5 Reference information, IRC5
5.3. Screw joints
3153HAC021313-001 Revision: K
© Copyright 2004-2008 ABB. All rights reserved.
5.3. Screw joints
General
This section details how to tighten the various types of screw joints on the controller.
The instructions and torque values are valid for screw joints comprised of metallic materials
and do not apply to soft or brittle materials.
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, i.e. do not jerk. Tighten the screw in a slow,
flowing motion.
• Maximum allowed total deviation from the specified value is 10%!
The table below specify the recommended standard tightening torque for oil-lubricated
screws with slotted or cross-recess 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
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