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HIGH PERFORMANCE BUTTERFLY VALVE
FIGURE HPA
7
•
Grease should be changed as follows: If
operated frequently, after approximately 3 years.
If operated rarely, after approximately 5 years.
•
Recommended Greases: Servo gem EP2
(Extreme Pressure), Mobilux EP2, Oline EP2,
Chevron EP2.
5.2.4
Electric actuator
, which gives a multi-turn output,
is fitted on the gear unit. The actuator drives the
gear unit which in turn rotates the stem. Electrically
actuated valves are provided with declutching
mechanism for manual operation of the valve.
For electric actuators, FNW or manufacturer
recommends to strictly adhere to the instructions
as per actuator manufacturer’s manual.
5.2.5
Pneumatic or hydraulic actuator
is fitted directly
on the valve, without a separate gear unit, unless
a separate manual override is requested as these
actuators have built-in quarter turn mechanisms.
For these actuators, FNW or manufacturer
recommends to strictly adhere to the instructions
as per actuator manufacturer’s manual.
5.3
FIRE SAFETY (FIRE SAFE DESIGN)
In the event of fire, the soft seals may burn out. In this
condition, the line pressure pushes the metal seat ring
against the disc. The disc makes contact with the metal
seat ring to provide a fire safe metal sealing. Valves are
tested to meet the fire safety requirements of international
standards according to either API 607.
CAUTION:
•
Apply gradual force on the handwheel
of the gear operator and do not apply
sudden impacts.
•
Do not apply extra leverage (using
pipe/bar) when the end stops of the gear
operator reach its extreme position.
CAUTION:
•
Use the valve only for applications for
which it is designed and recommended for
to avoid unexpected failure of the valve.
•
Suspended particles in the line fluid may
damage the soft components in valve.
DO:
•
Ensure that the valves in the pipeline
affected by a fire are replaced as soon as
possible for satisfactory performance.
Symptom
Possible Cause
Corrective Action
Stem packaging leaks
from top
1. Gland bolts loose
2. Packaging damaged or missing
3. Seal misaligned
1. Tighten the bolts
2. Replace packaging (shut down first)
3. Replace and aligned it correctly
Body gasket leaking
1. Body bolts loose
2. Body gasket damaged
1. Tighten the body bolts
2. Remove gasket
Valve leaks at
closed position
1. Seat is worn or damaged
2. Disc edge is worn or damaged
1. Replace seat as described in disassembly and assembly
2. Replace the disc. (Consult factory for potential
application problem.)
6. TROUBLESHOOTING
The table below lists some common problems that may be encountered with double eccentric butterfly valves, the probable
causes and recommended remedy to the problems. However, judgment and experience must be applied when working on
the valves in actual field, based on site conditions.
Table 1
Troubleshooting check list