SAE J995 covers the mechanical and chemical requirements for inch series nuts in three grades used in automotive and related industries in sizes to 1-1/2” inclusive.

J995 Mechanical Properties

Grade Nominal Size, inches Proofload, UNC and UN 8 Threads, psi Rockwell Hardness
2 1/4 thru 1-1/2 90,000 C32 Max
5 1/4 thru 1 120,000 C32 Max
Over 1 thru 1-1/2 105,000 C32 Max
8 1/4 thru 5/8 150,000 C24-C32
Over 5/8 thru 1 150,000 C26-C34
Over 1 thru 1-1/2 150,000 C26-C36
*Values listed are not normally applicable to lock, jam, slotted, castle, heavy or thick nuts.