-6an to 5/8-18 Inverted Flare Adapter Female

The RUSSELL -6AN to 5/8-18 Inverted Flare Adapter Female (Part #640610) is a straight hydraulic fitting adapter engineered for high-pressure fluid system applications where reliable connections are critical. This adapter bridges -6 AN male ports to 5/8-18 inverted flare female connections, making it essential for custom hydraulic line assemblies in industrial, marine, and performance vehicle environments where standard SAE or NPT configurations are insufficient.

Manufactured from steel with zinc oxide plating, this fitting delivers corrosion resistance and dimensional stability across temperature extremes. The inverted flare design—where the tubing is flared outward to create a seal against a conical seat—provides superior holding power under pulsating loads compared to straight thread connections. The -6 AN (3/8-inch) to 5/8-18 conversion allows integration of legacy equipment or specialized component configurations without custom fabrication. Zinc oxide plating protects against rust and oxidation, particularly important in salt-air or high-humidity environments where uncoated steel would degrade rapidly.

This adapter serves hydraulic system integrators, custom fabricators, and technicians restoring or modifying fluid circuits in marine engines, diesel performance builds, aircraft ground support equipment, and industrial machinery. It is suited for both fixed installations and field repair scenarios where standard adapter inventory is unavailable. The compact design (2.7" × 1.4" × 4.9") fits tight engine bays and equipment enclosures.

RUSSELL fittings are recognized for precision manufacturing and consistent tolerances, reducing leak risk and system downtime. This straight-body adapter eliminates elbows and reduces fitting count, lowering overall pressure drop and heat generation in hydraulic circuits operating at sustained high flow rates.