I'm installing a tub filler in my bathroom reno. I think sweating the copper from the valve pictured below back toward the supply line will be the easiest way to make sure things line up. My questions are: 1. Do I need to use plumbers tape on the male copper threads screwed into the valve. Pic below. 2. Will sweating the copper fittings melt the plumbers tape to the point it no longer holds the seal.