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3 Ways to Repair and Connect Copper Pipe

#TheHardWay, the easy way, and the in-between way
June 30, 2022

Remodelers inevitably run into situations that require rerouting pipes, or repairing them after enthusiastic nail gun operators forget to look before they leap.

The old ways still works great, but there are also a couple of improvements that can help you up your game or provide a solution to a particular scenario.

How to connect copper pipe, three ways:

  1. Sweating copper pipe (connecting with solder) is the conventional way.
  2. Sweating pipe with pre-soldered fittings
  3. Push-to-Connect fittings

1. Sweating copper pipe the old-fashioned way

Paul inserts this warning about using an open flame in wall cavities:

“On the fire department, I’ve seen some really bad fires from plumbers that have made the mistake of not using a heat shield causing embers to go down in the wall, they close the wall up and that night we have a roll-in fire."

So take precautions and move with a purpose.

Tools and materials:

  • Propane vs. Mapp gas: propane does not burn as hot, so use Mapp gas. Paul likes his Mapp gas gun because the fire lights when you pull the trigger. If you put it down, the fire turns off.

It also works great for fireworks, he points out.

  • Gloves to protect your hands from hot copper or solder. Because soldering gets hot.
  • Heat shield. Use a piece of galvanized sheet metal, about 15 inches wide to snap between two studs, joists, or rafters. This will keep all the heat away from the studs, insulation, and drywall.
  • A fire extinguisher or water in case something gets too hot, "especially when working in walls." Paul says.
  • Lead-free solder, not lead solder. The package usually says 'Plumbing' right on it. If you are standing in the supply warehouse and you cannot remember whether to get lead-free or leaded, think about how safe it is to drink water with lead in it.
  • Solder Paste or flux is a paste that you spread on the pipe before sweating.
  • Pipe cleaner for scuffing and polishing the outside end of the copper pipe. There are pipe cleaners for 1/2-in. pipe and for 3/4 in. pipe. If you don’t have a pipe cleaner, you can use 400-grit sandpaper or 00-steel wool.
  • Pipe cutters: It is good to have a pipe cutter that has a cutter head on both sides. Usually, the pipe that needs to be cut is in a tight space that won’t allow you to rotate the cutter 360 degrees. It is good to have a mini cutter in addition to a big one.

A step-by-step guide to sweating copper pipe:

  1. When cutting, don’t tighten the blade beyond *light* finger-tight. If you clamp the cutter on the pipe, you can crush the pipe, which will pretty much ruin your chances of it fitting tightly into the fitting that you fit it in. Snug the cutter, rotate, and twist the knob. Snug it, rotate, twist it. Snug, rotate, twist. Most cutters have a de-burring reamer. Use it to clean up your cuts.
  2. Plan the sweating order: solder all joints that are close to each other at one time. If you sweat one joint and then sweat another closed joint an hour later, the heat from the second solder will transfer to the first and cause pin holes. Sweat all the joints that are closed during the same session. If you MUST come back and sweat a joint near others, try to use as little heat as possible.
  3. Clean the inside of the fitting and the outside of the pipe with a pipe cleaner, emery cloth, or steel wool. Clean the inside of the pipe with the smaller wire brush.
  4. Apply the flux: Use a brush or Q-tip to apply the paste to the outside of the pipe and the inside of the fitting. "Don't use your fingers because the oils on your fingers can cause contamination in the flux." If you don’t like working with a little brush or a Q-tip, put on a latex glove and use your finger. "That way you don’t have to keep a flux brush in your tool kit making a mess." Be careful not to get your flux dirty, if you set the pipe down, prop the end over something so that the flux does not sit on the workbench, bucket, floor, or whatever.
  5. Heat the pipe at the joint, not the pipe.
  6. Apply the solder coil to the bottom of the joint and let it climb up the pipe toward the heat. Don’t run solder around the joint because the solder won’t be pulled into the joint. "You'll get a bad seat, and you’ll need to redo the joint." The pipe is hot enough when it migrates to the heat. Stages of solder: (1) the solder will not melt. (2) The solder melts but won't migrate. (3) The solder migrates up the pipe and into the joint.
  7. After soldering, wipe down the joint with a wet rag to cool the joint. All you should see is a small silver ring of solder around the joint. You should not see a blob of pipe frozen on the pipe.
  8. Wipe excess flux off the pipe when done. Flux is acidic and can corrode the pipe and fittings.

2. Pre-soldered fittings have solder already packed into the fitting.

When using pre-soldered fittings, all you need to do is clean the pipe, flux it, slip on the fitting and heat it up. For pre-soldered fittings, heat the pipe, not the fitting, because the solder migrates to the heat.

Heat the pipe until you see the solder come through to the outer edge of the joint.

To remove soldered fittings, melt the solder with heat. They can be used again after cleaning and fluxing.

When cleaning, just polish the surface; it is OK if there is still solder on the surface.

3. Push-to-connect fittings are fast to connect, slow to take apart

These are certainly the easiest connector to use. Just clean the pipe, slide it into the fitting, and you’re done. Teeth inside the fitting hold the pipe.

Be sure to mark the depth of the fitting on the pipe before sliding it on to make sure the pipe is pushed fully into the pipe for a tight fit.

To remove it, use a little plastic tool that costs about a buck at the hardware store. It does not work as well as they say it does, especially in tight spaces. To use the removal tool, slide it on the pipe, snug it close to the fitting, squeeze the two together tight, and pull hard.

Then pull harder.

More plumbing information on ProTradeCraft:

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