NPTF 6 step plug is used in tapered threaded holes. The NPTF 6 step plug inspects the crest truncation or profile of the internal threads and is used in conjunction with L1 plug.

NPTF gages are used to inspect pipe threads that are used in Dryseal applications. Insert the 6-step (crest check) plug into the fitting. When the L1 plug is at the maximum notch, the 6-step gage must go between “MX” and “MXT” notch.

When the L1 plug is at the Basic Notch, the 6-Step gage must go between “B” and “BT” notch. When the L1 plug is at minimum notch, the 6-Step gage must go between the “MN” and “MNT” notch.