Esquemas de pintura de proteção anticorrosiva para condições especiais de exposição

Abstract:

The performance of organic coatings is strongly influenced by the quality of the paints, surface preparation, and application procedures. Conventional paint requires about 10 days from preparation to complete curing, which represents a long period of equipment unavailability. In this project, the basic premise was to select systems that, in addition to high corrosion resistance, reduce cure time. Depending on the environmental conditions, high-thickness technologies and reduced curing time will result in superior performance because it minimizes contamination problems. Eight different coatings were applied in Vale’s units in Vitória and São Luís, and under controlled laboratory conditions. The test specimens were submitted to cyclic corrosion tests, immersion tests in DI water, synthetic sea water and the Atlas Cell, and evaluated for degree of rusting, degree of blistering, and corrosion under cut. Each parameter was assigned a set of letters and numbers associated with the quantity and size of defects. In order to classify the coatings performance, a criteria based on ISO 4628 was developed, which consisted in assigning grades varying from 0 to 10 for the degree of corrosion, degree of blistering, under cut corrosion and pull-off test. The notes were added to compose the final grade. The three systems that presented the best performances were selected to be studied in the next phase of the project. In the accelerated corrosion tests and in the immersion tests, the coatings BD; JK e FH presented no rusting or blistering, with surface treatment Sa 2½, even in the coupons coated in Vitoria unit. The coating BD presented the best performance in Vitoria and IPT, whose surface treatment was Sa 2½. In São Luís, with St 3 surface preparation, the GH coating presented the best performance following the by CD e FH. This study also showed that the surface treatment St 3, regularly practiced in São Luís, brings important damages to the performance of the coatings and consequently demands shorter intervals of maintenance interventions.


Reference:
ALMEIDA, Neusvaldo Lira de; ALMEIDA, Marcio Bispo de; LIMA Dii Taline; ROCHA, Bernardo Batista; ORRICO, Vitor Ribeiro. Esquemas de pintura de proteção anticorrosiva para condições especiais de exposição. In: INTERNATIONAL CORROSION MEETING, INTERCORR, 7., 2018, São Paulo. Proceedings… São Paulo: ABRACO, 2018. 21 p.

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