JIC Hydraulic Fittings : A Complete Guide

What is JIC fittings?

JIC (Joint Industrial Committee) fitting, according to SAE J514 definition, is a compression joint made of a 37 degree flared seat surface and parallel thread machining. They are usually made of nickel alloy, brass, carbon steel, and stainless steel.

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JIC hydraulic fittings are widely used in most hydraulic and fluid power systems. Both male and female JIC fittings feature a 37-degree flare seating surface, creating a reliable metal-to-metal seal. The sealing is achieved through direct contact between the male flare and the female cone seat, which is regarded as a mechanical connection. A complete JIC tubing assembly is made up of three components: the fitting body, flare nut, and sleeve. In the market, this is commonly referred to as a flared fitting, well known for its performance in high-pressure hydraulic applications.

A JIC fitting body without the sleeve and nut is often used as a hose adapter for hydraulic rubber hoses, connecting directly to the female swivel end of a hose assembly. The nut and body are standard components that work with both metric and inch-sized tubes, whereas the sleeve is the only component that varies based on the tube’s outer diameter. This adaptability makes JIC hydraulic fittings a great option for industries needing dependable, versatile, and leak-proof connections.

Advantages of Using JIC Hydraulic Fittings

From our experience running a hydraulic fittings production line, JIC hydraulic fittings are honestly one of the most practical choices for a wide range of systems.

Easy to get, easy to use – Because JIC fittings are so common, you rarely run into sourcing issues. In our factory, we keep a steady stock for fast replacement, and we’ve seen how having readily available fittings keeps machines running without unexpected downtime.
Lots of options that actually work – Over the years, we’ve produced JIC fittings in countless sizes, shapes, and materials. This variety isn’t just for show—it allows us to match the right fitting to the exact pressure, temperature, or fluid type a client needs. That flexibility is a big reason why engineers keep coming back to JIC.
Swap them without worries – Their SAE-compatible dimensions mean you can replace or interchange fittings without second-guessing. In our daily operations, that reliability saves a lot of headaches, especially when servicing hydraulic systems in the field.
Handles heat like a champ – Because JIC fittings don’t rely on O-rings, they stand up much better in high-temperature environments. We’ve tested them under extreme conditions, and they hold their seal even when the system is running hot, which is critical for heavy machinery.
Reusable and installation-friendly – One thing we always highlight to our clients: JIC fittings can be disconnected and reconnected multiple times without bending or leaking. In our assembly line, this makes installation and maintenance smoother, and pairing a male JIC with a female swivel really helps align the system without stress.

Disadvantages of Using JIC Hydraulic Fittings

While JIC hydraulic fittings are widely used and offer many advantages, there are also some limitations to consider:

Lower pressure rating in high-vibration environments – In certain applications where extreme vibration is present, JIC fittings may not provide the required pressure rating.
Metal-to-metal seal limitation – The 37-degree flare metal-to-metal sealing design restricts JIC fittings mainly to hydraulic, fluid, and non-critical applications, making them less suitable for extremely demanding systems.
Susceptibility to damage from over-tightening – Excessive tightening can cause flare damage and cracking, leading to a loss of clamping force and potential sealing failure.

How JIC Hydraulic Fitting Seals Affect Temperature Rating

The temperature performance of a JIC hydraulic fitting depends largely on its material and surface protection. Removing surface contaminants and applying proper protective treatment is essential to enhance corrosion resistance and extend the service life of the fitting. Different materials offer different temperature ratings:

Stainless Steel SS316 – -60 °C to 200 °C
Carbon Steel – -60 °C to 200 °C
Brass – -45 °C to 175 °C

By selecting the right material, JIC hydraulic fittings can maintain reliable sealing performance in a wide range of operating environments.

How to Tighten JIC Fittings? – Installation Guide

Installing JIC fittings can be done in four simple steps:

Step 1: Inspection & Preparation
Check the fitting body and sealing surfaces for any contamination, scratches, or damage. Cut the tube to the required length and flare the tube end to a 37° angle before assembly.

Step 2: Lubrication
Apply a thin, even layer of lubricant (such as hydraulic oil) on the threads and across the entire flared surface. This helps reduce galling and ensures a smoother tightening process.

Step 3: Assembly
Insert the nut and sleeve onto the tube end connection. Hand-tighten the nut to align the components, then rotate the flare nut until the sealing surfaces fully engage.

