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4. Disassembly
4.1 Removal of Actuator
(Figures 15 and 16)
Access to the internal components of the body should be
accomplished with the actuator removed. To carry out
this operation, follow the instructions below and refer
to the specific actuator instructions, reference
GEA19530A for a type 87/88 actuator and GEA31171 for
the type 37/38 actuator.
4.1.1 Disconnection of instruments
Disconnect all mechanical couplings between the
positioner and the other instruments on the one hand
and the valve stem/actuator stem coupling on the
other hand.
4.1.2 Plug stems screwed into the actuator stem
In the case of air-to-retract actuators, apply sufficient air
pressure on the diaphragm to retract the stem completely.
Loosen the counter-nut, unscrew the stem.
During this operation, make sure that the plug does not
turn when it is seated. If the plug travel is very small and
there is a large amount of plug stem inside the actuator,
it may be necessary to remove the yoke nut and lift the
actuator so that the plug is not touching the seat.
4.1.3 Stems attached with a stem connector
In the case of air-to-retract actuators, apply sufficient
air pressure on the diaphragm to retract the stem
completely.
Loosen the screws and remove the stem connector.
4.1.4 Removal of actuator
Disconnect all the ingoing and outgoing air and electrical
connections from the actuator. Loosen the yoke nut or
attachment screws and lift the actuator, making sure
that the concentricity and/or the thread of the bonnet is
not damaged.
4.2 Opening of the Pressurized Chamber
(Figures 17, 18 and 19)
Prior to disassembly, vent the process pressure and
isolate the valve if necessary.
Note: The valve must always be reassembled with new
packing rings and gaskets; before disassembly, make
sure that the appropriate parts are available.
A. Remove the packing flange nuts (3) then remove
the packing flange (4) and the packing follower (23).
B. Check that the exposed part of the valve plug
stem (1) is clean enough for the bonnet (7) to be
removed easily.
C. Remove the body stud nuts (8).
D. By means of a pad eye secured instead of the
actuator, lift the bonnet (7) up and separate it from
the valve body (18). During this operation, the valve
plug stem (1) must be pushed downwards so that
the valve plug remains in the valve body (18).
E. Remove the spring washer (17) and the body
gasket (10).
F. In the case of type 41305, 41375, 41505, 41605 and
41905 valves, remove the valve plug stem (1) and
valve plug (15) assembly from the cage by pulling the
valve plug stem upward, then remove the cage (16)
and “stack” (37) assembly for 41375 type valve.
Because of the cage gasket (31), the cage can
sometimes be lifted along with the valve plug. If this
should happen, press down on the cage so that it
remains in the body. If the cage is lifted along with
the valve plug, it could slip during handling and fall
In the case of a 41905 series valve [equipped with a
graphite ring (45)], make sure that the ring is not
damaged during the operation.
G. In the case of a 41405 valve, remove the valve
plug and body cage assembly by pulling the valve
plug stem upward; in this case, the valve plug has
a shoulder which prevents the cage from falling.
Remove the valve plug from the cage by pulling on
the end of the valve plug stem.
H. Remove the seat ring (13) and the seat ring gasket
(14) from the valve body (18).
I. Remove the packing (6), the packing spacer (5) and
the guide bushing (22) from the bonnet (7).
Note: A packing spacer (5) is only mounted when the
bonnet has a side connection.
