Cryogenic-Rotary Valve
Instruction Manual
Form 5482
February 2005
7
Maintenance
Valve parts are subject to normal wear and must be
inspected and replaced as necessary. The
frequency of inspection and replacement depends
upon the severity of service conditions.
WARNING
Avoid personal injury from sudden
release of process pressure. Before
performing any maintenance
operations:
D Always wear protective gloves,
clothing and eyewear when performing
any maintenance operations to avoid
personal injury.
D Disconnect any operating lines
providing air pressure, electric power,
or a control signal to the actuator. Be
sure the actuator cannot suddenly
open or close the valve.
D Use bypass valves or completely
shut off the process to isolate the
valve from process pressure. Relieve
process pressure on both sides of the
valve. Drain the process media from
either side of the valve.
D Vent the power actuator loading
pressure and relieve any actuator
spring precompression.
D Use lock-out procedures to be
sure that the above measures stay in
effect while you work on the
equipment.
D The valve packing box may
contain process fluids that are
pressurized even when the valve has
been removed from the pipeline.
Process fluids may spray out under
pressure when removing the packing
hardware or packing rings, or when
loosening the packing box pipe plug.
D Check with your process or safety
engineer for any additional measures
that must be taken to protect against
process media.
Figure 3. Properly Installed Cryogenic Valve
16B5084 / DOC
COLD BOX
TRANSITION
4” - 8” MIN
20_ MIN
Replacing Packing
The Type A31A Cryogenic valve is designed so the
packing can be replaced without removing the valve
from the process pipeline, provided there is no
internal pressure. Packing may be PTFE V-rings or
graphite.
Key numbers for the parts in this section may be
found in figures 7 and 8.
CAUTION
Tighten the packing flange only
enough to prevent shaft leakage.
Excessive tightening will only
accelerate wear of the packing and
could produce higher torques on the
valve than expected.
Usually, packing leakage can be eliminated by
merely tightening the hex nuts (key 15) located
above the packing flange while the valve is in the
pipeline. However, if leakage continues, replace the
packing.
(12 Seiten)
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