Instruction manual

A31A Valve
Instruction Manual
Form 5291
March 2008
10
Figure 6. Optional Shaft-to-Valve Body
Bonding Strap Assembly
VALVE BODY
ACTUATOR
A
AVIEW A-A
37A6528-A
A3143-2/IL
6. For more information, refer to the Packing
Maintenance section below.
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.
Key numbers in this procedure are shown in figure 9
unless otherwise indicated.
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
both sides of the valve.
D Vent the power actuator loading
pressure.
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.
Removing and Replacing the Actuator
Refer to the appropriate actuator instruction manual
for actuator removal and replacement procedures.
The actuator stops or travel stops must limit the
rotation of the valve shaft. See the CAUTION below.
CAUTION
When using an actuator, the actuator
travel stop (or actuator travel stop, for
actuators without adjustable stops)
must be adjusted so the disc stop in
the valve does not absorb the output
of the actuator. Failure to limit the
actuator travel can result in damage to
the valve, shaft(s), or other valve
components.
Packing Maintenance
The Type A31A control valve is designed so the
packing can be replaced without removing the valve
from the process pipeline.
CAUTION
For non-ENVIRO-SEAL packing:
Tighten the packing follower nuts only
enough to prevent shaft leakage.
Excessive tightening will accelerate
wear of the packing and could produce
higher friction loads on the valve stem.