I made up a lot of high pressure hydraulic lines JIC.
Flare Fittings
There are several differences between "comparable" industrial 37° flare (SAE/ISO) and AN 37° flare style fittings.
Threads
- AN 37° Flare: Male and female, Class 3A/3B UNJ/UNJF (radiused root threads)
- SAE/ISO 37° Flare: Male and female, class 2A/2B, UN/UNF series threads for tighter tolerances and better fatigue life for aircraft, aerospace, military applications
Military Conformance Standards
- AN 37° Flare: AN flare fittings conform to MIL-F-5509 specifications, and also AS4841
- SAE/ISO 37° Flare: Some fittings conform to MIL-F-18866 as shown on MS51500 through MS51534
Industrial Conformance Standards
- AN 37° Flare: Meets SAE Aerospace (AS) standards
- SAE/ISO 37° Flare: Meet the applicable dimensional and performance requirements of SAE J514/ISO 8434-2
General
In addition to the above-noted differences, drop lengths, hex sizes, hex widths may also vary between "comparable" AN 37° flare and industrial 37° flare fittings in some sizes.
AN and JIC Fittings Interchangeability
AN 37° flare and industrial 37° flare fittings function identically. In many cases, they appear to be functionally interchangeable, but they are not. What this means is that while the products may look similar, you must not use an industrial 37° flare fitting design as a direct substitution.