The water company has already shut off the water. There is copper coming up from the floor, to a brass 90, then the shut off. Replacing with ball valve. I will soon attempt to remove the old valve. I have already given it a shot lightly and it may be frozen. I'm thinking about heating up the threaded area with a torch to loosen it???, there's gunk on the threads and obviously I don't want to snap the pipe off. I am planning to block the pipe against the wall with a 2 x 4 so that when I attempt to remove it doesn't twist etc, or there is a spot on the 90 elbow for a double wrench setup, is there a preferred way to do this carefully? For the new ball valve gizmo is it correct to use teflon tape on the threads? Thanks