- Copper pipe compression fittings are devices used in plumbing when two tubes composed of different materials need to be joined and kept tight to avoid leaking. As the name suggests, these fittings work by compressing the two pipes together. The basic parts of a copper pipe compression fitting is the pipe itself, one of which will have a threaded end (the copper pipe typically). There is also an over-sized nut called a compression nut and a smaller ring called a compression ring.
- The compression nut is put over the end of the pipe lacking threads (often this pipe is made of PVC), while the compression ring is slipped inside the pipe with the threads. The two pipes are fitted together, and the compression nut is screwed onto the pipe with threads. The nut compresses the two pipes together while the ring on the inside provides resistance to prevent the pipes from buckling, pushed from both inside and outside; this makes the pipe both air and water tight.
- The first thing that must be done to remove a copper pipe compression fitting is to unscrew the compression nut. Oftentimes the compression nut may have become corroded, making turning it near impossible without damaging the pipe. Remove the corrosion with a swabbing of muriatic acid before rinsing it clean. After this, use glycerin or any other form of lubricating oil on the threads. The compression ring should come free with a few turns from a wrench. The pipes should come apart easily after this, though the compression ring on the inside of the pipes is another matter. Heat the pipe around the ring with a blow-torch. Doing so will cause the metal of the pipe to expand, which will allow you to work the ring free with a set of needle nose pliers.
