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Thread Identification

Quick Search: Please Enter Measurement Taken with Calipers


 

Step 1 (Thread Measurement) > Step 2 (Sealing Forms)Step 3 (Dash Sizes)

 

Step 1: Thread Identification

Use calipers to measure the diameter & thread pitch.

                 - For male threads measure the outside diameter

                 - For female threads measure the inside diameter

Match your measurements with the chart below; continue to Step 2 for sealing forms

Outside Dia. Male 
(mm)

Outside Dia. Male 
(inches)

Inside Dia Female 
(mm)

Inside Dia. Female 
(Inches)

Pitch/Inch

TPI

Forms

Metric DIN/ Metric ISO 6149

BSPP (G) /BSPT (R)

NPTF

ORB/JIC/ORFS (UNF)

3.8 - 3.9

0.150 - 0.154

3.2 - 3.4

0.126 - 0.134

0.7

-

M 4

-

-

-

4.0 - 4.2

0.158 - 0.165

3.4 - 3.6

0.134 - 0.142

36

E, F, G

-

-

-

No. 8

4.6 - 4.8

0.181 - 0.189

4.0 - 4.2

0.157 - 0.165

32

E, F, G

-

-

-

No. 10

4.8 - 4.9

0.189 - 0.193

4.1 - 4.3

0.161 - 0.169

0.8

-

M 5

-

-

-

5.7 - 5.9

0.224 - 0.232

4.9 - 5.2

0.193 - 0.205

1

B

M 6

-

-

-

7.7 - 7.9

0.303 - 0.311

6.9 - 7.2

0.272 - 0.283

1

B, C, E,

M 8

-

-

-

7.7 - 7.9

0.303 - 0.311

6.6 - 6.9

0.260 - 0.272

1.25

B

M 8

-

-

-

7.7 - 7.9

0.303 - 0.311

6.8 - 7.1

0.268 - 0.280

24

E, F

-

-

-

5/16

7.0 - 7.9

0.275 - 0.311

6 - 6.9

0.236 - 0.271

27

D

-

-

1/16

-

9.5 - 9.7

0.374 - 0.397

8.5 - 8.8

0.335 - 0.346

28

B, C, D

-

1/8

-

-

9.5 - 9.7

0.374 - 0.382

8.5 - 8.7

0.335 - 0.343

24

E, F

-

-

-

3/8

9.7 - 9.9

0.382 - 0.390

8.9 - 9.2

0.350 - 0.362

1

A, B, C, E

M 10

-

-

-

9.7 - 9.9

0.382 - 0.390

8.6 - 8.9

0.339 - 0.350

1.25

-

M 10

-

-

-

9.7 - 9.9

0.382 - 0.390

8.4 - 8.7

0.331 - 0.343

1.5

-

M 10

-

-

-

9.4 - 10.3

0.370 - 0.406

8.3 - 9.2

0.327 - 0.362

27

D

-

-

1/8

-

10.9 - 11.1

0.429 - 0.437

9.7 - 10.0

0.382 - 0.394

20

E, F

-

-

-

7/16

11.7 - 11.9

0.461 - 0.469

10.6 - 10.9

0.417 - 0.429

1.25

-

M 12

-

-

-

11.7 - 11.9

0.461 - 0.469

10.4 - 10.7

0.409 - 0.421

1.5

B,C

M 12

-

-

-

11.6 - 11.9

0.457 - 0.469

10.1 - 10.4

0.398 - 0.409

1.75

-

M 12

-

-

-

12.2 - 12.4

0.480 - 0.488

11.2 - 11.4

0.441 - 0.449

1.5

-

M 12.65

-

-

-

12.5 -12.7

0.492 - 0.500

11.3 - 11.7

0.445 - 0.461

20

E, F

-

-

-

1/2

12.9 - 13.2

0.508 - 0.520

11.4 - 11.9

0.449 - 0.469

19

B, C, D

-

1/4

-

-

12.6 - 13.7

0.496 - 0.539

10.7 - 11.5

0.421 - 0.452

18

D

-

