Plain washers, chamfered, hardened and tempered for high-strength structural bolting
This International Standard specifies those hardened and tempered circular washers intended for assembIy with large series hexagon high-strength Structural bolts and nuts of diameters from M12 to M36 inclusive.

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Threaded fasteners – Axial load fatigue testing – Part 1 : Test methods
Plain washers – Extra large series – Product grade C
Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
Steels for quenching and tempering – Part 2: Technical delivery conditions for non alloy steels – English version of DIN EN 10083-2:2006-10
Hardened parallel pins with internal thread (ISO 8735 : 1987) English version of DIN EN 28 735
NUT, PLAIN, HEXAGON, MACHINE SCREW UNC-2B