Transporting gargantuan volumes of oil through the oceans and seas of planet earth is no mean feat, as I’m sure you are already aware. One way the paints and coatings manufacturers can make life easier for the tanker operators involved is by providing a product that not only is resistant to the harsh environment met at sea, but also can cut through the water with as little friction as is possible.
Hempel recently announced the launch of its third generation anti-fouling based product, Hempasil X3. “We are so confident in Hempasil X3’s fuel saving potential that we also are offering a fuel saving guarantee with the coating system,” says Torben Rasmussen, Hempel’s group product manager.
The silicone biocide-free coating, something that Hempel lays claim to filing the first patent for in the early 1970s, secures adhesion between the epoxy system and the silicone topcoat, as well as obtaining a high fouling release capacity of the silicone topcoat.
The Hempasil X3’s functionality is based on a dual strategy, explains Rasmussen. Firstly, a fouling prevention capability is offered by the hydrogel microlayer between the solid silicone and the seawater. The second factor is the self-cleaning capability which is supposedly enhanced at lower speeds.
Hydrogel is a network of non-reactive polymer chains that are water-insoluble, and have a high degree of flexibility due to their water content. “Fouling organisms will perceive the undulating hydrogel as a liquid and will not be able to attach to the hull,” states Rasmussen.
But importantly it has been developed for both operational economy and global ecology, by giving fuel savings and reducing CO2 emissions.
Reductions in hull skin friction have shown substantial fuel savings compared to conventional solutions, and Hempel claims the new product can outperform tin-free self-polishing anti-foulings on offer.
Speaking to Oil and Gas Middle East, Stein Kjolberg, regional marine director, Jotun UAE, explained the importance of using low friction anti-fouling coatings on the hulls of tankers.
“Anti-fouling products reduce the roughness of a ship’s hull, helping to decrease the fuel consumption, which means less greenhouse gases, including carbon dioxide, nitrogen oxides and sulphur oxides are produced. There are two kinds of hull roughness; physical and biological,” explains Kjolberg.
“Biological roughness is typically derived from animal and weed fouling, whereas physical damage is produced by corrosion of the hull. By increasing hull roughness, the drag resistance increases, which requires a greater degree of fuel consumption to maintain the ship’s speed.”
Kjolberg explains that the biocide-free products, similar to the Hempasil x3 above, performance depends on regular cleaning of the hull to remove slime build up. Using a biocide coating, with copper proving to be the most effective, is the best option for the vessel.
“The biocide that has proved most effective is copper. This is because it has an effect on most fouling species and is accepted as an environmentally protective biocide. Copper is also an essential nutrient for marine life and is safe to handle,” he says.
“We use copperomadine in our SeaQuantum product, which dissolves in seawater from the surface of the anti-fouling preventing marine growth. Once the non-toxic silyl group in SeaQuantum is released, the polymer backbone, which is soluble in seawater, will then dissolve leaving the paint surface exposed; the process is repeated until the vessel re-enters drydock.”
With the right anti-fouling on a tanker, applied in the correct fashion, there is a 2-5% reduction in fuel consumption. The direct economical and environmental impact of this is clear for all to see.
But it comes at a price. Kjolberg says that the premium anti-fouling products using copper biocides can cost between US$30-35 per litre – a hefty figure when you’re painting a very large crude carrier.
“Yes, that’s true, but we estimate that with the fuel reduction, an investment of $60,000 in a SeaQuantum system can be returned in just 20 months,” says Kjolberg.
