ISO 4014
ISO 4014 - Hexagon head bolts
Hexagon head bolts with metric coarse pitch thread, product grades A and B. The bolt is turned by a spanner on a hexagon head and keeps a plain shank under it, so the thread stops short of the head and the joint is clamped on unthreaded metal; this is the fastener of steelwork, flanges and machine frames. A size is the pair d x l: the thread diameter fixes the width across flats s, the width across corners e, the head height k and the bearing face dw, while the length decides the thread length b - 2d + 6 mm up to 125 mm, 2d + 12 mm up to 200 mm and 2d + 25 mm above it - and the product grade, which is the close grade A up to M24 and 150 mm and the medium grade B beyond either. Covers threads M1,6 to M64 with nominal lengths 12 to 500 mm. Its German predecessor DIN 931 was replaced by DIN EN ISO 4014, but keeps wider spanner sizes on M10, M12 and M14; the fully threaded counterpart is ISO 4017 and the grade C version is ISO 4016.