7 Reference information
7.3. Screw joints
3HAC027151-001 Revision: B
262
©
Co
py
rig
h
t 200
6-
200
8 ABB. All righ
ts reser
v
ed.
Tightening torque
Before tightening any screw, note the following:
•
Determine whether a
standard
tightening torque or
special
torque is to be applied.
The
standard torques
are specified in the tables below. Any
special torques
are
specified in the Repair, Maintenance or Installation procedure descriptions.
Any
special torque specified overrides the standard torque!
•
Use the
correct tightening torque
for each type of screw joint.
•
Only use
correctly calibrated
torque keys.
•
Always
tighten the joint by hand,
and never use pneumatical tools.
•
Use the
correct tightening technique
, that is
do not
jerk. Tighten the screw in a slow,
flowing motion.
•
Maximum allowed total deviation from the specified value is
10%
!
The table below specifies the recommended standard tightening torque for
oil-lubricated
screws
with
slotted or cross-recess head screws.
The table below specifies the recommended standard tightening torque for
oil-lubricated
screws
with
Allen head screws.
The table below specifies the recommended standard tightening torque for
Molycote-
lubricated screws
with
Allen head screws.
Dimension
Tightening torque (Nm)
Class 4.8, oil-lubricated
M2.5
0.25
M3
0.5
M4
1.2
M5
2.5
M6
5.0
Dimension
Tightening torque
(Nm)
Class 8.8, oil-lubri-
cated
Tightening torque
(Nm)
Class 10.9, oil-lubri-
cated
Tightening torque
(Nm)
Class 12.9, oil-lubri-
cated
M5
6
-
-
M6
10
-
-
M8
24
34
40
M10
47
67
80
M12
82
115
140
M16
200
290
340
M24
725
960
1150
Dimension
Tightening torque (Nm)
Class 10.9, Molycote-lubricated
Tightening torque (Nm)
Class 12.9, Molycote-lubricated
M8
28
35
M10
55
70
M12
96
120
Continued
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