Step 4 · Remove Old Compression Nut and Ferrule

With the valve body removed, the old compression nut and the brass compression ring (ferrule) will remain on the copper pipe. Slide the old nut off. The ferrule is often stuck firmly in place. Sometimes you can carefully pry it off with two screwdrivers or by gripping it with pliers and twisting. If it won't budge, the safest method is to use a dedicated ferrule puller tool. As a last resort, you can very carefully cut a slot in it with a small hacksaw or rotary tool, being extremely careful not to cut into the copper pipe itself, and then split it off with a flathead screwdriver.