ISO 7040:2025

This document specifies the characteristics of prevailing torque hexagon regular nuts (with non-metallic insert), in steel and stainless steel, with metric coarse pitch thread M3 to M39, and with product grades A and B. NOTE These nuts are designed with an overall height equal to mmin (as specified in ISO 898-2 and ISO 4032 for style 1) plus the prevailing torque feature. The height of the prevailing torque feature (hmax – mmin) for the non-metallic insert is identical for regular, high and thin nuts for a given diameter. Nuts with sizes D < M5 and design principles in accordance with style 1 are specified in Annex A. 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.