The existing protective coating on the mud thickener steelwork had reached the end of its service life and had allowed damaging corrosion to the structure to occur, which in places meant that costly engineering works had to take place.
The existing protective coating system had completely failed with highly damaging sub film corrosion present. The steelwork was prepared by method of abrasive blasting, with the steelwork being prepared to Swedish Standard SA2.5. Following blasting works a thorough inspection was conducted by the client and the necessary repairs made.
Due to the acidic environment in which the structure operates and the presence of chlorides (both of which if not removed would result in premature coating failure), the structure was rinsed with copious amounts of fresh clean water by method of high pressure spinning jet to remove all remaining salts and contaminants. If we had been using conventional protective coatings products it would have been necessary at this point to re-blast the structure to remove the flash rusting that had occurred. However because the structure was being treated with Corroless rust stabilising products this additional disruption, cost and environmental impact was avoided.
At each stage of the coating cycle a high level of attention was applied to stripe coating the large number of angles edges and welds to ensure full film thickness was achieved. Following the initial stripe coat using Corroless EPF (epoxy primer finish) the structure received an overall coat of Corroless EPF to a dry film thickness of 200 microns. Because Corroless EPF contains a mined pigment that stabilises any corrosion present by converting it to inert magnetite we were able to coat ‘gingered’ steel that other protective coatings systems would not be able to tolerate. Corroless EPF also contains self leafing glass flake that laminate at the coatings surface to form an impermeable barrier to oxygen, moisture and chemical attack. This makes it suitable for use in the most demanding environments as seen here.
A second coat of Corroless EPF was applied in a contrasting colour to a dry film thickness of 200 microns. Regular wet film comb thickness readings were taken throughout application and dry film readings taken upon cure to ensure the protective coating system was applied to the thickness’s specified.