Soldering plumbing attachments

Tried my hand at soldering copper plumbing accessories the other day. I got the hang of it after about half a dozen attempts, but one thing still has me beat, and that is how to solder an accessory which has two or more joints, such as an elbow (2) or T-piece (3).

I have no problems in soldering the first joint, but then when it comes to the second joint and I reheat the accessory, it always ends up in the first joint becoming loose and mooving about, and then I end up trying to not only solder the second joint, but also correcting the position of the first joint, and the whole thing becomes a mess.

Any hints on how to solve this problem?

G'day FlyingDuck

What type of solder are you using
If you are using tin solder, this has a low melting point and will run to where the heat is
If you use silver solder it requires a fair bit of heat and normally only runs right on the spot where the oxy is, that is if you are using are oxy-acet torch
Are you cooling the joint between soldering, if you are using tin

Cheers DJ

I recall my dad just tied a wet rag around the end of the fitting he didn't want to loosen. His sweat soldering sessions were high drama affairs, but he never had a leaking joint.

greg

My plumber used MAPP gas to braze the first joint and then used less heat with soft solder for a nearby joint. Usually on the same fitting this wouldn't be needed. Try applying flux to both ends, dry fit and then solder at the same time, rather than one after the other.

Hope this helps, maybe some plumbers could shed some more light
Cheers
Pulse

Use tin solder, apply most heat to the pipe, not the joint.

djstimber, the type of solder is lead free plumber's, but I don't know if it is tin or silver as I don't have the packet with me at the moment.

I did think about soldering both joints at the same time, and will have to give this a go. I also like the suggestion about wrapping the completed joint in a wet rag, and will try this as well.

Hi FlyingDuck

Lead free is tin solder which is a very low melting point
If you are using oxy I would recommend that you go to a plumbing supplies and get some silver solder as it is a much stronger joint and will not run once you move to the other joint

Cheers DJ

I don't know why anyone would use tin over silver solder. Silver solder is easy to use and requires no flux on copper to copper joints. It basically runs itself if you use it right.

Dan

Quote:

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Originally Posted by djstimber

If you are using oxy I would recommend that you go to a plumbing supplies and get some silver solder

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Pardon my ignorance, but do you need an oxy torch to use silver solder? I am just using a propane gas torch, so don't know if it makes any difference. Do you use it in the same way as tin solder?

Hi FlyingDuck

Generally propane gas torches don't put out a hot enough flame to melt the sticks of silver solder
Silver solder is applied in pretty much the same way as tin solder, you just have to heat the copper up till the solder will run when applied to the copper

Cheers DJ

Never tried a propane torch but I can't see why not. It just might take a bit longer.

Dan

MAPP gas (yellow bottle) is what I've seen my plumber use, burns hotter than propane.

Cheers
Pulse

I started with propane, then went to MAPP gas - propane took forever to run the silver solder, my nozzle assembly takes both interchangeably - one point though, if you end up working on a fitted pipe you need to make sure all the water is out, as it will act as a heat sink and you will burn a lot of gas and get nowhere with mapp gas (I think oxy sets dont have this problem).

There is a little trick when soldering fittings with multiple joints. Cool the fitting slowly. (Torch on the joint, torch off the joint.) As the joint is cooling, apply more solder to the top of the joints, allowing the sloder to drip off the bottom. Try to get all the joints to cool simultaneously. When the joints are cooled and you have a nice fillet all the way around each joint, you're finished. If you have one joint with an uneven fillet, lightly heat the pipe running to the joint and apply solder.

Quote:

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Originally Posted by DanP

I don't know why anyone would use tin over silver solder. Silver solder is easy to use and requires no flux on copper to copper joints. It basically runs itself if you use it right.Dan

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Soft solder should not be used on copper pipes nowadays. Soft solder eventually deteriorates and requires re-soldering. Silver solder is supposed to be used on all water pipe plumbing. I think you will find that various plumbing regulations demand it. The reason being is that the assorted "chemicals" in the water are much less likely to attack and corrode silver solder.

As far as soldering multiple joints where they are close to each other, normally the flame is pointed in such a direction as to ensure the heat is facing away from any other existing joint. Also if you use silver solder, the joint should not normally become loose, or move because the other joint should be properly soldered before the heat has had sufficient time to heat the "other" joint to loosen it.

You need to use a small pinpoint flame to concentrate the heat on the specific area to be soldered. You also need to alternate the heat on the pipe, eg flame on the pipe/flame off the pipe.... repeating this flame on/off as necessary to ONLY heat the required area. Continuous flame on the joint will waste far to much heat as it is conducted away along the pipe.

You DO need FLUX when silver soldering copper pipe. A joint made without using a flux could corrode or fail. The flux is used to provide a "clean" surface on the pipe to allow the silver solder to both flow and adhere to the copper correctly.

You don't necessarily need to use a separate flux, as you can get flux coated silver solder.

Any oxy/acetylene outfit is the best for silver soldering, however a cheaper and very effective system used by plumbers these days is LPG and Oxygen. This is easily heats the joint enough to perform silver soldering.

HTH

The wet rag suggestion is a good suggestion if you are still having problems.