ISO 3161:1999 (R2021)

This International Standard specifies the general requirements and limit dimensions of inch series UNJ threads with controlled root radius for aerospace construction. It determines the basic triangular profile for this type of thread and gives a system for designating the diameter and number of threads per inch combinations. For all diameters 0,060 in (1,524 mm) to 6,000 in (152,4 mm), it offers in the form of tables the basic dimensions and tolerances for a selection of diameter and number of threads per inch combinations. It also provides the method of calculation for the dimensions and tolerances for any diameter and number of threads per inch combination not given in the tables, including threads with a diameter in excess of 6,000 in.