What is a critical sign of a defective lifting hook?

A critical sign of a defective lifting hook is the presence of over 10% wear in the throat. The throat of a lifting hook is the area that bears the most stress during lifting operations. When wear in this area exceeds a certain percentage, it can significantly compromise the hook's strength and integrity, leading to potential failure under load. This excessive wear may result from repeated use, improper loading, or environmental factors, which can weaken the hook's structural stability.

While a dirty hook, a painted hook, or a shiny hook may indicate other maintenance issues or handling practices, they do not directly reflect the mechanical integrity or safety of the hook like excessive wear does. Thus, monitoring the wear percentage in the throat is crucial to ensure safe lifting practices and prevent accidents in operations involving heavy machinery.