M30 Galvanised Heavy Hexagon Nut - A194 Grade 7 Tapped Oversize Since hot-dip galvanizing typically adds 2.2 to 5 mils of thickness to the threaded portion of a fastener, galvanized heavy hex nuts are tapped oversize to compensate for the corrosion resistant coating on the thread of the bolt Quenched & tempered alloy steel heavy hex nuts Where: m = thickness s = across flats d = Thread m - 30 mm s - 45 mm d - M30 Thread Pitch -3.5 mm