Thread data
Inverted flare thread chart and dimensions
A 45° flared tube clamped against a 42° seat inside the port by a tube nut. The seat is protected inside the fitting, which is why it is used on brake, fuel, transmission and power steering lines. Working pressure falls as the tube gets larger, from 2,800 psi at 1/8 in to 550 psi at 3/4 in with copper tube.
- Standard
- SAE J512 inverted flare
- Seals by
- 45° flared tube clamped on a 42° seat inside the port
- Used for
- Brake, fuel and transmission lines, and power steering
- Sizes
- 1/8 in to 3/4 in
Inverted flare dimensions
The dimensions we machine to. Pressure values are nominal working ratings for steel at room temperature.
| Size | Male | Female | Thread | Tube OD | Pitch dia | Minor dia, male | Minor dia, female | Male thread length | Tap drill | Seat | Rated to |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/8 in | 5/16-28 UN-2A inverted flare | 5/16-28 UN-2B inverted flare port | 5/16-28 UN | 3.17 mm | 7.35 mm | 6.82 mm | 6.96 mm | 8.13 mm | 9/32 (7.03 mm) | 42° inverted seat, takes a 45° flared tube and nut | 2,800 psi |
| 3/16 in | 3/8-24 UNF-2A inverted flare | 3/8-24 UNF-2B inverted flare port | 3/8-24 UNF | 4.76 mm | 8.84 mm | 8.23 mm | 8.38 mm | 9.14 mm | 21/64 (8.47 mm) | 42° inverted seat, takes a 45° flared tube and nut | 1,900 psi |
| 1/4 in | 7/16-24 UNS-2A inverted flare | 7/16-24 UNS-2B inverted flare port | 7/16-24 UNS | 6.35 mm | 10.43 mm | 9.81 mm | 9.97 mm | 9.14 mm | 25/64 (10.05 mm) | 42° inverted seat, takes a 45° flared tube and nut | 1,400 psi |
| 5/16 in | 1/2-20 UNF-2A inverted flare | 1/2-20 UNF-2B inverted flare port | 1/2-20 UNF | 7.94 mm | 11.88 mm | 11.14 mm | 11.33 mm | 10.16 mm | 29/64 (11.43 mm) | 42° inverted seat, takes a 45° flared tube and nut | 1,200 psi |
| 3/8 in | 5/8-18 UNF-2A inverted flare | 5/8-18 UNF-2B inverted flare port | 5/8-18 UNF | 9.52 mm | 14.96 mm | 14.14 mm | 14.35 mm | 10.16 mm | 9/16 (14.46 mm) | 42° inverted seat, takes a 45° flared tube and nut | 1,000 psi |
| 7/16 in | 11/16-18 UNS-2A inverted flare | 11/16-18 UNS-2B inverted flare port | 11/16-18 UNS | 11.11 mm | 16.55 mm | 15.73 mm | 15.93 mm | 11.18 mm | 5/8 (16.05 mm) | 42° inverted seat, takes a 45° flared tube and nut | 750 psi |
| 1/2 in | 3/4-18 UNS-2A inverted flare | 3/4-18 UNS-2B inverted flare port | 3/4-18 UNS | 12.70 mm | 18.13 mm | 17.32 mm | 17.52 mm | 11.68 mm | 11/16 (17.64 mm) | 42° inverted seat, takes a 45° flared tube and nut | 750 psi |
| 5/8 in | 7/8-18 UNS-2A inverted flare | 7/8-18 UNS-2B inverted flare port | 7/8-18 UNS | 15.88 mm | 21.31 mm | 20.49 mm | 20.70 mm | 12.19 mm | 13/16 (20.81 mm) | 42° inverted seat, takes a 45° flared tube and nut | 650 psi |
| 3/4 in | 1 1/16-16 UN-2A inverted flare | 1 1/16-16 UN-2B inverted flare port | 1 1/16-16 UN | 19.05 mm | 25.96 mm | 25.04 mm | 25.27 mm | 13.72 mm | 1 (25.40 mm) | 42° inverted seat, takes a 45° flared tube and nut | 550 psi |
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