Banca de DEFESA: BERNARDO AUGUSTO FARAH SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : BERNARDO AUGUSTO FARAH SANTOS
DATE: 14/11/2023
TIME: 14:00
LOCAL: UFSJ - CSA
TITLE:

“THE USE OF CORROSION INHIBITOR IN THE COMBAT OF CO2 LOCALIZED CORROSION PROPAGATION”.


KEY WORDS:
Localized corrosion propagation. Potentiostatic. Galvanic coupling. Corrosion inhibitor. Inhibition efficiency. High temperature. Imidazoline

PAGES: 169
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia Física
SPECIALTY: Corrosão
SUMMARY:
Corrosion has been reported as the main challenge faced in the oil and gas industry concerning
the management of the transmission pipelines integrity. While this deterioration mechanism
may take place in different manners, localized corrosion is known as the most dangerous and
unpredictable one, being the object of study of many research through the years. Over the years,
corrosion engineers have made significant progress in mitigating the effects of corrosion.
Among the most widely used strategies is the application of organic corrosion inhibitors, which
are highly effective in reducing corrosion. These inhibitors work by significantly decreasing
corrosion rates when added in small concentrations, usually measured in parts per million
(ppm). The initiation of carbon steel localized corrosion is commonly observed in inhibited
environments, both in field and laboratory settings, even though the uniform corrosion rate
remains low. While many reasons have been reported to explain pit initiation, little research has
considered whether these pits will propagate or not. In CO2 environments, the propagation is
likely to be driven by the local galvanic coupling established between the active pit and the
protected surrounding areas, either by the formation of protective corrosion products such as
iron carbonate or by the adsorption of corrosion inhibitors. The surface of the pit tends to present
a lower local potential than the protected surfaces, hence a galvanic current should be observed.
Complexity in simulating this phenomenon likely influences the paucity of research addressing
this mechanism. Although some authors have attempted to do so, there is a need of developing
new methodologies that can simulate pit propagation due to galvanic coupling in a simpler
manner. This current research focuses on proposing a new approach for the artificial simulation
of localized corrosion propagation scenario under produced water environment (5 wt.% NaCl,
pH 4.5, CO2) at temperatures of 55°C and 80°C. Given that its main driving force is the
difference in potential between both surfaces, the potentiostatic technique is an interesting
methodology to simulate this corrosion mechanism. Later, an actual galvanic coupling setup
was tested to confirm the observations made during the potentiostatic stage. A primarily
imidazolinium-based commercial inhibitor package was selected. Physico-chemical and
electrochemical characterizations were conducted to observe if the inhibitor selected is fit. An
understanding of the CO2 corrosion mechanism was also conducted seeking to improve the
understanding of water chemistry calculations. The results indicated that the potentiostatic
technique is an interesting tool to artificially simulate galvanic coupling, though it lacks on
providing information about the effects on the cathode. The inhibitor concentration and the
surface conditions (presence of cementite matrix) were detrimental to observing good inhibitor
efficiency. The potentiostatic tests also allowed improvement in the understanding of the so
called inhibitor desorption potential. The coupling experiments confirmed the decisive effect
played by the amount of cementite present on the microstructure of the carbon steel tested.
When a higher percentage of cementite is seen, inhibition is suppressed, and the galvanic
coupling lasts longer. The use of an actual galvanic coupling also confirmed the necessity of
higher dosages of corrosion inhibitor to properly stifle the propagation of localized corrosion.

BANKING MEMBERS:
Presidente - 1525125 - ALYSSON HELTON SANTOS BUENO
Interno - 1527524 - WAGNER SOUZA MACHADO
Externo à Instituição - MARC SINGER
Externo à Instituição - JOSE ANTONIO DA CUNHA PONCIANO GOMES - UFRJ
Externo à Instituição - DAVID YOUNG
Notícia cadastrada em: 13/11/2023 10:12
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