sweating a pipe

[robbmiller]

I am sweating a pipe from a valve to a 3/4" copper thread. What would cause the the threads to pop off the pipe?

It is almost as though I used no flux. Can flux become contaminated?

[havasu]

Is there water in the pipe? I've never heard of flux becomming contaminated, but know that too much heat can do damage while sweating pipes.

[robbmiller]

There is water in the pipe above the valve. Should I drain it?

I am installing a water softner. I need to sweat pipe in two more places. The first at the 3/4" valve. The second is 3/4" threaded end.

The four other joints I sweated are just fine. These last two don't seem to want to take solder. I'm on my third try.

[havasu]

Your pipes must be completely void of any water in order for the solder to adhere properly without complete melt down. Drain the pipes, using a tightly rolled paper towel to wick up any excess water and once it's competely dry, give it another shot. It should work alot better! Make sure to let us know how it turned out.

[phishfood]

Originally Posted by robbmiller

I am sweating a pipe from a valve to a 3/4" copper thread. What would cause the the threads to pop off the pipe?

It is almost as though I used no flux. Can flux become contaminated?

I am not quite following. Is the thread that is on the threaded adaptor breaking off of the fitting? Are you trying to sweat the thread to the valve? If so, this is not the common, accepted method of sealing copper thread joints. Teflon tape and/or pipe dope is the way to go.

On a standard sweat joint, the first step is to sand the outside of the pipe, then use an ID brush on the fitting. Apply a thin coating of flux to both surfaces, assemble. Heat until the flux runs and starts to smoke. Start touching the junction of the fitting and the pipe with solder until you see it start to flow, then wipe the tip of the solder around the joint.

Sorry if you already knew that, but sometimes someone doesn't know all the basics.

I have used flux that is pretty old without problems, so I would tend to doubt that it is the flux.

With a hot enough torch, you can solder one side of a valve with water on the other. You can also get it hot enough that it starts leaking, so I would attempt to drain it.

Hope you get it worked out.

[robbmiller]

Originally Posted by phishfood

Is the thread that is on the threaded adaptor breaking off of the fitting?

I am soldering a copper thread to the pipe. The flex hose from the softner will attach there.

Originally Posted by phishfood

Are you trying to sweat the thread to the valve? If so, this is not the common, accepted method of sealing copper thread joints. Teflon tape and/or pipe dope is the way to go.

No, not quite that bad (almost, but not quite).

Originally Posted by phishfood

On a standard sweat joint, the first step is to sand the outside of the pipe, then use an ID brush on the fitting.

Yep. Did that.

Originally Posted by phishfood

Apply a thin coating of flux

How thin? I've been coating it all the way to the top of the fitting.

Originally Posted by phishfood

Heat until the flux runs and starts to smoke.

I'm using MAP; can it get too hot? How about "Oatey Instant Solder"?

Originally Posted by phishfood

With a hot enough torch, you can solder one side of a valve with water on the other. You can also get it hot enough that it starts leaking, so I would attempt to drain it.

Will do. Perhaps I got it too hot.

Originally Posted by phishfood

Hope you get it worked out.

Me Too.

[robbmiller]

The job so far


The valve assembly



The installed 3/4" thread



The valve that is giving me trouble

[phishfood]

Originally Posted by robbmiller

How thin? I've been coating it all the way to the top of the fitting.

I'm using MAP; can it get too hot? How about "Oatey Instant Solder"?

Will do. Perhaps I got it too hot.

Using more flux than needed won't cause you problems soldering.

MAPP gas definitely can get a fitting too hot. So can most any torch if you leave the flame on it for too long.

I am not familiar with that type of Solder. Some solder alloys are more user friendly than others, but all should work.

It is possible that you did get things a little too hot, and if you do, solder will not take. As you heat it, keep checking it by trying to wipe the end of the solder into the joint. As soon as it starts flowing, run the solder around the entire joint and take the heat off.

Let us know how it goes.

Edit: Just saw your last post. Did you ever manage to completely drain the water above the valve? With the piping and the valve oriented that way, it is going to be hard to get the jpint hot enough to solder.

[havasu]

If your water input is on the left, the water is absorbing the heat, which would melt the exterior before the sweating could occur. It is similar to lighting a styrofoam cup filled with water. The water will remain, but the exterior will char.

[robbmiller]

Done!

I drained the pipe, re-cleaned, re-fluxed, and re-soldered. Bingo!



Now I can go to bed feeling like a man!

Thanks for your help. It will probably be sometime before I am a contributor here -- but I sincerely appreciate the service you are providing; this is what the internet was meant to be.