Thread Specifications

View Thread Identification Guide

National Pipe Thread Chart

NPT or National Pipe Thread is an American thread type commonly used in a variety of hydraulic and industrial applications. The most recognizable characteristic of NPT are tapered threads, and due to the metal-to-metal sealing method of NPT thread sealant is required in order to achieve a leak free connection.

 

National Pipe Thread
Inch Size Dash Size Nominal Thread Size Male Thread Female Thread
Fractional Numeric Fraction-TPI (Threads Per Inch) Outside Diameter Inside Diameter
1/8 2 1/8-27 .41 .38
1/4 4 1/4-18 .54 .49
3/8 6 3/8-18 .68 .63
1/2 8 1/2-14 .84 .77
3/4 12 3/4-14 1.05 .98
1 16 1-11 1/2 1.32 1.24
1-1/4 20 1 1/4 - 11 1/2 1.66 1.58
1-1/2 24 1 1/2 - 11 1/2 1.90 1.82
2 32 2-11 1/2 2.38 2.30

 

JIC 37 Degree Flare Thread Chart

 JIC or Joint Industrial Council Thread is an American thread type commonly used in a variety of hydraulic applications. The most common characteristic of JIC are a 37 degree sealing surface on the tip of the male, which seals upon the flare of the female mate. Even though JIC threads seal with a metal-to-metal connection, no thread sealant is required to achieve a leak free connection.

It is important to note, both the dash and nominal sizes listed in most thread charts do not refer to actual measurements of JIC threads. In order to properly identify JIC threads, please consult the outside and inside diameters of male and female threads respectively. Each of our JIC fittings contain a thread chart in the description for your convenience. Torque specifications and pressure ratings can be found within our resources as well. 

Caution: Dash Sizes 02, 03, 04, 05, 08, and 10 have the same threads as SAE 45 degree flare fittings, but the sealing surface angles are different. 

 

Inch Size Dash Size Nominal Thread Size Male Thread Female Thread
Fractional Numeric Fraction - TPI (threads per inch) Outside Diameter Inside Diameter
1/8 2 5/16-24 .31 .27
3/16 3 3/8-24 .38 .34
1/4 4 7/16-20 .44 .39
5/16 5 1/2-20 .50 .45
3/8 6 9/16-18 .56 .51
1/2 8 3/4-16 .75 .69
5/8 10 7/8-14 .88 .81
3/4 12 1-1/6 - 12 1.06 .98
7/8 14 1 13/16 - 12 1.19 1.10
1 16 1 5/16 - 12 1.31 1.23
1 1/4 20 1 5/8 - 12 1.63 1.54
1 1/2 24 1 7/8 - 12 1.88 1.79
2 32 2 1/2 - 12 2.50 2.42

 

SAE O-Ring Boss Thread Chart

SAE Straight Thread O-ring or O-Ring Boss (ORB) is a multipurpose thread ideal for medium and high-pressure hydraulic applications. The male thread contains an o-ring at the base which mates with a chamfer machined into the female counterpoint, which makes this thread type ideal for non-leak applications. In order to properly identify ORB threads, please consult the outside and inside diameters of male and female threads respectively. Each of our ORB fittings contain a thread chart in the description for your convenience. Torque specifications and pressure ratings can be found within our resources as well.

 

Inch Size Dash Size Nominal Thread Size Male Thread Female Thread
Fractional Numeric Fraction - TPI (threads per inch) Outside Diameter Inside Diameter
1/8 2 5/16-24 .31 .27
3/16 3 3/8-24 .38 .34
1/4 4 7/16-20 .44 .39
5/16 5 1/2-20 .50 .45
3/8 6 9/16-18 .56 .51
1/2 8 3/4-16 .75 .69
5/8 10 7/8-14 .88 .81
3/4 12 1-1/6 - 12 1.06 .98
7/8 14 1 13/16 - 12 1.19 1.10
1 16 1 5/16 - 12 1.31 1.23
1 1/4 20 1 5/8 - 12 1.63 1.54
1 1/2 24 1 7/8 - 12 1.88 1.79
2 32 2 1/2 - 12 2.50 2.42

 

O-Ring Face Seal

O-Ring Face Seal or ORFS is a thread often used in the most pressure critical hydraulic applications due to its high pressure ratings and non-leak sealing method. ORFS male threads contain an o-ring in the face of the fitting, which offers the best leak-protection of any imperial thread. In order to properly identify ORB threads, please consult the outside and inside diameters of male and female threads respectively. Each of our ORB fittings contain a thread chart in the description for your convenience. Torque specifications and pressure ratings can be found within our resources as well.

 

Inch Size Dash Size Nominal Thread Size Male Thread Female Thread
Fractional Numeric Fraction - TPI (threads per inch) Outside Diameter Inside Diameter
1/4 4 9/18-18 .56 .51
3/8 6 11/16-16 .69 .63
1/2 8 13/16-16 .82 .75
5/8 10 1-14 1.00 .93
3/4 12 1 3/16 - 12 1.19 1.11
1 16 1 7/16 - 12 1.44 1.36
1 1/4 20 1 11/16 - 12 1.69 1.61
1 1/2 24 2-12 2.00 1.92
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