Step 4: Final Tightening
Check the recommended torque values and tighten the fitting accordingly. Ensure the sealing connection meets the specified standard and that no gaps remain.

FAQ About Sinopulse JIC Hydraulic Fittings

1. What is a JIC hydraulic fitting?
JIC fittings are produced according to SAE J514 and ISO 8434-2 standards. A complete set of JIC fittings includes a sleeve, nut, and body, with the body featuring a 37-degree flared seating surface. These fittings are commonly referred to as flared fittings in the industry. They are designed for use in various sectors, particularly in high-pressure applications.

2. What is the difference between JIC and AN fittings?
JIC and AN fittings both utilize a 37° flare, but AN fittings are produced according to rigorous aerospace and military standards, while JIC hydraulic fittings adhere to the SAE J514 industrial standard.JIC is derived from the AN standard but has a more restricted selection of sizes. Consequently, JIC and AN fittings are not functionally interchangeable, requiring careful identification of connections to ensure a secure, leak-proof seal.

3. What is the difference between JIC and NPT fittings?
JIC and NPT threads are two different thread options for system installation. JIC hydraulic fittings utilize a metal-to-metal 37° flare seal, whereas NPT fittings depend on tapered threads and generally need thread sealant. JIC fittings are simpler to assemble, can be reused, and often provide greater sealing reliability. JIC fittings are simpler to assemble, can be reused, and generally provide greater sealing reliability. Sinopulse manufactures a range of JIC and NPT fittings for versatile hydraulic system compatibility. 。

4. How do I know my JIC fitting size?

The size of a JIC hydraulic fitting is based on the outside diameter (OD) of the tube. Dash sizes are measured in sixteenths of an inch; for instance, a -08 fitting is compatible with a 1/2" tube. Sinopulse offers a comprehensive selection of JIC fitting sizes, allowing for the appropriate fitting selection for your hydraulic system.

5. How JIC fittings seal

The male and female ends of a JIC fitting each have a 37-degree flare seat. When the male flare and female tapered ferrule are connected, this creates a sealed connection.

6. How to measure JIC hydraulic fittings?
To measure JIC hydraulic joints, for male joints, the outer diameter (OD) of the pipe or hose needs to be determined, and for female joints, the inner diameter (ID) needs to be determined. To complete this measurement, the overall diameter and thread spacing can be measured using a thread gauge or caliper. This measurement result helps determine whether the joint complies with metric or imperial standards. Additionally, it is necessary to confirm that the expansion angle is 37 degrees. Please refer to the SAE J514 size chart for accurate selection of connectors. Manufacturers of JIC hydraulic fittings typically provide comprehensive dimension sheets and technical support to assist customers in identifying and selecting suitable components.

7. What does JIC mean in hydraulic fittings?

JIC stands for Joint Industry Council (JIC), which is responsible for standardizing 37° flare fitting widely used in hydraulic and fluid delivery systems.

8. What does JIC stand for in hydraulic fittings?
JIC stands for Joint Industry Council, common used across industrial and mobile hydraulic applications.

9. Why do JIC fittings have a 37-degree flare seat?
The 37° flare creates a strong metal-to-metal seal, providing excellent reliability in high-pressure hydraulic systems. This design allows easy assembly and disassembly without damaging the sealing surface. No need for Teflon tape or pipe thread sealant. Therefore, JIC fittings are ideal for preventing leaks and can be used in high-pressure applications.Sinopulse JIC fittings are precision-machined to maintain consistent 37° flare angles for long-lasting performance. These JIC fittings are comparable to JIC fittings from Parker, Eaton, Aeroquip, Weatherhead, and Gates Hydraulics.

The 37° flare design can form a strong metal to metal seal, providing excellent reliability in high-pressure hydraulic systems. This design is easy to assemble and disassemble without damaging the sealing surface. No need to use Teflon tape or pipe thread sealant. Therefore, JIC connectors are an ideal choice for preventing leaks and can be used in high-pressure applications.

10. What are the types of JIC hydraulic fittings?

There are various types of JIC hydraulic fittings, including straight pipes, 45 ° and 90 ° elbows, tees, bulkhead fittings, swivel fittings, and adapters with other thread types such as NPT or BSP. The rich variety of products ensures its compatibility with various hydraulic and fluid power systems.