Thread: trying to solder copper pipe

Dunno for sure, but to me it sounds like it could be a problem with the flux, or technique.

Solder should flow naturally into the join. Do not remove the torch from the fitting before touching the solder to the pipe. The torch should be at the opposite side of the fitting from where you will touch the solder to the pipe. It cools below flow stage very quickly, so if you are removing the torch then touching the solder to the pipe it likely cools too much to flow the solder.

It's not difficult to do. Just work on your technique a bit, I suspect. And make sure you have put flux outside the pipe and inside the fitting.

How about.....................
Clean the Copper,
and
NO Flux

and

Go from there.............

Sounds like the copper is way too hot. (you are getting the leidenfrost effect).

Remember that you are trying to warm the copper up, not bring it to its melting point! If you hit red heat, its way too hot and all you are doing is oxidising the copper. Let it cool down, clean it, and re-flux it.

You don't need silver solder for copper, normal lead/tin solder is fine unless you are doing gas pipe work.

With normal solder, clean the joint, apply flux (the stuff that looks like brown boot polish works best for me) and assemble the joint. Heat slowly and evenly, and heat at a point furthest away from where you will be adding the solder. (heat at the very end of the joint, so that solder is drawn into the joint).

Don't hold the torch too near or you might overheat and burn out the flux; solder melts at about 200-300 degrees - copper glows red at about 1,000 degrees (I think).

The next step up from normal solder is Phos-Copper silver brazing rod. These are the coppery looking rods with a dab of yellow paint on the end that you find in the plumbing section. These DO NOT need flux when joining copper to copper, and the joints they do are pretty permanent (trying to take one apart is a right fiddle and not worth the time!).

IF you heating the copper to cherry red you are definitely overheating it, risk the chance of it crystalising and having it breakdown over time.

I would NOT use 'lead/tin' solder as it does not have the strength of silver solder. Remember the old solder filled fittings that one had to slip together and heat? AFAIK they are no longer made

If your copper is clean there is no need for any flux, unless joining to brass, Heat the joint keeping the flame moving and simply use the 'touch test' with the silver solder to see if its hot enough.

I've got one of those torches now too, have had it for over 5 years now, they work good.
The can of gas your using? to get best results, use the mappgas yellow or benzomatic yellow bottles - I think it's methacetylene gas or something. Butane (blue) and propane (red) won't burn hot enough for welding.

Tips- heat the pipe not the fitting, the heat will travel into the fitting via the pipe
if your heating the fitting then the heat has to travel right through the fitting and into the pipe for a weld to happen. ( your effectively heating a piece of copper twice as thick as you need)

no you dont need flux if the pipe is new and clean.
If you are using flux with a hand torch, you need to spend 30-60 seconds burning the residue away, as the torches are a different softer heat than an oxy unit- you can get specific flux for the hand unit's but it's about $40 for a tub so it is a rip off. Then you can solder on a clean pipe.

Try to solder in a still air environment, wind will definately make it harder to weld.

When applying solder with a hand unit you need to heat the joint and apply the solder directly into where the flame (heat ) is, they don't burn as hot as an oxy, I tend to put more solder than i need into the first section and then drag it around with the flame.

Let me know how you go.

Originally Posted by Jacksin

Remember the old solder filled fittings that one had to slip together and heat? AFAIK they are no longer made

I remember these as Yorkshire Fittings,
Had a ring of solder inside the Female fitting.

Yep
these;
from my Apprenticeship days at XXXX Brewery

http://www.yorkshirefittings.co.uk/p...ubFolderID=253

Barnsey the silver solder runs with the heat. Clean it all up again , apply flux ( though its not a must ) fit it all together and heat the copper pipe slowly watch the colour change as it goes into the fitting now add slightly more heat to the fitting a few secs only touch the silver solder stick to the fitting and it should run
I think that proberly in the first case by the time the copper tube was hot enough the fitting was far too hot , thus heat the copper pipe first , and carefull not to overheat , the rest is practise

