21. Taps for Pipe Threads products Taper pipe thread taps (NPTF) G Class Tc (Max) Tc (Min) Fc (Max) of Measurement Flank limit (deviation) Fc (Min) Description Flank limit (measurement) Number of threads (measurement) Tr (Max) Tr (Max) Fr (Max) Tr Fr (measurement) Fr (Max) Axis of tap Taper Unit : m Crest Root Size Tc Fc Tr Fr Max. Min. Max. Min. Max. Min. Technical Information Technical-63 834