Step 5 · Clean and Prepare the Copper Pipe
Once the old valve is off, inspect the copper pipe. You will see the old compression nut and a brass compression ring called a ferrule. Slide the old nut off. The ferrule must also be removed for a proper seal with the new valve. It can be stubborn. You may be able to carefully cut a slit in it with a utility knife (without cutting into the copper pipe) and pry it off. A dedicated ferrule puller tool is the safest method. Once the old parts are off, use emery cloth or fine-grit sandpaper to thoroughly clean the last inch of the copper pipe. It should be smooth and shiny, free of any corrosion, scale, or scratches. Wipe it clean with a dry rag.