ASME B1.21M-1997 (R2023)

This Standard establishes the basic triangular profile for the MJ thread form; provides a system of designations; lists the standard series of diameter/pitch combinations for diameters from 1.6 to 200 mm; and specifies limiting dimensions and tolerances. It specifies the characteristics of the MJ metric series of threads having a minimum 0.15011P radius at the root of the external thread, and also having the minor diameter of the external and internal threads increased above the ASME B1.13M-Metric Screw Threads: M Profile thread form to accommodate the external thread root radius.