acetylene to heat the tube at the smokebox tubeplate end and when the silver solder is molten blow it out with an air gun. Satisfied that the flue is freed, apply the heat at the firebox end and when molten pull the tube out from the smokebox end. The new tube would be the reverse of the removal. If anyone wishes to comment on my rework plan then please do. I disagree with your comment that Julian is being in anyway helpful. I agree that he is a competent in boiler construction but his style is to make comments on the real and in this case imaginary problems without providing solutions. I am confident that the foundation ring is sound, because the visual inspection shows it be completely covered and no signs of voids that could provide a leak. He also mentions other problems which he didn't specify, which leaves one wondering. He only has the pictures and comments that I have posted, so that is the only evidence that he has. If he considers that I have been unfair in my comments then he should respond and hopefully provide details, not innuendo. Brian |
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Post by Cro on Nov 17, 2021 6:45:13 GMT
The idea of heat, air gun etc sounds hideous to me! I’d be cutting it out and starting again. If you did manage to successfully free the tube enough you could draw it forward by the time you get the firebox end of the tube to the Smokebox tube plate the solder most likely won’t be molten again and you’ll end up with a tube that’s stuck.
As I said, not easy.
Adam
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Post by flyingfox on Nov 17, 2021 7:24:42 GMT
Greetings Brian, I think Adam is exactly right, cut it out, the method you describe, heat the compressed air will only lead to more problems, and I would think the air would instantly cool and solidify the joint, leaving a stuck tube.
Various tube removal tubes have been described in ME over the years, as has the technique for removal.
Regards
Brian B
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Nov 17, 2021 11:50:50 GMT
Hi Brian,
You make a fair point above.
So, according to your own words and pics, I have selected a few, all from 2021:-
21st May - BI rejected the joints on the inner firebox.
9th June - Completion of inner firebox before flues and tubes in place "wasn't the ideal sequence". See also final pic of firehole ring.
NB The silver soldering of the flues and tubes to the firebox tubeplate is missing from this thread.
13th August - "Foundation ring - small voids nothing of consequence. A proviso is that there is further rework required to address the invariably expected leaks in unplanned areas, which for me is par for the course".
See final pic of 13th August.
2nd September - "My first inroads to verify the boiler's water tight integrity failed miserably due to problems with the foundation ring".
Use of house bricks as insulation for the barrel.
Can someone please explain to me how reheating of a flanged joint or foundation ring sections is going to have a clean joint and ensure adequate penetration of silver solder into these joints?
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Post by runner42 on Nov 17, 2021 22:03:06 GMT
Greetings Brian, I think Adam is exactly right, cut it out, the method you describe, heat the compressed air will only lead to more problems, and I would think the air would instantly cool and solidify the joint, leaving a stuck tube. Various tube removal tubes have been described in ME over the years, as has the technique for removal. Regards Brian B Now that's helpful Brian B. I don't have any information on cutting out the tubes, is it possible that chapter and verse can be provided as the process doesn't appear to me to be intuitive. Brian |
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Post by runner42 on Nov 17, 2021 22:22:00 GMT
Hi Brian, You make a fair point above. So, according to your own words and pics, I have selected a few, all from 2021:- 21st May - BI rejected the joints on the inner firebox. 9th June - Completion of inner firebox before flues and tubes in place "wasn't the ideal sequence". See also final pic of firehole ring. NB The silver soldering of the flues and tubes to the firebox tubeplate is missing from this thread. 13th August - "Foundation ring - small voids nothing of consequence. A proviso is that there is further rework required to address the invariably expected leaks in unplanned areas, which for me is par for the course". See final pic of 13th August. 2nd September - "My first inroads to verify the boiler's water tight integrity failed miserably due to problems with the foundation ring". Use of house bricks as insulation for the barrel. Can someone please explain to me how reheating of a flanged joint or foundation ring sections is going to have a clean joint and ensure adequate penetration of silver solder into these joints? Hi Julian, now I better understand how you arrived at your concerns. You have studied the pictures together with my comments and see potential problems, but they were a snapshot in time and and fortunately things have moved on. I should remember in future to provide pictures that show features in the best light and not adopt a worts and all approach. Your last sentence is another example of a throw away comment that leaves one wondering. Am I to assume that you mean the silver soldering the foundation ring is a one shot attempt and cannot be revisited because the flux cannot penetrate possible voids to provide a sound joint? From the BI's perspective he has only the availability of a visual inspection and the 2x WP test. Brian PS On the subject of the BI's rejection of the inner firebox and attachment of flues and tubes these were presented again to the BI and he OK'd them for final assembly. |
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Post by John Baguley on Nov 17, 2021 22:34:29 GMT
Hi Brian,
A member of our club needed to replace some of the tubes in a Simplex boiler that they had bought (I can't remember exactly why now). They made a cutting tool like a counterbore. The outside diameter of the cutter was made the diameter of the outside of the tube and it had a boss the same diameter of the inside of the tube to keep it perfectly aligned. The cutter was used to accurately cut the end off the tubes where they were soldered into the tube plates without enlarging the holes.
The front tubeplate is easy as you have direct access to the end of the tube but the firebox end is a little more difficult. They made an extension rod that passed through the tube from the smokebox end which screwed into the cutter in the firebox. The cutter could then be pulled against the end of the tube whilst it was rotated. I think they may have used a cordless drill to rotate the cutter or you could do it by hand. It apparently worked very well. The difficult bit is probably retrieving the tube from inside the boiler once you have cut it free!
You coud probably adapt an existing counterbore if you can find one of the correct diameter.
John
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