#Plumbers: I am simply trying to install a ½" tapered thread fitting on a hot water tank. I first tried PTFE tape (13 clockwise wraps). It leaked. When I unscrewed the fitting all the PTFE tape was neatly compressed down as it should. No idea why that failed. I removed it all using a steel brush then used 8 wraps of #Loctite55 string. That also failed. What’s my next move? #AskFedi