Most standard pipe taps have a maximum chamfer length that ranges between 3 and 4 threads. Therefore, the tapping depth should be the approx. 5 threads for the “hand tight”, 3 threads for “wrench tight”, and 4 threads for the chamfer, or approx. 12 threads total.

How far do NPT threads engaged?

Outside Diameter DNominal Pipe SizeHand Tight Thread Engagement Length, L10.8401⁄20.3201.0503⁄40.3391.31510.4001.6601 1⁄40.420

How are pipe threads sized?

To determine the size of a pipe, the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4″ NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI).