Inverted flare fittings create a metal-to-metal pressure seal using a 37° double-flare on the end of soft steel, copper, or aluminum tubing — the opposite flare geometry from the 45° SAE flare used in refrigeration and HVAC. The 37° inverted (internally-seated) flare is the SAE J512 / ISO 8434-1 standard for automotive brake lines, fuel lines, transmission cooler lines, power steering, and high-pressure hydraulic applications where extreme vibration resistance and no-leak reliability are critical.
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1/4 in. Brass Steel Inverted Flare Nut -
1/4 in. x 1/4 in. (9/16-18) Brass Dual Master Cylinder Adapter -
1/4 in. x 1/8 in. Brass Female Inverted Flare x Female NPT Adapter -
1/4 in. x 1/8 in. Female Inverted Flare x Male NPT Elbow -
1/4 in. x 3/16 in. Male Inverted Flare x Female Inverted Flare -
5/16 in. Brass Steel Inverted Flare Plug -
5/16 in. x 1/8 in. Brass Female Inverted Flare x Female NPT Adapter -
3/8 in. x 1/4 in. Brass Female Inverted Flare x Male NPT Adapter -
3/8 in. x 1/4 in. Female Inverted Flare x Male NPT Elbow -
3/8 in. x 3/8 in. Female Inverted Flare x Male NPT Elbow -
7/16 in. Brass Steel Inverted Flare Nut -
1/2 in. x 3/8 in. Brass Female Inverted Flare x Female NPT Adapter -
1/2 in. x 3/8 in. Brass Female Inverted Flare x Male NPT Adapter -
127Bt01C 1/4 in. x 1/4 in. x 1/4 in. Brass Inverted Flare Brake Tee -
127Bt09 3/16 in. (7/16-24) Brass Brake Tee -
127Bt10C 1/4 in. x 3/16 in. x 1/4 in. Brass Male NPT Brake Tee -
39In 1/4 in. Brass Inverted Flare Plug -
41Inr 3/16 in. x 5/16 in. Brass Inverted Flare Nut -
48Sta03 1/4 in. x 7/16-20 Brass Inverted Flare Adapter -
Brass Converted Flare Adapter, 3/16 in. x 5/16 in.
Inverted flare and SAE 45° flare fittings are not interchangeable — the different cone angles will not seat correctly together and will leak under pressure. Always identify which flare standard your line requires before ordering.
Applications
Automotive brake line connections (by code in most markets), fuel system line connections, transmission oil cooler lines, power steering return lines, hydraulic brake and clutch systems on heavy equipment, and any high-vibration fluid circuit where the 37° inverted flare standard has been specified by the OEM.
Identification: 37° Inverted vs. 45° SAE Flare
The easiest way to identify the flare type: a 37° inverted flare fitting has a convex (domed) nose; a 45° SAE flare fitting has a concave (recessed) seat. See our SAE 45° vs. Inverted Flare Identification Guide for photos and full identification instructions before purchasing.