Areva HVX-E - Screw Fastenings; How to Treat the Contact Surfaces

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The following elements must be
used for all metal screw couplings:
• Screws and bolts:
Grade ≥ 8.8
• Nuts:
Grade 8.
Table 1:
Hex. bolts and socket-head caps-
crews (except slotted screws) and
nuts
Table 2:
Screw coupling between switching
device and conductor bar with cop-
per as conductor material
9.3 Screw fastenings
Thread
size
Tightening torque
[Nm]
min. max.
M5 3,8 4,7
M6 7 9
M8 16 24
M10 36 44
M12 63 77
Thread
size
Tightening torque
[Nm]
min. max.
M6 5,5 7,5
M8 15 19
M10 30 40
M12 60 76
Important:
Caution when handling
bars insulated by heat-
shrinkable sleeves: The
heat-shrinkable sleeve must not get
into contact with lubricant (swelling).
Important:
Contact areas coated with
lubricant Kontasynth should
not be touched, if possible.
Material of contact surfaces Pre-treatment
Silver-plated contact surfaces
Clean
1)
Copper or copper alloy
Clean
1)
, expose metallic surface
2)
Aluminium
Clean
1)
, expose metallic surface
2)
Zinc-plated steel
Remove passivation, not, however, the zinc layer
3)
Hot-galvanized sheet-metal
Clean
1)
, passivation need not be removed
9.4 How to treat the contact surfaces
1. Contact surfaces must be subjected to preliminary treatment before screw-fastening:
1)
Clean by means of lint-free cloth; use cleaning agent in case of serious contamination (see above)
2)
Expose metallic surface
– by treating the entire surface with emery cloth or a rotating grinding tool (grain size 100 or 80) or
– using a wire brush which is clearly marked for use exclusively for aluminium or exclusively for copper
3)
using a brass brush, steel brush
2. Immediately after the pre-treat-
ment, coat the contact surfaces
with lubricant Kontasynth so
that the space between the
contact surfaces is completely
filled once the screws have
been fastened.