Is teflon tape at the same time on same threads acceptable?
I am not a fitter
NFPA 13 says "or"
Does not say you cannot use both???
You can use both, but you'll be wasting money unless it is a really bad manufactured thread.
NFPA 13 2013 18.104.22.168
Joint compound or tape shall be applied only to male threads.
It's never a good idea to use both. One or the other. Some pipe thread/joint compounds cannot be used on PVC fittings as it will degrade the fitting. Make sure it specifically stipulates for use on PVC or plastic fittings. Teflon tapes are also graded as to which application they can be used on. Example, Teflon tape used for water cannot be used for gas applications.
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