UNIWORLD Series
M/UNIWORLD-P/E ed. 01 2020
4
– OPERATING ANOMALIES
Some problems are outlined below which can occur during operation of the valves and the measures to implement.
PROBLEMS FOUND
CAUSE
MEASURE
The stem does not run the entire
stroke and/or stroke incomplete
1. Air leak in connection pipe
between the case and the control
tool and/or the air source
1. Localise and eliminate the leak
2. Air leak from actuator perimeter
2. Tighten the perimeter nuts of the
actuator
3. Air leaking from actuator - broken
diaphragm
3. Replace the diaphragm
4. Waste
deposits
between
compartment and plug
4. If seizure not generated, remove
deposits
5. Indicator
label
movement
compared to index
5. Reposition the stroke reference
based on index
6. The instrumentation does not
supply the correct signal and is
necessary to execute stroke
6. Search the causes on the
instrumentation
7. The positioning unit on the valve
needs re-calibration
7.
Proceed to “setting” the positioner
in compliance with the relevant
manual
The stem moves in jolts
1. Stem seized and/or damaged
1. If possible, polish the stem,
otherwise replace the “trim”
2. Sediment in packing chamber
2. Replace the bonnet with packing
Heavy seal
compartment/plug leak
1. Soft seal class VI damaged
1. Replace the soft seal class VI
2. Metal seal class IV or V damaged 2. If possible, grind the cone of the
plug with the edge of the
compartment
with
“grinding
paste”
Otherwise, replace the trim
3. Differential pressure between
upstream and downstream of the
valve too high
3. Contact our Servicing to ask for a
quote for replacement, if possible,
of the actuator
Packing leak
1. Worn rings or seals
1. Replace the bonnet with packing
2. Soft seal broken
2. Given the complexity of the
operation, contact our Servicing
