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Cleaning copper rivets.

How to ensure rivets are clean enough for silver soldering boiler.

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not done it yet13/01/2021 22:10:13
5628 forum posts
20 photos

I would have thought everyone would have realised that lead acid batteries do not dissolve away in the sulphuric acid electrolyte!

For others (readers🙂 ), lead sulphate is only a tiny bit soluble in water so the solubility product (ionic product) is very low. That will mean that the high concentration of sulphate ions in the electrolyte will depress any likelihood of lead dissolving as lead sulphate to effectively zilch. Lead sulphate and lead oxide have fairly high densities so as long as the electrolyte is allowed to settle, before use, any lead from the battery will be found as insoluble sediment.

Keith Hale14/01/2021 08:38:13
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286 forum posts

Fizzy is bang on!

It matters not how clean the rivets are when assembled, it matters only how clean they are at brazing temperature 660 °C. AND THAT IS THE FUNCTION OF THE FLUX. All you need to do is make sure that the components are free of oil and grease or anything else that will prevent capillary flow of the filler metal.

To be successful, I suggest that you appreciate what to do and why when brazing/silver soldering. It is a very simple process but skilful. Not acknowledging that will inevitably lead to problems, maybe not now but certainly in the future..

Several companies produce excellent data and information. Use it. Don't trust salesmen? Read the information in the form of BS 13424.

After all, if you want help with the selection of your Sunday roast, do you ask the person behind you in the shop or the butcher?

Regards

Keith

Brian H14/01/2021 11:40:07
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2039 forum posts
111 photos

I certainly bow to the superior knowledge of Keith. The main reason that I use a pickle is because most of my rivets were purchased in a job lot many, many years ago and are now a very dark brown colour.

I use a pickle to remove this and give the flux the best chance.

Brian

br14/01/2021 11:53:26
461 forum posts
3 photos
Posted by Brian H on 14/01/2021 11:40:07:

I certainly bow to the superior knowledge of Keith. The main reason that I use a pickle is because most of my rivets were purchased in a job lot many, many years ago and are now a very dark brown colour.

I use a pickle to remove this and give the flux the best chance.

Brian

 

I do exactly as you Brian, only because at Reeves many years ago when doing my first silver soldering, Alec Farmer stressed on me the importance of having everything scrupulously clean.

br

Edited By br on 14/01/2021 11:53:56

Robert Atkinson 214/01/2021 12:25:54
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904 forum posts
17 photos
Posted by br on 13/01/2021 21:54:54:

Dave

In simple terms, anybody buying one shot, as I have just done tonight, without a licence, is breaking the law ?

br

Unless you are a business or professional, yes.

Possesion of any of the restricted chemicals is also an offence, even if you have had them for years.

James Hall 315/01/2021 12:08:46
36 forum posts
8 photos

Thanks again for all of the helpful replies.

Just one minor point - should I rinse off pickling solution (whatever used) before soldering? Should soldering be done asap after pickling or can it wait a while?

Thanks.

James Hall 318/01/2021 14:42:55
36 forum posts
8 photos

img_0934-lr.jpg

Seems to have turned out ok with all joints nicely filled with solder and good fillets where required. Fitments not made yet so no pressure test but in the meantime no drips or weeping when filled with water. A certain amount of expensive solder strayed onto areas where not needed (forgot the tippex) but only cosmetically damaging and not strayed into bush threads. I'm content so far with my first boiler-making and silver-soldering adventure.


Once again, thanks to all for the advice.

Jeff Dayman18/01/2021 14:49:31
2073 forum posts
45 photos

Looks like a good job James. Be sure to hydrostatic test it before lighting a fire in it. Usual recommendation is two x working pressure, it should be able to hold that for 30 minutes (or longer). No air at all in the boiler, just cold water, for the hydrostatic test. If it passes with no leaks or weeps you are good to go.

br18/01/2021 15:14:01
461 forum posts
3 photos

Fine looking boiler -well done

I use very fine wet and dry and gentle rubbing on the not required clanger areas and it soon comes off.

br

Brian H18/01/2021 17:38:42
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2039 forum posts
111 photos

Looks to be an excellent job, well done.

