In fastener design, what does the term torque callout specify?

• A. Minimum torque value for fastener seating
• B. Torque value for fastener tightening depending on material and size
• C. Maximum permissible torque for safety
• D. Recommended lubrication method for threads

Answer: (B)

Torque callout specifies the recommended tightening torque to apply to a fastener in order to achieve the intended preload (clamping force) for that joint. This value arises from how material, fastener size (diameter and thread pitch), surface finish, and lubrication affect friction, so the same torque doesn’t give the same preload in every case. The callout is therefore a targeted setting that accounts for these factors to produce a reliable joint without over-stressing threads or under-clamping. In practice, loosening or over-tightening can lead to leaks, fatigue, or failure, which is why the specified torque is crucial.