CoatingsPro Magazine

NOV 2018

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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Page 64 of 76

64 NOVEMBER 2018 COATINGSPROMAG.COM chemical reaction, which may — after six months — produce a possible coating failure. e coatings subcontractor presented more than a couple of reports to the shipyard. A ll of the reports included dierent degrees of tests and samples taken and lab analysis. None of these really tackled this problem. e shipyard assigned a coating system responsible speaker: the person who wrote the coating speci•cation and was in charge of the project. e person who the shipyard identi•ed for this job did not have the training or proper education to understand the complete coating schemes. He mentioned that he had learned by reading about corrosion but never really studied it. He did not have any practical coating experience to understand coating systems. is responsible person contracted three dierent experts on the job — all of whom completed various tests that proved more inconclusive than anything else. Some reported that the coating was applied with a much higher thickness than it was allowed per the data sheet. ere were reports that temperatures were out of range of application, and too many coats were applied, adding thus more weight to the total surface, and that there was no actual control of mixing the coat. Some statements determined that the air circulation in the room was the cause of the failure and that the subcontractor did not follow the necessary parameters for the coating application. One report analyzed only the thicknesses of the coating samples that failed and fell to the -oor, ignoring those that didn't fail. None of the reports analyzed the actual relationship between the zinc primer and intumescent paint and the possible chemical reaction created in this area. In reality, 90 percent of the failures were due to the adhesive failure between these two coats. All dolly tests conducted on the zinc primer alone showed an adhesive failure, which, in this case, meant that the adhesiveness between the steel substrate and the zinc were not responsible for the failure. Other areas of adhesive failures were noticed between the zinc and topcoats and the intumescent paint. Some of these were attributed to the high degree of DFT of the intumescent coating, which, in some cases, reached up to 3,500 microns (137.8 mils). According to data sheet, 2,500 microns (98.4 mils) should have been the max. Call for New Experts As this was a major problem during the construction of the •rst -eet shipment, the initial coating inspector who had been working for the shipyard was replaced. Additionally, a third inspector with coating inspection certi•cations was hired a month later. As an expert on coatings, the third inspector was assigned to review the reports that had been given by a group of experts on both sides of the coating scheme. e shipyard was weeks from reapplying the coating system again. Within a few days, the third coating inspector determined that the coating system didn't work in practice despite working in the lab, and that no paper produced by the paint manufacturer from the intumescent paint was going to say otherwise. e third inspector recommended that the shipyard revert back to the last known working system (with the original primer), which had been working for more than 20 years. Additionally, after carefully reviewing all application logs, that third inspector recommended that the shipyard replace the subcontractor that had applied the coating the •rst time. ey didn't apply the coating according to the data sheets and didn't uphold the working condi- tions necessary. Unfortunately, the shipyard didn't listen. One year into reapplying the same system and again within six months of application, the coating on the next generation of ships failed — in a lesser degree as before, but still, some areas were as big as 6 m² (64.6 ft.²) on a 20 m² (215.3 ft.²) surface. Only then did the shipyard take steps to resolve this issue, replacing the coating system that included the zinc primer, reverting back to the old system that had worked. e shipyard also replaced the coatings subcon- tractor and told them to re-apply the tried-and-true coating system but only to the aected areas to save time and money; they left the intact areas as is in hopes that they, too, wouldn't experi- ence a premature coating failure. Lessons Learned e •rst coating inspector detected the failure within six months of application, causing a mainstream of delays and "panic" at the shipyard. is inspector was quickly replaced but not until at least another three months had gone by, meaning the same problematic coating system continued to be applied during that time. e responsible body, the shipyard, did not contribute to a better outcome; they should have raised a red -ag immediately after realizing something was wrong. Over 120 million Euros were spent because the coating experts had been ignored. Coating inspectors should be trained properly to do their job, and then the responsible parties should trust in their abilities. Finally, the team should have completed a sample of the system in the real-world environment. Despite strict controls, the re-application of the same system with the same subcontractor did not eliminate the delamination problem. In fact, changing one coating in a successful system to "save" money actually ended up costing a lot more.CP D A V, CEO/CFO at CC Cor rosion Cont rol Consu lt ing UG, has t ravel led t he world on ships as a naut ica l of f icer for more t han 10 years and has been work ing for t he past nine years in Ger man shipyard s. In 2010, Viana became a NACE Cer t if ied Coat ing Inspector w it h emphasis in Mar ine Coat ings. For more infor mat ion, contact: Dar io A g ust in Viana , d avag ust in@hot ma i Bulkhead Delamination

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