Failure Analysis of a Chain End Bolt

A chain end bolt used in an industrial lifting device fractured in service. Metallurgical failure analysis revealed reversed bending fatigue cracks that consumed the entire cross-section, despite the design employing specific details to avoid fatigue. This presentation will explain the metallurgical failure analysis and the specific design details that led to the failure. The general aspects of this failure to be discussed include: fastener pre-load, loss of pre-load due to vibrations, and design alternatives for ‘thread locking’ (e.g., various types of washers, thread locking adhesives and mechanical solutions).