Flare Fitting


How to measure SAE Flare Fittings
 

The SAE male has straight threads and a 45 degree flare seat. The SAE female has straight threads and a 45 degree flare seat. The seal is made on the 45 degree flare seat.

SAE 45 Flare Male  SAE 45 Flare Female


1) With a caliper, measure the thread diameter at the widest point across the threads (See image below).

Outside diameter (O.D.) of male threads. Inside diameter (I.D.) of female threads.
 DimOut  DimIn

2) Compare measurements to chart below. For example, a 3/8” male flare has an actual outside diameter of 5/8”.

Nominal
Size
 

 Female
Thread
I.D. (In.)

 Male
Thread
O.D. (In.)

No. of
Threads
Per Inch

Steel
Torque
Recommended
(Ft-Lbs.)

1/8

17/64

5/16

24

-

3/16

21/64

3/8

24

-

1/4

25/64

7/16

20

10 - 11

5/16

29/64 

1/2

20

13 - 15

3/8

9/16

5/8

18

17 - 19

7/16

5/8

11/16

16

 -

1/2

11/16

3/4

16

34 - 38

5/8

13/16

7/8

14

50 - 56

3/4

63/64

1 1/16

14

70 - 78

1

1 13/64

 1 5/16

11 1/2

65

The how to measure information courtesy of