4 | Baker Hughes
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Post Weld Cleaning & Assembly
Inspect the body, bonnet, and trim components for cleanliness
and surface condition. Remove any foreign materials, such as
weld chips, slag or scale. Make sure there are no nicks, scratches,
burrs or sharp corners on sealing and sliding surfaces. Clean all
gasket interface surfaces and reassemble using new gaskets to
ensure sealing integrity.
Actuator Assembly
Assemble the actuator onto the control valve using the appropriate
instructions for the specific actuator model and type. Connect air
pressure lines to the actuator ports to meet intended operating
mode (i.e., air-to-extend, air-to-retract, or double-acting).
Disassembly
Prior to performing any maintenance on the valve, iso-
late the valve and vent the process pressure.
Valve Actuation
Access to the internal components of the valve should be
accomplished with the actuator removed. Follow the detailed
instructions below and refer to the appropriate actuator instruction
manuals.
Actuator may be pre-loaded with tension from air
pressure or springs. Prior to disconnecting instru-
mentation read all instructions for the specific actua
-
tor.
Disconnect Instrumentation
Disconnect all mechanical connections between the positioner
and the other instruments. Disassemble the valve stem, actuator
stem, and lever connectors as described in the following sections.
Note: The 77000 Series is an up-seating control valve
design, which is the opposite action of most reciprocating
control valves. For this design air-to-extend actuators will
use the plant supply air to open the valve and air-to-retract
actuators will use the plant supply air to close the valve.
Air-to-Extend (Open) Actuators
Lever and Linkage Removal
Apply sufficient air pressure to the actuator to extend the stem
completely and take the plug off of the seat. Remove the
Body Clevis Retaining Rings (22) and Actuator Link Retaining
Rings (29); along with the respective link pins (21) and (28).
Unscrew the actuator connector link (27) from the actuator stem
connection. Disengage and remove the lever (23), Body Clevis
(20), and for sizes 1” to 3” remove the Actuator Link Clevis (37)
from the valve assembly.
Actuator Removal
Disconnect all electrical and air connection to and from the
actuator.
Disassemble drive nut (32) and attachment screws, and lift
actuator off of the valve being careful not to damage the drive
nut threads.
Valve Disassembly 77001
and 77002 Series
The valve must always be reassembled with new packing set
and gaskets. Before disassembly, make sure the recommended
spare parts are available for reassembly. Refer to Parts
Reference Table (page 10) and Figures 11-12 (pages 11 and 12).
1. Disconnect the piping to the leak detector or lubrication
connection on the body/bonnet (if applicable).
2. Unlock the lock nut (26) and remove the anti-rotation screw
(25) then unscrew the stem pivot adapter (24) from the plug
stem (5). Loosen the packing box nuts (16) to reduce the
friction of the packing on the plug stem.
For Bottom Entry 77001 Series Designs follow disassembly
instructions 3-8:
3. Remove the spool nuts (10) from the bottom entry spool (2)
section on the valve. Remove the spool (2) from the body
(1), along with the lower spider gasket (7). Remove the
spider (4) from inside the valve body. If the spider is difficult
to remove you may nudge it out by applying downward force
on the plug stem (5). Remove the upper spider gasket (8).
Note: Some designs may be equipped with an integral
spider as part of the bottom entry spool. For these
designs remove the spool and associated gaskets and
proceed to step 4.
4. Remove the plug stem (5) along with the seat ring (3).
Be careful not to damage the plug stem (5) or the
seat ring (3) while removing these parts from the
body. Scratches or damage to these parts can
result in leakage and premature wear.
5. Remove the packing flange nuts (16), packing flange (14),
and packing follower (13).
6. Remove the old packing set (11) and lantern ring (12).
Note: Lantern ring is applicable only for units with the
optional leak detector option.
7. Remove the upper stem guide bushing (6).
8. Inspect the body (1), spool (2), seat ring (3), spider (4), and
plug stem (5) for any visual defects or damage. Carefully
inspect the dynamic sliding surfaces and seal interface
areas.
Ensure all parts are clean, particularly the seating surfaces
prior to reassembly.
For Top Entry 77002 Series Designs follow disassembly
instructions 9-15:
9. Remove the packing flange nuts (16), packing flange (14),
and packing follower (13).
