7 Reference information
7.4. Screw joints
3HAC026660-001 Revision: C234
© Copyright 2006-2008 ABB. All rights reserved.
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 description. Any special torque
specified overrides the standard value.
• 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
Dimension
Tightening torque (Nm)
Class 10.9, Molycote-lubricated
Tightening torque (Nm)
Class 12.9, Molycote-lubricated
M8 28 34
M10 55 66
M12 96 115
M16 235 280
Continued
Continues on next page
To Next Page
Loading...
