A/N Fittings -Plumbing We Will Go !

 

Most likely, at one time in your life you have seen a killer custom car or race car that has had fittings like these and wondered , how do they work ? And where are the clamps to how can I use them on my car ?

 

Lets start with how these fittings came about. A/N fittings  were originally designed for use in aerospace and  military applications. The size & specifications were established by the military back in World War II, and stems from a joint standard agreed upon by the Army and Navy, hence AN. The Army-Navy involvement is also the origin of the red/blue color combination that was traditionally used in the anodized finishing process.

AN sizes range from -2 (dash two) to -32 in irregular steps, with each step equating to the OD (outside diameter) of the tubing in 1⁄16-inch increments. 

Therefore, a -8 AN size would be equal to 1⁄2-inch OD tube. However, this system does not specify the ID (inside diameter) of the tubing because the tube wall can vary in thickness. Each AN size also uses its own standard thread size.

A/N fittings use  37° flared tubing to form a metal-to-metal seal. They are similar to other 37° flared fittings, such as ( JIC ), which is their industrial variant . 

The two are interchangeable in theory, though this is typically not recommended due to the exacting specifications and demands of the aerospace industry. The differences between them relates to thread class and shape (how tight of a fit the threads are), and the metals used. 

Although similar, 37° AN and 45° SAE fittings and tooling are not interchangeable due to the different flare angles. Mixing them can cause leakage at the flare. You can get aluminum and stainless steel A/N fittings.

As an example , a Holley electric fuel pump has standard pipe threads , there are endless adapters that you can use to go from pipe thread to A/N thread making the use of braided line that much easier . Now you an get a fitting with a pipe thread on one end with a typical hose end on the other side , that way you can eliminate the adapter if you have a tight fit .

This example is a A/N -12 to 1/2 inch pipe thread adapter.

The pipe threaded end would fit the pump , while the 37 degree flare would fit the A/N hose end.

This is a scale to show how common automotive lines can be sized to A/N fittings.

 

 

AN O-Ring aka ORB

ORB or O-Ring Boss fittings utilize the same thread as AN, but the type of seal is an O-ring instead of a tapered surface. ORB fittings are commonly found on aftermarket fuel systems: Fuel rails, regulators, and pump hats, for example.

 

 

This hose fitting can be used to connect a custom oil line to an 18mm inlet fitting on engine or trans oil coolers. This custom fitting seals with an o-ring as opposed to using pipe threads. 

 

This fitting also swivels after it is fully tightened to ensure a kink free installation.

 

The main reason you would want to convert your car over to A/N fittings & lines is safety , then long lasting performance , the lines can be assembled and disassembled many times with out a chance of leaking , not unlike hose clamps.

You have many choices of hoses to chose from , if you are running E85 or Nitro-Methane you need lines like these, because a parts store rubber hose will fail and seep as soon as the fuel flows through it .

These are a must for oiling systems , great for wet sump and dry sumps , they have a higher burst pressure rating, 500-1000 PSI  . They also won't collapse under suction . 

😀Remember : 

When shopping for hoses and lines stick with a well known brand and don't mix brands between adapters and fittings , to prevent leaks . 

Only use pipe sealer on pipe threads and add just a drop of light oil or anti-seize to the flared threads to prevent galling .

Stay tuned for more !