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The HRV choke, which is our third generation of insert-retrievable
chokes, is qualified for water depths up to 18000 feet (5500
m). It consists of a right-angle body with an insert module
that can be installed or retrieved by a cable-deployed running
tool with the assistance of a remotely operated vehicle (ROV).
The choke insert module (CIM) includes all of the valve internals,
the actuator, and an ROV-operated clamp connector, which secures
the insert to the valve body. Metal-to-metal seals are used
at all critical sealing areas including a double-tapered metal
bonnet seal. This product is available in a number of sizes
and pressure/temperature ranges.
The insert clamp connector (ICC) is available with either
horizontal or vertical ROV access in several positions relative
to the valve piping. This clamp system is designed so that,
should it fail, the connector stem can be cut by an ROV-mounted
tool thereby allowing emergency release of the insert module.
Because this clamp connector is part of the insert module,
it can then be repaired once retrieved to the surface.
The HRV choke
comes standard with our model SL hydraulic rotary stepping
actuator, which features pressure/volume compensation and
a piston design that balances the back-pressure due to hydraulic
head. This design also ensures that there is no volume change
within the actuator housing throughout the stepping cycle.
The hydraulic couplers for the actuator are built into the
valve body and bonnet and are connected and disconnected automatically
during installation and retrieval of the insert module. The
actuator comes with a high-visibility local position indicator.
As well, an optional linear variable differential transformer
(LVDT) is available to directly measure the position of the
valve stem for accurate electrical feedback of the choke position.
The electrical leads for the LVDT are terminated in a bulkhead-mounted
ROV-mateable connector. Finally, an override interface is
also supplied to allow ROV operation of the valve.
Choke-Insert Running Tool (CIRT) The Master Flo CIRT
is designed to align the choke insert in the correct orientation
and to control the final landing speed on docking with the
choke valve. It is also designed to protect the choke insert
from damage during handling. The CIRT is a simple, reliable
mechanical system; it requires assistance from an ROV, but
it has no electrical or hydraulic requirements. The running
tool latches onto a modified API-17D receptacle on the Choke
Insert Module. The latch mechanism is engaged and released
by an ROV-operated lever. The lower guide frame interfaces
with a guide funnel that surrounds the valve body and ensures
that the tool is in correct horizontal and rotational alignment
before final landing. Three soft-landing cylinders on the
running tool control the final rate of descent during landing.
The HRV choke valve is also available configured for use with
third-party running tools.
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