Help...

I am trying to replace a kitchen faucet. The copper water supply pipe is connected to a plastic shut-off valve. I want to replace the plastic shut-off valve with a metal valve. The plastic shut-off valve will not come off the copper water supply pipe.

How do I get this off? I tried unscrewing, but it does not appear to be screwed on the copper pipe.

Help....

I am trying to replace a kitchen faucet. The copper water supply pipe is connected to a plastic shut-off valve. I want to replace the plastic shut-off valve with a metal valve. The plastic shut-off valve will not come off the copper water supply pipe.

How do i get this off? I tried unscrewing, but it does not appear to be screwed on the copper pipe.

You have a plastic compression valve. Put one wrench on the valve so it doesn't turn and another on the nut that faces the wall side. Back the nut off counterclockwise and pull out the valve and the plastic compression nut and ferrule. Replace with a Brasscraft 1/2 X 1/4" compression angle stop. Do not use teflon tape or pipe joint compound on the metal faces or threads. Good luck, Tom