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Termite 02-23-2009 07:53 PM

How To Solder Copper Pipes
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Here's a very basic pictorial lesson on soldering copper pipe together. I'll hit on the high points...

The first picture is what you'll need for basic work on copper pipes:
  • Torch. The one pictured has a hose to the torch head, which is very convenient. I prefer mapp gas over propane just because it gets hot fast. Propane works fine...I'll cover that later on.
  • Pipe/fitting cleaning brush. You have to have a wire brush to clean the inside of the fittings. The brush pictured is a combination brush that cleans both the fittings and the outside of the pipe, in both 1/2" and 3/4". Emery cloth is also great for cleaning pipes, but not fittings.
  • Flux. I like the stuff in the picture. It is a dark cruddy amber color and is very thick. I do not care for the black or dark gray stuff that usually comes in the small tins and "kits"...That stuff is too thin.
  • Pipe cutters. Don't use hacksaws or sawzalls unless it can't be avoided. Tubing cutters don't deform the pipe. It is also a good idea to deburr the end of the pipe after cutting it, and many pipe cutters come with a tip for doing that.
  • Solder. Plumbing solder!
  • Have a rag handy for wiping up the fittings after soldering.
  • Wear shoes and long pants. Hot dripping solder that hits the floor splatters liquid hot metal in all directions. It hurts if it hits you.
  • It is also wise to have a fire extinguisher handy. You never know. Fire and hot metal don't mix well with some interior surfaces.
  • Pipe and fittings. Duh.
  • Labrador retrievers are optional

Termite 02-23-2009 07:55 PM

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The pipe is not clean enough to solder, even when new. Sanding it or wire brushing it will clean off the oils. It'll also give a rough surface for the solder to really bite to.

Termite 02-23-2009 07:57 PM

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Here's the pipe after brushing or rubbing with emery cloth. You should see about 1" of fresh copper.

Termite 02-23-2009 07:58 PM

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Use the brush to clean the inside hubs of the fittings.

Termite 02-23-2009 08:02 PM

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Then flux is applied to the fitting and the pipe. The way I see it, the stuff is cheap, so I use plenty. Pros probably use less. More isn't necessarily better, but a thorough coat on all surfaces is critical. Be sure it is free of sawdust or bristles from the flux brush.

Put the fitting and the pipe together. Be aware that as soon as you heat it, it'll want to move because when the solder melts it gets a lot more viscous. So, when doing this, orient your fittings so gravity won't cause them to rotate on you.

Termite 02-23-2009 08:05 PM

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For the record, this fitting rotated because I left it horizontal for photo purposes. I'd normally do this vertically whenever possible.

Heat is applied to the fitting (not the pipe). The solder will be drawn into the flux TOWARD THE HEAT. So here, I'm heating the underside and the solder will be touched to the top side of the fitting hub.

Termite 02-23-2009 08:16 PM

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I didn't get a picture of it, but I roll several inches of solder off the roll and use the roll as a handle to keep my hand far enough away that molten flux and solder won't drip on it.

Apply the heat. Hold the torch head about 4" away. Watch for the flux to melt and start to boil. Just heat one area of the fitting...The heat will conduct to the entire fitting. You'll see the color of the copper sort of change a little bit, kind of like watching water freeze and expand on a very cold windshield. When you see that, time to apply solder and back the heat off.

The solder is TOUCHED to the side of the fitting opposite the heat. If it melts instantly your fitting is hot enough and you can pull the torch away. Feed the solder into the joint until you see it come out the other side. I feed it in until a drip forms. It doesn't really take much because you're filling a very tiny gap.

Termite 02-23-2009 08:18 PM

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In this picture you can see where I touched the solder to the fitting/pipe joint. THERE IS NO NEED TO MOVE THE SOLDER AROUND, JUST TOUCH IT IN ONE PLACE. This isn't welding. Any solder that you see on the outside of the joint is just extra and isn't the solder doing the work of keeping the water back.

Termite 02-23-2009 08:19 PM

At this stage I quickly wipe off the joint with a dry cloth rag. It will burn the heck out of you and the rag, so be careful.

Termite 02-23-2009 08:21 PM

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Here's the underside of the fitting I just soldered. See how the solder started to form a drip when the joint got full?

Termite 02-23-2009 08:31 PM

Valves and other brass fittings...

They can be tricky for a first timer. Brass seems to take more heat than copper, probably due to the fact that it is thicker than the copper pipes and fittings more commonly soldered.

With valves, be careful not to heat the guts if you can help it. Shower valves' inner workings should be removed before heating. You have to remember to orient the valve so that liquid solder doesn't run down into the valve and cause things not to close or parts not to fit.

skeeter 152 02-23-2009 08:34 PM

very good lesson! clean outside pipe inside fitting.lots of flux.heat attracts solder.thats the way i helped my son understand the basics

Termite 02-23-2009 08:36 PM

Sometimes people ask "can I re-heat the joint or add some solder if there is a pinhole leak?" My answer is always no. The pinhole leak is there for some reason, and globbing extra solder on the outside is a band aid. Leaks will form in areas where the flux completely melts out, so the solder just won't go there. Re-heating won't work most of the time. So, I usually advise re-heating and removing, cleaning the pipe, cleaning (or replacing) the fitting, and trying again.

Termite 02-23-2009 08:44 PM

Any water in the pipes will be drawn toward the heat you are applying. Do whatever you can to drain all the water out. You can't solder pipes with water in them. It cools the joint just enough, and will often cause a lousy seal resulting in a leak.

There are ways to keep the water at bay when necessary. I use bread. There are commercially available products like the little gel-filled eggs they sell at the big box stores or more professional products like Jet Swet that are inserted into the pipe and removed after finishing. White bread formed into a doughball can be jammed a few inches into the pipe will hold the water and steam back, and will liquify into something resembling baby vomit instantly when water pressure is restored to the pipe. Just open a downstream valve to clear the line. Some people say to remove the aerators from the sinks or to let the toilet supply lines shoot into a bucket to avoid getting the bread into the fixtures. Personally I've found that it clears out within seconds and doesn't hang up in the fixtures. Common sense prevails...Don't use the crust and don't use any kind of grainy bread with seeds and chunks of anything. Its a great trick that a master plumber taught me years ago, and I've used it a hundred times with great success.

Termite 02-23-2009 08:45 PM

Hopefully some other folks will have some other tips or scenarios to make this thread more informative. :yes:

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