CoatingsPro Magazine

SEP 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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68 SEPTEMBER 2018 COATINGSPROMAG.COM Never Again Using direct-fired propane heaters meant that the steel was below the dew point, and moisture formed on the bottom of the sloped plates of the hopper cars during the coating process. By Jon R. Cavallo, PE, FASTM, Consultant for Jon R. Cavallo PE LLC The Case of the Puzzling Railcar Lining Delamination W ith any coating failure analysis, I always recommend that these steps be performed: Step 1: Define the failure; Step 2: Complete interviews and examine records; Step 3: Review the specification; Step 4: Make field observations; Step 5: Conduct labora- tory examinations; Step 6: Examine the actual coatings involved; Step 7: Survey the literature; Step 8: Hypothesize the failure mechanism; Step 9: Confirm the failure mecha- nism hypothesis. From successful — and sometimes unsuccessful — failure analysis, I have learned that if any of the nine steps is skipped because of a fallacious assump- tion, such as "that obviously couldn't have happened," a coating failure may not be correctly diagnosed. Here is an example of a coating failure that I was involved with that almost went badly. The Situation An international plastic supply company ordered a large number of covered hopper cars from a well-equipped railcar manufactur- ing facility. Each of the new hopper cars was to be lined using a two-coat commercial epoxy that had been used worldwide on similar projects. e coating system consisted of abrasive blast surface preparation to meet NACE No. 2/Society for Protective Coatings (SSPC) Surface Preparation (SP) 10: Near-White Metal Blast Cleaning at a specified surface profile range followed by the application of two coats of the specified epoxy coating. e railcar manufacturer had recently installed an almost completely automated abrasive blasting and coating application line that could be adjusted via computer programming to Photos courtesy of Jon R. Cavallo PE Photo courtesy Getty Images The cars were subsequently sent to many shops to be relined due to the sheer number of cars involved.

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