AN Fittings

Why Does Your Build Need AN Fittings?

A worm-gear clamp on a barbed nipple is fine for a windshield washer line. It is not fine for a 60 psi fuel feed or a hot oil line that lives above an exhaust manifold. AN hardware exists to remove the clamp from the equation and replace it with a machined, reusable metal seal. Three failure modes push builders off barbed fittings and onto AN:

Weeping Clamp Connections Under Pressure

A rubber hose on a barb relies on hose tension and a clamp to hold fluid. As the hose ages, heat-cycles, and softens, that tension drops and the joint weeps, then drips, then sprays. A 37-degree AN flare seats metal to metal, so the seal does not relax as the rubber ages.

Vibration and Thermal Cycling

A barbed fitting in a vibrating chassis backed by a clamp will walk loose over thousands of heat cycles. AN fittings use a nut-and-cone mechanical lock that tightens under line pressure and stays put through vibration, so a fuel or oil line routed past the frame rail holds its seat mile after mile.

Mismatched Thread Standards

NPT, ORB, inverted flare, and 37-degree AN all look similar but do not mate. Forcing a pipe-thread fitting into a flare port cross-threads the seat and creates a leak you will chase forever. The right adapter, not a bigger wrench, is the fix.

What Can AN Fittings Solve?

37-Degree Flare Sealing

The AN flare cone mates to a matching female flare and forms a reusable metal-to-metal seal rated for fuel, oil, coolant, and hydraulic pressure. Once torqued, it holds through thermal cycling without a clamp or sealant on the seat.

O-Ring Boss Port Conversion

An ORB (O-ring boss) straight-thread port seals at the shoulder with a Viton O-ring, not at the threads. The flare-to-ORB adapter lets you land a 37-degree AN flare line onto a threaded boss port on an oil cooler, fuel filter head, or accumulator without cutting new threads.

Dead-Port Block-Off

Every deleted or relocated component leaves an open port that will weep. A female flare block-off cap squares up against the cone seat and seals the dead end cleanly, whether you are capping a fuel rail port, an oil gallery, or an unused adapter outlet.

Shop AN Fittings by AN Size & Connection Guide

• AN6 AN8 AN10 Flare to 6AN 8AN 10AN ORB Male O-Ring Fitting Adapter (Black, 2pcs) - Covers 6AN, 8AN, and 10AN. Converts a 37-degree AN flare to a matching O-ring boss (ORB) port. CNC-machined, black hard-anodized 6061-T6 billet aluminum with a high-temperature Viton O-ring for a leak-free boss seal on fuel, oil, coolant, and hydraulic plumbing.
• 4/6/8/10/12 Female AN Flare Fitting Cap, Block-Off, Aluminum (2pcs) - Covers 4AN, 6AN, 8AN, 10AN, and 12AN. CNC-machined 6061-T6 aluminum female 37-degree flare caps that plug and seal unused AN ports on fuel rails, oil coolers, adapters, and dead-ended hard lines.

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What does AN stand for in fittings, and what are AN fittings used for?

AN stands for Army-Navy, the military specification for a 37-degree flare fluid fitting now governed by the SAE J514 standard, the same joint the commercial world calls JIC.
A true AN fitting seals metal-to-metal: the male cone flares at 37 degrees and mates into a matching female flare, so the joint holds fuel, oil, coolant, and hydraulic pressure without a hose clamp.
Builders use them for fuel feeds and returns, oil cooler and accumulator lines, coolant reroutes, transmission and power steering plumbing, and brake lines where a leak is not acceptable.
Automotive AN fittings are the reusable, vibration-resistant standard for any line that lives above an exhaust manifold or behind a hot radiator.

How do AN fitting dash sizes work, and what do AN6, AN8, and AN10 mean?

The dash number is the fitting size in sixteenths of an inch of tube outside diameter, so AN6, written -6 or 6AN, is 6/16 inch or 3/8 inch, AN8 is 8/16 or 1/2 inch, and AN10 is 10/16 or 5/8 inch.
That means AN4 is 1/4 inch, AN12 is 3/4 inch, AN16 is 1 inch, AN20 is 1-1/4 inch, and AN24 is 1-1/2 inch, and AN6 in millimeters is roughly 9.5 mm.
The thread pitch scales with the dash size, with AN6 at 9/16-18, AN8 at 3/4-16, and AN10 at 7/8-14, so a larger dash number is a physically larger, higher-flow fitting.
The two kits in this collection cover the most common street and race sizes: 6AN, 8AN, and 10AN on the flare-to-ORB adapter, and 4AN through 12AN on the block-off cap.

Are AN fittings the same as JIC fittings?

Yes, for every practical shop purpose, AN and JIC are the same 37-degree flare joint.
AN is the Army-Navy aerospace designation with tighter Class 3B thread tolerances, and JIC is the commercial and industrial name for the identical SAE J514 flare.
Both flare at 37 degrees, so an AN male and a JIC female will mate and seal cleanly.
The AN JIC and 37-degree flare terminology you see all refers to this same seat angle, and either name points you at the same hardware on this page.

