For design calculations the SAE AS 8879 coarse threads, UNJC, shall be used for 0.164 size and smaller and fine threads, UNJF, for larger sizes.
For particulars of thread runout and lead threads for bolts, see SAE AS 3062.
To establish design requirements for bolts, screws and nuts in the UNJ thread inch series primarily for use on propulsion systems.
As defined by the Federal Cataloging System, thread sizes less than 0.190 are referred to as screws and larger are referred to as bolts. For the purpose of this document, the term bolt will be used for all sizes.