PTFE tape direction matters — wrap clockwise when facing the thread end

Wrapping PTFE tape counterclockwise causes it to unravel when you thread the fitting on. Always wrap clockwise (when looking at the thread end face-on), 3-5 wraps for standard connections. For gas lines, use yellow PTFE rated for gas per UL 181. White tape is for water only. This is one of the most common apprentice mistakes and it causes callbacks.