Brian

James Hall 319/01/2021 15:08:59
36 forum posts
8 photos
Posted by Jeff Dayman on 18/01/2021 14:49:31:

Looks like a good job James. Be sure to hydrostatic test it before lighting a fire in it. Usual recommendation is two x working pressure, it should be able to hold that for 30 minutes (or longer). No air at all in the boiler, just cold water, for the hydrostatic test. If it passes with no leaks or weeps you are good to go.

Thanks for this Jeff. One thing puzzles me (or am I just being dense) - why fill with water? Compressed air and immersed in water to show any bubbles would surely serve the same purpose.

Brian H19/01/2021 15:18:55
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2039 forum posts
111 photos

Compressed air in water will show any leaks but does not prove structural integrity.

The 2X test with water will do that but you don't want air inside because there is a danger of it exploding in the event of failure.

With 100% water the pressure drops as soon as there is a problem.

Brian

James Hall 319/01/2021 15:32:13
36 forum posts
8 photos

Makes sense - thanks Brian.

br19/01/2021 18:03:27
461 forum posts
3 photos
Posted by Tony Wright 1 on 19/01/2021 17:51:29:

What is hydrostatic test ? I always thought it was an hydraulic test !

Tony

Google is your friend here,Tony.

Hydrostatic (Hydro) Testing is a process where components such as piping systems, gas cylinders, boilers, and pressure vessels are tested for strength and leaks

br

br19/01/2021 18:47:50
461 forum posts
3 photos
Posted by Tony Wright 1 on 19/01/2021 18:31:10:

Yes I did google it ,but when did It change from hydraulic test to hydrostatic test ? I must have made well over 50 boilers all had hydraulic tests !

Latest edition Southern Fedaeration Regs 2018 , and from my copy section 10 heading is as follows :-

10 Hydraulic Test procedure

So good enough and your boilers comply with the book.

br

br19/01/2021 19:24:18
461 forum posts
3 photos

Tony -- perhaps a question Jeff Dayman can answer?

Hydraulic is the term in the regs so good enough for me.

br

James Hall 323/01/2021 23:33:44
36 forum posts
8 photos

Well, today the moment of truth: 30mins at 4bar and 30mins at 6bar. No leaks or weeps so as it's designed to steam simple oscillators at 2bar I'm happy.

First failure also today - my safety valve refused to hold against any pressure. Cured the problem with Instant Gasket - but don't know how it will stand the test of time and it's not really exactly an elegant solution. Any suggestions for a relatively simple safety valve design?

Jeff Dayman24/01/2021 15:59:23
2073 forum posts
45 photos

Sorry been away from my PC for a few days for a medical matter (not Covid related at all).

Hydraulic vs hydrostatic test - this is just word choice these days, the terms are used interchangeably for boiler testing. I remember at school we were told that hydraulic was to be used for describing systems that involve moving fluid from place to place to transfer energy / force, where hydrostatic was used for describing pressure testing of pressure vessels with water only, no air, to high pressures, and very little or no fluid movement during the test.

I mentioned no air in my first post in this thread as a safety precaution. Water is for practical purposes not compressible at temps and pressures found on earth. (Scientists may be able to compress it in special labs and equipment, and I can't comment about water on other planets, in the universe, etc - just want to be clear). Air is very compressible and stores energy as it is compressed. If a boiler under test with water only in it, and fails, you get a small spurt and the pressure drops safely. If a boiler under test with compressed air or steam, and fails, you get an explosion and there can be shrapnel or fragments flying around. Test only with water in boilers, no air, for safety.

Re your safety valve leak - was it leaking at the thread or at the valve and seat? You can use sealant on the threads but NOT on the valve itself. For the best designs I have seen on safety valves look up the ones by Gordon Smith. Some time ago someone published his designs in various sizes for various scales or models in PDF form. I can't forward them here due to copyright issues but you should find them easily with google.

Good luck.

James Hall 324/01/2021 18:40:33
36 forum posts
8 photos

Thanks for your reply Jeff Dayman.

Leaking at the valve. I used the safety valve design shown by Myfordboy in his Youtube video series on making a simple boiler. It is essentially a cone in a taper with adjustable spring force. Of course I didn't seal the valve with instant gasket - I used it to form a cone-shaped silicon washer which makes a good enough contact to build pressure but as it's only a washer still allows a blow when required. Tested and adjusts and operates reliably at the 2bar I want.

I'll check out the designs you suggest.

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