NPT 鉆頭徑
Drill dia

NPS (NPSC)

使用絞刀之場合
Use with reamer

不使用絞刀之場合
Without reamer

鉆頭徑
Drill dia

mm

inch

mm

inch

mm

inch

1/16-27

5.94

0.234

6.15

0.242

6.35

0.250

1/8-27

8.33

0.328

8.43

0.332

8.74

0.344

1/4-18

10.72

0.422

11.13

0.438

11.13

0.438

3/8-18

14.27

0.562

14.27

0.562

14.68

0.578

1/2-14

17.48

0.688

17.86

0.703

18.26

0.719

3/4-14

22.63

0.891

23.01

0.906

23.42

0.922

1-11 1/2

28.58

1.125

28.98

1.141

29.36

1.156

1 1/4-11 1/2

37.31

1.469

37.69

1.484

38.10

1.500

1 1/2-11 1/2

43.26

1.703

43.66

1.719

44.45

1.750

2-11 1/2

55.17

2.172

55.58

2.188

56.36

2.219

2 1/2-8

65.48

2.578

66.27

2.609

67.46

2.656