What is the rule of thumb formula for calculating the SWL of a grade 80 lifting chain?

The correct choice for calculating the Safe Working Load (SWL) of a grade 80 lifting chain is based on the understanding that grade 80 chains are designed to have specific load capacities based on their diameter. The rule of thumb formula you mentioned, which involves taking the diameter in millimeters and squaring it before multiplying by 32, is a simplified way to estimate the SWL in kilograms.

The reason this formula is effective stems from the material properties and design standards associated with grade 80 chains. These chains are manufactured with high-strength alloy steel and subjected to rigorous testing to ensure safety and reliability under load. The factor of 32 in the formula correlates with the tensile strength of the materials and provides a conservative estimate of the chain's capacity to safely lift loads.

Using this established formula ensures that operators are aware of the maximum weight that can be lifted with a specific grade 80 chain, ultimately promoting safe practices in lifting operations. It's important to remember that using correct calculations is crucial to prevent loads from exceeding the chain's rated capacity, which could lead to equipment failure or accidents. Understanding this rule provides a foundational piece of knowledge for anyone working with lifting equipment.