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toroidal swivels to the vessel’s main deck piping and process
facilities. Lift gas is compressed on board the FPSO and
transferred by a high-pressure swivel to the gas lift riser. Inject
water is pressurized on board and transferred by a high-pressure
water injection swivel to the water injection riser.
The turret’s manifold area is protected from possible wave
action (green water) by a wave breaker structure mounted on the
vessel. A pedestal crane serves the complete turret to handle
swivels and perform other maintenance functions. A stair tower is
integrated with the crane superstructure to provide access to the
swivel stack area.
A hydraulic power unit provides power via the swivel to
activate the different valves in the manifold. Swivels are also
provided for well control fluid and signals. Electric power is
provided via a distribution system serving an exterior floodlighting
and an interior accessway lighting of the complete turret.
The turret would be classified as the hazardous area,
consisting of Zones 1 and 2. The turret cylinder would be
monitored for the presence of gas. Fire and gas detectors would be
located in the manifold swivel area. All signals would be
transmitted to the FPSO’s central fire and gas control panel.
During inspection, temporary ventilation inside its annulus
and cylinder would be provided by air fans. The manifold area and
the swivel stack are situated above the vessel’s main deck and are
thus freely (naturally) ventilated.
Fire protection inside the turret cylinder area is effected
using portable fire extinguishers, as the possibility of fire
occurring in this area is considered remote.
Moorings Interface
The mooring forces applied to the vessel are introduced and
accommodated by the turret
components contained within the vessel’s hull.
These components are:
1. The chain-table, including chainstoppers,
2. The turret cylinder,
3. The friction pad assemblies and support structure,
4. The main weathervaning bearing and its support
structure,
5. The turret moonpool structure.
These components are described in more detail as follows:
The chain-table forms the connection point for the anchor
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