Standard DTI FAQs
You have a bolt grade that is something other than ASTM A325 or A490. What should you do?
To help you select a DTI that will fit your bolting application please see special DTI's.
Standard Applied Bolting DTI's are made to ASTM F959, which only covers the behavior of DTI's with heavy hex structural bolts made to A325 and A490 specifications. For other bolts, chances are one of our standard DTI's will work, at some residual gap. For instance, an SAE J429 Gr 5 bolt will react about the same as an ASTM A325, and an SAE J429 Gr 8 bolt about the same as an A490. A (JIS)B1186 F10T bolt will react a little higher in tension than a metric 8.8 bolt (in this case we offer a special F10T DTI because this combination is frequently found in the Far East). A DIN 6914 bolt and a DIN 6915 nut, only availale in what ASTM calls an A490 strength, or 10.9 strength in metric terms, is a bolt that may strip when fully tensioned. Consequently, DIN 18800 application specification calls for it to be tensioned lower than the 70 percent of minimum uts. Nevertheless, installing a DIN 6914 bolt with an ASTM A325 or 8.8 strength DTI can be done effectively.
How the non-ASTM bolts react with DTI's is affected by the geometric fit between the bolt and the DTI. Does the bolt head adequately cover the DTI bumps? The rule of thumb here is to try it and see how they fit together. If they don't fit together too well for some reason, put the DTI under a flat washer instead of directly under a bolt head. Check this in a hydraulic bolt tension calibrator like a Skidmore-Wilhelm calibrator. If you can't find one of these anywhere close, call us and we'll send you one, or we can do the testing for you.
