All the Details (the fine print)

FOR IRONWORKERS AND OTHER BOLT INSTALLERS

You can locate the DTI on either end of the bolt. Just make sure the DTI bumps bear against the underside of the bolt head or against a hardened flat washer, never directly against the nut or the steel plates.
Never never never grind the DTI bumps down by turning either the bolt head or the nut directly against the DTI - put a flat washer in between.
Always snug an array of bolts before final tightening, just as you would when DTIs are not used. Make sure you don't fully compress the DTI on the snug (first) pass. On the final pass, compress the DTIs in the same sequence as you would if there were none present - that is, from the most rigid point outward.
If impact wrenches are used, final DTI compression should take less than 10 seconds, or perhaps 20 seconds for larger, A490 bolts. Choose a wrench with sufficient muscle (size, air pressure, condition) to do this. Other types of wrenches are also acceptable, such as electric or hydraulic, but if they're non-compacting, ignore the "10 second" rule. See the following FAQ's (compressing DTI's, recommended wrench capacity and make, flattening DTI's, torque control, twist-off (TC) bolts)
Don't try to use a feeler gage very much. Judge the DTI gap closure mainly by eye. Remember, a "completely flattened" DTI is okay for all but the larger A490 bolts.. Check with the inspector, or call us for guidance. See the following FAQ's (failure or stripping of bolts , flattening DTI's)
You're not supposed to take more bolts out of their kegs than can be stuffed, snugged, and tightened in one shift, (oh sure!). But just in case keep some lubricant handy if the bolts and nuts are getting too rusty to tighten efficiently.
Remember, DTIs don't change the torque resistance of the bolt, and they don't change the (flat) washer requirements either. (Regular thickness F436 washers over short slots or oversized holes, but extra thick 5/16" F436 washers if the bolts are A490 larger than 1" dia.). See our Special Advisory.
As with any approved bolt tensioning method, don't forget to do the RCSC's Pre-Installation Verification to make sure the bolt assembly, the bolt installer, and the wrench all work together to get the right bolt tension. If there's a Skidmore around, you might try this first on it and check the results. Show the inspector - he/she will be impressed. As with any approved bolt tensioning method, don't forget to do the RCSC's Pre-Installation Verification to make sure the bolt assembly, the bolt installer, and the wrench all work together to get the right bolt tension.

FOR INSPECTORS

Check all bolt, nut, flat washer, and DTI certifications for conformance with the project specifications, especially the rotational capacity (RC) tests, if applicable, for nut lubrication. See rotational capacity test in FAQ's. (Remember, when DTIs are used, every bolt gets an "in situ" RC test, because, no matter how much the bolt/nut friction factor has deteriorated, if the DTI has been sufficiently compressed and the bolt has not broken, the rotational capacity of the assembly must be ok.
Check the calibration of the Skidmore, if any, on the site, and use it to spot check the bolts and DTIs (see #4 below). That is, on the Skidmore, see how much compression of the DTI is indicative of bolt tension*. See bolt tension chart in FAQ's.
Have some .015" and/or some .005" feeler gages available which will fit into the openings of the DTI between the DTI bumps. These are available free from Applied Bolting and are in every keg. See the following in FAQ's (feeler gage inspection criteria , failure or stripping of bolts)
Put a DTI on a bolt into the Skidmore, tighten it to a bolt tension 5 percent higher than the required minimum, (see bolt tension chart in FAQ's), using a manual wrench, and check that the residual DTI gap (as judged by a feeler gage) is bigger than the project inspection gap which you will use up in the steelwork. See feeler gage inspection criteria in FAQ's. For problems some times encountered with this test, see inspection procedure in FAQ's.
Make sure that the bolt installers snug all the bolts in the connection before final tensioning. Listen for or otherwise time the final tensioning operation. If impact wrenches are used, the rule of thumb is 10 seconds or less but it might take as long as 20 seconds for large diameter A490 bolts. If they're not able to tighten the bolts this quickly, tell them to try do better. See compressing DTI's in FAQ's. It's important for the health of the bolts. If non-impacting tools are used, the "10 or 20 second rule" can be ignored.
Check for too much thread stickout "above" the nuts - if it is more than half the bolt diameter, there MAY be insufficient threads ahead of the nut for proper bolt ductillity, and thread runout may prohibit proper compression of the DTIs and be the cause of bolts breaking. "Zero" stickout (bolt shank flush with top of nut) is acceptable for heavy hex nuts.
With a bolt in place, check a sample of compressed DTIs using the proper thickness feeler gage between the compressed DTI bumps half way around the DTI (our DTIs are marked only at openings to help you judge where to try to insert the feeler gage). If you CANNOT insert the feeler gage all the way into the bolt shank half way around the DTI, THE BOLT IS OKAY. If you CAN insert it all the way into the bolt shank more than half way around, THE BOLT IS NOT OKAY. In the latter case, ask the bolt installer to tighten the bolt a little more. If the DTI is almost compressed enough, it is probably OK. (Remember the Skidmore test in #4 above). Don't over inspect the bolts. See section feeler gage inspection criteria in FAQ's.
Remember, a completely flattened DTI is NOT cause for rejection except by special edict of the engineer-of-record. It's possible and safe to "completely flatten" A325 DTIs. A490 DTIs probably should NOT be completely flattened, although this occasionally happens. If in doubt, try flattening the DTI on a bolt in a Skidmore, and see how much bolt tension it produces. Then disassemble the bolt after this test and run the nut down the threads of the bolt. If too much stretch has occurred in the bolt, the nut probably will not run more or less freely to the root of the thread. In this case, some caution should be exercised to limit the A490 (and only A490) DTI compression. See FAQ's ( failure or stripping of bolts, flattening DTI's)