Compression fittings are used in plumbing and electrical conduit systems to join two tubes or thin-walled pipes together. In instances where two pipes made of dissimilar materials are to be joined (most commonly PVC and copper), the fittings will be made of one or more compatible materials appropriate for the connection. Compression fittings for attaching tubing (piping) commonly have ferrules (or olives in the UK) in them.
Compression fittings are also used extensively for hot and cold water faucets (taps) and toilet stop valves; compression fittings are well suited to this application, as these valves are usually located in confined spaces where the copper pipe would be difficult to solder without creating a fire hazard. Also, the fittings allow easy disconnection and reconnection.
