3. Check the packing box bolting to ensure the correct
adjustment (See Section 11: Valve Maintenance).
4. Continuously increase load until operation parameters
are reached.
5. Minor relaxation of the flange bolting is possible after
initial assembly. Retorque the bolting if necessary
before installation or following an initial temperature
excursion to ensure the gaskets do not leak.
Recommended Maintenance Actions
No.
Service
Inter
val
Valve Condition
Good Adequate
Inadequate
1 Visual inspection of
the valve
Bi-
weekly
No action
Clean valve stem with a soft
cloth
Overhaul or replace valve after product
lifecycle.
2 Visual inspection of
the packing
Bi-
weekly
No action Retighten leaky packing box Replace leaky packing box immedi-
ately
Preventive change of
the PTFE-packing
Dependent upon results of previous maintenance (see numbers 1 and 2 above) or a
minimum of once every 24 months
Preventive change of
the Graphite-packing
Dependent upon results of previous maintenance (see numbers 1 and 2 above) or a
minimum of once every 18 months
3 Visual inspection of
body bolting
Yearly No action
Retighten body bolting if
bonnet gasket leaks.
Remove from service and replace body
bolting immediately if gasket leakage
persists or if bolting is damaged.
4 Visual inspection of
the actuator
Bi-
weekly
No action
Clean actuator stem with a
soft cloth
Overhaul or replace actuator after prod-
uct lifecycle.
5 Preventive overhaul of
the valve
Dependent upon results of previous maintenance (see numbers 1 to 4 above) or a
minimum once every 60 months
11 Valve Maintenance
Maintenance intervals and service life of a valve can only be
determined empirically on site. The intervals specified in the
User Instructions are recommendations and serve only as a
guide. Under problematic operating conditions, maintenance
intervals may be significantly reduced. We strongly recom-
mend a site survey followed by establishing a documented
procedure for performing the maintenance work. Maintenance
personnel should perform and log the work accordingly. The
data collected can be used as a basis for dynamically deter-
mining the maintenance intervals and activities.
WARNING
Due to risk of crushing hazard, do
not work between the yoke legs
while the valve is in operation.
Prior to start-up, we strongly recommend that you:
1. Stroke the valve and compare the plug position
indicator on the stem clamp to the stroke indicator
plate. The plug should change position in a smooth,
linear fashion.
NOTICE
Graphite packing commonly creates
more friction than other materials,
such as PTFE. If over tightened, excessive friction may
impair smooth control.
2. Adjust instrument signals to ensure a full stroke.
NOTICE
Over tightening can cause excessive
packing wear and high stem friction
that may impede plug movement.
Table 4: Service activities checklist
MaxFlo 4 Control Valve FCD VLENIM0064-02-AQ – 09/16
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