Page 44: of Maritime Reporter Magazine (September 2015)

OFFSHORE ENERGY

Safe stroll

Crew aboard the

Maersk Peregrino

FPSO off Brazil.

Photo: Oeyvind Hagen Statoil

FPSO contractors agree years of cataloging mainte- nance helps decide whether life-extension is possible.

A cursory look just won’t do, regardless of where in the world the vessel might be from.

“The North Sea have their share of marine fatigue issues, too,” Anaturk says, pointing to a long list of possible stoppers to life-extension. In his A-to-Z of dangers, anodes attached to hinder corrosion can be lost when a newly refurbished FSPO or candidate is towed to location. The resulting rust leads to eventual structural failure. Coatings failures at riser supports are now believed to be more common than thought, and failure where phase-carrying riser is festooned to a hull can be catastrophic. Corrosion at coating gaps in general can affect large areas that then become “the ? rst to go”. “Anodes are not good enough when coatings fail,” Anaturk says, adding, “The areas can be quite large. Fatigue cracks are common in all ship- shaped hulls save, perhaps, the Sevan-designed “cy- lindrical” FPSOs and are caused by the endless ? exing of a long structure atop the waves. “Uncertainties in fatigue,” Anaturk calls it, a nod to his buyer side need for certainty.

Green and white water on deck due to storms cre- ates structural erosion and impact damage, and so the trend is to install custom bulwarks to bows and decks.

Sea chests housing moving parts and tools are prone to water leaks: ? rewater systems are housed in these enclosures at the stern, and Anaturk advises they be avoided in vessel designs, since “it’s not double hull in these equipment holds,” and they cause “uncontrolled weight increases” when they ? ll with water.

Other marine-only issues facing operators and con- tractors considering life-extension projects include “marine life” in ballast tanks and on external caissons.

Class approves hull, but not topsides or mooring or 44 Maritime Reporter & Engineering News • SEPTEMBER 2015

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