Page 230 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

21 2 Major Process Equipment Maintenance and Repair

depressurized. Also, before installing the packing, record all identifying
markings from the case and packing for reference when replacing indi-
vidual components.
Operational break-in of a packing is very important. Improper break-
in can result in faulty sealing and damage to the piston rod. The following
points will in most cases assure proper break-in and operation. Break-in
time will vary depending upon conditions.
1. Cleanliness-The packing and rod must be clean! If the rod has any
nicks or corrosion in the area that will enter the packing, carefully
remove nicks and clean the rod.
2. Pressure-During the break-in period, it is advisable to gradually
increase the cylinder pressure and vary the operating speed if possi-
ble. This allows the packing to “wear-in” and to conform to the
piston rod before being subjected to full load pressure. Wear-in time
will be shortened if it is possible to operate at a low load, rather
than at no load. If during break-in, leakage or overheating appears
to be increasing, or out of control, reduce pressure and/or speed to
allow packing to stabilize. If this does not reduce leakage, the unit
should be stopped for packing inspection to determine the cause.

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PACKING
CARTER
FLqNCE SFRINGS

Figure 5-15. Typical nonlubricated piston rod packing showing coolant flow.