-

1/4

-

13.8 - 14.0

0.543 - 0.551

12.4 - 12.6

0.488 - 0.496

1.5

B, C, E

M 14

-

-

-

14.0 - 14.2

0.552 - 0.561

12.8 - 13.1

0.502 - 0.515

18

E, F, G

-

-

-

9/16

14.1 - 14.2

0.554 - 0.561

13.1 - 13.4

0.517-0.527

24

-

-

-

-

9/16

15.7 - 15.9

0.618 - 0.626

14.4 - 14.7

0.567 - 0.579

1.5

B, C, E

M 16

-

-

-

15.6 - 15.9

0.614 - 0.626

13.8 - 14.2

0.543 - 0.560

2

-

M 16

-

-

-

15.7 - 15.9

0.618 - 0.626

14.4 - 14.7

0.567 - 0.579

16

-

-

-

-

5/8

15.9 - 16.1

0.626 - 0.634

14.4 - 14.6

0.567 - 0.575

18

-

-

-

-

5/8

16.4 - 16.7

0.646 - 0.657

14.9 - 15.4

0.587 - 0.606

19

B, C, D

-

3/8

-

-

16.0 - 17.1

0.629 - 0.673

14.2 - 14.8

0.559 - 0.582

18

D

-

-

3/8

-

17.2 - 17.4

0.677 - 0.685

15.7 - 15.9

0.618 - 0.626

16

G

-

-

-

11/16

17.8 - 18.0

0.701 - 0.709

16.4 - 16.6

0.646 - 0.654

1.5

B, C, E

M 18

-

-

-

18.8 - 19.0

0.739 - 0.748

17.3 - 17.7

0.682 - 0.696

16

E, F

-

-

-

3/4

19.7 - 19.9

0.776 - 0.783

18.9 - 19.2

0.744 - 0.756

1

A

M 20

-

-

-

19.7 - 19.9

0.776 - 0.783

18.4 - 18.7

0.724 - 0.736

1.5

A

M 20

-

-

-

19.6 - 19.9

0.772 - 0.783

17.3 - 17.7

0.681 - 0.697

2.5

A

M 20

-

-

-

20.4 - 20.6

0.802 - 0.811

18.9 - 19.3

0.745 - 0.759

16

G

-

-

-

13/16

20.7 - 20.9

0.815 - 0.823

18.6 - 19.2

0.732 - 0.756

14

B, C, D

-

1/2

-

-

20.4 - 21.3

0.803 0.839

17.4 - 18.5

0.728 - 0.685

14

D

-

-

1/2

-

21.7 - 21.9

0.854 - 0.862

20.4 - 20.7

0.803 - 0.815

1.5

A

M 22

-

-

-

21.9 - 22.6

0.862 - 0.890

20.3 - 20.8

0.799 - 0.819

14

E, F

-

-

-

7/8

23.7 - 23.9

0.933 - 0.941

22.4 - 22.7

0.882 - 0.894

1.5

A

M 24

-

-

-

23.6 - 23.9

0.929 - 0.941

20.8 - 21.3

0.819 - 0.839

3

A

M 24

-

-

-

25.1 - 25.4

0.989 - 1.000

23.1 - 23.6

0.909 - 0.929

14

G

-

-

-

1

25.7 - 26.0

1.012 - 1.024

24.4 - 24.6

0.961 - 0.969

1.5

A

M 26

-

-

-

26.2 - 26.4

1.031 - 1.039

24.1 - 24.7

0.949 - 0.972

14

B, C, D

-

3/4

-

-

26.6 - 26.9

1.047 - 1.059

24.8 - 25.2

0.976 - 0.992

2

A

M 27

-

-

-

26.8 - 27.0

1.055 - 1.063

24.7 - 24.9

0.972 - 0.980

12

E, F

-

-

-

1 1/16

25.5 - 26.7

1.00 - 1.051

22.5 - 23.6

0.886 - 0.929

14

D

-

-

3/4

-

28.3 - 28.6

1.114 - 1.126

26.3 - 26.8

1.035 - 1.055

12

-

-

-

-

1 1/8

29.7 - 29.9

1.169 - 1.18

28.4 - 28.7

1.118 - 1.130

1.5

-

M 30

-

-

-

29.7 - 29.9

1.169 - 1.18

28.4 - 28.7

1.118 - 1.130

2

B, C, E

M 30

-

-

-

30.0 - 30.2

1.181 - 1.189

