There are two methods for joining copper pipe, Soldering and Compression. Soldering is perhaps the most difficult, but can result in a better joint. Compression joints use special nuts sealed with PTFE tape.
Soldering
Before you start soldering a pipe, make sure you have everything you need close at hand. You will need flux (which is a chemical cleaner), a gas torch, solder wire (lead free if the pipe supplies drinking water), a pipe cutter or hacksaw and wire wool. Once the pipes are cut to length, your first task should be to clean the ends that will be soldered using the wire wool. Once the ends are clean and free from grease, coat them with flux. Flux is fairly nasty stuff, so be careful to follow the manufacturers safety instructions.
Bring the ends together and start to heat them with the gas torch. When the flux begins to bubble, remove the heat and apply the solder wire to the joint in three or four places. You will be able to tell if the pipe is soldered correctly if a bright ring appears around the joint. Allow to cool thoroughly before touching the pipe.
Compression
The Compression method uses a nut (known as a slip coupling) to replace the damaged piece of the pipe. Cut out the damaged piece. Pull back the coupling so you can connect with the other cut end. Unscrew the compression nuts and slide them together with the metal rings (olives) along the pipe and clear of the screw threads. Apply the PTFE tape clockwise around the exposed screw threads and slide the metal rings and nuts back. Use two spanners to tighten the nuts and seal the joint.
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