[emahsman]

I recently replaced an old, leaky shut-off valve with a compression shut-off valve. I cut off the copper pipe cleanly and made sure the end was clean and burr free. After tightening the nut as instructed, I still had a leak from where the valve connects to the stub. I've adjusted it a couple of times and added teflon tape to the threaded portion of the valve. The leak is now very minimal, but still exists. Any suggestions? As I have a second one to replace, I want to get this correct. Thanks.

[speedball1]

Taping the threads on a compression nut won't stop anything as it isn't the threads that hold water it's the ferrule,(see image). You do have a ferrule installed don't you? If so, then crank down a little harder. If not then the compression goes on the pipe first then the ferrule and finally the anglestop. Good luck, Tom

[emahsman]

Thanks so much for the help. So the teflon tape is pointless in this situation? Being very simple-minded about plumbing, I just always use it. Also, I learned a new word, ferrule. I did use the ferrule but didn't know what it was called.