A crane operator is performing a visual inspection of a hook with a rated capacity of 10 tonnes. They notice a twist in the hook, indicating permanent deformation. According to CSA Z150, what is the maximum permissible twist from the plane of the unbent hook that would necessitate replacement?

Question: A crane operator is performing a visual inspection of a hook with a rated capacity of 10 tonnes. They notice a twist in the hook, indicating permanent deformation. According to CSA Z150, what is the maximum permissible twist from the plane of the unbent hook that would necessitate replacement?

Answer options: ✅ Any discernible twist, regardless of degree.

• 10 degrees.
• 5 degrees.
• 15 degrees.

Correct answer: Any discernible twist, regardless of degree.

Explanation: CSA Z150 specifies that any visibly apparent deformation, including twisting, bending, or excessive opening of the throat, requires immediate removal of the hook from service. Unlike wear, which has specific dimensional limits, deformation like twisting signifies that the hook has been overloaded or improperly used, compromising its structural integrity and making it unsafe. Therefore, any discernible twist is cause for replacement.