Installation, Operation and Maintenance Manual
SERIES T/TE/TW/TWE
ONE-PIECE TOP ENTRY
TRUNNION BALL VALVE
Page:
11
of
12
Document Name: IOM-T
Revision:
15333
Release Date: 06/26/2015
FAULT
FINDING
CORRECTION
Internal
Leakage
Stroke the valve to the fully closed position.
Discharge the residual pressure left inside
the cavity through the drain valve and the
vent plug (when provided).
Allow the system to stabilize for half an
hour minimum.
If the valve is tight no water should drip out
the drain valve.
Small leaks can be stopped by
injecting sealant into grease
nipples
Bad ones require replacement
of seat seals.
Body Leakage
When any of the body flanged connections drips
verify the bolt tightening torque of the joint
concerned.
External leaks can be stopped
replacing body gaskets.
Increase in
torque
requirements
A slight increase in the valve torque
requirement is natural during the valve life
and has been taken in account when
designing the operator device.
This torque increment tends to stabilize with
time.
Torque increasing rate that does not trend
to stabilize can be caused by external affairs
such as sand / debris trapped between ball-
stem and bonnet flange or foreign objects,
left into the pipeline that gets trapped
between seats and ball.
Inject lubricant grease through
the ball-stem grease fitting.
If this operation does not bring
any benefit dismantle the
stem/gland flange group and
verify no galling, scores or
damages have occurred.
If possible, remove the foreign
objects from the pipeline.
Verify that the operator is
correctly set and is delivering
its nominal torque.
Ball-Stem
leakage
Leakages from ball-stem depend from
damage of primary and secondary seal
on the ball-stem in case the grease injector
is not between the two sealing areas. In this
case the leakage is recorded through ball-
stem seal.
In case the grease injector is positioned
between the seals (primary and secondary)
the leakage of primary seal can be recorded
removing the grease injector or plug forecast
during the design stage.
Small leakages can be stopped
or reduced injecting grease
sealant through the grease
injector.
Big
leakages
require
the
dismounting of the valve.
