How to Distinguish JIC and AN fittings
Figure 1: An example of a AN fitting (up), and a JIC fitting (down)
Both JIC and AN fittings look similar and perform similar functions, yet they differ significantly in their respective uses and specifications. What are the differences between the two standards?
AN and JIC (SAE J514 standard) both have a 37° flare connection on the male and female sides of the fitting and straight threads. A seal is achieved by threading in the JIC male flared connection with the female coned connection.
JIC stands for the Joint Industries Council, and AN stands for Air Force – Navy Aeronautical Design Standards. Army-Navy fittings first made their appearance around the second world war and have been designed to be used in U.S. military aviation applications. In contrast, JIC fittings are used primarily in industries such as agriculture; these are now often referred to as SAE J514 Flare fittings. We look at the differences between the two and how you can choose the best fittings for your application.
Table of contents
- A short history of Army Navy couplings
- Differences between AN and JIC fittings
- How to measure JIC and AN couplings?
- AN and JIC size chart
- FAQ
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A short history of Army Navy couplings
Army Navy couplings are used primarily for military aviation systems. As such, these have been produced to the highest possible specs and performance standards. During the second part of the last century confusion sparked between AN fittings and those used in industrial applications, the 37° flare fitting. All these fittings claimed to be made to the AN standards, although they usually were not. This created not only confusion but also a potentially dangerous situation.
A new standard was introduced to clean up the confusion called the JIC (Joint Industries Council) fitting standard. These JIC hydraulic fittings have a slightly lower class of thread quality and are considerably less expensive than their AN counterparts. AN fitting sizes and JIC fitting sizes are comparable. JIC fittings are now defined by standard SAE J514 of the Society of Automotive Engineers (SAE).
Differences between AN and JIC fittings
Although they look similar and have similar functions, there are several differences between the JIC/ SAE J514 fittings and the AN 37° flared fittings. These differences include:
Threads
- On AN 37° flare fittings, both male and female fittings are made according to class 3A/3B UNJ/UNJF radiused root threads. J screw threads have a root radius that improves the tensile stress area of the fastener while reducing the stress concentration in the thread. This makes the thread stronger and offers the benefit of tighter tolerances and better fatigue life for aircraft, aerospace, and military applications.
- On SAE 37° Flare fittings, the male and female threads are made according to class 2A/2B UN/UNF series threads. Fastener classes 2A and 2B are designed for optimum thread fit that balances fastener performance, manufacturing, economy, and convenience.
Military vs industrial Standards
- AN flare fittings conform to MIL-F-5509 specifications and also AS4841.
- SAE/ISO 37° fittings conform to the United States Department of Defense MIL-F-18866 and SAE J514/ISO 8434-2
Read more about JIC fittings and the SAE J514 standards in our technical article.
Materials
Not only are there differences in the thread and standards of production. Materials differ as well.
- AN fittings are commonly available in carbon steel, stainless steel (CRES), aluminum, titanium, and copper-nickel.
- SAE 37° fittings are commonly produced out of carbon steel, stainless steel, and brass.
How to measure JIC and AN couplings?
As you can see in the image below, AN and JIC dimensions are measured through the outer diameter on the male connection and the inner thread diameter on the female connection. Keep in mind that AN, JIC, and SAE J514 use the same dimensions. See the JIC and AN chart for thread sizes.
Figure 2: Male JIC fitting outer diameter (A) and female JIC inner diameter (B)
- AN fittings are commonly available in carbon steel, stainless steel (CRES), aluminum, titanium, and copper-nickel.
- SAE 37° fittings are commonly produced out of carbon steel, stainless steel, and brass.
AN and JIC size chart
| Dash size | Female thread inside diameter (mm) | Male thread outside diameter (mm) | Thread size | Threads per inch |
|---|---|---|---|---|
| -2 | 6.7 | 7.9 | 0.3125 | 24 |
| -3 | 8.3 | 9.5 | 0.375 | 24 |
| -4 | 9.9 | 11.1 | 0.4375 | 20 |
| -5 | 11.5 | 12.7 | 0.5 | 20 |
| -6 | 12.7 | 14.3 | 0.5625 | 18 |
| -8 | 17.5 | 19.1 | 0.75 | 16 |
| -10 | 20.6 | 22.2 | 0.875 | 14 |
| -12 | 24.6 | 27 | 1.0625 | 12 |
| -14 | 28.2 | 30.2 | 1.1875 | 12 |
| -16 | 31.4 | 33.3 | 1.3125 | 12 |
| -20 | 39.3 | 41.3 | 1.625 | 12 |
| -24 | 45.6 | 47.6 | 1.875 | 12 |
| -32 | 61.5 | 63.5 | 2.5 | 12 |
FAQ
What does JIC stand for?
JIC stands for the Joint Industries Council, which first standardized industrial use fittings. These compression couplings have a 37° flared seat on the male and female threaded connections.
What does AN stand for?
AN stands for Air Force – Navy Aeronautical Design Standards, and it is used for fittings.
Can I combine AN and JIC couplings?
AN fittings are made to a much higher standard than JIC/SAE fittings. Also, AN fittings are much more expensive. Using these interchangeably is not recommended.
What are AN fittings used for?
Army-Navy fittings are used extensively in the U.S. military, military contractors, general aviation, and commercial aviation and are specifically designed to a high standard for this purpose.
What are JIC fittings used for?
Although developed and produced to a lower standard, JIC and SAE fittings are nearly identical to AN-type couplings. These are used extensively in agricultural equipment, construction, heavy machinery, and automotive industries.
What does a class 1A and 1B thread fit mean?
These classes have an extremely loose tolerance thread fit. Suitable for quick and easy assembly and disassembly. It is uncommon to find this class of thread fit.
What does a class 2A and 2B thread fit mean?
These classes offer a thread fit that creates a balance between performance, manufacturing, economy, and convenience. It is the most commonly used class as 90% of all commercial and industrial fasteners use it. SAE J514/ISO 8434-2 fittings are produced to this class.
What does a Class 3A and 3B thread fit mean?
These classes are for close tolerance fasteners where safety is of paramount concern. This class of fit has restrictive tolerances and no allowance. SAE Aerospace (AS) and MIL-F-5509 standards use this class of thread fit.
