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Tap Drill Chart | National Pipe Threads

NPT & NPTF

NPS & NPSF

Pipe Tap Size

Pitch (TPI)

Drill Size* (inch) 0.242 (C) 0.332 (Q)

Pitch (TPI)

Drill Size (inch) 0.348 (S) 29/64 19/32 47/64 15/16 1-3/16 1-33/64 1-3/4 2-7/32 2-21/32 3-9/32 3-25/32 4-9/32 -

1/16

27 27 18 18 14 14

-

1/8 1/4 3/8 1/2 3/4

27 18 18 14 14

7/16 9/16

45/64 29/32 1-9/64 1-31/64 1-23/32 2-7/32

1

11-1/2 11-1/2 11-1/2 11-1/2

11-1/2 11-1/2 11-1/2 11-1/2

1-1/4 1-1/2

2

2-1/2

8 8 8 8

2-5/8 3-1/4 3-3/4 4-1/4

8 8 8 8

3

3-1/2

4

*Without taper reamer

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