THE PROBLEM – Potable Water Tank Relining
Throughout this tanks life it had already been recoated twice. The first coat a bitumen type coating followed by an epoxy tank lining. This epoxy tank lining was now de-bonding and corrosion was present creating an environment unsuitable for a drinking water tank.
THE SOLUTION – Potable Water Tank Relining
Due to the presence of a bitumen coating it was necessary to remove the existing protective coating in its entirety. Therefore the entire tank internals were prepared by method of abrasive blasting to Swedish Standard SA2.5 ensuring that all existing coatings were removed. Correct preparation is essential to the tank relining process as any tank lining system is only as good as what it is adhered to.
Because we were using Corroless EPF rust stabilising epoxy as the primer for this tank lining project it was not necessary to hold the blast standard using heaters and/or dehumidifiers. This is one of the major benefits of using the Corroless Water Tank lining system as these added costs and complexities are negated in already restricted working environments.
Following the removal of the spent blast abrasive from within the tank and thorough cleaning using vacuums all angles and edges received a heavy stripe coat of Corroless EPF (in buff) to ensure full coating thickness. A full coat of Corroless EPF was then applied throughout the tank by method of airless spray in a contrasting colour (black) to a wet film thickness of 200 microns.
Once the first coat in the tank lining process had cured a second coat of Corroless EPF was then applied throughout the tank by Airless spray in a buff colour to a wet film thickness of 200 microns. The stripe coat was applied following the full coat as it enabled any pin holes identified when the tank lining was spark tested following the second coat in the tank lining process.
Finally once satisfied with the primer coats and spark testing the final and third coat was applied. The tank lining finish selected was Corroless RF35, a high quality WRAS approved glass flake reinforced epoxy. Following the application of the stripe coat by brush to all angles, edges, nuts and bolts a full coat was applied throughout the tank by method of airless spray to a wet film thickness of 190 microns.
The finished tank lining was provided with a 10 year warranty with an expected service life in excess of 15 years until first maintenance.