Packing Maintenance; Replacing Packing - Fisher EHD Instruction Manual

EH Valves (NPS 8 through 14)
lubricator/isolating valve operates the same way
except open the isolating valve before turning the
cap screw and then close the isolating valve after
lubrication is completed.

Packing Maintenance

WARNING
Personal injury could result from
packing leakage. Valve packing was
tightened before shipment; however,
the packing might require
readjustment to meet specific service
conditions.
Valves with ENVIRO-SEAL live-loaded packing or
HIGH-SEAL live-loaded packing installed probably
will not require this initial re-adjustment. See the
Fisher instruction manuals titled ENVIRO-SEAL
Packing System for Sliding-Stem Valves or
HIGH-SEAL Live-Loaded Packing System (as
appropriate) for packing instructions. To convert an
existing packing arrangement to ENVIRO-SEAL
packing, refer to the retrofit kits listed in the parts kit
sub-section near the end of this manual. Figure 10
shows typical ENVIRO-SEAL packing systems.
For spring-loaded PTFE V-ring packing (figure 4),
the spring maintains a sealing force on the packing.
If leakage is noted around the packing follower
(key 13, figure 11), check to be sure the shoulder on
the packing follower is touching the bonnet (key 1,
figure 11). If the shoulder is not touching the bonnet,
tighten the packing flange nuts (key 5, figure 11)
until the shoulder on the packing follower is against
the bonnet. If the packing leakage is still excessive,
replace the packing by following the Replacing
Packing procedure.
If packing leakage is undesirable with other than
spring-loaded PTFE V-ring packing, first try to limit
the leakage and establish a stem seal by tightening
the packing flange nuts (key 5, figure 11) to at least
the minimum recommended torque in table 5.
However, do not exceed the maximum
recommended torque in table 5 or excessive friction
may result.
6
Table 5. Recommended Packing Flange Nut Torques
STEM
VALVE
DIAMETER
RATING
mm Inches
CL1500
31.8 1-1/4
CL2500
CL1500
50.8 2
CL2500
If the packing is relatively new and tight on the stem,
and if tightening the packing flange nuts does not
stop the leakage, the valve stem may be worn or
nicked so that a seal cannot be made. The surface
finish of a new stem is critical for making a good
packing seal. If the leakage comes from the outside
diameter of the packing, the leakage may be caused
by nicks or scratches around the packing box wall.
While replacing the packing according to the
Replacing Packing procedure, inspect the stem and
packing box wall for nicks or scratches.

Replacing Packing

WARNING
Refer to the WARNING at the
beginning of the Maintenance section
in this instruction manual.
Key numbers referred to in this procedure are shown
in figure 11 unless otherwise indicated.
1. Remove the stem connector cap screws shown in
figure 3, and separate the two halves of the stem
connector. Then exhaust all actuator pressure, if any
was applied, and disconnect the actuator supply and
any leakoff piping.
2. Remove the hex nuts (key 26) and remove the
actuator from the bonnet (key 1). Loosen the
packing flange nuts (key 5) so that the packing
(key 6, or 7 and 9, figure 4) is not tight on the valve
plug stem (key 4, figure 12 or 13). Remove any
travel indicator disk and stem locknuts from the
valve plug stem threads.
WARNING
Do not remove a stuck bonnet by
pulling on it with equipment that can
stretch or store energy in any other
manner. The sudden release of stored
energy can cause uncontrolled
movement of the bonnet. To avoid
Instruction Manual
April 2009
NSm LbfSft
Min Max Min Max
68 102 50 75
81 122 60 90
98 146 72 108
115 170 85 125