What is the rule of thumb formula for the working load limit (WLL)?

The working load limit (WLL) is a critical aspect of ensuring safety and performance in lifting and rigging applications. The formula WLL = d² x 8 is widely accepted as a rule of thumb in the industry for determining the safe working load of a chain or rope based on its diameter. In this formula, "d" represents the diameter of the chain or rope in inches.

This formula is derived from empirical evidence that relates the diameter of the rope or chain to its strength. The factor of 8 is used to translate the diameter into a weight limit, providing a safety margin to account for variations in material quality and environmental factors. This makes it a reliable guideline where fast and practical calculations are needed for the safe utilization of lifting equipment.

In contrast, the other formulas have different factors and mathematical relationships that do not align with the established safety practices for calculating WLL based on diameter. Using a different factor or power would not accurately represent the strength characteristics needed for ensuring safety in lifting operations.