Knowing how to check bolt torque is a key ingredient in making sure fasteners don’t fail. There are several ways to determine bolt torque, including torque auditing.
As Bill Eccles of Bolt Science writes, there are three ways this can be achieved:
The on-torque method – This is the most commonly used form of torque auditing, measuring the torque required to turn the bolt/nut by a small angle (usually two to 10 degrees) in the tightening direction.
The off-torque method – This method involves measuring the torque needed to rotate the bolt/nut in the untightening direction (this is usually less than the tightening torque).
The marked fastener method – This requires you to mark the position of the bolt and nut relative to the joint, loosening it by an angle of approximately 30 degrees, then measuring the torque needed to get the bolt back to the marked position.