prBAS EN ISO 7040:2026

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.