Flowserve V-377 R4 Edward Valves - Manual (Page 18)

18
Flow Control Division
Edward Valves
Introduction
Step-by-step disassembly procedures are
described for all types of Edward pressure-
seal bonnet valves, including those with
manual and motor operators. It is impor-
tant that the following paragraphs be read
and understood before any specific
disassembly work is started.
First Determine the Area
of Failure
Failures or maintenance problems, for
other than check valves, can be divided
into three major areas. The area involved
will affect the disassembly procedure to be
followed. These areas, in general, are:
Area 1 The impactor Handwheel or
Handle, or the Limitorque
Operator.
Area 2 The yoke assembly, including the
yoke and yoke bushing, and in
addition on non-revolving stem
valves, the yoke bearings and
stem guide collar.
Area 3 The valve internals, including the
bonnet, body, stem, disk, disk-nut,
gland and seats.
If failure is indicated in Area 1, refer to the
applicable section “Disassembly Procedure
for Impactor Handles” on page 19, or
“Disassembly Procedure for Removing Limi-
torque Operators from Valve Yokes” on
page 20.
If failure is indicated in Area 2, it will be
necessary to first remove the valve opera-
tor. Therefore, refer first to the applicable
operator disassembly procedure described
in the above paragraph. Then proceed to
the section “Disassembly Procedure for
Yoke Assemblies” on page 27, for the
actual disassembly of Area 2.
If failure is indicated in Area 3, two meth-
ods are available. In method 1, the opera-
tor and yoke assembly may be removed
from the valve body as a unit. This requires
less time but requires adequate clearance
area above the valve. Also, large hand-
wheels, say 48” diameter and above, are
massive and sometimes difficult to handle
when attached to the yoke assembly. For
these reasons, the second method is to first
remove the operator from the yoke, and then
the yoke from the body, in separate steps.
Disassembly Procedures for Pressure-Seal Valves
CAUTION
As a general reminder, make sure all pressure is removed from
valves, both upstream and downstream, before any disassembly
work is started. An exception to this is valves requiring service
only on the operator (Area 1) or Yoke Assembly (Area 2),
where the valve can remain in service. NOTE: Removal of the
yoke assembly under pressure does not apply to revolving stem
valves, only non-revolving. The following stem positions should
be observed:
1. For service in Area 1:
a. If pressure is to be maintained in the valve, back seat to the full
open position. On Limitorque operated valves, only torque-only
operators will permit service in Area 1 under pressure. See
definition of “torque-only” units on page 22.
b. If no pressure is to be maintained in the valve, close the
valve fully and open approximately 1/8”.
2. For service in Area 2:
a. For non-revolving stems only, if pressure is to be main-
tained in the valve, back seat to the full open position.
Never service revolving stem valves in Area 2 while
under pressure.
b. If no pressure is to be maintained in the valve, close the
valve fully and open approximately 1/8”.
3. For service in Area 3:
Close the valve fully and open approximately 1/8”.
Service Area 3 only without pressure in the valve.