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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 industry, and this catalog.

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 recommend 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 M.M. 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 MaximumOperating 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 2,000 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
Pressure Ratings for Hydraulic Adapters

NPT Pressure Ratings for Hydraulic Adapters

Note: In the case of a fitting that is a jump size, it is recommend 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.

Nominal Pipe Size Fittings with Pipe Thread MPa Fittings with Pipe Thread PSI Max. Oper. Pressure MPa NPSM Std. Pipe Thread Maximum Operating Pressure PSI
  1/8 34.5 5,000 34.5 5,000
  1/4 27.5 4,000 27.5 4,000
  3/8 21.0 3,000 24.1 3,500
  1/2 21.0 3,000    
  3/4 17.0 2,500 15.5 2,250
1      14.0 2,000 13.8 2,000
1  1/4 8.0 1,150 11.2 1,625
1  1/2 7.0 1,000 8.6 1,250
2      7.0 1,000 7.8 1,125

MPa (Mega Paskels): 1 MPa = 145 PSI


JIC and O-Ring Boss Pressure Ratings for Hydraulic Adapters

Note: In the case of a fitting that is a jump size, it is recommend 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 M.M. Nom Tube O.D. in Inch Straight Thread 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
2 3.18 0.250 5/16 24 34.5 5,000 34.5 5,000
3 4.76 0.188 3/8 24 34.5 5,000 34.5 5,000
4 6.35 0.250 7/16 20 34.5 5,000 31.0 4,500
5 7.94 0.313 1/2 20 34.5 5,000 27.5 4,000
6 9.52 0.375 9/16 18 34.5 5,000 27.5 4,000
8 12.70 0.500 3/4 16 31.0 4,500 27.5 4,000
10 15.88 0.625 7/8 14 24.0 3,500 21.0 3,000
12 19.05 0.750 1 1/16 12 24.0 3,500 21.0 3,000
14 22.22 0.875 1 3/16 12 21.0 3,000 17.0 2,500
16 25.40 1.000 1 5/16 12 21.0 3,000 17.0 2,500
20 31.75 1.250 1 5/8 12 17.0 2,500 14.0 2,000
24 38.10 1.500 1 7/8 12 14.0 2,000 10.5 1,500
32 50.30 2.000 2 1/2 12 10.5 1,500 8.0 1,125

MPa (Mega Paskels): 1 MPa = 145 PSI


SAE J1453 Working Pressure Ratings - Capable of 4-1 Minimum Burst
Face Seal 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, Face Seal 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 wording pressure rating for that fitting.

Nom SAE Dash Size Straight Fittings Working MPa Straight Fittings Working PSI Straight Fitting Proof MPa Straight Fitting Proof PSI Straight Fitting Min.Burst MPa Straight Fitting Min.Burst PSI Adjustable Fittings Working MPa Adjustable Fittings Working PSI Adjustable Fittings Proof MPa  Adjustable Fittings Proof PSI  Adjustable Fittings Min Burst MPa Adjustable Fittings Min Burst MPa
4 41.3 6,000 82.5 12,000 165 24,000 41.3 6,000 82.5 12,000 165.0 24,000
6 41.3 6,000 82.5 12,000 165 24,000 41.3 6,000 82.5 12,000 165.0 24,000
8 41.3 6,000 82.5 12,000 165 24,000 41.3 6,000 82.5 12,000 165.0 24,000
10 41.3 6,000 82.5 12,000 165 24,000 41.3 6,000 82.5 12,000 165.0 24,000
12 41.3 6,000 82.5 12,000 165 24,000 41.3 6,000 82.5 12,000 165.0 24,000
16 41.3 6,000 82.5 12,000 165 24,000 34.5 5,000 69.9 10,000 138.0 20,000
20 27.5 4,000 55.0 8,000 110 16,000 27.5 4,000 55.0 8,000 110.0 16,000
24 27.5 4,000 55.0 8,000 110 16,000 20.7 3,000 41.3 6,000 82.5 12,000

MPa (Mega Paskels): 1 MPa = 145 PSI


SAE J1453 Working Pressure Ratings - Capable of 4-1 Minimum Burst
Code 61 & Code 62 Flange Fittings
Nom SAE Dash Size Code 61 Nominal Flange Size Inch Maximum recommended Working Pressure MPa Maximum recommended Working Pressure PSI Code 62 Nominal Flange Size Inch Maximum recommended Working Pressure MPa Maximum recommended Working Pressure PSI
8   1/2 34.5 5,000   1/2 41.4 6,000
12   3/4 34.5 5,000   3/4 41.4 6,000
16 1      34.5 5,000 1      41.4 6,000
20 1  1/4 27.6 4,000 1  1/4 41.4 6,000
24 1  1/2 20.7 3,000 1  1/2 41.4 6,000
32 2      20.7 3,000 2      41.4 6,000

MPa (Mega Paskels): 1 MPa = 145 PSI

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