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Fractional Size Codes
Know your adapter sizes, and the corresponding number and letter codes that commonly represent them. North American Fluid Power Thread sizes are measured in 1/16" increments, and are used throughout the industry, and our catalogue.

Hydraulic adapters and malleable iron fittings are identified with number codes representing each size, while brass pipe thread fittings use letter codes to represent each size. Both systems are commonly used throughout the industry.

Nominal Thread Size (Inches)

SAE Number Dash Sizes

NPT Letter Dash Sizes

Fraction Size

1/16

1

 

0.0625

1/8

2

A

0.1250

3/16

3

 

0.1875

1/4

4

B

0.2500

5/16

5

 

0.3125

3/8

6

C

0.3750

1/2

8

D

0.5000

5/8

10

 

0.6250

3/4

12

E

0.7500

7/8

14

 

0.8750

1

16

F

1.000

1 1/4

20

G

1.250

1 1/2

24

H

1.500

2

32

I

2.000

2 1/2

40

J

2.500

3

48

K

3.000

4

64

L

4.000

Hydraulic Adapter - Pressure Ratings
SAE J514 Working Pressure Ratings - Capable of 4-1 Minimum burst SAE and NPT Fittings


Note: In the case of a fitting that is a jump size, it is recommended that the lower pressure of the two ends must be recognized as the working pressure rating for that fitting. This is also the case if the fitting has one or more different style ends. For example, straight threads to pipe threads. In this case it is also recommended that the lower pressure rating of the two different style ends must be recognized as the working pressure rating for that fitting.

Nom SAE Dash Size

Nom Tube O.D. in MM

Nom Tube O.D. in Inch

Straight Thread Size

Nom Pipe Size

Rigid SAE St. Thread Unions & Bulkhead MPa

Rigid SAE St. Thread Unions & Bulkhead PSI

Adjustable SAE Std. Thread & Female Swivel MPa

Adjustable SAE Std. Thread & Female Swivel PSI

Fittings with Pipe Thread MPa

Fittings with Pipe Thread PSI

NPSM Std. Pipe Thread Maximum Operating Pressure MPa

NPSM Std. Pipe Thread Maximum Operating Pressure MPA

2

3.18

0.250

5/16 24

1/8

34.5

5,000

34.5

5,000

34.5

5,000

34.5

5,000

3

4.76

0.188

3/8 24

1/8

34.5

5,000

34.5

5,000

34.5

5,000

 

 

4

6.35

0.250

7/16 20

1/8

34.5

5,000

31.0

4,500

34.5

5,000

34.5

5,000

5

7.94

0.313

1/2 20

1/8

34.5

5,000

27.5

4,000

34.5

5,000

 

 

6

9.52

0.375

9/16 18

1/4

34.5

5,000

27.5

4,000

27.5

4,000

27.5

4,000

8

12.70

0.500

3/4 16

3/8

31.0

4,500

27.5

4,000

21.0

3,000

24.1

3,500

10

15.88

0.625

7/8 14

1/2

24.0

3,500

21.0

3,000

21.0

3,000

 

 

12

19.05

0.750

1 1/16 12

3/4

24.0

3,500

21.0

3,000

17.0

2,500

15.5

2,250

14

22.22

0.875

1 3/16 12

3/4

21.0

3,000

17.0

2,500

17.0

2,500

 

 

16

25.40

1.000

1 5/16 12

1

21.0

3,000

17.0

2,500

14.0

2,000

13.8

2,000

20

31.75

1.250

1 5/8 12

1 1/4

17.0

2,500

14.0

2,500

8.0

1,150

11.2

1,625

24

38.10

1.500

1 7/8 12

1 1/2

14.0

2,000

10.5

1,500

7.0

1,000

8.6

1,250

32

50.30

2.000

2 1/2 12

2

10.5

1,500

8.0

1,125

7.0

1,000

7.8

1,125

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