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Bridges & Structures

High Strength Bolts

Procedures for Performing Rotational Capacity Test

Appendix A1 - A490 Procedure for Performing Rotational Capacity Test Long Bolts in Tension Calibrator

Revised February 2005

Equipment Required:
  1. Calibrated bolt tension measuring device of the size required for the bolts to be tested.
  2. Calibrated torque wrench and spud wrenches.
  3. Spacers with hole 1/16 larger than bolt to be tested or nominal diameter washers.
  4. Steel section to mount the tension calibrator.

A Rotational Capacity Test Consists of 2 Assemblies.

  1. Measure the bolt length, the distance from the end of the bolt to the washer face at the bolt head to shank interface.

  2. Install the bolt in the tension calibrator with the required spacers or washers so that the bolt stick-out is flush with the nut to a maximum of three threads. This will typically provide three to five threads within the grip, the distance between the bolt head and the inside face of the nut. This same stick-out requirement applies during installation.

  3. Tighten the fastener assembly using a spud wrench to the tensions listed below -0 / +2 kips.

    Bolt Dia. (in.)  1/2   5/8   3/4   7/8   1   1 1/8   1 1/4   1 3/8   1 1/2 
    Initial Tension (kips)   2 2 4 5 6 8 10 12 15

  4. Match mark the bolt, nut and face plate of the calibrator.

  5. Using the calibrated torque wrench, tighten the fastener assembly to at least the minimum installation tension listed below and record both the tension and torque. Torque shall be read with the nut rotating. The torque value from the test shall not exceed T= .25 PD. P= tension in pounds. D= Dia. (in.)/12 = bolt diameter in feet.

    Bolt Dia. (in.)  1/2   5/8   3/4   7/8   1   1 1/8   1 1/4   1 3/8   1 1/2 
    Tension (kips)   15 24 35 49 64 80 102 121 148
  6. Further tighten the bolt to the rotation listed below. The rotation is measured from the initial marking in step 4.

    Bolt Length (from step 1)    4X bolt dia. Or less   Greater than 4 dia. But no more than 8 dia.   Greater than 8 bolt dia. 
    Required Rotation 2/3 1 1 1/6
  7. Record the tension at the completion of the rotation in Step 6. The tension shall equal or exceed 1.15 x the minimum installation tension. The minimum required values are listed in the table below.

    Bolt Dia (in.)  1/2   5/8   3/4   7/8   1   1 1/8   1 1/4   1 3/8   1 1/2 
    Tension (kips)   17 28 40 56 74 92 117 139 170
  8. Loosen and remove the nut. There shall be no signs of thread shear failure, stripping or torsional failure. The nut shall turn, with your fingers, on the bolt threads to the position it was in during the test. The nut does not need to run the full length of the threads. If you cannot turn the nut with your fingers it is considered thread failure.


The following constitute a failure of the rotational capacity test.

  1. Exceeding the maximum allowable torque in the torque/tension comparison.
  2. Failure to achieve the required rotation.
  3. Failure to achieve the required tension at the required rotation.
  4. Thread failure.

Failure of any one of these items on either assembly constitutes a failure of the rotational capacity test. When a failure occurs, the subject lot of fasteners is rejected. The contractor is given the option to clean and re-lubricate as necessary and then retest the fastener assemblies.

Updated: 08/16/2017
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