prBAS EN ISO 7720:2026

This document specifies the characteristics of prevailing torque (all metal) hexagon high nuts with slot(s), in steel and stainless steel, with metric coarse pitch thread M5 to M39, and with product grades A and B. NOTE            These nuts are designed with mmin as specified ISO 4032 and with an overall height h greater than in ISO 7042, in order to accommodate the prevailing torque feature with slot(s); this height h contributes to the nut resistance due to the number of engaged threads. hmin values have been calculated as a function of hmax together with a ratio hmax/D that progresses regularly with increasing diameter; therefore, the tolerance (hmax – hmin) does not follow the ISO code system for tolerances (IT system). If in certain cases other specifications are requested, property classes and stainless steel grades can be selected from ISO 898-2 or ISO 3506-2.