What is the tap drill for 2" NPT?

The tap drill for 2" NPT is 2-7/32" (2.2188" / 56.36 mm) per ASME B1.20.1. NPT uses a 1:16 taper — the tap itself cuts the tapered thread form.

What is the outside diameter of 2" NPT pipe thread?

The outside diameter of 2" NPT pipe thread is 2.3750" (60.32 mm) per ASME B1.20.1. The nominal pipe size does not equal the actual OD.

How many threads per inch is 2" NPT?

2" NPT has 11.5 threads per inch (TPI) with a 60° thread angle and 1:16 taper per ASME B1.20.1.

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2" NPT Thread Specifications

Complete dimensions for 2" NPT (National Pipe Taper) thread per ASME B1.20.1. TPI: 11.5, Pitch: 0.08696" (2.209 mm). Taper: 1 in 16 on diameter (3/4" per foot).

Thread Dimensions

Designation	2" NPT
Nominal Pipe Size	2"
TPI	11.5
Pitch	0.08696" (2.209 mm)
Outside Diameter	2.3750" (60.32 mm)
Pitch Diameter at E0 (hand-tight)	2.27000" (57.658 mm)
Pitch Diameter at E1 (wrench makeup)	2.29625" (58.325 mm)
Minor Diameter at E0	2.23199" (56.693 mm)
Taper Angle	1.7899° (1:16 taper ratio, 3/4"/ft)
Thread Depth (h = 0.8p)	0.06957" (1.767 mm)

Values per ASME B1.20.1 Table 1. E0 = hand-tight engagement pitch diameter; E1 = wrench-makeup pitch diameter.

Tap Drill Size

Tap drill: 2-7/32" (2.2188" / 56.36 mm)

NPT tap drills allow the tap to cut the taper thread. The tap itself creates the taper geometry; drill size provides initial clearance at the large end.

Common Applications

Plumbing connections
Gas piping
Hydraulic fittings
Pneumatic connections