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 with height m = 1 d, - thread length of the bolt according to ISO 888. Bolt and nut assemblies conforming to this part of this European Standard include washer(s) according to EN 14399-6 or to EN 14399-5 (under the nut only). NOTE Attention is drawn to the importance of ensuring that the bolts are correctly used if a satisfactory result is to be obtained. The test method for suitability for preloading is specified in EN 14399-2 and in Clause 8.