Special consideration to cargo tank coatings is required where a vessel is required for storage purposes
Following the collapse of global crude oil demand earlier in 2020, the requirement for floating storage for oil and petrochemicals has led to near-record high earnings for tanker asset owners. When oil prices plummeted into negative territory for the first time in history in April 2020, and demand for quality onshore storage facilities far surpassed availability, tanker owners and operators were quick to act.
There are now 163M bbls of crude oil in floating storage, according to Lloyd’s List Intelligence data. This is more than the tanker industry has seen since 2009, following the last global financial crisis. According to research provided to Lloyd’s Register (LR) and published in early May 2020, between 40M bbls and 65M bbls of clean products such as gasoline, jet fuel, diesel and gasoil are also being stored on tankers.
While the shipping industry must be commended for its quick response to managing this unprecedented scenario, it is crucial that tanker owners, operators and managers carefully review the suitability of their vessels for storage before rushing into a deal. Factors to consider include: the vessel’s flag state, age and size; the cargo type; if surveys are due; and the storage duration and location.
“By improving a ship’s corrosion resistance, they are less prone to rusting early”
Tanker owners therefore need to check if their existing tank coatings can withstand exposure to crude oil, or other oil products, for sustained periods. For product tankers, an amine adduct curing phenolic epoxy (novolac) system – which cures to a coating with excellent resistance to a wide range of chemicals – is a suitable option. An example is Hempel’s tank coating Hempadur 15500. Alternatively, an amine adduct curing pure epoxy coating, such as Hempadur 15600, might be required. This has a very high resistance to crude oil and most refined oil products. These cargo tank coatings are also used at onshore storage facilities, including airports, refineries and oil terminals
Both products are certified in accordance with IMO Performance Standard for Protective Coatings (PSPC-Resolution MSC 288(87) COT (crude oil tankers) and are suitable options for long-term storage requirements. These products are also designed to allow a quick return to service due to the fact that they are easy to clean and provide high cargo flexibility, so are a suitable option for tankers used as floating storage.
Technological advances in coatings have a significant operational impact on reducing the time to turnaround a tanker from storage to full-time trading. The application efficiency, and hence the time in dock, is also shortening. In 1998, Nippon Paint launched a range of paints under the banner Nippon Optimised and Advanced (NOA) coating system. The key feature of these is that the NOA coating uses pigments that have various opacities depending on film thickness. The NOA coatings are self-indicating, in that if the layer is too thin, the NOA coating remains transparent. Once optimal thickness has been reached, the coating becomes opaque.
Nippon Paint Marine has added to its NOA range of self-indicating epoxy coatings with a new system specially developed to protect chemical and product carrier tanks from corrosion and cargo contamination. NOA PC 700 is a phenolic/novolac-based epoxy and is resistant to a wide range of chemicals, solvents and petroleum products, including those containing xylenes, methyl ethyl ketone, methanol, caustic soda and low sulphur marine fuel oil.
Nippon Paint Marine Coatings (Osaka)’s general manager sales and marketing Makoto Nakagawa, said: “The addition of NOA PC 700 to our NOA range significantly protects inner cargo tanks from corrosion while preventing cargo contamination. As with all our NOA coatings, application is self-indicating which enables the applicator to visually confirm the correct wet/dry film thickness has been achieved during the application process. Correct film thickness is crucial to mitigating against corrosion risk to maintain ship structural strength.”
He added: “Achieving correct film thickness, especially on edges and corners, is a challenge but this concept allows shipyard staff, surveyors and coatings inspectors to literally see when the coating has been correctly applied. If the coating appears transparent, then film thickness is incorrect. When it is opaque, correct film thickness has been achieved.”
Nippon Paint Marine (Europe) technical manager Hiro Yamashita said: “While NOA application improves coating quality and helps to reduce man hours and costs, the coating system is fundamental to maintaining structural integrity. This is becoming more and more apparent with the increase in areas requiring coatings and the reduced availability of skilled applicators.
“In drydock, for instance, our NOA 10M system – specifically developed for hull maintenance and repair – means just one touch-up coat can be applied in the knowledge that the self-indicating function will ensure the thickness applied is correct. This means fewer days in dock, which contributes to lower drydock costs for the owner. By improving a ship’s corrosion resistance through more accurate coating application, ships are less prone to rusting early.”
With the introduction of NOA PC 700, Nippon Paint Marine hopes to emulate the market success of its NOA60 HS product, which has been applied to the ballast tanks of more than 1,300 newbuild vessels since its introduction in 1998.
NOA60 HS is a superior grade pure epoxy formulated with special phenol-based resins to reinforce resistance to cracking, especially on welds, providing greater resistance to saltwater and cathodic disbonding.
Applied in two coats at 160 µm per coat, NOA 60HS meets all PSPC acceptance criteria for water and cargo resistance, adhesion, cathodic disbondment, pinholes and undercutting. It is easy to clean and has low emissions of volatile organic compounds, say the company. Suitable for multipurpose use, its enhanced resistance to freshwater and seawater has led to the system becoming a favourite NOA coating for ballast tanks and void space protection, claims Nippon Paint Marine.
Chugoku Marine Paints (CMP) has also been busy launching new products for the ballast water tank coating space. Its latest is a solvent-free epoxy coating that can be applied to water ballast tanks. Named Bannoh 5000, CMP’s new solvent-free epoxy coating will be applied to the water ballast tanks of three MR tankers to be built in Hyundai Mipo Dockyard from April 2020.
This is the first application of a solvent-free coating to a water ballast tank and follows years of extensive prototype trials in field tests, according to CMP. Solvent-free coatings require special equipment and the paints need to be warmed, due to high viscosity in cold temperatures. Their use has been limited to specific areas due to treatment difficulties. CMP said its new epoxy coating is designed to overcome the existing limitations of using solvent-free coatings. The company said Bannoh 5000 will conform to new Korean regulations under the Atmospheric Environment Conservation Act for managing volatile organic compounds.
Riviera will host a week of 45-minute webinars centred on coatings-related topics commencing 6 July www.rivieramm.com/events/events/marine-coatings-webinar-week