Ask Me Help Desk - Sweating copper pipe

I understand that you flux the outside and inside of copper pipe/elbow fitting

What about copper pipe using a male brass fitting?

Do you flux the INSIDE of the copper pipe and the brass male fitting? Before attempting to heat/solder.

I need to replace a water pressure relief valve and attach to existing copper piping.

Thanks

David

Hey Dave it goes like this.

First you make sure everything's dry. No moisture at all. Next you take plumbers sand cloth and shine both the copper pipe and the brass fitting. Then you flux both fittings and place your torch flame under the two fittings and the solder on top. When the two are hot enough to melt the solder run the solder all around the joint. The solder will be drawn up into the joint completing the solder job. Good luck, Tom

I'm not an expert in this area.

If you've had any issues sweating pipe before I can tell you using oateys 95 tinning flux (avail at home stores) seemed to help me. Maybe my technique has just gotten better, but I first used it at the recommendation of a friend when I had some difficult areas to plumb and had complained about my previous jobs having a few more pinhole leaks than I was comfortable with.

Oateys 95 doesn't replace using some solder, but when you coat the fittings and sweat, when you reach the right temp there is some solder in the flux you'll see fill the joint. Usually at this time ill do a quick touch with some solder just to make sure its good. Since I've switched I haven't had one single leak... even with a couple of jobs I swore wouldn't work because of how tight it was and hard to heat evenly. Thrilled.

Maybe its just with some solder flowing from the flux I'm not overheating now. Just an amateurs thought, in case you had any issues with this. Your post didn't mention it so maybe I'm rambling for no good reason. I've just had such good experience with it I tend to pass it on.

Quote:

Originally Posted by kp2171

. . .oateys 95 doesnt replace using some solder, but when you coat the fittings and sweat, when you reach the right temp there is some solder in the flux youll see fill the joint. usually at this time ill do a quick touch with some solder just to make sure its good. since ive switched i havent had one single leak...even with a couple of jobs i swore wouldnt work because of how tight it was and hard to heat evenly. thrilled.

maybe its just with some solder flowing from the flux im not overheating now. just an amateurs thought, in case you had any issues with this. . .

KP, you are right on target. Tinning flux works so well because the tiny particles of solder in the flux, melt easily. Once they are liquid they conduct heat much better than flux does so they allow the fittings to heat more evenly, and thus the lack of "holes".

P.S. Just to make sure that we're answering Dave's specific question: you apply flux to all of the surfaces (inside or out) which will be in contact with the solder. The job of the flux, which is just a type of acid, is to clean off all oxidation from the metals so that the solder will bond to them cleanly.

Speedball is right on target about starting with everything COMPLETELY DRY AND SHINY and also in pointing out that the metal you are soldering (i.e. the pipe and fittings) needs to be hot enough to melt the solder--don't melt the solder with the torch--and that once they are hot enough, the molten solder will flow into the joint on its own (this is due to "capillary action" if you want to look it up ;-).

How do I know so much about soldering? Well, I am a certified electronics technician and when I was in school we spent an entire quarter learning and practicing soldering techniques and theory. It's actually pretty interesting stuff (to me at least ;-) and though I am not a plumber, I have renovated several bathrooms and have sweated my share of copper pipes and fittings.

Good luck, and please indicate if this answer was helpful to you.

--John