Flowserve V-377 R4 Edward Valves - Manual (Page 11)

11
Flow Control Division
Edward Valves
Leakage of steam through a valve that is
badly steam-cut has a whistling or
sonorous sound. If the valve is only slightly
steam-cut, however, leakage is identified
by subdued gurgling or weak popping
sounds. These sounds can be heard
through a stethoscope or by placing one
end of a stick against the valve body while
holding the other end between the teeth,
with hands over the ears.
To check for a properly closed valve, on
valves with nonrising type handwheels
(non-revolving stem), an indicator is
attached to the lower side of the yoke
bushing that coincides with a pointer
attached to the yoke, when the valve is
tightly closed. This can be viewed through
one of the yoke windows and it represents
the same relative position between the
yoke and yoke bushing, as when the valve
was hydrostatically seat-tested and found
to be tight at the factory. The hydrostatic
pressure is stamped on the indicator. It is
only natural that the indicator will travel
past this mark after repeated closings.
Some operators hesitate to force the valve
crossarm under the handwheel further than
this button, but no harm will be done even
if the indicator travels more than an inch
past the mark when holding a desired
pressure. If a tight seal is not made after
repeated impact blows, it must be conclud-
ed that the pressure is bypassing either at
the seat joint or body diaphragm between
the inlet and the outlet passage. Inspection
of the interior of the valve now is advisable.
HANDWHEEL–
IMPACTOR TYPE
BEARINGS–USED ON NON-
REVOLVING STEM VALVES ONLY;
TAPERED AND SPHERICAL ROLLER
BEARINGS ALSO USED
LOCATION OF “INDICATOR” ON
YOKE BUSHING TO INDICATE
WHEN VALVE IS TIGHTLY SEATED
LOCATION OF “POINTER”
ON YOKE TO INDICATE WHEN
VALVE IS TIGHTLY SEATED
ONE-PIECE PACKING GLAND
(OR 2-PIECE GLAND FLANGE
AND GLAND ASSEMBLY)
YOKE LOCK RING
(2 PIECES)
BONNET BACKSEAT
COVER RETAINER
STUDS OR
CAP SCREWS
COVER RETAINER
USED ON
CHECK VALVES
PRESSURE-SEAL
COVER, USED ON
CHECK VALVES
YOKE BUSHING USED ON VALVES
WITH NON-REVOLVING STEMS
(CALLED STEM BUSHING ON
LIMITORQUE OPERATED VALVES)
TYPICAL YOKE–USED ON VALVES
WITH NON-REVOLVING STEMS
(YOKES USED ON OTHER VALVE
TYPES DIFFER)
BONNET RETAINER
SPACER RING
PRESSURE-SEAL GASKET
PACKING CHAMBER
STEM THREADS
STEM GUIDE COLLAR ON
NON-REVOLVING STEMS
STEM
STEM BACKSEAT
DISK NUT
STEM COLLAR
DISK
LOCK
WELD
BODY GUIDE RIBS
(ONLY ONE SHOWN)
SEAT WITH STELLITE
HARD FACING
FOR STOP
CHECK
VALVES
DISK PISTON
ASSEMBLY
PISTON
PISTON
FOR
CHECK
VALVES DISK
BODY
FOR STOP
VALVES
DISK STEM
ASSEMBLY
TYPICAL PRESSURE-SEAL
BONNET AS USED ON STOP &
STOP-CHECK VALVES
GASKET RETAINER SEGMENTS
(SEVERAL PIECES)
}
Illustration No. 5
Typical Globe Valve Nomenclature
Service Problems
(continued)