Copper pipe fittings, whether couplings (copper joints that attach one piece of copper pipe to another) or shutoff valves, require installation by soldering. The process of preparing and soldering the fittings is fairly easy, but can become easier with practice. You should practice preparing and soldering with a few spare couplings and some old copper pipe before you begin actual installation. This will help diminish the possibility of leaking fittings and headaches in the future.
Cut the copper pipe to the required length using a tubing cutter: Mark the pipe in the place where you want to cut it, then place the tubing cutter over the pipe and tighten the blade down onto the mark. Rotate the cutter once before tightening and rotating a second time. Repeat the until the pipe is cut through. Sand the end of the pipe (1 inch) and inside of the coupling (or fitting) with an emery cloth.
Apply a thin layer of lead-free soldering paste (flux) with a small brush to all sanded areas. Push the coupling (or fitting) onto the end of the copper pipe. Pull out 10 inches of lead-free solder from its spool, and bend the last 2 inches 90 degrees.
Light the propane torch, and hold the flame against the coupling (or fitting), moving the flame from side to side. When you hear the flux sizzling, remove the flame. Touch the seam between the coupling (or fitting) and pipe with the end of the bent 2 inches of solder. If it melts, apply 3/4 inch of solder to the seam; capillary action will suck the solder down between the coupling and pipe.
Wipe away all excess solder with a rag, but remember that the coupling (or fitting) will be hot.
If you are installing a long length of copper pipe with multiple couplings, prepare and install all the pipe/couplings first. Then work your way from one end of the pipe to the other, soldering each coupling as you go. Copper pipe usually comes in 1/2-inch or 3/4-inch diameters. Choose the correct diameter pipe for your needs. Couplings come in straight, 30-, 45-, 60- and 90-degree angles to help you installing pipe around corners.
Always be aware of all flammable objects that are close to the flame when soldering. Keep a water spray bottle close at hand.