JIC and NPT hydraulic fittings are popular specifications. But they are different and cannot be mixed.
This article will compare JIC and NPT connectors.
What are JIC accessories?
A JIC (Joint Industry Council) fitting is defined by SAE J514 and MIL-DTL-18866 standards and is a flared fitting machined with a 37 degree flared surface. They are usually made of nickel alloys, brass, carbon and stainless steel. JIC fitting hydraulic connections are common in most fluid power systems. It consists of parallel threads and a 37⁰ cone at the fitting end and can be attached to a flared pipe or hose fitting. JIC fittings are widely used in fuel transfer and fluid power applications, especially those involving high pressures (up to 10,000 psi).
Advantages of JIC Fittings
JIC fittings offer many of the same benefits as other fittings and seals plus additional unique benefits.
Universal and affordable
The simplicity and affordability of manufacturing JIC fittings—along with a wide selection of sizes and styles—has made them the industry standard for hydraulic fittings for decades. JIC fittings are now available in many variants, easily adaptable to both imperial and metric, allowing them to fit almost any hose or port, and are generally accepted by foreign and US companies.
High/low temperature performance
JIC connectors perform well in high and low temperature environments. Metal-to-metal seals in JIC fittings are not as affected by temperature as O-rings, which are typically made of rubber or other elastomeric materials that can withstand milder temperature ranges.
Connectivity
In addition to the versatility of allowing JIC fittings to connect to almost any hydraulic system, JIC fittings can also be disconnected (and then reconnected) without loss of performance, further explaining how they have become the industry standard.
Applications of JIC fittings
Today, JIC fittings are most commonly found in the aerospace and plumbing industries.
Aerospace industry
JIC accessories are heavily used in the aerospace industry by commercial airline manufacturers, NASA, and private aerospace companies. They can be found in commercial airliners, aviation ground equipment, and aviation fluid systems.
Plumbing industry
JIC fittings are also used in flexible piping systems that connect pipes together in hydraulic systems. They can be attached to hoses as adapters for SAE female fittings for versatility and flexibility wherever needed within the system.
What is an NPT connector?
NPT (or National Pipe Taper) is the American standard for tapered threads, also known as ANSI/ASME B1.20.1 pipe threads. . These standards include straight thread series and tapered series for a variety of applications requiring pressure sealing or rigidity, and sometimes both. Threaded pipe provides an effective seal on pipes used to convey hydraulic fluids, steam, gases or liquids.
NPT connections rely on thread deformation - a metal-to-metal seal design in which the threads of the connector itself are formed together. NPT pipe threads are the traditional tapered thread fittings that have been used for 100 years. They are available in low pressure black iron and brass, and high pressure steel and stainless steel. This type of connection is used in pneumatic and process systems as well as hydraulic systems. Pipe threads are designed with or without the included thread sealant, depending on the specific application they are used for.
Advantages of using NPT fittings:
Tapered threads for better sealing. The male and female threads compress and wedge themselves together. Therefore, these connections are stronger and leak-proof. NPT pipe threads are the most commonly used tapered pipe threads in the US and Canada and are not compatible with BSPT pipe threads.
Disadvantages of using NPT fittings:
- Ports may easily swell or crack due to over-tightening.
- May make it more difficult to correctly position the profiled connector.
- The required thread lubricant can cause system contamination.
- Not suitable for maximum pressure
What is the difference between JIC and NPT fittings?
JIC fittings and NPT fittings are absolutely different seals and are not interchangeable. JIC hydraulic fittings are used for high pressure systems and NPT fittings are used for low pressure systems.
NPT |
JIC |
The threads taper at an angle measured from the central axis of the fitting. |
These fittings are parallel to each other. |
The angle between each successive thread is 60°. |
Threading comes in many forms, including coarse, fine or extra fine thread sizes. |
Sealing depends only on the taper of the thread. |
There is a 37° opening angle at the end of its fitting. Therefore, it has better sealing ability. |
It has a relatively small sealing capacity, making it ideal for low pressure applications. |
Provides excellent sealing, making it the first choice for high pressure applications. |
Conclusion
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