I am new to soldering copper (although I solder circuit boards all electrical all the time). I had to remove the 3/4 shut off valve because it was stuck in the water off position.

The system to be replace calls for:
water in = 3/4" copper pipe connected to a 3/4" street elbow (it has a reduced diam.) that sweats into another 3/4" street elbow which reduced diameter sweats into the shut off valve. Then the other side of the shut off valve (straight) connects to another 3/4" street elbow which fits to a 3/4" copper pipe.

Soldering to the copper pipe was no problem. However soldering the two sweat street elbow did not work because the soldering agent beads down the pipe (vertical soldering here). The melted metal does not get sucked in by capillarity between the two fittings. I tried everything unsuccessfully.

This drives me nuts because I have to then shut off the water, unsolder everything, remove all the water, sand the pipes...

Help! Are these supposed to be soldered together?

Thanks for your help.

Did you clean and flux the copper? Your valve must be open to let the steam out or it will push the solder out of your joints.

You are not trying to solder with your electrical rosin core solder, are you? You are describing the problem with a joint which is not properly fluxed.



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hello all, thanks for your help.

I am using silver bearing lead free solder diam. 3mm (bernzomatic brand). The pipes were cleaned and sanded using the proper tool (twist stainless steel bristles brush). The flux I am using is water soluble plumbing flux (bernzomatic).

before soldering I added the flux on each part. Today, I tried with regular elbows and 3/4" copper pipe as a nipple. It did not work again. So, I clearly am doing something wrong. I had no leaks on the copper pipes that sweat onto the shut off valve though.

Still puzzled. My pipe is hot enough since as soon as I add the solder, it melts, but it tends to bead and does not get sucked in.

I used a wick to remove all the water in the pipe and the shut off valve is disassembled to allow the air to freely move in and out.

I really do not know what I am doing wrong. Should I add some flux just before I solder when the pipe is scorching hot?

Water soluble flux can be very difficult to work with. If you get it too hot it will "burn" and do just what you describe. "painting" flux on the joint would just "clean" the visible area, it would do nothing to get the solder to flow into the joint. We cannot tell you what you are doing wrong just by seeing your description of how you are doing it, but since we do it many times a day without that difficulty, it is obvious you are doing something wrong.

Try Oatey # 5 flux. [www.homedepot.com]

Hello all,

it was the flux. I did not use enough. I did have the problem about the water soluble flux getting too hot for the soldering that was in a very tight recessed place. I am happy that all went well after all but I sweated a lot of sweat (hot in Florida). Best to all!



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Send some of that FL heat up this way, would ya?

If you have excess rain, we will trade some AZ heat for it.

also make sure you clean the inside of the fitting well before applying flux

use either 160 aluminum oxide 'plumbers roll' or a dedicated fitting brush

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638