What is a significant drawback of using screw-pin shackles?

Screw-pin shackles are widely used in rigging and hoisting applications, but one of their significant drawbacks is the potential for the pin to unscrew. This usually happens if the pin is not secured properly after installation or if the load shifts during operations. An unscrewed pin can lead to the entire load being released unexpectedly, posing serious safety risks and potentially causing accidents.

While weight, cost, and durability are also important considerations in choosing rigging equipment, they do not directly impact the safety and reliability of the shackle as much as the unscrewing issue does. Proper installation and regular maintenance can mitigate some concerns regarding weight and cost, but the risk of a screw-pin shackle becoming unscrewed remains a critical factor that must be addressed in safety protocols and operational practices.