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Torque each elevated baseplate fixture bolt to 120 ±30 in-lbs. (13.6 ± 3.4
N·m). Do not
over-torque elevated baseplate bolts as this may d
amage the baseplate gasket.
Use a manual calibrated torque wrench to tighten the bolt.
Alternately, use an automatic wrench set at a low torque value (for example: 25 in-lbs.
[2.8 N·m]). Then use a manual calibrated torque wrench to finalize the torque.
Always torque the bolts in opposing pairs.
12 inch, 6-bolt fixture
(See Figure 27, which shows an in-pavement fixture. Use the same
procedure for a baseplate.)
:
— Tighten bolt #1, then tighten bolt #4. Next tighten bolts #2 and #5. Finally, tighten
bolts #3 and #6.
Figure 27:
6-Bolt Torque Sequence
Use the above guidance for any bolted connection on a non-load bearing base can.
This includes:
•
6 bolts used on a 12-inch in-pavement fixture.
•
6 bolts used on either an 8-to-12 inch in-pavement fixture adapter ring.
•
All bolts used on an 8-inch fixture mounted in an 8-to-12 inch snow plow ring.
WARNING
When a stainless steel base can is used, take steps to insure that galling
does not occur. Galling is often referred to as a cold-welding process, which
can occur when the surfaces of male and female threads come in contact
under heavy pressure. The risk of galling can be minimized with the
following measures:
— Thread lubrication is one of the most effective measures to lessen the
potential for galling. The lubricant reduces friction, which is a key
element in thread galling. Avoid installing a stainless steel bolt dry with
no lubricant.
— Heat contributes significantly to thread galling. Installing a bolt
generates heat and high-speed installation generates significantly
more heat. Torque the bolt slowly into the base can.
— Do not use an impact wrench to torque the bolt quickly, resulting in an
overtorqued bolt. If the bolt is over tightened, the threads can begin to
yield which will induce friction between the mating surfaces.
