Soldering copper pipe -- Help!

[tonyv]

Hi all,

I thought I could do this, having installed a kitchen in th UK years ago. Now doing the same here, but find I cannot get the solder to "take".

I'm cleaning the pipe and the interior of the fitting with steel wool 'till it gleams; applying a smear of "Pate Decapante"; assembling the joint; heating the joint until the solder melts on it; applying a bead of solder round the joint, and letting it cool.

The joint frequently just falls apart, with no evidence of soldersucked into the joint; ie a dry joint.

What am I doing wrong? Not applying enough heat? Too much heat? Wrong sort of flux?

I've read Gluestick's FAQ, and it looks like I'm overheating things, but I can't get the solder to melt otherwise. ( Soft solder, Tin/Copper 3%)

Cheers, Tony

[redkite]

Is the pipe 'live' ie: in situ with other pipes and closed ends? If this is the case and/or if you have water or moisture anywhere in the pipe line the solder will not take.

Really annoying I know and the only solution I've found it to incorporate either a valve or compression joint left as an open end.

[Anton Redman]

Respectfully suggest 'Decapent Pate' is not flux atall but simply cleaning paste. Believe you want 'Pate A Etamer' which my dictionaryof building and civil enginerring translates as 'tinning'

http://www.bricodepot.fr/bordeaux/node/60635

[redkite]

Ah yes Anton!

[Chancer]

Maybe I is ignorant but I have been using only pate à decapant for soldering copper for the last 4 years without any problem (except of course the dregs of water in some pipes), I didnt know that there was anything else available, I quite like it as it is easy to use from the tube.

I even used some last night with an oxy-acetylene torch to braze up the pot d'echappement of my dameuse.

I reckon the OP may have a trace of water in the pipe.

[gosub]

Check out Jean-Luc. Plumbing

[tonyv]

Thank you everybody, for your hepful replies.

This is brand-new plumbing, which has never seen any water. Both (all?) ends are open. I shouldn't have called the pate "flux", but I believe, according to the instructions on the tube, it fulfils the same purpose, with the advantage that it's non-toxic, and water-soluble. The video doesn't seem to be working at present, I'll check it out later.

I believe my mistake was that I only applied the paste to the interior of the fitting, thus it did not run up the pipe exterior, preventing a "pool" of solder forming at the edge of the fitting for it to be a souce of capillary action.. I was probably overheating things as well. By taking more care, I now seem to have made some good joints. I think I now need to retrace my steps and re-make the dodgy joints before applying pressure. Hey-ho!

Thanks again...

Cheers, Tony.

[PaulT]

I was under the impression that you should be using hard solder not soft solder due to the pressures etc.

Paul

[BIG MAC]

I assume you are using compatible solders and fluxes?

I never flux the fitting always the pipe (Even although most will say do both) I don't get over excited with cleaning either simply using a scothbrite pad rather than steel wool.

Use a 1/2 paint brush as a fluxing brush (And wrap in polythese after use). Flux the pipe (Joint as well if you must) but don't go mad! give pipe a little wiggle when inserting into joints.Use an appropriate heat resistant mat behind the job if needs be using a decent quality gas torch and a good quality steady flame heat the knuckle of the joint uniformly till you see a slight suggestion of staining and flux boils from the lip of the fitting.  Bend the end of your solder (Say last inch or so) to allow the back of the joint to be accessed easily (Away from the heat). Touch the solder to the blind side of the joint and look for a bright ring to appear on the hot side of the lip to the fitting (Do both / all sides of the joint in this manner) then immediately withdraw the heat. Use flux brush on hot joint to wipe it  and clear any residues (Smooth away any excess solder - with practice there will rarely be any) Wipe joint with a damp cloth and move on to the next one.

Ensure all new pipe work is flushed with water prior to being pressurised / tested / put to work.

[Le Plombier]

Sounds like you are cleaning and assembling the joint properly

It is important to use a flux suitable for soft solder, fluxes for brazing will not run until they are very hot

When the joint is heated to the correct temperature just a touch of the solder at one point on the edge of the joint and you will see the solder run in to and all around the joint

If the joint is too hot the solder will not run, just fall off the pipe, if the joint is too cold the solder will not melt

Heat the joint and test periodically with the solder to find when it will run, do not put the solder in the blowlamp flame

You will know when you have the correct temperature as the solder will appear to be sucked in to the joint

If you purchased you blowlamp in France you should be aware some of them produce a very hot flame, up to 3000C

One of these will heat your little joint very quickly

I have one which I use for brazing when I am installing in brazure forte and I cannot get access with my oxy/acetelyene bottles

You need to do some pratice joints to get the feel of the correct temperature

Le Plombier

[BIG MAC]

For the avoidance of confusion..........

Is there something fundamentally wrong with my method  ?

Use compatible materials..yup, Clean... yup,  Assemble positively... yup,  Heat applied to keep below pinking...yup,  Apply solder blind side / away from heat ..yup, 

Bar for the flushing and cleaning afterwards (which I have stated but we all likely do) I would say they were pretty much the same processes.

 

Wondering in Waterlooville

[tonyv]

Thanks Plombier,

Having disassembled and remade some of the joints I condemned as dodgy, and found the union beautifully covered in solder, I'm now convinced I prematurely cried for help. I simply hadn't got the ring of solder on the edge of the joint, so it didn't look right. Then, in despair I started overheating the joints, and cindering the paste.

I'm pretty certain the paste is soft solder compatible, and I now seem to be making acceptable joints, although I've yet to pressurise the system. My torch is made by Camping Gaz (i.e. French), but I bought it in the UK some 30 years ago.

Big Mac, what do you men by flushing before pressurising? I would expect to pressurise, then run it all for a few minutes to remove any remaining clag. Can't do that before pressurising.

Cheers, Tony

[BIG MAC]

Push fit stop ends on open pipes before fittings attached (Or compression ones fitted loosely if fittings on). leaving lowest open and connected to a hose running to drain run water through starting from highest point and working down replacing the caps as you go. This will get rid of any remaining flux / scale or solder snots  which can cause problems. I have replaced so many shower cartridges over the years because they were DIY installations! I have seen solder jamming the flow switch in boilers, flux inside garden  taps. All for the sake of ten to 15 minutes and a few gallons of water.

[tonyv]

Thanks for the advice, BM, I'll do that.