What should not be used for torque values that relate to pretension?

Torque values from tables or equations are typically derived from theoretical models or standardized testing but may not account for specific variables that can affect pretension, such as surface conditions, the coating on the bolt, or thread friction. Each connection can have unique characteristics that affect how much torque is needed to achieve the desired level of pretension. Therefore, relying solely on these pre-determined values may not ensure that the bolts are properly tensioned in real-world applications.

Using torque charts alone, performing manual calculations, and employing tightening machines can be more adaptable in reflecting the actual conditions of the bolted connection, allowing for adjustments based on the specific context of the installation. Tightening machines, for example, can provide the necessary control and feedback to achieve precise pretension, which is crucial for the structural integrity of steel connections.