Development of high performance and efficient coating repair systems for offshore tropical marine environment

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dc.contributor.advisorKnutsen, Robert Den_ZA
dc.contributor.authorAgostinho, Francisco Joséen_ZA
dc.date.accessioned2018-05-03T12:16:34Z
dc.date.available2018-05-03T12:16:34Z
dc.date.issued2018en_ZA
dc.description.abstractRehabilitation coatings of offshore equipment rarely perform as well as the original coating, despite the high cost involved. The performance gap is probably due to high relative humidity, salt contamination and limitations on the use of abrasive blast cleaning. Thus, this research aims to deepen the understanding of surface preparation parameters that affect organic coating performance. Carbon steel samples were subjected to a variety of surface alterations consisting of salt contamination, mechanical (wire brushing) and chemical (rust converter and remover) surface preparations followed by coating application and performance testing. The samples were first pre-corroded in a corrosion chamber to mimic degradation from service then surface preparations were performed after which a coating was applied. Coated new samples (RN) and fully corroded samples (SN) were the reference sets, while other samples were prepared to a variety of surface conditions. Visual inspection and electrochemical impedance spectroscopy (EIS) were performed prior to exposure and periodically during accelerated cycling corrosion testing for a period of 30 days. The visual condition of the samples was used to rank the performance of the prepared samples. These results were used as benchmark to decide the optimum EIS method, either phase angle at high frequency or total impedance at low frequency, for early evaluation of the organic coating performance under the conditions studied. Furthermore, adhesion pull-off testing was performed to rank the effectiveness of the coating over various prepared coating. The reference new samples (RN) proved to be the best surface condition and the corroded samples without preparation (SN) had the worst performance for all tests performed. In addition, it was established that salt contamination had a stronger impact on the coating performance than the amount of corrosion product remaining on the surface. Moreover, it was determined that the best preparation approach after precorrosion of the plates was to apply rust converter to the surface before coating. Adhesion measurement was of secondary concern on the studied coated surfaces as cohesive failure occurred on the pre-treatment layers rather than coating adhesion failure between the coating and the treated surface.en_ZA
dc.identifier.apacitationAgostinho, F. J. (2018). <i>Development of high performance and efficient coating repair systems for offshore tropical marine environment</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering. Retrieved from http://hdl.handle.net/11427/27865en_ZA
dc.identifier.chicagocitationAgostinho, Francisco José. <i>"Development of high performance and efficient coating repair systems for offshore tropical marine environment."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 2018. http://hdl.handle.net/11427/27865en_ZA
dc.identifier.citationAgostinho, F. 2018. Development of high performance and efficient coating repair systems for offshore tropical marine environment. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Agostinho, Francisco José AB - Rehabilitation coatings of offshore equipment rarely perform as well as the original coating, despite the high cost involved. The performance gap is probably due to high relative humidity, salt contamination and limitations on the use of abrasive blast cleaning. Thus, this research aims to deepen the understanding of surface preparation parameters that affect organic coating performance. Carbon steel samples were subjected to a variety of surface alterations consisting of salt contamination, mechanical (wire brushing) and chemical (rust converter and remover) surface preparations followed by coating application and performance testing. The samples were first pre-corroded in a corrosion chamber to mimic degradation from service then surface preparations were performed after which a coating was applied. Coated new samples (RN) and fully corroded samples (SN) were the reference sets, while other samples were prepared to a variety of surface conditions. Visual inspection and electrochemical impedance spectroscopy (EIS) were performed prior to exposure and periodically during accelerated cycling corrosion testing for a period of 30 days. The visual condition of the samples was used to rank the performance of the prepared samples. These results were used as benchmark to decide the optimum EIS method, either phase angle at high frequency or total impedance at low frequency, for early evaluation of the organic coating performance under the conditions studied. Furthermore, adhesion pull-off testing was performed to rank the effectiveness of the coating over various prepared coating. The reference new samples (RN) proved to be the best surface condition and the corroded samples without preparation (SN) had the worst performance for all tests performed. In addition, it was established that salt contamination had a stronger impact on the coating performance than the amount of corrosion product remaining on the surface. Moreover, it was determined that the best preparation approach after precorrosion of the plates was to apply rust converter to the surface before coating. Adhesion measurement was of secondary concern on the studied coated surfaces as cohesive failure occurred on the pre-treatment layers rather than coating adhesion failure between the coating and the treated surface. DA - 2018 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2018 T1 - Development of high performance and efficient coating repair systems for offshore tropical marine environment TI - Development of high performance and efficient coating repair systems for offshore tropical marine environment UR - http://hdl.handle.net/11427/27865 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/27865
dc.identifier.vancouvercitationAgostinho FJ. Development of high performance and efficient coating repair systems for offshore tropical marine environment. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 2018 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/27865en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentCentre for Materials Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMaterials Engineeringen_ZA
dc.titleDevelopment of high performance and efficient coating repair systems for offshore tropical marine environmenten_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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