High-strength structural bolting assemblies for preloading - Part 9: System HR or HV - Direct tension indicators for bolt and nut assemblies

This technical document specifies requirements and test methods for direct tension indicating washers used in high-strength bolted connections for steel structures. It focuses specifically on the HR and HV systems, outlining procedures to verify preload consistency through the deformation of indicator washers during bolt tightening. The standard addresses the compatibility between bolts, nuts, and these washers to ensure uniform clamping forces in preloaded joints. It provides guidance for manufacturing, testing, and marking of the components to maintain structural integrity under operational loads. Detailed criteria for washer performance under tension are included, ensuring that the indicated load corresponds accurately to the target pre-stress value. This specification supports consistent application of pre-tensioned fasteners in critical steel construction projects where reliable joint behavior is essential. It complements broader frameworks for high-strength bolt assemblies by offering a precise method for monitoring installation quality without relying on torque values alone. The document serves as a reference for engineers, manufacturers, and inspectors involved in structural steel fabrication and assembly processes across various industries.