BS EN ISO 10642:2026

This document specifies the characteristics of hexagon socket countersunk head screws with reduced loadability due to head design, in steel and stainless steel, with metric coarse pitch threads M2 to M20, and with product gradeA. NOTE1 Other dimensional options are given in ISO 888, ISO 965-1 and ISO 4753. NOTE2 The reduced loadability (related to the countersunk head dimensions in combination with penetration of the hexagon socket specified in this document) implies a limitation of ultimate tensile load shown by a specific marking (property class preceded by a zero). The loadability in the head is assumed to be 80% of that in the thread for all sizes and all property classes; see Table5. NOTE3 Particular attention is needed to ensure alignment of the countersunk head with the bearing surface of the countersink in the assembly.