JIC (Joint Industry Council) and AN (Army-Navy) fittings are widely used in hydraulic and pneumatic systems. However, they serve different purposes and adhere to different standards.
AN fittings are a type of flared fitting that utilizes a 37° flare to create a metal-to-metal seal. They resemble other 37° flared fittings, such as their industrial counterpart, the JIC fitting. While theoretically interchangeable, such interchangeability is generally not recommended due to the stringent specifications and requirements of the aerospace industry.
In terms of application, AN fittings are ideally suited for high-stress, high-precision environments, such as military and aerospace sectors. JIC fittings, on the other hand, are better suited for general industrial use, offering a cost-effective way to meet performance requirements.
Below, we break down the differences between them and provide guidance on how to choose the right one.
AN fitting
The AN (Army-Navy) standard originated from joint specifications for fluid connections established by the U.S. Army and Navy during World War II. Its core features include standardized thread angles, tapers, and sealing methods: a 60° thread profile and a 37° flare on the male fitting, which mates with the female fitting to create a metal-to-metal seal.
Today, these fittings are widely used in high-performance automotive, racing, and vehicle modification applications.
Unlike standard threaded connections, AN fittings utilize a 37° flared sealing surface and metal-to-metal compression. This design enables them to withstand high pressure, vibration, and extreme temperatures while effectively preventing fluid leaks.
Both male and female fittings feature a precision-machined 37° flare that creates a metal-to-metal seal. While other standards—such as JIC and SAE flare fittings—employ similar systems, they may not be compatible; mixing them can result in damaged fittings or leaks at the flare connection.
Material
Its main body is typically made of aluminum alloy or stainless steel, ensuring strength while reducing weight.
Applications
It does not rely on tape or sealant, instead forming a leak-proof barrier through the compression of precision-machined surfaces; consequently, it is widely used in high-performance oil, fuel, brake, and oil-cooling systems.
Size
It defines hose diameters in inches—such as AN3, AN4, and AN10—where a higher number indicates a larger diameter and higher flow rate. AN sizes range from -2 to -32, though larger sizes can be manufactured if required. This sizing system is known as "dash sizing," with increments of 1/16 inch; for example, a -8 fitting measures 8/16 inch, or 1/2 inch.
| AN size | -2 | -3 | -4 | -5 | -6 | -8 | -10 | -12 | -16 | -20 | -24 | -28 | -32 |
| Tube OD (inches) | 1⁄8 | 3⁄16 | 1⁄4 | 5⁄16 | 3⁄8 | 1⁄2 | 5⁄8 | 3⁄4 | 1 | 1+1⁄4 | 1+1⁄2 | 1+3⁄4 | 2 |
| Nominal hose ID (inches) | 1⁄8 | 3⁄16 | 1⁄4 | 5⁄16 | 3⁄8 | 1⁄2 | 5⁄8 | 3⁄4 | 1 | 1+1⁄4 | 1+1⁄2 | 1+3⁄4 | 2 |
| Actual hose ID (inches, approximate) | 1⁄16 | 1⁄8 | 3⁄16 | 1⁄4 | 5⁄16 | 7⁄16 | 1⁄2 | 5⁄8 | 7⁄8 | 1+1⁄8 | 1+3⁄8 | 1+5⁄8 | 1+3⁄4 |
JIC Fittings
JIC fittings are a cornerstone of engineering, thanks to standards established by the Society of Automotive Engineers (SAE). These JIC fittings—including hose and tube connectors—are widely used in automotive, aerospace, and industrial fluid power systems. Their distinctive 37-degree flared sealing surface creates a secure metal-to-metal seal, eliminating the need for thread seal tape or sealants. This design is particularly critical in high-pressure applications, as it effectively prevents potential leaks.
Applications
JIC fittings are commonly used in hydraulic systems, fuel delivery systems, and other high-pressure applications.
Sealing
This method employs a conical seal, where the internal conical surface of the fitting body mates tightly with the external conical surface of the tube end; the seal is achieved by tightening the nut. Capable of withstanding high pressures, this sealing method is generally suitable for hydraulic systems operating at 3000 psi / 6000 psi (approximately 20.7 MPa / 41.4 MPa); it offers high sealing reliability and effectively prevents leakage.
