Bolted connections tend to work themselves loose under certain operating conditions. Vibrations cause particular problems as they can overpower the “self-locking effect” of bolted connections. This can lead to functional failure or even to the connection coming apart. As it’s not always possible to know what forces are acting on the structure, and as constructional measures cannot be implemented everywhere, securing elements are often used. However, certain securing elements no longer comply with state-of-the-art technology and are ineffective in modern,

weight and cost-optimised structures using high-tensile bolts and nuts. The corresponding standards have been withdrawn by the German Institute for Standardisation (DIN). A few others have been downgraded to the rank of bolt retainers as they do not prevent self-loosening but do stop the connection from falling apart. Effective securing elements maintain a high pre-load force, reliably supporting the function even under extreme operating conditions.