Fisher EHD Instruction Manual page 12

EH Valves (NPS 8 through 14)
crisscross pattern. Repeat until all cap screws are
tightened to the torque value specified in table 7.
Repeat the final torque and if any cap screw still
turns, tighten every cap screw again.
2. Install one of the cage gaskets (key 11) between
the valve body and cage (key 2), and install the
cage.
3. If the cage used has multiple sizes of windows,
attempt to orient the largest window toward the valve
body web (a shelf-like projection of the casting into
the flow cavity). As an alternate reference, orient the
largest window toward the process outlet for a
flow-down and toward the process inlet for a flow-up
valve.
4. Inspect the valve plug stem threads for any sharp
edges that might cut the packing. Use a whetstone
or emery cloth to smooth the threads if necessary.
5. To install the piston rings or seal ring (key 8),
proceed as appropriate:
For an EHD valve, if installing a new piston ring, the
replacement piston ring will arrive in one piece. Use
a vise with smooth or taped jaws to break this
replacement piston ring into halves. Place the new
ring in the vise so that the jaws compress the ring
into an oval. Slowly compress the ring until the ring
snaps on both sides. If one side snaps first, do not
try to tear or cut the other side. Instead, keep
compressing until the other side snaps.
Remove any protective tape or covering from the
valve plug and stem assembly, and set it on a
protective surface. Then place the piston ring in the
piston ring groove with the fractured ends matched.
For an EHT valve, install the seal ring (key 8) onto
the valve plug (key 3). Install the ring with the open
side facing the seat ring end of the valve plug for a
flow-down application (view B of figure 13) or with
the open side facing the valve stem end of the valve
plug for a flow-up application. Slide the backup ring
(key 9) onto the valve plug. Secure with the retaining
ring (key 10). For an EHT valve with a Whisper Trim
Level D cage, install the piston ring (key 30,
figure 13) using the procedure given in the EHD
instructions immediately preceding this paragraph.
6. Install the valve plug into the cage.
7. Install the other cage gasket (key 11) between
the cage and the bonnet.
CAUTION
Failure to comply with good
bonnet-to-body bolting practices and
12
the torque values shown in table 6 may
result in cage crushing, cage diameter
reduction, and/or bonnet deformation.
Cheater bars or slug wrenches should
not be used for this procedure.
Hot torquing is not recommended; it
may result in damage to valve
components.
8. Install the bonnet over the valve stem and onto
the valve body. Lubricate the threads of the studs
(key 13) and the faces of the hex nuts (key 14) with
anti-seize lubricant (key 24). Secure the bonnet with
hex nuts (key 14) and washers (key 29). Torque the
nuts in a crisscross pattern to no more than 1/4 of
the nominal torque value specified in table 6. When
all nuts are tightened to that torque value, increase
the torque by 1/4 of the specified torque value and
repeat the crisscross pattern. Repeat this procedure
until all nuts are tightened to the specified nominal
value. Repeat the final torque value and if any nut
still turns, tighten every nut again.
9. Install new packing and the metal packing box
parts according to the appropriate arrangement in
figure 4. Slip a smooth-edged pipe over the valve
stem, and gently tamp each soft packing part into
the packing box.
10. Slide the packing follower, wiper, and packing
flange into position. Lubricate the packing flange
studs (key 4) and the faces of the packing flange
nuts (key 5) and then install the packing flange nuts.
For spring-loaded PTFE V-ring packing: Tighten
the packing flange nuts until the shoulder on the
packing follower (key 13) contacts the bonnet
(key 1).
For other kinds of packing, except ENVIRO-SEAL
and HIGH-SEAL: Tighten the packing flange nuts to
the maximum recommended torque shown in
table 5. Then, loosen the packing flange nuts and
retighten them to the recommended minimum torque
in table 5.
For ENVIRO-SEAL and HIGH-SEAL packing: 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.
11. Mount the actuator by following the Actuator
Mounting procedure. Check for packing leakage as
the valve is being put into service. Retorque the
packing flange nuts as required (see table 5). Then,
retighten the hex nuts (key 14) to the torque shown
in table 6.
Instruction Manual
April 2009