Flowserve V-370 R3 Edward Valves - Manual (Page 22)

EDWARD UNIVALVE USER INSTRUCTIONS ENGLISH 12-13
22
NOTES ON VALVE OPERATION
Valves equipped with electric motor actuators have special
tags attached which indicate the correct torque switch
setting for the valve. Exceeding these torque switch settings
can cause damage to the valve.
Never use an electric motor actuator to backseat a valve.
This can result in damage to the valve stem and bonnet
backseat.
NOTES ON VALVE MAINTENANCE
When replacing the bonnet gasket in the unwelded Univalve,
follow the torque requirements on page 15 closely. Failure
to torque the gasket properly will result in gasket failure.
When replacing the valve stem packing, never machine the
packing chamber oversize. This will result in blowout of the
packing.
LUBRICATION
In order to obtain full service life, valves require periodic
lubrication of the stem threads. Exposed threads should be
wiped clean of old grease and accumulated dirt and fresh
lubricant applied. This is most effectively done with the
valve in the closed position.
For valves that see frequent operation, such as motor
actuated, the lubricant should be replenished every three
months. If extreme service conditions dictate, a more
frequent re-lube schedule is recommended. Motor actuated
valves have a lubricant fitting at the yoke flange.
The recommended lubricant for all stem threads is Rykon
EP #2, manufactured by the American Oil Company. This
is an extreme pressure, extreme temperature lubricant
of high quality. For vaIves that are operated infrequently,
relubrication should be at least once a year.
GENERAL INFORMATION (continued)
SEAT AND DISK JOINT LEAKS
A leak existing between the seat and disk of a closed valve
might be indicated by one of the following: a definite
pressure loss in the high-pressure side of the valve;
continued flow through an inspection drain on the low-
pressure side; or, in hot water or steam lines, a downstream
pipe that remains hot beyond the usual length of time and
conductivity range.
Such a leak may be the result of closing on dirt, scale
or other foreign matter in the line. It may also develop
because of the operator’s failure to close the valve tightly.
An increased velocity is imparted to a flow forced through
a very small opening. This increased velocity subsequently
gives rise to the “cutting” of both disk and seat, particularly
by particles of line scale or rust in suspension or normal
solids in solution. In spite of the fact that the hard surfaced
material on the seat and disk is corrosion and erosion
resistant, grooves, pit marks, or other surface irregularities
may be formed on the seat and disk joint surfaces when
the disk is closed against a foreign body on the seat. This
sometimes occurs during the initial startup of a piping
system.
Leakage of steam through a valve which 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 weakly 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.
HOW TO ORDER PARTS
During normal working hours, call 800/225-6989 or
919/832-0525. To assure the correct parts for your
Univalve, include the valve size, the figure number ñ
including any prefix and/or suffixes and if available, the
B/M number. All nuclear valves require the B/M number to
properly identify your Univalve.
This information is located on the valve nameplate. The
nameplate is attached to a yoke leg via a cable. If the
nameplate is inaccessible, you can use your Edward sales
drawing; please include the drawing number as well.