Cleaning copper rivets.

[Brian HParticipant @brianh50089]

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

[Former MemberParticipant @formermember12892]

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[Robert Atkinson 2Participant @robertatkinson2]

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 3Participant @jameshall3]

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 3Participant @jameshall3]

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 DaymanParticipant @jeffdayman43397]

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.

[Former MemberParticipant @formermember12892]

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[Brian HParticipant @brianh50089]

Looks to be an excellent job, well done.

Brian

[James Hall 3Participant @jameshall3]

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 HParticipant @brianh50089]

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 3Participant @jameshall3]

Makes sense – thanks Brian.

[Tony Wright 1Participant @tonywright1]

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

Tony

[Former MemberParticipant @formermember12892]

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[Tony Wright 1Participant @tonywright1]

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 !

[Former MemberParticipant @formermember12892]

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[Tony Wright 1Participant @tonywright1]

Yes my locomotive boilers (7) have all had southern fed tests . As for my other boilers I test them as prescribed by Tubal Cain , Evans LSBC . So I’m pretty well up with procedures 😄 just wondered why the change in name? Anyone know?

[Former MemberParticipant @formermember12892]

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[James Hall 3Participant @jameshall3]

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 DaymanParticipant @jeffdayman43397]

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 3Participant @jameshall3]

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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