#3 Flare/#3 Flare Steel Union

The #3 Flare/#3 Flare Steel Union from A-1 Products is a precision hydraulic or pneumatic fitting designed for fuel, coolant, brake, and transmission line applications in modern automotive builds and restorations. Whether you're assembling a custom fuel system, upgrading brake lines on a classic restoration, or fabricating a performance engine bay, this steel union connector provides reliable, leak-free pressure retention where multiple fluid lines converge. Mechanics and fabricators trust flare fittings for their superior sealing geometry and compatibility with industry-standard tubing sizes.

The #3 flare designation refers to a specific tube diameter and connection standard—in this case, 3/16-inch tubing with a 45-degree flare seat geometry that creates a metal-to-metal seal when torqued properly. Steel construction ensures durability under high-pressure cycles, thermal cycling, and exposure to aggressive fluids common in engine bays, fuel cells, and transmission cooler circuits. The union design allows two flared tube ends to connect without requiring special block-mount or manifold ports, making it ideal for inline connections, splitters, and custom plumbing where space or accessibility is limited.

This fitting benefits drag racers, hot rod builders, and street performance enthusiasts who demand reliability under sustained boost or high-flow conditions. Installation requires only two wrenches—one to hold the union body, one to turn the fitting nut—making it a straightforward addition to existing systems or new fabrication projects. Ensure your tubing is properly flared to 45 degrees and torque to manufacturer specifications to prevent weeping or system failure; inspect periodically, especially after engine modifications or track use, to confirm seal integrity under operating pressure.