Standard DTI FAQs
Failure or stripping of bolts
- Your DTI's have been completely flattened so that not even a .005"
thick feeler gage can be inserted. Is this OK?
- You are compressing the DTI's OK but you think you are 'overtensioning'
your bolts. What should you do? See condition
of bolt threads
- Do you have some evidence of stripped threads? See Stripping of Bolts
Your DTI's have been completely flattened so that not even a .005" thick feeler gage can be inserted. Is this OK?
Yes. The Research Council on Structural Connections states that "… all tightening methods "may product tensions in excess of what is required, but this shall not be cause for rejection"(In FAQ bolt tension is listed the minimum bolt tensions. There is no maximum bolt tension.) Our recommendation is to test the bolts by compressing the DTI to the "dead flat" condition, and remove a couple from their holes. If the bolt threads look intact, if there is no sign of thread stripping, if you can remove the nut and rethread it on the bolt at least to where it was when tightened, it is perfectly acceptable.
Note that some "necking" of the bolt in the first few threads is possible, and acceptable. See: The Effects of Over-Compressing ASTM F959 Direct Tension Indicators on A325 Bolts Used in Shear Connections, for more information.
