Coatings cut to a new cloth

March 1, 2012

Whether it's providing protection for kit in HP/HT environments, keeping corrosion at bay or defending vessels against fouling or iceberg damage, the offshore industry sure does ask a lot of its paint jobs nowadays.

Jennifer Pallanich talks to market leader Hempel about state-of-the-art offshore coatings, which on a major offshore project can account for as much as 5% of capex costs.

One of the trends Jose Luna, Hempel's Americas marketing & business development manager, has observed of late in the offshore deepwater market is a focus on high pressure, high temperature (HP/HT) conditions. There, he notes, the challenge lay with thermally insulating flexible coatings to protect oil flowing from the seabed to the surface through subsea components.

‘The oil is becoming hotter and cruder,' Luna says. ‘How will we protect those structures?'

Jose Luna

Luna says Hempel has teamed up with companies that manufacture the larger pieces of subsea equipment to create technology to address those needs. ‘They are facing those challenges and they are partnering with paint companies to see how they can meet these challenges,' he says.

‘We're working on thermal insulation coatings for crude transport from the well through the flowlines to the FPSOs,' Luna says, adding Hempel aims to make a coating capable of dealing with 350°F or higher temperatures commercially available in the short term.

Anti-fouling

Another issue facing the offshore industry is barnacles.

‘Right now we see a lot of activity and interest in regards to fouling relief coatings for structures that stay stagnant in offshore waters,' Christian Fenger, strategic alliance manager, says, noting drillships, semis and platforms that stay on one location for months or years could acquire thousands of pounds of barnacle growth if conventional anti-fouling coating is used. ‘Marine growth will attach itself to any structure that is submerged.'

Barnacles attach to an area of a hull not treated with X3.

Conventional anti-fouling coatings tend to rely on biocides. Soluble when wet, these coatings rely on friction produced by vessels in motion to create a barrier that prevents barnacles from attaching. Rigs or FPSOs staying on location to drill or produce oil have nothing but the current for friction, allowing barnacles to make themselves at home on the hulls.

The barnacle problem is twofold. They don't just add a lot of unwanted weight, but they also make it difficult to inspect the condition of the steel. Owners can spend a couple of million dollars per year removing the barnacles on stationary assets. ‘If you don't, the ship can actually sink. But it does take a couple of years,' Fenger says.

With these concerns in mind, along with calls from shipowners for a fouling control solution that works at low speeds and remains effective for five years, Hempel developed its third-generation fouling release coating Hempasil X3. When used, Hempel says, Hempasil X3 makes the hull self-cleaning, so even if a rig sits idle barnacles are unable to proliferate. Hempel also says customers that have used the coating, which has been commercially available since late 2008, have mentioned fuel cost savings of 6-8% on cruise and container ships.

The self-cleaning capability stems from a silicone composition while fouling prevention arises from a hydrogel layer between the paint surface and the seawater that ‘tricks fouling organisms into perceiving the hull as a liquid instead of a solid surface, greatly hindering their ability to settle,' according to the company. ‘You might have some [barnacles] but can use your hands to remove it,' Fenger says.

The company also uses a software program called SeaTrend, designed by FORCE Technology, to monitor the operational performance of the ship's speed, rpm of the engines and fuel consumption. The onboard reporting tool provides operational data to maximize fuel savings and optimize overall efficiency, the company says.

The next generation of fouling release will focus on a tie-coat that can dry at 10°C or below, key for countries with long winters.

Technicians water blast a surface to prepare it for paint application to hinder biological slime (Main photograph) and (left, from top) seaweed/green algae; barnacles; Gooseneck barnacles; and tubeworms.

Anti-corrosion

Corrosion is a greater problem in some regions of the world than others, such as Brazil with its mix of tropical environment of warm air, high humidity and high salinity. ‘The Brazilian coastline is very, very aggressive in corrosion terms,' says Michael Bak, managing director for Hempel in Brazil. It has ‘very warm waters with a lot of animal life'. He says he's heard some claim that country's corrosion rate is as much as three to five times as fast as the North Sea.

Rigs moving from the Gulf of Mexico to Brazil ‘need better protection than what they're used to in the Gulf of Mexico', Bak says.

Beyond the need for dealing with a highly corrosive environment, Brazil is also a hotbed of offshore oil & gas activity, with considerable newbuild construction and maintenance work in progress. The equipment market is tight, human resources are tight, and the country has some strict environmental legislation issues. Bak says this quartet of conditions leads to higher costs in Brazil.

Extreme conditions

Another trend Luna notes is the industry's continued expansion into Arctic areas in Alaska, Greenland and Russia. Coatings for this market must be abrasive, resistant to ice, able to withstand freezing conditions, have to assist ice slip, have good flexibility, and comply with environmental and safety requirements, Luna notes. To meet the demands for cold weather, Hempel uses a lowered cure catalyst so the product will cure and work at below freezing conditions. To provide roughness, Hempel uses an abrasive to help the coating traditionally used in the splash zone withstand impacts from icebergs.

Anti-failure

Hemple's plant in Conroe, Texas.

Fenger says about 80% of coating failures come down to inadequate preparation or poor application. To ensure proper application, he says, Hempel endeavors to always be present when its coatings are applied. While Hempel manufactures the paint, construction yards and subcontractors apply the paint. As such, Fenger notes, the company depends on qualified applicators to apply the coating properly.

‘As you can imagine, a lot of things can go wrong. That is where Hempel Technical Services becomes very critical,' Fenger says. For example he says, a fabricator, in order to meet a deadline, may need to apply the coatings in less-than-ideal weather conditions, such as rain, high humidity or low temperatures. Fenger says if Hempel's technical services team is on site for the application, they can provide ‘alternative technical solutions' to allow the meeting of the deadline.

As Luna notes, pre-preparation of the hull has a lot to do with how well a coating works. Bak estimates using the correct pre-treatment will solve about 80% of potential problems. In the new construction market, the hull can be prepared with dry abrasive blasting, but in the maintenance market, it may be prepared by ultra-high pressure water jetting or wire brush. As such, the maintenance market needs coatings that will tolerate low surface preparation.

About 70% of Hempel's offshore oil & gas business comes from the maintenance and repair market globally, but it does vary by region. For example, Brazil has a huge newbuild program ongoing, but Mexico has little new construction.

Bak says correctly applying coatings at the correct thickness is necessary to have a coating that will carry out its protective functions. The application should be carried out by trained, certified and experienced applicators, he says.

This is one instance where Brazil's personnel shortages are apparent, Bak says. ‘We still lack enough experienced people.'

He says the schools are providing some of the needed people, but ‘it's not enough, and they don't come out of school with practical experience'.

Bak urges companies seeking to reduce overall project cost not to focus only on price per foot or price per gallon on coatings. For instance, on newbuilds, scrimping on coatings will likely defer costs from capex to maintenance budgets, he says. Bak says cheaper product will not ‘meet your protection needs'.OE



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