EZ-C, ET-C, and EWT-C Valves
Instruction Manual
Form 5376
August 2006
6
against the bonnet. If leakage cannot be stopped in
this manner, proceed with replacing packing
procedures.
If there is undesirable packing leakage with other
than spring-loaded packing, first try to limit the
leakage and establish a stem seal by tightening the
packing flange nuts.
If the packing is relatively new and tight on the stem,
and if tightening the packing flange nuts does not
stop the leakage, it is possible that the valve stem is
worn or nicked so that a seal cannot be made. The
surface finish of a new valve stem is critical for
making a good packing seal. If the leakage comes
from the outside diameter of the packing, it is
possible that the leakage is caused by nicks or
scratches around the packing box wall. If performing
any of the following procedures, inspect the valve
stem and packing box wall for nicks and scratches.
Replacing Packing
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
in this instruction manual.
Key numbers and sequence of assembly of packing
parts are shown in figures 2, 3, and 4. Bonnet key
number locations are shown in figure 7, and valve
key number locations are shown in figures 8 and 9,
unless otherwise noted.
1. Isolate the control valve from the line pressure,
release pressure from both sides of the valve body,
and drain the process media from both sides of the
valve. If using a power actuator, also shut off all
pressure lines to the power actuator, and release all
pressure from the actuator. Use lock-out procedures
to be sure that the above measures stay in effect
while you work on the equipment. Observe the
Warnings
at the start of the Maintenance section.
2. Disconnect the operating lines from the actuator
and any leak-off piping from the bonnet. Disconnect
the stem connector and remove the actuator from
the valve by unscrewing the yoke locknut (key 15) or
hex nuts (key 26, not shown).
3. Loosen the packing flange nuts (key 5) so that
the packing is not tight on the valve stem. Remove
any travel indicator parts and stem locknuts from the
valve stem threads.
WARNING
D
To avoid personal injury or
property damage caused by
uncontrolled movement of the bonnet,
loosen the bonnet by following the
instructions in the next steps.
Do not remove a stuck bonnet by
pulling on it with equipment that can
stretch or store energy in any other
manner. The sudden release of stored
energy can cause uncontrolled
movement of the bonnet.
D
To avoid personal injury or
damage to the seating surface caused
by the valve plug and stem assembly
dropping from the bonnet after being
lifted out of the valve body, observe
the following instructions.
4.
When lifting a Design EZ-C bonnet,
temporarily
install a valve stem locknut on the valve stem. This
locknut will prevent the valve plug and stem
assembly from dropping out of the bonnet.
5.
When lifting a Design ET-C or EWT-C bonnet,
be sure the plug and stem assembly and cage
remain in the valve body.
WARNING
To avoid possible personal injury,
review your process shutdown
procedures to be sure process
pressure is not applied to the valve for
the following procedure.
6. Hex nuts (key 16) attach the bonnet to the valve
body (key 1). Loosen these nuts or cap screws
approximately 3 mm (1/8 inch). Then, loosen the
body-to-bonnet joint by either rocking the bonnet or
prying between the bonnet and valve body. Work
with a prying tool around the bonnet until the bonnet
loosens.
D
If fluid leaks from the joint, it may indicate that
process pressure is applied to the valve. Review
your process shutdown procedures, and be sure
process pressure is not applied to the valve.
D
If no fluid leaks from the joint, remove the nuts
completely and carefully lift the bonnet off the valve
body.