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How to measure threads

BSP - British Standard Pipe (BSPP Parallel & BSPT Taper)

JIC - SAE J514 37° Flare

ORFS - SAE J1453 O-Ring Face Seal

Metric DIN 3902

NPTF - National Pipe Tapered Fuel

 

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How to measure threads

Vernier Caliper

1. Using a vernier caliper, measure the O.D. of the male thread or the I.D. of the female thread.

 

NOTE: Threads can become worn and may not compare exactly to our tables.

2. Use a thread pitch gauge to determine the number of threads per inch or the distance between threads in metric connections.

Thread Pitch Gauge

Seat Angle Gauge

3. Use the seat angle gauge to determine the angle of the sealing surface.  The centreline of the fitting and the gauge should be parallel.

Compare these three measurements to the tables below to find the closest match.

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BSP - British Standard Pipe (BSPP Parallel & BSPT Taper)

The British BSP connections include two types of thread, BSPP which are straight (or parallel) and BSPT which are tapered.  The BSPT tapered male will mate with a BSPT tapered female (usually a port) and seals on the thread.  The BSPP parallel male has a 30° chamfered seat which seals with a BSPP female on its 30° cone seat.

BSPP Thread

BSPT Thread

Inch Size

Thread

Male Thread O.D. mm

Male Thread O.D. inches

Female Thread I.D. mm

Female Thread I.D. inches

-02 (1/8)

1/8-28

9.7

0.38

8.9

0.35

-04 (1/4)

1/4-19

13.2

0.52

11.9

0.47

-06 (3/8)

3/8-19

16.5

0.65

15.2

0.60

-08 (1/2)

1/2-14

20.8

0.82

19.1

0.75

-10 (5/8)

5/8-14

22.4

0.88

20.3

0.80

-12 (3/4)

3/4-14

26.4

1.04

24.6

0.97

-16 (1)

1-11

33.0

1.30

31.0

1.22

-20 (1 ¼)

1 1/4-11

41.9

1.65

39.6

1.56

-24 (1 ½)

1 1/2-11

47.8

1.88

45.5

1.79

-32 (2)

2-11

59.7

2.35

57.4

2.26

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JIC - SAE J514 37° Flare

Commonly referred to as 37° JIC, this connection is widely used in hydraulic systems. When the straight threads are engaged, the 37° male seat seals on the  37° female flare seat.

 

JIC Thread

 

Inch Size

Thread

Male Thread O.D. mm

Male Thread O.D. inches

Female Thread I.D. mm

Female Thread I.D. inches

-02 (1/8)

5/16-24

7.9

0.31

6.9

0.27

-03 (3/16)

3/8-24

9.6

0.38

8.6

0.34

-04 (1/4)

7/16-20

11.2

0.44

9.9

0.39

-05 (5/16)

1/2-20

12.7

0.50

11.4

0.45

-06 (3/8)

9/16-18

14.2

0.56

12.9

0.51

-08 (1/2)

3/4-16

19.0

0.75

17.0

0.67

-10 (5/8)

7/8-14

22.3

0.88

20.3

0.80

-12 (3/4)

1 1/16-12

26.9

1.06

24.9

0.98

-16 (1)

1 5/16-12

33.3

1.31

31.0

1.22

-20 (1 ¼)

1 5/8-12

41.4

1.63

39.1

1.54

-24 (1 ½)

1 7/8-12

47.7

1.88

45.5

1.79

-32 (2)

2 1/2-12

63.5

2.50

61.2

2.41

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ORFS - SAE J1453 O-Ring Face Seal

This connection is designed for leak-free use to 6000 PSI. The o-ring in the  face of the straight thread male end seals against the flat face female seat and  is mechanically held in place by a swivel nut.

 

ORFS Thread

 

Inch Size

Thread

Male Thread O.D. mm

Male Thread O.D. inches

Female Thread I.D. mm

Female Thread I.D. inches

-04 (1/4)

9/16-18

14.2

0.56

12.9

0.51

-06 (3/8)

11/16-16

17.3

0.68

16.0

0.63

-08 (1/2)

13/16-16

20.6

0.81

19.0

0.75

-10 (5/8)

1-14

25.4

1.00

23.6

0.93

-12 (3/4)

1 3/16-12

30.0

1.18

27.8

1.10

-16 (1)

1 7/16-12

36.6

1.44

34.5

1.36

-20 (1 ¼)

1 11/16-12

42.7

1.68

40.6

1.60

-24 (1 ½)

2-12

50.8

2.00

48.8

1.92

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Metric DIN 3902

This connection style consists of a common male and three different female halves.  The male has a straight metric thread, a 24° included angle and a recessed couterbore that matches the tube O.D. used with it.  The female may be a tube, nut and olive, a tapered nose /Globeseal flareless swivel or a tapered nose/Globeseal flareless swivel with an O-Ring in the nose.

 

Metric Thread

 

Tube O.D. Light

Tube O.D.  Heavy

Thread

Male Thread O.D. mm

Male Thread O.D. inches

Female Thread I.D. mm

Female Thread I.D. inches

6mm

 

M12x1.5

12.0

0.47

10.5

0.41

8mm

6mm

M14x1.5

14.0

0.55

12.5

0.49

10mm

8mm

M16x1.5

16.0

0.63

14.5

0.57

12mm

10mm

M18x1.5

18.0

0.71

16.5

0.65

 

12mm

M20x1.5

20.0

0.78

18.5

0.73

15mm

14mm

M22x1.5

22.0

0.87

20.5

0.81

 

16mm

M24x1.5

24.0

0.94

22.5

0.89

18mm

 

M26x1.5

26.0

1.02

24.5

0.96

22mm

20mm

M30x2.0

30.0

1.18

28

1.11

28mm

25mm

M36x2.0

36.0

1.41

34.0

1.34

 

30mm

M42x2.0

42.0

1.65

40.0

1.57

35mm

 

M45x2.0

45.0

1.77

43.0

1.70

42mm

38mm

M52x2.0

52.0

2.04

50.0

1.97

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NPTF - National Pipe Tapered Fuel

This connection is used in America and may be found on machines/equipment from that country.  The thread is tapered and the seal takes place by deformation of the threads.  It is also sometimes known as A.P.I. The male thread can also be referred to as MIP and the female thread as FIP.

 

NPTF Thread

 

Inch Size

Thread

Male Thread O.D. mm

Male Thread O.D. inches

Female Thread I.D. mm

Female Thread I.D. inches

-02 (1/8)

1/8-27

10.3

0.41

9.4

0.37

-04 (1/4)

1/4-18

13.7

0.54

12.4

0.49

-06 (3/8)

3/8-18

17.3

0.68

15.7

0.62

-08 (1/2)

1/2-14

21.3

0.84

19.3

0.76

-10 (5/8)

5/8-14

22.9

0.90

21.1

0.83

-12 (3/4)

3/4-14

26.9

1.06

24.9

0.98

-16 (1)

1-11½

33.3

1.31

31.5

1.24

-20 (1 ¼)

1 1/4-11½

42.2

1.66

40.1

1.58

-24 (1 ½)

1 1/2-11½

48.3

1.90

46.2

1.82

-32 (2)

2-11½

60.4

2.38

57.9

2.29

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