27.9 - 28.1

1.098 - 1.106

12

E, F, G

-

-

-

1 3/16

31.5 - 31.7

1.240 - 1.248

29.5 - 30.0

1.161 - 1.181

12

D

-

-

1 1/4

-

32.9 - 33.2

1.295 - 1.307

30.3 - 30.9

1.193 - 1.217

11

B, C, D

-

1

-

-

32.7 - 33.0

1.287 - 1.299

30.8 - 31.2

1.213 - 1.228

2

B, C, E

M 33

-

-

-

32.4 - 33.2

1.276 - 1.307

31.1 - 31.3

1.224 - 1.232

12

E, F

-

-

-

1 5/16

32.4 - 33.4

1.275 -1.315

28.5 - 29.6

1.122 - 1.165

11 1/2

D

-

-

1

-

35.7 - 35.9

1.406 - 1.413

34.4 - 34.7

1.354 - 1.366

1.5

-

M 36

-

-

-

35.6 - 35.9

1.402 - 1.413

33.8 - 34.2

1.331 - 1.346

2

B, C

M 36

-

-

-

36.2 - 36.5

1.425 - 1.437

34.2 - 34.4

1.346 - 1.354

12

G

-

-

-

1 7/16

37.7 - 37.9

1.484 - 1.492

36.4 - 36.7

1.433 - 1.445

1.5

-

M 38

-

-

-

37.8 - 38.1

1.488 - 1.500

35.8 - 36.4

1.409 - 1.433

12

-

-

-

-

1 1/2

41.1 - 41.3

1.618 - 1.626

39.1 - 39.3

1.539 - 1.547

12

E, F

-

-

-

1 5/8

41.6 - 41.9

1.638 - 1.650

38.9 - 39.6

1.531 - 1.559

11

B, C, D

-

1 1/4

-

-

41.7 - 41.9

1.642 - 1.650

40.4 - 40.7

1.591 - 1.602

1.5

-

M 42

-

-

-

41.6 - 41.9

1.638 - 1.650

39.8 - 40.2

1.567 - 1.583

2

B, C, E

M 42

-

-

-

41.3 - 42.2

1.626 - 1.661

37.0 - 38.1

1.457 - 1.500

11 1/2

D

-

-

1 1/4

-

42.6 - 42.8

1.677 - 1.685

40.6 - 40.8

1.598 - 1.606

12

G

-

-

-

1 11/16

44.7 - 44.9

1.760 - 1.768

43.4 - 43.7

1.709 - 1.720

1.5

-

M 45

-

-

-

44.7 - 44.9

1.760 - 1.768

43.4 - 43.7

1.709 - 1.720

2

B, C

M 45

-

-

-

47.4 - 47.8

1.866 - 1.882

44.8 - 45.5

1.764 - 1.791

11

B, C, D

-

1 1/2

-

-

47.4 - 47.6

1.866 - 1.874

45.3 - 45.5

1.783 - 1.791

12

E, F

-

-

-

1 7/8

47.6 - 47.9

1.874 - 1.886

45.8 - 46.2

1.803 - 1.819

2

B, C, E

M 48

-

-

-

47.4 - 48.3

1.866 - 1.902

43.5 - 44.9

1.713 - 1.768

11 1/2

D

-

-

1 1/2

-

50.5 - 50.7

1.988 - 1.996

48.5 - 48.7

1.909 - 1.917

12

G

-

-

-

2

51.8 - 52.0

2.039 - 2.047

49.8 - 50.0

1.961 - 1.969

2

-

M 52

-

-

-

51.7 - 52.0

2.035 - 2.047

50.4 - 50.6

2.003 - 2.011

1.5

-

M 52

-

-

-

59.3 - 59.6

2.335 - 2.346

56.7 - 57.3

2.232 - 2.256

11

D

-

2

-

-

59.7 - 59.9

2.350 - 2.358

58.4 - 58.7

2.299 - 2.311

1.5

-

M 60

-

-

-

59.7 - 59.9

2.350 - 2.358

58.4 - 58.7

2.299 - 2.311

2

B, C

M 60

-

-

-

59.5 - 60.3

2.342 - 2.374

55.0 - 56.5

2.165 - 2.224

11 1/2

D

-

-

2

-

79.7 - 79.9

3.138 - 3.146

78.4 - 78.7

3.087 - 3.098

1.5

-

M 80

-

-

-

 

Continue onto Step 2: Sealing Forms