Maintenance - Fisher NPS 12 Instruction Manual

Instruction Manual
D103553X012
process liquid may cause irreparable erosion damage to the seating surfaces and may plug cage holes and passages,
causing cavitation damage. During valve installation or the plant cleaning cycle, install a strainer upstream from the valve
to help free pipelines of foreign material.
3. The control valve assembly may be installed in any orientation unless limited by seismic criteria. However, the
normal method is with the actuator vertical above the valve. Other positions may result in uneven valve plug and
cage wear and in improper operation. Support the actuator if it is not installed in the vertical position. For more
information, consult your Emerson Process Management sales office.
4. Use accepted piping and welding practices when installing the valve in the line. You can leave internal elastomeric
parts in place when welding. For flanged valves, use a suitable gasket between the valve and pipeline flanges.
CAUTION
Depending on valve body materials used, post weld heat treating might be required. If so, damage to internal elastomeric
and plastic parts, as well as internal metal parts is possible. Shrunk-fit pieces and threaded connections might also loosen. If
post weld heat treating is to be performed, all trim parts should be removed. Contact your Emerson Process Management
sales office for additional information.
5. With a leak-off bonnet construction, remove the 1/4 NPT pipe plugs (key 14, figure 4) from the bonnet to hook up
the leak-off piping.
6. If continuous operation of the plant is required during inspection or maintenance of the valve, install a three-valve
bypass around the control valve assembly.
7. If the actuator and valve are shipped separately, refer to the actuator mounting procedure in the appropriate
actuator instruction manual.
WARNING
Personal injury could result from packing leakage. Valve packing was tightened before shipment; however some
readjustment will be required to meet specific service conditions.
If the valve has ENVIRO-SEALt live-loaded packing or HIGH-SEAL ULF live-loaded packing installed, this initial
re-adjustment will probably not be required. See the Fisher instruction manuals titled ENVIRO-SEAL Packing System for
Sliding-Stem Valves (D101642X012) or HIGH-SEAL ULF Live-Loaded Packing System (D101453X012) (as appropriate)
for packing instructions.

Maintenance

Valve parts are subject to normal wear and must be inspected and replaced as necessary. Inspection and maintenance
frequency depends on the severity of service conditions. This section includes instructions for packing lubrication,
packing maintenance, trim maintenance, lapping seating surfaces, and valve plug maintenance. All maintenance
operations may be performed with the valve in the line.
WARNING
Avoid personal injury from sudden release of process pressure. Before performing any maintenance operations:
Large ET and ED Valves
July 2014
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