Super Yacht - Hot Water Tank Lining Project

We were contacted by the chief engineer of a super yacht during a recent refit at a shipyard located in the Mediterranean regarding a marine tank lining project. The work required was the relining of three carbon steel tanks (marine calorifiers) used in the production and storage of hot water for general use aboard the motor yacht. (The name of the yacht and location of the shipyard are withheld for reasons of client confidentiality). The criteria the required was that the lining was to be potable water approved for hot water use and capable of withstanding elevated water temperatures (in the 60oC to 70oC range). For this application we proposed an especially developed glass-flake reinforced epoxy resin tank lining system that has international potable water and food contact approval for hot water and high temperature use. We proposed that to reduce costs that the tanks should be abrasive grit-blasted by a local company in the shipyard and we would be supplying and applying the new tank lining materials. We travelled to site to carry out the tank lining works, sending a small team of two tank lining and resin specialists. We made a detailed inspected the quality of the blasting and had areas re-blasted that were not to the required standard. After the tanks were cleaned and all traces of spent abrasive removed from the tanks and the surrounding area we applied the new tank lining. With this tank lining material we would normally expect to apply one coat to each of the three tanks during a working day and then applying the next coat the following day and the final coat on the third day. However because the working temperature within the room where the tanks were located was around 30oC this method of working would have meant missing the over-coating window for the resin (the resin would have hardened too much to accept another coat without re-abrading the surface of the previous coat) so we changed the pattern of work to applying all coats of the lining material to one tank at a time during a single working day. The risk of secondary corrosion forming within the tanks was avoided by the low humidity in the room where the tanks were located. Areas of deep corrosion on the nozzle flange faces were infilled with a paste version of the same epoxy resin tank lining material. After hardening the surplus material was removed and the flange face smoothed flat ready for refitting. Following the application of the new lining we tested all three tanks thoroughly for overall thickness and absence of micro-porosity. After the curing or hardening period had elapsed the tanks (calorifiers) were returned to normal service. We completed our side of the project 2 days ahead of the expected schedule and on budget. We are unable to give more details regarding this project for reasons of client confidentiality.