When a bolt is cleaned and lubricated how is tightening torque adjusted?

When a bolt is cleaned and lubricated how is tightening torque adjusted?

• A. By tightening to the recommended torque
• B. By applying more torque
• C. By loosening slightly
• D. By following the torque angle method

Answer: (A)

When a bolt is cleaned and lubricated, the friction between the threads and under the head changes. Lubrication lowers friction, so the same applied torque would normally produce a higher clamping force. To get the intended preload, you follow the torque specification that matches that lubrication condition. The manufacturer’s recommended torque accounts for the reduced friction, so tightening to that value is the correct way to deliver the proper clamping without over-stressing the fastener. Applying more torque would risk over-tightening, while loosening slightly would reduce preload and fail to achieve the correct clamp. The torque-angle method is used only when the service data specifies it; otherwise, you rely on the recommended torque.

When a bolt is cleaned and lubricated, the friction between the threads and under the head changes. Lubrication lowers friction, so the same applied torque would normally produce a higher clamping force. To get the intended preload, you follow the torque specification that matches that lubrication condition. The manufacturer’s recommended torque accounts for the reduced friction, so tightening to that value is the correct way to deliver the proper clamping without over-stressing the fastener. Applying more torque would risk over-tightening, while loosening slightly would reduce preload and fail to achieve the correct clamp. The torque-angle method is used only when the service data specifies it; otherwise, you rely on the recommended torque.