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Protective Coatings
Once the production line is in place , the local shipyard starts dismantling the coolers and after a course cleaning with pressurized water , the coolers are handed over to an authorized party , e . g . Multi Solutions from Norway , a company with profound knowledge in safe , efficient and environmentally friendly cleaning of equipment and surfaces on all types of vessels at yard stays . After cleaning , the box coolers are blasted to SA 3 , which means all old and deteriorated coating has been removed . Next the coolers are carefully inspected . Damaged tubes can either be plugged or even be exchanged . Once those steps are completed , the coolers are ready to be coated . After the coating is fully polymerized , the coolers are handed over to the shipyard , ready to be re-installed into the hull of the vessel . Finally , any damages that may have occurred during installation are touched up . Multi Solution is not only an authorized partner of Säkaphen for re-coating but also of NRF for maintenance and onsite repair of their box coolers .
A box cooler coated with baked phenolics after being in service for 5 years . The marine growth has been removed by cleaning and pressure washing . The condition of the coating requires a full re-coating .
The initial idea of both parties involved was to establish a network of Authorized Applicators for Säkaphen ’ s baked phenolics in all relevant locations , such as Rio de Janeiro , Singapore , Eastern Europe , Scandinavia , Middle East and so forth . But this was quickly discarded , considering the high investment costs per location , foremost due to need an oven in order to polymerize this type of coating , but also due to the relatively large number of potential docking sites . Based on the unavailability of polymerization ovens , it became clear that a coating solution would have to be cold-cured , while offering a pot life long enough to allow the coating to be applied in a certain way that the cooler surface is completely coated but at the same time curing fast enough to have a feasible processing time . Furthermore , all of this had to work under various environmental conditions ranging from colder temperatures in Scandinavia ( 10 ° C ) to elevated temperatures in South America or the Middle East ( 38 ° C ) and potentially at elevated humidity up to 80 %. Last but not least , the application procedure had to be simplified to allow cleaning and re-coating of the box coolers around the world in or near the respective dry dock location chosen by the vessel operator for the 5-year class renewal .
Cold-curing solution One such coating solution that fulfils all these requirements is the new and innovative epoxy hybrid coating system Säkatonit Extra AR-F from Säkaphen . With a volume of solid over 80 % and applied at DFTs around 150 microns , the coating provides very good protection while at the same time maintaining the heat transfer rate . The re-coating process for box coolers on-site starts with setting up a mobile production line beginning with a cleaning station to remove marine growth followed by an abrasive blasting station and completed by the coating station .
Inspection and review Having started with the application of this technology in February 2018 and since then having coated several 10.000m ² of box cooler tubes around the world , everybody was keen to see the real-life performance of this solution . Since the class renewal of a vessel is usually due every 5 years , the first vessel being operated with box coolers recoated with Säkatonit Extra AR-F was due for drydocking for class renewal at the end of 2022 . Säkaphen recently had the opportunity to inspect and review the set of 31 box coolers in Denmark that had been re-coated onsite within a shipyard in Stavanger , Norway over 4 years ago – at the time , this was only the second project carried out using Säkaphen ’ s ultra-high solids twopack coating system , Säkatonit Extra AR-F . The box coolers were part of an ROV construction support vessel carrying out subsea operations . The original scope in February 2018 included the dismantling and cleaning of the box coolers to remove barnacles and other marine growth prior to grit blasting to remove the old coating and carrying out a complete recoating of the box coolers with Säkatonit Extra AR-F . During the dry docking , all 31 box coolers were removed from the hull to be cleaned , inspected , have their gaskets renewed and pressure tested prior to being placed back in the vessel .
Säkatonit Extra AR-F is an ultra-high solid coating material with over 80 % volume of solids ( VS ) and contains no biocidal filler ensuring a move towards a greener , environmentally friendly , and sustainable world . The coating withstands the harsh marine environment in warm and cold waters . The use of box coolers as well as cleaning and re-coating with Säkatonit Extra AR-F allows vessel operators to prolong the life cycle of their box cooler and at the same time improve sustainability . It supports them in their efforts to reach UN sustainability development goals and ESG standards .
48 Heat Exchanger World April 2023 www . heat-exchanger-world . com