Siemens FLENDER K SH Series - Screw Connection Classes and Tightening Torques

71 / 109
BA 5846 en 05/2015
6.19 Screwconnection classes, tightening torques and initialtensioning forces
6.19.1 Screwconnection classes
The specified screw connections are to be fastened applying the tightening torques specified observing
the table below.
Table 11: Screwconnection classes
Screw-connection
class
Scatter of the
torque emitted
on the tool
Tightening procedure
(Usually the tightening procedures lie within the stated
tool distribution.)
C ± 5 % up to ± 10 %
– Hydraulic tightening with mechanical screwdriver
– Torque-controlled tightening with torque wrench
or signal-emitting torque wrench
– Tightening with precision mechanical screwdriver
with dynamic torque measuring
D ± 10 % up to ± 20 %
– Torque-controlled tightening with mechanical screwdriver
E ± 20 % up to ± 50 %
– Tightening with pulse screwdriver or impact wrench
without adjustment checking device
– Tightening by hand, using a spanner without torque
measuring device
NOTICE
Material damage
Risk of damage to the bolts and/or mating threads through incorrect tightening.
Foundation bolts, hub bolts and bearingcover bolts must always be tightened in accordance with the
specifications for screwconnection class "C".
6.19.2 Tightening torques and initialtensioning forces
The tightening torques apply to friction coefficients of μ
total
= 0.14.
The friction coefficient μ
total
= 0.14 applies here to lightly oiled steel bolts, blackannealed or phosphatised
and dry, cut mating threads in steel or cast iron. Lubricants which alter the friction coefficient must not be
used and may overload the screw connection.
Table 12: Initialtensioning forces and tightening torques for screw connections of strength
classes 8.8; 10.9; 12.9 with a common friction coefficient of μ
total
= 0.14
Nominal
thread
diameter
Strength
class of the
bolt
Initial-tensioning force for
screw-connection classes
from table 11
Tightening torque for
screw-connection classes
from table 11
C D E C D E
d
mm
F
M min.
N
M
A
Nm
M10
8.8 18000 11500 7200 44.6 38.4 34.3
10.9 26400 16900 10600 65.4 56.4 50.4
12.9 30900 19800 12400 76.5 66.0 58.9
M12
8.8 26300 16800 10500 76.7 66.1 59.0
10.9 38600 24700 15400 113 97.1 86.6
12.9 45100 28900 18100 132 114 101