I LOVE Speedfit!

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This is basically as originally posted uk.d-i-y on 13/06/1996, with spelling corrections, and incorporating comments from the original thread. See thread snipped-for-privacy@news.demon.co.uk. The original subject (complete with spelling error) was "Capilliary fittings - how to solder successfully (LONG)"
This time the post is prompted by David W.E. Roberts who wrote on Fri, 1 Aug 2003 12:38:47 +0100 re "I LOVE Speedfit!" in message bgdjg8$nusf2$ snipped-for-privacy@ID-122774.news.uni-berlin.de

Capillary Fittings - How to Solder them Successfully (Version 2) ----------------------------------------------------------------
Capillary Fittings are used for joining copper pipes with solder. There are two basic types, with and without a pre-formed solder ring inside them. Those with the solder ring are usually referred to as Yorkshire, after the original manufacturer. Those without it are called end-feed, because you have to supply the solder by feeding it in between the end of the fitting and the pipe.
The following question - typical of those frequently asked - inspired this description. Thanks to Peter Neville for the original question, and to useful contributions at the time from Matthew Marks, John Laird, Jon Rouse, Andrew Willoughby, Karel Hladky, Andy the Pugh, Wookey, Ed Sirett, Simon Jenkins, and John Stumbles. This topic has been revisited many times since, and a Google search will surely elicit additional hints.
snipped-for-privacy@swansea.ac.uk (Peter Neville) wrote:

These things don't need THAT much heat.
The fitting MUST be bone dry and so must the inside of the tube for AT LEAST 12" from the joint. If there is ANY water lying in the pipe, or dripping from above, you WILL NOT be able to solder it. Get rid of the water, use a compression joint, or try that brilliant idea with the bread. If there is no water flow you can dry out this 12" length with the flame until steam stops appearing.
You MUST remove all traces of copper oxide from the mating surfaces with wire-wool. Yes wire wool. Emery paper will NOT work, it reacts with the copper in some way, neither will a file. Well, that's my experience - others tell me that wet-and-dry paper works fine. Others say Scotchbrite works. You can SOMETIMES get away without wire-wooling the INSIDE of the fitting but its not worth omitting it because of the hassle of reworking when it fails :-(. My little finger is just small enough to go into a 15mm capillary with a bit of wire-wool wrapped round it. Just one 360 degree wipe does the trick.
Some people swear by the use of acid fluxes which are said to avoid the need for this thorough cleaning. I have not tried them myself.
Having cleaned BOTH parts you must lightly smear BOTH with flux. As well as letting the solder flow this helps transfer heat between the parts.
Do NOT OVERHEAT. If the solder ring does not appear before the flame goes green something has gone wrong. Further heat will just distort the parts and can prevent you getting them apart without wrecking something.
You are not supposed to need to add any extra solder but I most always use extra solder to 'help' the solder ring to flow nicely. I use wire solder from a reel, not the stuff in a solid bar.
WIPE off any external flux while still hot. This is easy to do but plumbers never seem to bother. It eventually makes a green mess if you leave it.
INSPECT the finished joint when cool to be sure the solder flowed all round - otherwise you might have a leak. Visual inspection is final the secret of good joints. If you cannot see a thin silver ring of solder all around the jointed edge, there is something wrong.
If you want to solder the fitting to only one pipe leaving the other connections till later, you MUST put a short length of UNCLEANED and UNFLUXED tube in the other outlet(s) and make sure you use just enough heat to flow the solder, and keep the heat away from the other ends. A damp rag wrapped around the dummy stub will keep it cool if necessary The idea is to be SURE the solder ring does not melt on that end. When it's cool you can remove the dummy and the inner solder ring should be intact.
Other tips:-
Make sure the pipe is cut square. Don't use a hacksaw, invest a fiver in a pipe cutter tools which will make a square cut and with less effort.
Solder tends to run towards the heat, even uphill (a bit). So when you solder a vertical tube coming upwards out of a fitting, get the pipe hot before playing the flame on the fitting.
Always keep the heat even, i.e. move the flame all around the joint (or at least heat a bit one side then the other).
Use a metal sheet to protect nearby materials, or an asbestos gauze sheet obtainable from plumbers merchants for this purpose. Aluminium cooking foil, wet rags or wet tissues have been used, too.
Be VERY careful when aiming the flame downwards between floorboards etc. Dry wood ignites easily.
Use gloves to handle hot parts (ouch).
Cleaning surplus solder from parts: Heat until the solder melts, tap the part on the bench edge to jolt the molten solder out, then WIPE the surplus off with a DRY cloth. For cleaning off internal parts, attach cloth to a wire and pull it through the component after heating to melt solder.
Think about future modifications or repair to the system. You WILL NOT be able to unsolder the joint if it is in a leg of pipe from which the water cannot be drained. Consider using a compression joint, or a drain cock, at a strategic place to allow dead legs to be drained. Otherwise you have to cut the pipe.
Don't reuse old central heating tube on drinking water circuits - it tastes foul.
Do make a practice assembly of all parts before soldering to be sure lengths and bends are correct - much easier than unsoldering and starting over!

