Disassembly Of The 4900 Posrv; Removal Of Pilot Valve From Main Valve; Disassembly Of Main Valve - Baker Hughes Consolidated 4900 Series Instruction Manual

XII. Disassembly of the 4900 POSRV
A. Removal of Pilot Valve From
Main Valve
1. Make sure there is no media pressure in the
vessel, in the valve inlet, in the main valve, or in
the pilot valve.
2. Mark the Coverplate, Inlet Adaptor, and Main
Base for ease of reassembly.
3. Loosen the four Socket Head Cap Screws (Main
Valve) and remove the pilot assembly including
the Inlet Adapter from the Coverplate.
4. Loosen and remove the four Socket Head Cap
Screws (Pilot) to separate the pilot valve from
the Inlet Adapter.
5. Place parts in the order they are disassembled
to facilitate reassembly.
B. Disassembly of Main Valve
Note: If the pilot valve has not been removed,
then refer to Section XII.A.
1. Loosen and remove the Nuts (or Cap Screws) on
the Coverplate.
2. Lift off the Coverplate
3. Install a lifting bolt into the drilled and tapped
hole in the Disc's center and lift from the Base.
Note: The Guide may lift out of the Base with
the Disc. If so, do not allow the Guide to
fall and become damaged. Also, the D
Orifice through 3" L Orifice will lift the
Guide out with the Disc due to its design.
4. Remove the Guide from the Base if it did not
come out with the Disc.
5. Remove the Sensing Retainer Nut.
Note: For valves with separate retainer and
sensing tube, remove the retainer from
the disc and then remove the tube.
6. O-Ring Disc Disassembly: The O-Ring seat
requires the Lock Screw(s) on the bottom of the
Disc to be removed by turning counterclockwise
so that the O-Ring Retainer and Seat O-Ring
can be removed.
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Baker Hughes
Lower pressure
and stand clear of
discharge when
working on valve to
avoid severe personal
injury or death.
7. If the Nozzle requires rework or replacement,
remove the Nozzle from the Base by unscrewing
counterclockwise with the appropriate socket or
spanner wrench shown in Figure 45 and Table 9
in the Maintenance Tools and Supplies section.
This applies to all main valve sizes except the 8"
(203.2 mm) and 10" (254 mm) full bore valves.
The latter are disassembled by removing four
Nozzle Cap Screws, inserting two eyebolts
(5/8 – 11 UNC) 180° apart, and pulling the
nozzle out.
8. Discard all O-Rings, guide rings, and seals.
Do not remove bolts
if pressure in line, as
this will result in severe
personal injury
or death.
© 2020 Baker Hughes Company. All rights reserved.
Wear necessary
protective equipment
to prevent possible
injury
Know all valve
exhaust/leakage
points to avoid possible
severe personal injury
or death