Thread: AN Fittings

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AN Fittings

Since there seems to be a good deal of confusion regarding what AN fittings are and what they do, here is a short primer on them. First, AN fittings seal by making an interference fit between two cones. One cone has a 37º angle and the other is slightly different so that there is a circular line of contact between the two cones. AN fittings never require sealant to make the seal leak proof. However, some confusion arises on the adapters; the part that adapts the AN fitting to the item being connected. REMEMBER, there is no such thing as an AN tap. Holes that adapters are installed into can have NPT threads, metric threads, threads and an inverted flare, weld on bungs, or several other styles but NEVER do they have an AN profile. The term AN refers to the flare and the specs on the fitting. A close cousin is the JIC 37° flare fittings…think of them as a commercial grade AN fitting.

Fittings are sized by the size of the tube that they accommodate…and the approximate fitting hole size. The size is expressed in 1/16s of an inch. Thus, a -6 (spoken as “dash six”) is 6/16ths or 3/8ths of an inch size. Common fuel lines are -6 or -8 size.

Inverted flare fittings commonly used on stuff like brake fittings and steering boxes is a 45° flare that operates just like an AN flare but is not interchangeable.

Connections using AN fittings usually include either a hose or a tube connecting to an adapter. There are several styles of hose used, some as low as 350psi capacity (in the sizes under -16). You can go to the Earl’s catalog and learn a lot more: http://holley.com/Catalogs.asp?Catal...EarlsCover.jpg

Mike in Tucson

Good and helpful info Mike.
Here's a quick refference I use, for those interested, below the two charts that appear are more links to info on the other items Mike refers to.

http://flyboybob.com/web_pages/kr2/r..._NTP_size_info

Thanks, Bob

It seems that the most confusing situation for most folks is adapting AN hose to power steering applications where there
are either inverted flare females in the steering box or metric threads in the steering box.

Mike in Tucson