Standard DTI FAQs
Do DTI's change the bolt length required?
DTI's do not change the bolt length required. DTI's are about 1/8" thick when compressed, similar to the thickness of a flat ASTM F436 washer. When placed on a bolt, DTI's add therefore about 1/8" to the thickness of steel clamped together by the bolts.
However, because the length of structural bolts is calculated according to known procedures and then rounded up to the next 1/4" increment, adding 1/8" rarely or never results in bolts being ordered longer than they would be if there were no DTI being used. Note that 'stick-through', the length of threads projecting above the nut when the nut has been tightened, for structural bolts can be zero because heavy hex nuts are sufficiently deep to develop the full strength of the bolt without any stick-through. When bolts are 2" or longer, DTI's almost never result in a bolt length change.
However, it is advised to check this carefully when the bolt length is less than 2".
