What is a JIC Fitting? - Titan Fittings

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The Difficulty with finding the right fitting for your fuel and hydraulic system is that the industry does not conform to one particular standard and varies based on your geographical location. JIC fittings are commonly used for most fluid conveyance systems based on the SAE J514 and MIL-DTL- standards; however, AN (Army-Navy), JIS, Komatsu are also seen within tooling and machinery.

It is crucial to know the differences between the different standards when purchasing fittings for hydraulic assemblies as they are manufactured to specific dimensions and tolerances. Failure to do so may result in the fitting having a loose connection, leading to leaks and hydraulic failure in your lines or hoses.

Difference in Standards

The commonality between all these fittings is that they define how a component joins and seals to other hydraulic components like their female counterparts, pipes, hoses, and valve blocks. The sealing mechanism depends on the metal-to-metal contact achieved when two compatible fittings are linked. Each standard is defined by the internal diameter, thread sizing dimensions of the adapter, the flare angle on their nose, and whether the threads run parallel or taper.

AN vs JIC:

The only difference between AN and JIC fittings is that AN fittings are manufactured as per more stringent tolerances for military applications.

JIS and Komatsu vs JIC:

JIS and Komatsu are similar in their appearance to JIC fittings; however, they have a 30° flare on their fittings as opposed to the 37° flare in JIC fittings. Additionally, JIS conforms to the BSP (British Standard Pipe) thread sizing and Komatsu to the millimeter.

SAE vs JIC:

The thread sizing in JIC fittings are based on SAE parallel running thread sizing. It is for this reason why SAE 45° flare thread fittings can thread onto JIC fittings; however, caution must be taken as they do not have the same flare angle for seating.

Advantages of Using JIC Fittings

JIC fittings are one of the most adaptable types of fittings in the market. It is for this reason they are most commonly used in the hydraulic and automotive sectors. The market displays a wide variety of multi-standard fitting interconnections such as JIC unions, JIC to pipe, or JIC to the bulkhead. Additionally, variations within these products can also be found, including elbows, reducers, expanders, straight sections, swivels, tees, crosses, and many more. The volume and variety of material available in stock with most vendors ensure that you’re never short on inventory. Hence, you can be sure that no bottlenecks present themselves during maintenance operations. Common materials used to make JIC fittings like carbon and stainless steel, brass, and nickel-copper alloys, enable their use for custom applications where cost, resistance, temperature rating, and pressure rating are a factor.

Shortcomings of JIC Fittings

With advancements in heavy machinery, more and more applications are coming forward that require tighter seals. Unfortunately, JIC fittings are not as capable of sealing high-pressure fluids unless the standard for manufacturing conforms to stricter tolerances for flare seat faces. O-ring sealed fittings are better suited for these applications as the compression of the O-ring enables them to withstand higher pressures.

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Hey everyone,

First time posting and really using this site so here is my obligatory apology if this question has already been asked and I missed it.

I am looking for best practice/standards for installing JIC/AN fittings (and if there are installation differences between the two fitting types). There are three steps of the installation process I have identified which I am looking for clarification and direction on. Google has largely failed to help clarify these points so here I am!

1. Should gaskets like SECO seals be used by default? At a previous place I worked we only used SECO seal gaskets on persistent leaks or very high pressure (think +5k psia) systems or helium systems. However, my current place wants gaskets on all joints. While I understand that this decreases the possibility of leaking in general, it feels unnecessary and creates another process during installation/maintenance (aka expensive) but I may be wrong.

2. Is anti-galling compound required for SS fittings? Again, at my previous place we usually did not use Krytox to prevent galling. In fact, we never talked about galling with 316SS fittings and I never heard anyone every mention it happening in their past. However, my current place wants Krytox on all fitting joints which again feels unnecessary and creates an additional process. Without knowing better, I would only use Krytox to lubricate a problematic joint which at that point the joint should either be fixed or just replaced.

3. Torque vs turn method on tightening. If running torques are known using a torque wrench seems good enough however I would rather default to the turn method for consistency of load in the joint but I would like another opinions.

If needing specifics, my use case is 0- psia, helium and up molecule sizes with temperatures from -100C to 100C. Some systems will flow oxidizers.

Thanks everyone for their thoughts and pointing me to the different standards which I likely missed.
Cheers!

TugboatEng said: Have you considered using Swagelok or a Swagelok clone for this?

We have considered it a bit. The main reason we are staying away from swage is we can machine male & female AN fittings into our flight hardware fairly easily unlike swage so we have a lot of heritage with AN style fittings. Therefore, we apply AN to our ground support equipment and test stands even if swage would be a reasonable substitute. For now, we are tooled for AN and therefore will likely be sticking with it (just too much momentum to change easily).

LittleInch said: Plus everywhere seems to be saying they are most commonly used for hydraulic systems, not gas.

You are right that JIC purpose is primarily for hydraulics so I should have been a bit more rigorous in my question sorry. AN fittings are defined by SAE AS and AS for use in aircraft and spacecraft. I was grouping JIC and AN together because I was assuming (probably incorrectly) that the installation best practices would be the same for the two fitting types.

Thanks for the quick responses! ello and welcome to the community!

It's great that you're seeking best practices for installing JIC/AN fittings, and your questions are quite detailed. Here are some insights that might help:

Use of Gaskets like SECO seals:

SECO seals can be beneficial in high-pressure systems, and using them by default may provide an extra layer of security against leaks. However, the necessity can depend on the specific requirements of your system and the materials being transported.
If your current place insists on gaskets for all joints, it might be a precautionary measure to ensure a higher level of integrity in the system. It's essential to balance the cost with the potential risks and benefits.
Anti-galling compound for SS fittings:

The use of Krytox or other anti-galling compounds for SS fittings can be a preventive measure to avoid galling issues. While it might seem unnecessary in certain cases, it can contribute to the longevity and reliability of the fittings, especially in applications with temperature variations.
Considering your specific use case with temperatures ranging from -100C to 100C, the use of anti-galling compounds becomes more relevant to prevent issues like galling in extreme conditions.
Torque vs Turn method on tightening:

Both torque and turn methods have their merits. Using a torque wrench can provide a precise measure of the applied force, ensuring that fittings are tightened to the specified level. This is particularly important in applications with known running torques.
The turn method, on the other hand, can be practical for achieving consistent load in the joint. It may be a matter of personal preference and the specific requirements of your system. Ensure that whichever method you choose aligns with any industry or manufacturer guidelines for the fittings you're using.
It's always a good idea to consult relevant industry standards, manufacturer recommendations, and possibly involve your team or colleagues in the decision-making process. Additionally, you might want to explore specific standards such as those provided by organizations like SAE (Society of Automotive Engineers) for AN fittings or other relevant bodies in your industry.