DTIs that were installed incorrectly 2

[Lutfi]

I am being consulted on some DTI (Direct Tension Indicators) that were installed as follows:

1. ¾ inch diameter A325, for slip critical joints, contractor used DTI
2. Contractor installed DTI under nut which is not the best application
3. Contractor did not use a hardened washer between DTI and nut (turning element)
4. Contractor asked DTI manufacturer to duplicate the filed condition using Skidmore tool
5. Test results from six (6) bolts indicated that only at tension of 34 kips; the feeler gage had refusals to qualify proper tension

Does any one have words of wisdom? There are many bolts that already installed. Your quick response would be greatly appreciated.

Good night

 

[Ron]

Lutfi...I would look at two parameters. One, do the test again with Skidmore-Wilhelm device but put DTI under bolt head to see if different value obtained. Next I would inspect the 6 tested assemblies to see if any smearing or galling on the DTI from the nut rotation.

Look at the torque values to see if they are reasonable. If somewhere around 400 ft-lb (+/- 25 ft-lb) then in reasonable range. If way above that to achieve tension, maybe the DTI's are faulty. Then you can check hardness of DTI's to evaluate.

 

[Lutfi]

Ron,

Thanks for th input. I like the idea of testing the DTIs under the bold head. However, I am not sure if I can use the "torque" word anymore since everybody is using "tension" including AISC and RCSC. I used the torque for many years, actually over 23 years without any problems.

Thanks again.