Materials
JIC fittings are typically made from materials such as carbon steel, stainless steel, and aluminum alloy. Carbon steel fittings offer low cost and high strength, making them suitable for general industrial applications. Stainless steel fittings are corrosion-resistant and commonly used in sectors with strict hygiene and anti-corrosion requirements, such as the food and chemical industries. Aluminum alloy fittings are lightweight and widely used in weight-sensitive sectors like aerospace.
Sizes
They come in a wide range of sizes, making them suitable for various applications. JIC fitting sizes are based on tube diameter, with specifications ranging from 1/16 inch to 4 inches—including common sizes such as 1/4 inch, 3/8 inch, and 1/2 inch. Size designations specify parameters such as outer diameter, inner diameter, and thread specifications, ensuring compatibility between fittings produced by different manufacturers. For a 1/4-inch fitting, the thread is typically UNF with 20 threads per inch, and the outer thread diameter is approximately 0.540 inches.
Differences Between JIC and AN
Design and Thread Specifications
Both JIC and AN fittings utilize a 37° flare connection and straight threads. This facilitates a secure seal between the male and female fittings. However, there are significant differences in their thread specifications:
AN Fittings: AN fittings utilize Class 3A/3B UNJ/UNJF root threads. This design increases the tensile stress area and reduces stress concentration. This results in higher thread strength and tighter tolerances, making AN fittings suitable for high-stress environments such as aerospace and military applications.
JIC Fittings: JIC fittings comply with Class 2A/2B UN/UNF thread standards. Their design balances performance, manufacturing efficiency, and cost.
Standards and Applications
AN Fittings: AN fittings were developed for military aviation and comply with MIL-F-5509 and AS4841 specifications. They are designed for high-performance applications in both military and commercial aviation sectors.
JIC Fittings: JIC fittings comply with SAE J514 / ISO 8434-2 standards and are widely used in industries such as agriculture, construction, and automotive. Compared to AN fittings, JIC fittings are lower in cost and are manufactured to slightly less stringent standards.
Measurement and Compatibility
AN and JIC fittings are sized based on the male fitting's outer diameter and the female fitting's internal thread diameter. Despite sharing the same nominal sizes, AN and JIC fittings are not interchangeable due to differences in thread quality and standards.
| Category | JIC fittings | AN fittings |
| Full Name | Joint Industrial Council | Army-Navy |
| Application focus | Industrial, agricultural, automotive | Aerospace, military |
| History | Created after WWII as a cost-effective version of AN fittings | Originated during WWII for military applications |
| Sealing geometry | 37° flaring | 37° flaring |
| Material | Typically, steel or stainless steel | Typically, aluminum or stainless steel |
| Thread specification | Standard UN/UNF threads | J-profile UNJ/UNJF threads |
| Precision level | Class 2 (Standard precision) | Class 3 (Enhanced precision) |
| Pressure rating | Moderate | High |
| Governing specifications | SAE J514/ISO 8434-2 | MIL-F-5509 |
| Cost | Low | High |
FAQs
Can I combine AN and JIC couplings?
AN fittings are made to a much higher standard than JIC/SAE fittings and are much more expensive. Therefore, it is not recommended to use these interchangeably.
What are AN fittings used for?
AN fittings are used extensively in the U.S. military, military contractors, general aviation, and commercial aviation. They are specifically designed to a high standard.
What are JIC fittings used for?
JIC fittings are widely used in agriculture, construction, heavy machinery, and automotive industries.
What is the difference between JIC and AN threads?
JIC and AN threads are similar, but AN threads have tighter tolerances and are used in aerospace, while JIC is used in industrial applications.
Who uses JIC fittings?
37-degree elbows are used in fuel and lubrication systems (including as hydraulic fittings in hydraulic power applications). While they are still used in these applications today, they have also been adopted by many other industries, such as water treatment, car wash systems, and chemical transfer systems.
Can JIC fittings be used with AN fittings?
As previously mentioned, AN fittings are subject to extremely strict manufacturing tolerance standards. In contrast, JIC fittings utilize more easily achievable tolerance standards to reduce manufacturing costs and complexity. This means that if AN fitting tolerances are excessive, systems relying on AN standards may encounter issues. Furthermore, using the incorrect type of fitting could result in the system failing to meet any guaranteed pressure ratings.