SAE-AS33514 specifies:

Up at 70,000 feet, where the air is thin and the temperature drops to -60°F, the metal of the drone contracted. But the AS33514 held. The 37-degree cone, designed decades ago by engineers who obsessed over fractions of an inch, stayed pressed firmly against its seat.

For modern projects, engineers are directed to use AS4375 (Flareless Fitting End) or AS5863 (24° Cone Flareless Fluid Connection). Technical Specifications