Fragola -8AN Tube Nut - Black Anodized (10-Pack)
Updated June 9, 2026
The Fragola -8AN Tube Nut is a black anodized aluminum nut designed for use with -8 AN (dash 8) fittings and tubing. It secures the tube end to an AN fitting or hose end, creating a leak-proof connection in high-performance fuel, oil, and brake systems. Sold in a 10-pack, these nuts are commonly used in custom plumbing for race cars, street rods, and other performance vehicles.
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How It Works
The tube nut threads onto an AN fitting or hose end and compresses a metal ferrule (sleeve) onto the outside of the tube. This compression creates a mechanical seal that holds the tube in place and prevents fluid leaks. The –8 AN size is designed for tubing with an outside diameter of 1/2 inch.
Common Failure Symptoms
Leaks at the connection are the most common sign of a failing tube nut, often caused by overtightening (stripping threads) or undertightening. Corrosion is rare due to the black anodized coating, but physical damage to the nut or ferrule can compromise the seal. Inspect for cracked anodizing or deformed threads.
Installation Notes
Slide the tube nut over the tube first, then the ferrule. Insert the tube into the fitting until it bottoms out, then tighten the nut by hand until snug, followed by a final turn with a wrench (typically 1/4 to 1/2 turn). Do not overtighten. Use a drop of lightweight oil on the threads to ensure smooth engagement and proper clamping force.
