In order to improve the safety of bolting in European steel structures, the Nord-Lock Group and PEINER Umformtechnik are currently collaborating to offer maintenance-free structural bolting consisting of PEINER HV bolts and nuts according to EN 14399-4/-. 8 and a pair of Nord-Lock Steel Construction (SC) wedge lock washers according to ETA – 20/0010.
The basic idea behind bolted connections is that the components come from the same manufacturer. The manufacturer is responsible for the components as well as the coefficient of friction (torque preload factor). Replacing the flat washers commonly used in standard bolt assemblies with the more reliable Nord-Lock SC washers turns this basic idea on its head. But why would a user change from a regular flat washer to a Nord-Lock SC washer?
Nord-Lock points out that self-loosening bolting and the problems associated with it are often underestimated. If bending, vibration, shock loading, or thermal movement is likely to occur during the life of the connection, these must be considered when determining the type of bolted connection to be used. If the wrong criteria are used for the conditions in which the bolted joint will be, the fastener or the entire assembly may fail.
Practical experience generally shows that lower initial preload due to poor friction conditions in bolted joints or higher preload loss due to settlement can have a critical effect on the load bearing capacity of a bolted joint.
Numerous tests by PEINER and Nord-Lock on preload torque characteristics, settling, dynamic load behavior, etc. have resulted in a reliable bolted connection and an official building permit from Germany’s highest building authority, DIBt. A maintenance-free bolt assembly has been created to comply with the limitations of EN 1090-2.
Will joined Fastener + Fixing Magazine in 2007 and has covered every facet of the fastener industry for the past 15 years, interviewing key industry figures and visiting leading companies and trade shows around the world.
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Post time: Feb-10-2023