On the now decommissioned Brent Charlie Offshore Platform Rig, SPS was applied to reinstate area on the gas tight floor plating and peripheral seal as part of the concrete gravity base structure repair. The use of SPS allowed safe and unhindered repair work to proceed while the operations continued. The existing cavity surface was prepared using a needle gun and bristle blaster.  The perimeter flat bars were adhered to the existing deck with the structural adhesive Plexus MA832.  A new 8 mm thick SPS top plate was adhered to the perimeter flat bars with elastomer injection taking place from 16 December 2009 to 17 January 2010. In total, 54 cavities on the gas tight floor and 17 peripheral seal cavities were filled.

The Charlie GBS is a four-legged concrete gravity based structure with a square base of 36 rectangular reinforced concrete cells (4 leg-base cells plus 32 oil storage, ballast and conductor cells). The cells are attached to a base slab and are closed by trapezoidal roofs. With a weight in air of approximately 296,900 Te, the structure itself (i.e. excluding solid ballast) is substantially heavier than either of the Condeeps.

Four of the cells form the bases of the legs, which extend upwards to approximately 7 m above LAT. There is a 15.7 m high steel transition piece (called the ‘conus’) on the top of each leg which changes in cross-section from circular to square. This connects with the truss girder Cellar Deck that carries the topside. The four legs on Brent Charlie serve different functions. Leg C1 contains utilities, pipework for the drawdown system, and spare risers; Leg C2 contains the fire and services water systems; Leg C3 contains risers, J-tubes, and fire and service water systems; and Leg C4 connects the topside to the oil storage cells, and also contains risers and J-tubes. Legs C3 and C4 are more heavily reinforced than the other two legs because they also support the external conductor guide frames.

SPS Technology’s Cold Work solution was used in the leg column 1 on Gas Tight Floor el. 108100.


Repairs to assets and vessels with Sandwich Plate System, SPS are approved by all major Classification Societies. The structural composite SPS brings a repair that is stronger than the original and will last the lifetime of the vessel or asset.

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