This standard establis es the nominal profile and main dimensions of threads with diameters from No. 4 to 1/2 in. This standard will be applicable only to the production of standardized fastening elements that are not possible or economically not feasible to replace with metric ones.
NC 16-16-1986 history
1986NC 16-16-1986 Interchangeability Basic Standards. Thread in Inches. Profile and Main Dimensions