Squirter® DTI FAQs
Squirter® DTIs Don't Squirt Much or In All Possible Places
What if the DTI bumps compress, or apparently compress, but the Squirt event has not occurred??
SQUIRTER® DTIs always squirt when the DTI bumps are compressed and the underside of the DTI is supported on standard sized holes, that is 1/16" diameter over the nominal bolt shank diameter. The SQUIRTER® DTIs DTI calibration procedure will show if the squirting is occurring normally.
Occasionally, however, the squirt event is weak, or nonexistent, and yet it appears the bumps have been correctly compressed. The bolt installer, expecting a squirt event to signal them to stop tightening, may have even gone on to break the bolt.
As soon as this starts to occur, the problem must be found and remedied before continuing to drive the bolts while not to observing a proper calibrated squirt event. The problems causing this to occur can be as follows:
- The hole is oversized, not standard diameter. SQUIRTER® DTIs DTI's are normally used directly against the steelwork and only over standard sized holes. In this case, as with standard DTI's, the normal flat washer requirements are necessary. A hole larger than standard size (1/16" over nominal) in the steelwork will not allow the squirt feature to function correctly, therefore over larger holes special flat washer requirements are necessary - please see the application advisory: SQUIRTER® DTIs & oversized or short slotted holes
- The flat washer used against the DTI bumps is too soft. For instance, hot dipped galvanized flat washers are sometimes encountered as soft as Rc 26 (click here for the advisory on galvanized flat washers). Since DTI's are about Rc 32, it is imperative to supply the normal hardness of ASTM F436 flat washers of Rc 38 minimum. This minimum hardness is always found on mechanically galvanized flat washers, and can be specified on hot dipped galvanized flat washers also at no cost. ASTM F436 has now been corrected to require a minimum Rc of 38, no matter what coating is used.
- The bolt has "shanked out". Check the thread stick-through to eliminate this possibility.
- The SQUIRTER® DTI has been installed over a thick bed of grease, concealing the squirt feature under grease.
- The underside of the SQUIRTER® DTI has not been placed against a flat surface which covers all of the silicone-filled depressions. Flat washers with very large inner diameters may be the cause. Flat washers with small outer diameters may be the cause. Ragged, out-of-round, oversized, or very uneven holes in the face of the steelwork may be the cause.
- Occasionally, a very weak impact wrench will be unable to tighten the bolt to proper tension in about ten seconds. If the bolt installer continues to try to tighten the bolt with this equipment, perhaps banging away on it for 30 or more seconds, still not compressing the DTI bumps sufficiently, the squirt event will look weak. The DTI has squirted, but only just a very little amount. To correct this situation, get a stronger wrench, or reduce the friction factor on the bolt by using lubricant.
- The SQUIRTER® DTIs DTI has been installed upside down, with its bumps facing the structural steel. In this case the DTI bumps will not be sufficiently compressed because the structural steel surface is very soft compared to the DTI.
- A really dried out nut may drag the flat washer and DTI around with it, causing the squirt to be distributed radially, rather than all in one place. This kind of situation can be interpreted to mean the squirt has not occurred. Properly lubricated nuts will correct the situation.