BS ISO 7380-3:2026 PDF

1 Scope This document specifies the characteristics of hexalobular socket button head screws with reduced loadability due to head design, in steel and stainless steel, with metric coarse pitch threads M3 to M12, and with product grade A. If, in certain cases, other specifications are requested, property classes and stainless steel grades can be selected from ISO 898‑1 or ISO 3506‑1 , and the dimensional options from ISO 888 or ISO 4753 . NOTE     The reduced loadability (related to the head dimensions in combination with penetration of the hexalobular 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 Table 4.