24
198846 R12
6.3. Recommended Bolt Assembly
When tightening bolts, tighten the nut on the bolt until a “snug-tightened condition” has been achieved. A
“snug-tightened condition” is defined in
Specification for Structural Joints Using ASTM A325 or A490 Bolts
(Research Council on Structural Connections: June 2004), which states:
“
The snug-tightened condition is the tightness that is attained with a few impacts of an impact wrench or the
full effort of an ironworker using an ordinary spud wrench to bring the connected plies into
firm contact
.”
A properly tightened bolt will compress the sealing washer noticeably. All assembly crew members must be
made aware of this requirement, and must know how to achieve a snug-tightened condition using common bin-
building tools.
It is important that the bolts in the vertical wall sheet seams are tightened enough to squeeze the caulking and
bring the wall sheet surfaces into firm contact with each other. This is especially important to monitor when
installing bolts in temperatures approaching -10°C (14°F).
The following table shows the minimum impact gun torque capacity necessary to achieve a snug-tightened
condition for bolts used in the assembly process.
Table 6.
Recommended Impact Gun Torque Values Capacity to Achieve Snug-Tightened Bolts
Bolt Diameter
Bolt Grade
Grade Mark
Recommended Torque Capacity
in-lb
ft-lb
N-m
1/4”
Grade 8.2
75
6
8
5/16"
Grade 8.2
215
18
24
3/8"
Grade 8.2
370
31
42
7/16"
Grade 8.2
600
50
68
1/2”
Grade 8.2
960
80
108
5/8”
Grade 8.2
1800
150
203
3/4”
Grade 5
3230
269
365
For proper sealing, do not overtighten the wall seam connections. Sealing is not critical on upright splice
connections; these connections should be tightened securely to prevent loosening.
Hold the bolt head securely when tightening the nut to prevent damage to the sealing washer.
Important
ALWAYS TIGHTEN THE NUT, NOT THE BOLT!
Avoid bin assembly at temperatures below -10°C (14°F) if possible. Erection in low temperatures does not
ensure strong, well sealed connections. Do not substitute bolts in place of those supplied by Westeel.
BIN ON HOPPER PEA UPGRADE KIT – GRAIN BIN
