Assessment of Existing Structures and Repairs - Offshore Structures: Design, Construction and Maintenance - page 550

platforms used FRP. The fiberglass components consisted of 10% by weight of
composites, including the following:

Office and equipment modules

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Diesel- and water-storage tanks

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Pultruded glass/phenolic gratings for floors

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Ladders

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Walkways ●

Handrails ●

Enclosures and heat-protection for walls.

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Glass-reinforced epoxy was also widely used for the pipe work and tubular
members.
The main benefit of FRP was the reduction in weight, which was important
for these lightweight structures because it reduced the cost, reduced the topside
weight and eliminated the cost of regular maintenance.

7.12.14 Case Study: Conductor Composite Repair
In this case, an 8-legged jacket drilling platform, installed in 1964, was operat-
ing in 75 m of water in the Gulf of Mexico. Its original conductors were heavily
corroded. The 5-year conductor maintenance plan identified the required con-
ductor restoration work.
Cost analysis revealed that composite repair would be the most cost-
effective repair method. The process included:

Underwater and above-water repair-site inspection

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Planning the staging area for equipment and material

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Surface preparation, including removal of excess scale, removal of grout
that was not structurally sound and grit blasting to near-white metal

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Installation of shear lug, rebar cage, and translucent FRP jacket outside rebar
cage

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Pumping of epoxy grout into FRP jacket from bottom up

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Installation of wear pads and conductor centralizers at guide bell.

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7.12.15 Fiberglass Access Decks
For the past decade, use of fiberglass for grating and handrails has been grow-
ing in offshore structures. Fiberglass is used for both new platforms and for
replacing existing ones.
Fiberglass access decks and stair towers are lighter than the steel equivalent
and are easier to install.
Fiberglass structural decks can be designed to meet any load requirements.
The decks can be custom built and installed offshore with no welding and or
heavy lift equipment required.