ORFS tube nut size chart is according to SAE J1453 or ISO 8434-3 standards, including Standard tube nut (NA) and high-strength tube nut (NB).
a Thread minor diameter.
b Chamfer or radius hex corners L 45 minimum, both ends.
c Corner break, 1 mm max.
d Required identification for style B (high-strength) nut; see 4.3.
e Both sides.
f Tube nut style A (NA) (standard) is not suitable for copper braze assemblies.
g Tube nut style B (NB) (high-strength) is suitable for all assemblies.
h For tube outside diameter u 12 mm.
i For tube outside diameter > 12 mm.
j Corner break.