What is the difference between an AN flare fitting, an ORB port, and NPT?

An AN flare fitting seals on a 37-degree metal cone, an ORB, or O-ring boss, fitting seals on a Viton O-ring at a machined shoulder with straight threads, and NPT, or national pipe taper, seals on the tapered threads themselves.
They look similar but do not interchange, which is exactly why a flare-to-ORB adapter exists to land a 37-degree flare line onto a boss port without cross-threading.
The same logic applies to AN-to-NPT adapters and inverted-flare adapters when you are tying AN plumbing into a factory steel hard line or stock fuel line.
That covers the main types of AN fittings: flare, ORB, NPT, inverted flare, and the barb and push-lock hose-end styles for soft line.

How do I install AN fittings on braided hose, and how do I make fuel lines with them?

For a reusable AN hose end, push the socket onto the braided hose, flare or cut the inner liner to the manufacturer's mark, lubricate the nipple, and thread the nipple into the socket while holding the hose steady.
Tightening AN fittings means wrenching the nipple into the socket until the cone seats; do not spin the hose, and use an aluminum-jaw wrench so you do not gouge the anodize.
The same method works for installing AN fittings on steel braided hose and on nylon braided hose, since the seal is the machined flare, not the braid.
Making fuel lines with AN fittings is then a matter of cutting hose to length, assembling the ends, and routing the line clear of heat and abrasion; always pressure-test a fresh assembly before buttoning up the job.

Do you carry AN fittings for LS water pump, radiator, and power steering swaps?

The an-fittings collection here ships two universal hardware kits, the AN6/AN8/AN10 flare-to-ORB adapter pair and the AN4-to-AN12 flare block-off cap pair, not LS swap-specific water pump or radiator fittings.
LS swaps need bespoke AN water pump fittings, radiator AN fittings, and LS power steering pump AN fittings sized to the specific GM pump and radiator outlet, and those vehicle-specific conversion pieces are not in this two-SKU catalog.
The adapters and caps on this page can cap or convert a generic ORB or flare port on an LS build, but confirm your exact water pump and radiator thread before ordering a swap-specific piece.
If you need a dedicated LS1 water pump AN fitting or LS radiator AN fitting, confirm fitment first rather than assuming a universal adapter will land.

Do you have AN to barb, push-lock, and quick-connect adapters?

The two kits here are a flare-to-ORB adapter set and a flare block-off cap set; they are not AN-to-barb, push-lock, or quick-connect styles.
An AN-to-barb or AN-to-hose-barb adapter is used to transition a 37-degree flare down to a slip-on rubber hose, and a push-lock hose end grips soft line without a clamp.
AN quick-connect and quick-disconnect fittings are the spring-lock style used on many factory fuel and transmission lines, which is again a different hardware class than a flare cap or ORB adapter.
For a barb, push-lock, or quick-connect application, confirm the specific style you need before ordering, since this page covers flare-to-ORB and block-off duty only.

What materials are AN fittings made from, and where can I buy the best ones?

Quality AN fittings are CNC-machined from 6061-T6 or 7075-T6 billet aluminum and hard-anodized for corrosion resistance, with higher-end and aircraft AN fittings cut from 303 or 304 stainless steel for the hottest, highest-pressure service.
The two kits on this page are 6061-T6 aluminum, black hard-anodized on the flare-to-ORB adapter, with Viton O-rings on the boss seal, which is the material set you want for fuel, oil, and coolant under the hood.
Stainless AN fittings and steel AN fittings handle brake and extreme-heat duty where aluminum softens, so pick the material to match the fluid and temperature.
Rather than searching for an AN fittings store near me, order the best AN fittings online from this page with free shipping, and skip the counter markup.

Can AN fittings be used for fuel, oil, coolant, and AC lines?

Yes, a true 37-degree AN flare fitting is rated for fuel lines, oil lines, coolant lines, and hydraulic service, which is why AN fuel fittings and AN oil line fittings are the default on race and high-output builds.
AN coolant fittings and AN coolant lines handle the heat of a rerouted cooling loop, and AN heater hose fittings cap the heater circuit when you delete or relocate the core.
AN brake fittings and brake line fittings use the same flare standard on a hardened line for a clamp-free, vibration-proof joint.
For AC lines, the AN flare can be adapted, but factory AC uses dedicated spring-lock and barrier-hose styles, so confirm the AC connection type before substituting an AN flare.

Are these AN fittings street legal, and what is your shipping and return policy?

AN fittings themselves are universal plumbing hardware that removes or bypasses no emissions device, so they are 50-state street-legal components used in factory and aftermarket builds alike.
The literal competition and closed-course off-road use only framing applies when AN plumbing is part of a fuel or oil line rerouting on an emissions-deleted competition truck, not to the fitting itself, and local emissions laws vary by jurisdiction, so confirm your build before installing.
Fitment is application-specific, so match the AN size, such as 6AN, 8AN, or 10AN, and the connection type, flare to ORB or block-off cap, to your port before ordering.
Every order includes free shipping, is backed by a 1-year warranty, and comes with our 45-day return policy.