Standard DTI FAQs
Coatings for DTIs
- You are using galvanized bolts and nuts. Should
you also use galvanized DTI's?
- You have plain finish DTI's (that is, without any
coating), and you are contemplating sending them out to be galvanized.
Is this OK?
- You need corrosion protection greater than afforded by mechanically
glavanized surfaces on the bolts and DTI's. What should you specify?
See corrison protection
- You have ASTM A490 bolts and ASTM F959 DTI's made to compatible A490
grade. you have been asked to mechanically galvanize all the hardware
including the DTI's. What should you do? See galvanizing
A490 DTI's
- See Corrosion Protection
You are using galvanized bolts and nuts. Should you also use galvanized DTI's?
Yes, although not for any reason except that of compatible materials. An uncoated DTI will function fine with a coated bolt. If it is necessary to use this combination, use the thicker of the two feeler gages for inspection.
Note - Hot dipped galvanized DTI's are not allowed, only mechanical galvanizing is used for DTI's.
Note - Hot dipped galvanized bolts can be used with mechanically galvanized DTI's. back to FAQ Index
You have plain finish DTI's (that is, without any coating), and you are contemplating sending them out to be galvanized. Is this OK?
Definitely not.
All DTI compression load testing and certification must be done after the coating process. Such testing must be done by an accredited laboratory, and for DTI's requires special tooling and test jigs per ASTMF 959 Appendix A1. Any warranty on Applied Bolting DTI's is voided by application of a non-approved coating.
