Method and apparatus for auditing a tension load in the threaded fastener

A method for comparing relative clamp loads between a plurality of previously installed threaded fasteners comprising:

• providing a plurality of previously tightened threaded releasing fasteners;
• applying an additional torque in a releasing direction a first of the previously tightened threaded fasteners until a break away torque is reached;
• measuring the torque values applied to the first previously tightened fastener and measuring the angle through which the first fastener rotates;
• defining a first zero-angle point to be a point at which a tangent from a torque versus angle plot, created from the measured torque and angle values from the first previously tightened fastener, crooses an angle axis;
• defining a first audit angle to be the angle between the first zero-angle point and the angle associated break away torque for the first previously tightened threaded fastener,
• applying a torque in a releasing direction a second of the previously tightened threaded fasteners until a break away torque is reached;
• measuring the torque values applied to the second previously tightened fastener and measuring the angle through which the second fastener rotates;
• defining a second zero angle point to be a point at which a tangent from a torque versus angle plot, crested from the measured torque and angle values from the second previously tightened fastener, crosses an angle axis;
• defining a second audit angle to be the angle between the second zero angle point and the angle associated break away torque for the second previously tightened threaded fastener;
• and
• comparing the first and second audit angles to determine relative clamp loads.