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Figure 4.7 – Cantilevered bow turret (SBM-Imodco)
A typical internal turret arrangement is shown in fig. 4.8.
This is the SBM Top Mounted Internal Turret (TMIT) system.
Similar systems can be supplied by any of the other turret
contractors. This turret design has been employed on several
production FPSOs, e.g. Chevron’s Alba FSU, Shell’s CNS FPSO
and Curlew FPSO. The turret presents benefits from previous
applications, and limits the number of critical mechanical
components, such as the bearings, by using a single roller bearing
located above the vessel main deck.
The system comprises a chain-table structure anchored to
the seabed anchor points via an array of nine (9) catenary mooring
lines. The chain-table structure is attached to a turret cylinder
structure which is suspended from a heavy duty roller bearing
located above the vessel’s main deck. The bearing is supported on
the vessel’s side and integrated into the forward part of the FPSO
vessel’s hull. The turret cylinder is mounted to the earth-fixed side
of the main bearing. The turret cylinder houses the riser ‘I-tubes’
and supports the manifold deck (where the risers terminate), the
manifold structure, the swivel deck together with the swivel stack
and all the earth-fixed part of the rigid piping.

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