Pre Tap Drill Size

Pipe Tap NPSF

Tap
Drill Size
Decimal Equivalent
2in - 11-1/2
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1.50 - 11-1/2
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1.25 - 11-1/2
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1in 11-1/2
1in 5/32
1.1562
3/4 - 14
59/64
0.9218
1/2 - 14
18MM
0.7086
3/8 - 18
37/64
0.5781
1/4 - 18
7/16
0.4375
1/8 - 27
R
0.339
1/16 - 27
D
0.246