Standard DTI FAQs
Your bridge project requires the use of DTI's, but you have been given five lots of DTI's of one diameter and grade instead of just one. You're not sure how many FHWA DTI installation Verification Procedure tests you should do
On bridge projects, the FHWA requires that each lot of DTI's be tested with each lot of bolts. Consequently the overall number of tests can be large on larger projects. As an alternative, DTI users should consider specifying only one lot of DTI's. (Applied Bolting manufactures lots of DTI's as large as necessary but easily 100,000 pieces). However, end users should consult with their local state and FHWA representative for the project and request approval of an abbreviated test program. Such an abbreviated program is based on testing the DTI lot showing the highest mean compression load resistance with the lot of (same diameter) bolts showing the lowest rotational capacity test value. Theoretically, if this combination still passes, any subsequent lot of DTI's which is "less strong" will work properly with any subsequent lot of bolts which are "stronger" in the FHWA test.
