For many years the tightening and torquing of bridge bolts traditionally have been done with impact guns being checked on a Skidmore/Calibore bolt load testing device for verification.   While this has always been acceptable in the past, many engineering and inspection firms are now requiring calibrated shut off tools to be used in place of impact guns. The Skidmore/Calibore used in conjunction with an impact gun verifies that that tool has the capacity to go to the required bolt load. The issue with this method, is that it’s operator dependent on the time the tool operator continues to hold down the trigger on the impact. There is no shut off when the correct bolt load is achieved. Therefore, the tool operator could over or under apply the proper bolt load required.

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