Discovery II
GENERAL INFORMATION
03-11
Bolt and Nut Identification
Bolt identification
An ISO metric bolt or screw made of steel and larger
than 6 mm in diameter can be identified by either of
the symbols ISO M or M embossed or indented on
top of the bolt head.
In addition to marks identifying the manufacturer, the
top of the bolt head is also marked with symbols
indicating the strength grade, e.g. 8.8; 10.9; 12.9;
14.9. As an alternative, some bolts and screws have
the M and strength grade symbol stamped on the
flats of the hexagon.
Encapsulated bolts and screws
Encapsulated bolts and screws have a micro-
encapsulated locking agent pre-applied to the
thread. They are identified by a coloured section
which extends 360
°
around the thread. The locking
agent is released and activated by the assembly
process and is then chemically cured to provide the
locking action.
Unless a specific repair procedure states otherwise,
encapsulated bolts may be re-used providing the
threads are undamaged and the following procedure
is adopted:
l
Remove loose adhesive from the bolt and
housing threads.
l
Ensure threads are clean and free of oil and
grease.
l
Apply an approved locking agent.
An encapsulated bolt may be replaced with a bolt of
equivalent specification provided it is treated with an
approved locking agent.
