Rigging

A working load limit identifies the rated load that a sling, shackle, hook, or other rigging component is permitted to handle under specified conditions. The applicable rated capacity may depend on the type of hitch, sling angle, component configuration, temperature, and manufacturer requirements. Wear, deformation, corrosion, heat damage, missing identification, or other deterioration may instead make equipment unsuitable for continued service rather than simply reduce its working load limit. Identification markings, specifications, inspection findings, and the actual rigging arrangement are therefore important when evaluating capacity for a lift.

A freely suspended load tends to settle with its center of gravity below the effective lifting point. If sling lengths, lifting points, or attachment locations do not account for the center of gravity, the load may tilt, rotate, or shift as tension develops. Uneven weight distribution, irregular geometry, moving contents, and inaccurate load information can further change how the load is shared among the rigging components.

Relevant conditions can include broken wires, cuts, abrasion, crushed or kinked sections, corrosion, stretched or distorted components, bent or opened hooks, damaged latches where fitted or applicable, distorted shackles, heat damage, and missing or illegible identification. The significance of each condition depends on the type of sling or hardware and the applicable inspection and removal criteria. Inspection records and photographs from before and after a lift can help assess whether deterioration was present before an incident.