Rgds

Do a basic welding course, that way you will be shown, and if you must work on your own water service there will be less chance of ruining something and having a plumber sting you for repairing something you tried to! Easier to be shown rather than read it or watch it on pootube

pootube keeps me occupied at work, that's where i learnt how to make a paper origami rose.....then the pyromaniac in me burnt it with the torch.
I am using the yellow bottled mapp gas with the torch.
I tried again this morning except this time a bit quicker (applied the flame for less time). this time the solder stuck to the pipe a bit when i touched the solder but it still didn't suck up through the fitting and even then the solder didn't look 'wet' like i assume it should look (if it is anything like soldering electronics anyway), it was more crystalised as you guys have mentioned.
i will try heating the pipe first next time and see if that works better.
i have also picked up one of those brazing rods to see if that is easier or not
Inciidentally it is copper pipe i have been given for free (i know, in this era of copper salvage rates it does seem very weired) and it is definitely not new. it is virtually a dull brown .colour. It comes up nice and shiny when i sand it for a minute or two however.

Originally Posted by Master Splinter

You don't need silver solder for copper, normal lead/tin solder is fine unless you are doing gas pipe work.

Don't hold the torch too near or you might overheat and burn out the flux; solder melts at about 200-300 degrees - copper glows red at about 1,000 degrees (I think).

Slightly off topic but just a word on 60/40 Tin/Lead resin core solder, which is primarily used for electronics & the like. This solder melts at 183 degrees Celsius. The correct soldering temperature for this solder is between 280 & 300 degrees Celsius, which is well below what a gas torch can produce. If higher temperatures are used with this type of solder, the result can be fractures, dry joins & oxidisation.

Originally Posted by Ashore

...... fit it all together and heat the copper pipe slowly watch the colour change as it goes into the fitting now add slightly more heat to the fitting a few secs only touch the silver solder stick to the fitting and it should run

Rgds

One of the benefits of using flux, besides its cleaning action, is that it gives you a clue to how hot the piece is.

As you heat the part to be silver soldered:
Flux starts off as white paste.
First the water boils off so you have white crystal residue,
Then the flux starts to turn into a clear liquid
This is the time to add the silver solder. Gently raise the temp a little more and you should get the solder to run.

If the flux goes black ... too hot, start again and next time not so hot.

Talking of Silver solder, what is being used? I've forgotten CIG numbers (That tells you how long since I've bought any) but the phos copper gear 2%, 5% or 10% silver is what i think the plumbers used to use. The more silver, the lower the melting temperature. 5% is as low as I'd go for propane torches.

The model guys use 245 (blue tip) but on NO account use it with water supplies as it has cadmium in it. Fantastic stuff for joining things as it works on ferrous and non ferrous metals, melts at relatively low temps and the join if well done can be stronger than the base metal!

Silver Solder
For copper you want it a DULL cherry red, fitting included. If the pipes hot and the fitting isnt it will run down the pipe but not bond to the fitting properly. With copper, and brass you not only need the capillary attraction when silver soldering but you also rely on inter-granular ( i think thats what its called) attraction where the structure of the copper opens up like pores in your skin and actually "soak" the silver solder in giving you a proper joint. You can use 2% silver with a turbo torch though it takes a little more work. I usually keep a stck or two of 15% just for the turbo torch.
Soft Solder
Clean both the pipe and the inside of your fitting. Apply a smidgin of flux. Join the two and heat gently. You will see the yellow-ish coloured flux go a brown colour. Take the heat off and apply the solder to the joint. If its hot enough it will draw itself in, if not apply a LITTLE more heat and repeat the process. If the joint is at the right temp. the solder will instantly draw itself in, when it does this just give a touch of heat to the back of the fitting to draw it in and leave it. Once cooled enough wipe off excess flux with a damp rag, Essential. BTW, soft solder for water pipes shall not contain more than 0.1% of lead by weight.

ok i got my self a stick of silver solder.
It had a yellow tip i think.
i again tried with the soft solder first but i just can't get it to flow into the joint properly.
I used less heat though and it did flow better, but it just didn't seem to flow into the join.

now with the stick of silver solder (which looks more like a small copper rod):
both fitting and pipe were clened and put together. I did not use flux when putting them together.
i heated the pipe first then the fitting, both got to a cherry red colour. then i dipped the silver solder in the flux and put it against the fitting.
It bubbled a bit then flowed all around the joint...it definately flowed a lot more fluently than the soft solder.

I took photos this time so i will show you them when i get home to show what i am using and how the joints came out.

sounds like your getting there, but use NO flux when welding copper to copper. None at all. BTW yellow tip silver is 2%.