3 | Baker Hughes Copyright 2020 Baker Hughes Company. All rights reserved.
3. Maintenance
If it is necessary to disassemble the valve for cleaning,
maintenance or replacement of a damaged part, proceed as
follows:
3.1 Disassembly
• Depressurize the line and stroke the valve to mid-travel.
• Separate the valve from the line and make sure that the
body is depressurized. Remove the valve from piping.
• Unscrew the packing stud nuts (B028) in order to reduce the
packing adhesion to the plug stem.
• Disconnect the plug stem (B008) from the actuator stem.
• Remove the yoke nut (B013) and separate the actuator with
its yoke from the bonnet (B034).
• Unscrew the bonnet stud nuts (B032) and remove them
together with the bonnet studs (B033), lift up the bonnet
(B034) until it gets free from the end of the plug stem (B008).
• Remove the guide gasket (B010) (size 8’’, 10’’ and 12’’ only)
and remove the plug stem (B008). If this operation becomes
difficult because of residues of solidified hydrocarbons
present on the parts, replace the bonnet supported only with
four bolts with nuts situated one pair opposite the other, then
leaning on a flat bar iron and a cylindrical distance piece set
on the top of the bonnet, turn a nut which has been screwed
previously on the plug stem in order to “unstick” the plug and
the guide (B006), then lift them off slowly either together or
separately.
• Remove the bonnet. Pull out the plug with its stem as well
as the plug guide (B006) and separate them if necessary.
Remove the gasket (B009); pull out the packing (B011).
• Unscrew the seat ring retainer (B001) and remove the
seat ring (B002). Thoroughly clean all of the parts before
reassembling.
3.2 Reassembly
• Replace all parts with significant dimensional defects caused
by the corrosion, erosion or wear. It is also recommended to
replace the gasket (B009), the guide gasket (B010) and the
packing (B011) with new parts after each disassembly.
• Replace the seat ring (B002) in the valve body. Screw and
lock the seat ring retainer (B001) with torque value indicated
in the table below for each valve size.
Note: A sealant compatible with the process should be
applied sparingly on the retainer thread.
• Insert the plug guide (B006) in the valve body following with
the plug (B005) fitted with its stem (B008). Place the gasket
(B009) on the body.
CAUTION
CAUTION
WARNING
DANGER
For bonnet with purge or injection connection: NPT or
ange. Before achieving metal to metal contact with
the body, rotate the bonnet to orient this connection
in front of the existing piping.
Center the guide gasket (B010) on the top of the guide (B006),
and then place the bonnet down over the plug stem until it is
centered on the upper part of the guide.
• Assemble the bonnet with the body by means of bonnet
studs (B033) and bonnet stud nuts (B032). Tighten the nuts
to obtain metal-to-metal contact between the bonnet and
valve body (size 8’’, 10’’ and 12’’ only) and/or tighten them
with torque value indicated in the table below for each valve
size.
• Insert the packing as follows: first, one braided ring, then
the die-formed rings and finally another braided ring. It is
important to tamp down the rings in the packing box one
by one. If packing rings have a radial cut, stagger the cut of
adjacent rings by 180°.
• Slip the packing follower and flange over the plug stem.
Tighten the nuts (B028) manually. Verify if the plug
accomplishes its normal stroke in the valve body. Tighten
the nuts (B028) to another full turn with the wrench.
• Replace the actuator and fasten it by means of the yoke nut
(B013).
• Be sure that the plug sits normally on the seat ring and
connect the actuator to airline or to electrical circuit.
• Connect the actuator stem to the valve stem in accordance
with the appropriate actuator instruction manual.
• Replace the valve on the piping, carry out the connections
and start it up again.
