
The nominal size of a Pipe Tap is that of the pipe fitting to be tapped, not the actual size of the tap. The thread tapers 3/4 of an in. to 3-1/2 in. thread chamfer. Carbon Steel NPT Pipe Tap. NPT pipe tap sizes included in set are: 1/8 in., 1/4 in., 3/8 in., 1/2 in., 3/4 in.