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Post by mutley on May 7, 2008 7:10:59 GMT
I know of a 7.25" gauge boiler that was 'rebuilt', although only the barrel was kept in the end so in theory you can do it . In practice by the time youve cleaned all the plates up and made new stays it would as quick to start again.
Andy
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brozier
Part of the e-furniture
Posts: 335
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Post by brozier on May 7, 2008 8:32:07 GMT
Heyfordian,
Are you sure the stays were silver soldered to begin with?
If they were originally (or subsequently) soft solder caulked my understanding is you will not be able to Silver Solder afterwards.
Not sure if this is chemical or just due to the heat affecting other joints.
If it were me (and I took my own advice!) I'd pressure test with air under water to see where the leaks are and Comsol those and then see if the boiler will pass the hydraulic test.
I'm assuming the stays are screwed? So you only need to stop water leaking....
Better than scrapping the boiler....
Cheers Bryan
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Post by baggo on May 7, 2008 9:16:42 GMT
Good point Bryan. Comsol has a grey colour and looks very different to silver solder. It's also very soft and scrapes off easily.
It would be worth trying the Comsol route to try to repair the boiler - there's nothing to lose really.
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Post by Shawki Shlemon on May 7, 2008 9:21:06 GMT
Hi Ausden I have always used Comweld no 2 and still have some , it seems OK to me .
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Post by heyfordian18 on May 14, 2008 19:12:04 GMT
Hi there guys! Sorry that its gone a bit quiet from me, but progress has been made. After considerable research and discusson with professional boiler makers, I have decided that there is no alternative but to scrap the boiler. I am certain that silver solder was used, and have identified it as Silver Flow 55. I am reliably informed, that over the last few years, there have been some batches of Silver Flow 55 (no particular manufacturer involved) which have a slight orange tinge when put side by side to other sticks of the same specification. This filler can have an orange peel or aero bar type surface finish if heated for too long when used, and, this is where I believe that my boiler has suffered, will go porous when re-heated. Nothing to do with the flux or gases. To test this report, I have cut some of the solder from an undisturbed joint on the throatplate, and re-used it on a test piece. Under the eye glass it has a very rough surface finish after re-heating, and (subjectively and not through any scientific test) the joint is very weak and easily dismantled. I am minded to put the boiler on the band saw, to cut through the firebox to have a look inside. Might learn something about solder penetration around the foundation ring which is where the problem started. Then I suppose its 'weigh-in' time at the scrappy to subsidise the material for the new one! So, thanks to you all for your words of wisdom and advice, the response from you all has been very much appreciated.
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Post by chris vine on May 14, 2008 22:11:44 GMT
Heyfordian,
It is too late now, but I was once told that it is a good idea to put fresh flux over joints which are to be reheated as it protects them from oxidation.
Anyone else know about this? is it true?
Chris.
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ianmac
Part of the e-furniture
Posts: 308
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Post by ianmac on May 15, 2008 3:44:46 GMT
Just by chance i read this today from nsa.kpu-m.ac.jp/gijutu/kousaku/easyweb.easynet.co.uk/chrish/wrk_tips.htm"To prevent silver solder from leaking to unwanted places on the part(s) to be soldered, before you begin use your acetylene torch and with no oxygen, run the flame along the part(s) leaving behind a sooty covering. Now wipe off the area(s) to be soldered. The excess solder will not stick to the soot.."
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Post by heyfordian18 on May 15, 2008 19:01:08 GMT
Hi Chris, all joints in the vicinity of the working area were always generously fluxed. That was pointed out to me some time ago when re-working another boiler.
I know that on a couple of occasions I softened joints outside the direct working area with the pre-heat torch while concentrating on the stay with the direct heat. It is one of those joints that has now gone porous with the orange peel finish.
After that experience I have always found someone else to assist with the work and watch what was going on with the pre-heat torch.
There is no going back now, a painful lesson learnt, but there's always next season to run the engine!
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Post by AndrewP on May 15, 2008 20:21:29 GMT
Chris,
If I want an already silver soldered joint NOT to be affected by subsequent soldering near to it then I dirty it up before doing the second (or 20th) soldering, habitually use Tipex but any 'solder stop' will do. I don't have a half finished or gash boiler to try it on the larger scale than jewellery but I would have thought the process was sufficiently similar......
Fluxing the nearby joint is counter intuitive to me since it promotes solder flow and that is a good joint so the last thing we want is solder to flow out of it.
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