This part of this European Standard specifies, together with EN 14399-1, the requirements for assemblies of high-strength structural bolts and nuts of system HRC suitable for preloaded joints, with hexagon head (large widths across flats) or cup head, thread sizes M12 to M30 and property class 10.9/10.Bolt and nut assemblies conforming to this part of this European Standard have been designed to allow preloading of at least 0,7 fub X As ) according to EN 1993-1-8:2005 (Eurocode 3) and to obtain ductility predominantly by plastic elongation of the bolt. For this purpose the components have the following characteristics:- nut according to EN 14399-3, or- nut