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What In The World Is a Compression Fitting?

We all have performed some kind of plumbing repairs in our homes, usually cleaning out a drain line or replacing a faucet, but when it comes to the shut offs or angle stops under our sinks, we often hit a road block because they do not use conventional threads, they have compression fittings.

A compression fitting is a coupling used to connect two pipes or a pipe to a fixture or valve. It consists of three parts, the compression nut, the compression ring, and the compression seat. The angle stops or shut off valves under our sinks are often have compression fittings as they attach to copper pipe, which has no thread.

The compression rings or ferrules as they are known, make the seal between the copper pipe the nut and seat, compressing as the nut is tightened sealing the connection. These are easy to install, but getting that ring off to replace the nut can be a real problem.

I have struggled mightily trying to remove these rings as once they compress they cling to the pipe as if welded into place. Usually one must use a hacksaw and cut a groove in the ring, this weakens it and allows a puller to take it off the pipe.

Compression fittings use fine thread for the nut and seat, many modern braided water supply lines use compression connections with a rubber O-ring instead of the copper compression ring, this makes changing the supply line much easier.

The next time you need to replace a shutoff valve under your sink, just tell the plumbing associate it has a compression fitting.


Mike, The Home Depot Answer Man

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Posted 2018-12-04T00:25:14+0000  by Mike_HD_OC Mike_HD_OC