I had a pig of a job with some brass screw joints. Used PTFE tape and ensured the rubber seating washers were perfectly in place but found it damn near impossible to get a perfect join without a tiny leak somewhere.
Would it have been better to forget the rubber washer / PTFE and go straight to putting some flux on the threads, tightening up and soldering the joints? Is this "acceptable practice"?
It was very complex joint for some bath taps. For each supply (hot and cold) there was a brass fitting for connection to the tap. Attached to this was a small extension brass fitting to reach through the tiled wall. Attached to that was a brass fitting to take a flexible pipe. This meant there were three separate brass fittings between the tap and the flexible pipe the other side of the wall. The ensemble of three brass fittings taking two rubber washers. If you include the rubber washer on the flexible hose and at the tap join that is four rubber washers for the hot supply and another four for the cold supply. 8 bleedin rubber washers in all! I just couldn't get every damn joint tightened up properly without a leak somewhere.
So regarding the three brass fittings in the middle, would it have been better to simply solder those three together and forget the supplied rubber washers / PTFE tape?