I removed what I didn't realize was a compression fitting on a copper pipe for my kitchen cold water supply. Is it possible to reuse the compression fitting or do I need to buy a new one to replace it?
It looks like it's some kind of plastic. It took a tremendous amount of force to loosen, and a fairly cursory attempt at re-tightening resulted in a leak. Also, I assume I should wrap everything in teflon tape when replacing the connectors?
If it hasn't been tightened many times, it should be okay to reuse.
Clean off the mating faces thoroughly and don't use tape, putty, or anything else. And don't be gentle tightening: The seal is formed by forcing the surfaces together and "bending" them to mate.
Even with threaded steel pipes, it can take a day or two for the tightened fittings to form a good seal and they can drip at first. The essential observation is whether the drip rate slows hour by hour—if it does, it is probably okay and going to seal.
If it doesn't drip more slowly, try tightening a little more with water pressure applied until two consecutive small turns (1/8 turn) doesn't immediately decrease the drip rate.
Had super short copper stubs and no shut off valves under bathroom sink. To add the compression shut off valves I cleaned the ferrule ring and wrapped it several times with Teflon tape. I tightened very tight and that worked for me - no leaks. Just passing it on. Not an expert or plumber so very grateful for these posts. Good luck all~~~
I would be cautious reusing this. Reason being if the surface has a slight indentation from the previous seat from the prior install, and the shape of that end is kind of half spherical, which allows the mating surfaces to change locations depending on the angle to pipe approaches its counterpart.
If the surface is not marred from the prior install though, it is safe to use. Perhaps even a slight mar may be reformed when tightened, worth a shot to me if that is the case.
Do clean it and inspect it first, apply pipe dope if you choose, not teflon tape
I'm going to directly contradict the other answers. As stated in "See Jane Drill episode on "When to Use PFTE Tape, Pipe Dope or Neither" (see 6:06 onward), warping your ferrule with some plumbers tape is the preffered way to reuse a ferrule you can't remove.
As others have stated, the ferrule is usually scored during the initial fitting and that scoring will likely make it leak during reuse, the teflon tape workes by filling the fills the scored area of the ferrule.
That said, the preferred thing do to is remove the ferrule if you can. If I were in your situation, I'd cut and replace with a 'push fit' hose + fitting combo (if your valve needs to be replaced your hose should be too, so you might as well buy them as a combo) as they are easy to remove later.
