Direct Tension Indicators: Flattening DTIs 
 



Flattening DTIs 

  1. You notice that the DTI seems to compress all the way to flat on one side, but still leaves a gap greater than the thickness of the feeler gage on the other side. Is this OK?

  2.  
  3. Your DTI's have been completely flattened so that not even a .005" thick feeler gage can be inserted. Is this OK? See failure or stripping of bolts 

You notice that the DTI seems to compress all the way to flat on one side, but still leaves a gap greater than the thickness of the feeler gage on the other side. Is this OK?

Yes. In general, no bolt enters a hole exactly perpendicular to the surrounding steel surfaces. If the slope of the mating surface and the underside of the bolt head is up to one in twenty, the DTI should still record the bolt tension to an acceptable accuracy. However, depending on this slope, the flat of the nut might meet severe resistance to turning when it encounters surrounding steel, and the wrench may not be able to compress the DTI any further, or if it does, the bolt may be bent by trying to flatten the DTI any more. 

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Applied Bolting Technology Products, Inc. 
1413 Rockingham Road Bellows Falls, Vermont, USA 05101 
Phone: 1-800-552-1999  International: 1-802- 460-3100 USA 
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Email :appliedbolting