Structural Fatigue Happens: Maintain Your Cranes!

by Patrick McCarthy

Structural maintenance is most efficiently, i.e., cost effectively, achieved through varying inspection intervals for the different crane components, depending on predicted cumulative “damage.” In this sense, cumulative damage refers to fatigue crack growth, not accidental damage.

For a crane structure, maintenance includes frequent visual inspection, periodic non-destructive testing (NDT), and repairing any cracks or damage caused by regular usage or accidents. Regular maintenance is not only essential for a reliable crane but is recommended to justify the allowable stresses. The crane is not designed to last forever with no limits on its fatigue life. This is impossible. Cranes will experience fatigue crack growth and if used indefinitely without inspection will eventually fail. The designer and operator must recognize this.

This article discusses the rationale behind structural maintenance programs for cranes.