If used as the intermediate or second coat in a three-coat interior coating system, such as the AWWA D102-03 Interior Coating Systems No.2, No.3, or No.5, the OAP coat could be illuminated before application of the finish coat. Illumination of the OAP coat would point out areas with insufficient film thickness or areas where the substrate, the epoxy or zinc-rich primer is visible through the fluorescing film. The areas of low film thickness could not be determined or located with traditional holiday detection. Since many of these areas with insufficient film thickness occur in areas that are difficult to coat and inspect, attempting to monitor by checking dry film thickness would also be ineffective.
In all of the AWWA D102-03 Interior Coating Systems, if the OAP coating was the prime or the intermediate or second coat, a final inspection could be done after topcoating by illuminating the tank interior to see if the OAP product is visible. If visible, it would indicate either a holiday in the finish coat, or insufficient film thickness of the finish coat. Again, neither condition can be easily or effectively monitored by traditional means. Stripe-coating with OAP coatings would allow the inspector to verify that all areas requiring stripe coating are done, that the stripe coat is of sufficient film thickness to cover the edges, and that the coat is, in turn, covered by successive coatings.
Lastly, in-service and scheduled inspection of linings during “wash outs” or annual anniversaries could show early topcoat wear, inter-coat blistering and peeling, or breaks in the topcoat film that expose the OAP material beneath. Again, easy determination and detection of premature coating wear or breaks in the film are not possible with traditional means of inspection. Early identification of coating failure could allow consultants and owners to quickly remedy the situation before further loss of substrate and corrosion occur.
Since the testing equipment does not need to be in direct contact with the OAP file to fluoresce and since the OAA is reactive in the wet film as well as in the dry film, a contractor could monitor his progress and coverage during application of the coatings, provided that he had the appropriate lamp and the lamp was explosion proof and intrinsically safe.