Andrew, I do agree, and all I said above also applies to end-feed fittings (which have no pre-applied solder ring inside). You just need to be even more rigorous to follow the advice, plus thoroughly wire-wool the inside of the fitting, and of course feed in solder wire which has been dipped in the flux tin.
More tips:
Practice with Yorkshires till you have the knack then try end-feeds. As Andrew says, they are much cheaper. Use Yorkshire for that awkward situation where the end-fed solder would have to go seriously uphill, e.g. the fitting at the top of a vertical pipe.
A good joint has a convex meniscus ring of solder visible all around the joint. If you don't see it, re-read the advice and start again.
-- Phil Addison The uk.d-i-y FAQ is at http://www.diyfaq.org.uk / Remove NOSPAM from address to reply
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Yes - if using a modern flux it's water soluble, and comes off easily. I think the original article is referring to Fluxite type paste - which isn't as good anyway.
--
*Avoid clichs like the plague. (They're old hat.) *

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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I knew what you meant. ;-) And Fluxite will wipe off while the pipe is still hot, but long after the solder has set. It just takes a little experience to know when this is.
--
*Always borrow money from pessimists - they don't expect it back *

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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Phil Addison wrote:

No? Not at all? In that case, if you heat up a test join and continually move it as the solder solidifies, the joint strength won't be compromised - is that what you're saying?
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On Thu, 7 Aug 2003 12:59:11 -0400, in uk.d-i-y "jerrybuilt "

No, of course not. Did you forgot the /pedant mode/ warning?
Just for you...
Solder for capillary fittings is tin-rich and does not have a *a wide* pasty phase.
-- Phil Addison The uk.d-i-y FAQ is at http://www.diyfaq.org.uk / Replace NO DOT SPAM with BIGFOOT DOT COM to reply
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Phil Addison wrote:

Thank you. So you appreciate why handling/wiping a hot solder fiting is not recommended. You can do it, I can do it - but some grunt somewhere could well bog it up unless ordered not to touch it when warm (on pain of having the re-heated join inserted somewhere!).
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Phil Addison wrote:

QED.
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On Fri, 1 Aug 2003 12:38:47 +0100, "David W.E. Roberts"
I found the key issue was preparing the solder joint, which means liberal use of wire wool on the pipe to be soldered, followed by a smidgen of flux before bringing the joint together.
Any residual dirt on the pipe invariably leads to a poor joint.
I prefer the pre-soldered elbows though.
Andrew
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While proper cleaning is a good idea, the use of an aggressive flux is belt and braces. I've tried experimenting soldering green copper using this stuff, and it made a perfect joint.

I don't think they're worth the considerable additional cost. Moreover, with separate solder you're in no doubt when it melts, especially when say you can't see the back of the fitting. Oh, and end feed are neater looking.
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But what do you do if a soldered joint does leak? How do you dry it out etc? Can you unsolder a joint by re-heating it? My pessimism in regard to my own joints is such that I just assume I'll have to re-do all of them at least twice, which is why I'm more comfortable with compression fittings. Actually, most of them are spot on first time but anxiety's a funny thing.
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The chances of this *really are* slim if you do it properly.

You drain down in the normal way, and simply unsolder by heating it. If it were at the bottom of a loop with water lying in it this wouldn't be possible, but then you shouldn't have such a loop anyway. But if you had, you'd simply cut if off with a pipe cutter, and extend the pipe to fit when re-making. Let's face it, pipe and end feed fittings are so cheap you don't have to worry.

Know what you mean, but there's far more chance of a leak with a compression fitting as it's susceptible to mechanical damage - a bad scratch or whatever - that solder would easily fill.
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