The AN thread is a particular type of fitting used to connect flexible hoses and rigid metal tubing that carry fluid. It is a US military-derived specification that dates back to World War II and stems from a joint standard agreed upon by the Army and Navy, hence AN.
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" increments. Therefore, a -8 AN size would be equal to 1/2" OD tube (8 x 1/16 = 1/2). 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.
AN fittings are a flare fitting, using 37° flared tubing to form a metal-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 relate to thread class and shape (how tight a fit the threads are), and the metals used.
Back in 1958 we drove an old V8 and when it’d gone a hundred thou’ we got out and pushed it a mile
We didn’t know who we were, we didn’t know what we did
We were just on the road
Headin’ down from Canada on a gravel road a mile from Montana
Then my Daddy read a sign and took us in the wrong direction
I asked my Daddy where are we goin’, he said we’ll just follow
Our nose, so I looked out the window and dreamed I was a cowboy
We didn’t know who we were, we didn’t know what we did
We were just on the road
I met a girl in a truck cafe, fell in love almost right away
Then the Mercury was ready to go and I had to leave her
Shoo-be-doo-be-doo-Sh-doo
Shoo-be-doo-be-doo-Sh-doo-Sh-doo
Go home said the man in the moon go home
Go home said the man in the moon go home
Because it’s gettin’sorta late and I’ll soon turn out my light
Go home said the man in the moon
Go home
We didn’t know who we were, we didn’t know what we did
We were just on the road
We didn’t know who we were, we didn’t know what we did
We were just a ridin’ on