Flare Fitting

What Are Flare Fittings?

Flare fittings are specialized connectors designed to join metal tubing and create a secure, leak-free seal in pressurized fluid systems. Flare fittings work by deforming (or "flaring") the end of a tube outward so it seats tightly against the fitting's angled surface, creating a metal-to-metal seal that can withstand significant pressure and vibration. They are widely used in systems that require robust, high-pressure connections, such as automotive fuel lines, brake systems, and industrial hydraulic applications.

Types of Flare Fittings

Understanding the different flare standards is essential before shopping. Most automotive hard line connections center on two flare angles: the 45-degree and the 37-degree.

• 45-Degree Inverted Flare (SAE): The most common style found on North American vehicles. The 45-degree inverted flare is an SAE standard used on hard lines for brakes, transmission lines, and fuel systems. It uses a two-step double-wall flare for added strength and is highly resistant to vibration, making it ideal for safety-critical brake lines.
• 37-Degree JIC / AN Flare: JIC (Joint Industry Council) fittings, defined by SAE J514, feature a 37-degree flare seating surface and are widely used in fuel delivery and fluid power applications, particularly where high-pressure performance is required. AN (Army-Navy) fittings share the same 37-degree geometry and are popular in racing and high-performance custom builds due to their precision and robustness.
• Bubble Flare (DIN/ISO): Commonly found on European and some Japanese vehicles, bubble flare fittings create a rounded, bubble-shaped seat. They are typically used in hydraulic brake and clutch systems on vehicles built to DIN/ISO standards.

Why Flare Fittings Matter

In any hydraulic or fuel system, a fitting failure is not merely an inconvenience — it can be a serious safety hazard. Improperly flared tubing can lead to leaks and system failures, making it critical to use the right fitting type, material, and thread standard for the application. For automotive brake systems specifically, DOT requirements call for at minimum a double flare on any repair — compression fittings are not a suitable substitute. Matching the fitting to the correct flare angle, thread type (SAE, AN, DIN), and tubing material (steel, aluminum, brass, or copper) is the foundation of a safe, long-lasting repair or build.

Top Flare Fitting Brands

Gates is a leading flare fitting brand in this category, offering a comprehensive range of SAE inverted flare and JIC 37-degree flare adapters. Gates inverted flare adapters are compatible with aluminum, brass, copper, and steel tubing and are recommended for hydraulic brake, fuel, oil, air conditioning, marine, and mobile applications — and are manufactured to meet or exceed OEM specifications.

Earl's Performance is a long-respected name in the performance and racing world, known for high-quality AN/JIC flare fittings and hose ends used in fuel, oil, and brake line plumbing on street performance cars and competition vehicles alike.

Aeroquip brings a legacy of aerospace and motorsport engineering to its flare fitting lineup. Aeroquip's SAE 37-degree JIC/AN inverted flare fittings are trusted across automotive, marine power steering, and fuel injection conversion applications.

Red Horse Performance is a go-to source for AN-style flare fittings popular in drag racing and high-performance street builds, offering a wide selection of black-anodized aluminum fittings — including AN-to-inverted-flare adapters — that combine competitive value with race-proven reliability.

ContiTech rounds out this category with a broad catalog of fittings suited for OEM-style replacement applications, making them a practical choice for technicians working on production vehicle repair and maintenance.

Choosing the Right Flare Fitting

When selecting a flare fitting, confirm the flare angle (45-degree SAE vs. 37-degree AN/JIC vs. bubble/DIN), the thread standard (SAE, AN, DIN, or NPT), and the tubing material and diameter. Ensuring compatibility between your fitting and the existing system is crucial for maintaining a safe and efficient brake, fuel, or hydraulic circuit. When in doubt, consult your vehicle's service manual or a flare fitting reference chart to match the correct standard for your application.