New Jersey

Department of Transportation

Standard Specifications

for Road and Bridge Construction


NJDOT S-1 – Rotational-Capacity Test on Long Bolts
in Tension Calibrator

  1. Scope. This test method is used for determination of high-strength steel bolt assembly acceptance for rotational capacity using a tension calibrator. Use this test method for bolts long enough to fit in the tension calibrator. Use NJDOT S-2 for bolts that are too short to fit in the tension calibrator.

  2. Apparatus. Use the following apparatus:

    1. Calibrated bolt tension measuring device of size required for bolts to be tested, such as Skidmore-Wilhelm Calibrator.
    2. Calibrated torque wrench (dial type).
    3. Spacers and/or washers with hole-size no larger than 1/16 inch greater than bolt to be tested.
    4. Steel section for mounting the bolt calibrator such as a flange of a girder or cross frame accessible from the ground.

  3. Procedure. Perform the following steps:

    1. To determine if the bolt is long enough for testing, mark the first 3 to 5 full threads that are located closest to the bolt head. Insert the bolt into the tension calibrator and assemble a washer and nut onto the bolt up to the marked threads. Use a rotational capacity washer from the same rotational capacity lot as the bolt and nut. If a washer is not required for the installation, use an ASTM F 436 washer of the proper diameter for the test. If the nut can not be fully threaded onto the bolt shank then the bolt is too short for testing and must be tested as specified in NJDOT S-2. If the nut is at least flush with the end of the bolt shank, then continue testing.
    2. Take apart the bolt assembly. Use shim plates or washers under the bolt head, as needed, to ensure that the 3 to 5 threads that were marked in Step 1 are located within the grip of the device but are just visible from the opposite side. Re-assemble the bolt, washer, and nut.
    3. Tighten the nut using a hand wrench to the minimum snug tension as specified in Table S-1-1. Do not exceed the minimum snug tension by more than 2 kips.

    4. Table S-1-1 – Snug Tension Requirements
      Bolt Size 1/2 5/8 3/4 7/8 1 1-1/8 1-1/4 1-3/8 1-1/2
      Minimum Snug Tension, kips 1 2 3 4 5 6 7 9 10

    5. Match mark a corner of the nut and the face plate of the bolt calibrator.
    6. Using the calibrated manual torque wrench, tighten the bolt to the minimum tension listed in Table S-1-2. Read and record the wrench torque required to reach the tension with the nut in motion. Read the actual bolt tension and record as the initial tension.

    7. Table S-1-2 – Initial Tension Requirements
      Bolt Size 1/2 5/8 3/4 7/8 1 1-1/8 1-1/4 1-3/8 1-1/2
      Minimum Initial Tension, kips 12 19 28 39 51 56 71 85 103

    8. Further tighten the bolt to the rotation listed in Table S-1-3. Measure rotation from the match mark in Step 4. Record the bolt’s final tension as indicated on the calibrator. If an assembly fails by stripping or fracturing before reaching the rotation listed in Table S-1-3, the assembly fails the test.

    9. Table S-1-3 – Required Rotation
      Rotation Bolt Length
      240 degrees (2/3 turn) ≤ 4 diameters
      360 degrees (1 turn) > 4 diameters and ≥ 8 diameters
      480 degrees (1-1/3 turns) > 8 diameters

    10. The final bolt tension measured in Step 6 must equal or exceed the value in Table S-1-4. Assemblies that do not meet this tension fail the test.

    11. Table S-1-4 – Final Tension Requirements
      Bolt Size 1/2 5/8 3/4 7/8 1 1-1/8 1-1/4 1-3/8 1-1/2
      Minimum Final Tension, kips 14 22 32 45 59 64 82 98 118

    12. Loosen the assembly and remove nut to examine the threads on the nut and bolt. Check for signs of thread shear failure, stripping, or torsional failure of the nut and bolt. Assemblies that have evidence of thread shear, stripping, or torsional distress fail the test.

  4. Calculations. Calculate the maximum allowable torque in foot-pounds as follows:

      Maximum Allowable Torque = 0.25 × P × D
      P =  Measured initial tension in pounds
      D =  Bolt diameter in feet

      Compare the torque as measured in Step 5 to the maximum allowable torque. If the measured torque is greater than the maximum allowable torque, the assembly fails the test.

  5. Report. Report the following:

    1. Size, manufacturer and lot number for the bolt assembly.
    2. Measured initial tension and torque.
    3. Measured final tension and torque.
    4. Observations of the thread condition.
    5. Pass/Fail status of the bolt assembly.

Last Document Correction:
December 14, 2007