PAINTS & COATINGS

24 www.motorship.com December 2012

While the shipping industry as a whole isexperiencing a slump in terms of newbuilds,one maritime sector is bucking that trend:

the offshore exploration and drilling industry. Theoffshore industry is a shining light in the maritimesector: capital outlays and discoveries, productionand profits are all healthy. One area where significantimprovements still can be made is in the mitigationof the lost production from, and high costs of,maintenance of ships and equipment, working asthey are so remotely and in generally very challengingenvironments.

It is projected that world energy consumption (themajority of which is oil based) will grow by 53% from2008 to 2035. Much of the growth in energyconsumption occurs in non-OECD nations, wheredemand is driven by strong long-term economicgrowth. Projected energy use in non-OECD nations willincrease 85% by 2035, compared with an increase of18% for the OECD economies.

The prediction is for new discoveries of oil tobe near zero by 2050, or, in the words of ExxonMobilexecutive William J Cummings: “All the easy oiland gas in the world has pretty much been found.Now comes the harder work in finding and producingoil from more challenging environments andwork areas.”

EXPLORATIONThe huge Tupi underwater oil field was discovered byBrazil in 2008. It is estimated to hold the equivalent of5-8 billion barrels of light crude oil. And when RoyalDutch Shell sank five wells off Alaska recently, itwas the first drilling in US Arctic waters in decades.Encouraged by high commodity prices and shrinkingsea ice, not only oil exploration, but the cruise andfishing industries as well, among others, are gearingup to tap the Arctic’s riches, previously inaccessiblebecause of the year-round ice. Shrinking summerArctic ice is opening new, and shorter shipping lanes, an open invitation to general shipping to chart

Arctic courses.The US Geological Survey estimates that nearly 13%

of the world’s undiscovered oil reserves, and 30% ofits undiscovered gas reserves, are to be found north ofthe Arctic Circle. That’s 90 billion barrels of oil and1,670 trillion ft3 of natural gas. And these estimatesdon’t include so-called unconventional oil and gasdeposits, such as hydrocarbons found in shale rock, ormethane hydrates on the sea floor.

While Arctic oil exploration is more challengingtechnically than any other environment, continuinghigh oil prices and advances in technology combineto fan the petroleum industry’s interest in theregion, with countries such as Canada, Russia, Norway,and Denmark (Greenland), whose northern areasall extend into the Arctic, being likely targets for future exploration.

It is clear that the migration to offshore explorationand production that has already begun will only gainmomentum. It is also clear that, as it does, thedemand for vessels and rigs will also continue to rise.

However, an unfortunate reality with thesedevelopments is that the farther from shore—such as

into the Arctic (or Antarctic)—exploration andproduction takes oil companies, the farther vessels andrigs will find themselves from drydock for cleaning andservicing as needed—meaning significant downtimeand lost production.

Keeping a ship’s hull free of even a small degree ofaccumulated fouling (slime) and ensuring that thecoating is in good, smooth condition can save about20% of fuel consumption; while a heavily fouledhull can require as much as 80% more power to propelthe vessel at the same speed. In other words, itis very good business, both economically andenvironmentally, to ensure that hulls of both oil-exploration service vessels and tankers are kept assmooth as possible.

Keeping the hulls of exploratory vessels and rigsclean makes business sense as well, but for a differentreason. Since these are stationary vessels, kept inplace by thrusters or tethers, the fouling problem isnot one of increased hull friction, but one of increasedhull weight as a result of heavy biofouling. This foulingnot only reduces the deck loads commensurately, but, over time, will also have a damaging effect onthe hull itself.

Green hull coatings forthe offshore sectorSteven Ferry, on behalf of Hydrex, looks at the importance of choosing the right hull coating system and maintenance regimen for vessels inthe offshore oil and gas industry.

With an STC coating in place, regular in-water cleaning can be done in-situ with no ill effect on coating or the environment

A large vessel can accumulate as much as 5,000t of fouling ina couple of years, which must be cleaned to permit inspection

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PAINTS & COATINGS

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Stationary vessels are open invitations to bothmicro and macro fouling, especially considering thatconventional biocidal antifoulants require flowingwater to work. These factors allow stationary vesselsto accumulate fouling to almost hard-to-believe levelsin a relatively short time.

In fact, a large vessel can accumulate as much as5,000t of fouling in a couple of years, which will, if notaddressed, not only have a detrimental effect on thehull itself, but will also reduce the vessels’ effectivedeck loads. It is also well worth noting that in order fora vessel to be approved for underwater inspection inlieu of drydock (UWILD) by the classification societies,the hull must be sufficiently clean to permit inspectionby divers under the supervision of a classificationsociety inspector.

Since biocidal antifouling coatings – like the effectivebut now banned TBT and its copper-based replace-ments – need to move through water to work, onstationary vessels such as drillships these coatings arelargely ineffective. Biocidal antifouling paint problemshave been compounded recently by research findingsthat show existing heavy-metal-based anti-foulingshave the potential of worsening rather thanpreventing invasions of non-indigenous (alien) aquaticspecies, as these become tolerant of the copper andother biocides in the coatings.

Hence, a good, long-term solution for cleaning hullsrules out paints that have a leaching function or othersuch active ingredients.

A possible solution to this problem would be a hardhull-coating, free of active ingredients. This coatingwould be as inert and long-lasting as possible, andwould provide excellent hull protection. It would alsobe easy to keep clean of fouling. It would improve insmoothness and performance over time.

A coating known as Surface Treated Composite (STC)

answers all aspects of the problem when properlyapplied and maintained. It combines a hard, durable,non-toxic hull coating with advanced in-water hullcleaning technology. It is wholly environmentally safe,and it can save shipowners and operators millions ofdollars annually in operational costs. Such STC coatingsalso ease the much dreaded drydock curse bypermitting vessels to be cleaned and maintainedin-situ by divers using special equipment.

The highest single expenditure for any shipownerin maintaining a ship, after delivery of the vesselfrom the builder, is the cost of drydocking. Today,shipowners and operators run on tighter budgets andmargins, meaning the costs of hull protection andmaintenance must be balanced carefully against fuelsavings. Docking is expensive, difficult to schedule,and disrupts operations for a protracted period of time.

When it comes to stationary vessels, drydockinggrows even more complex and time-consuming, sincemany such vessels are equipped with multiple non-retractable thrusters that must be removed beforeentering drydock and replaced afterwards.

A vessel should not need to see drydock morefrequently than is required to keep it in class. Theprimary reason more frequent drydockings arenecessary is unchecked fouling build-up, something aproperly applied and maintained STC coating can

Stationary vessels are open invitations to both micro andmacro fouling, especially considering that conventionalbiocidal antifoulants require flowing water to work

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