Mestrado em Engenharia Mecânica

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http://repositorio.ufes.br/handle/10/17622

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Navegando Mestrado em Engenharia Mecânica por Assunto "Ácido acético"

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    Avaliação do efeito do etanol e do ácido acético na corrosão do aço carbono por CO2 em condições de não-formação de filmes protetores
    (Universidade Federal do Espírito Santo, 2013-09-27) Guisso, Ricardo Marcondes; Magalhães, Alvaro Augusto de Oliveira; Macêdo, Marcelo Camargo Severo de; Silva, Paulo Rogério Tavares da; Ponte, Haroldo de Araújo
    The natural gas produced in offshore platforms is sent to shore through pipelines made of carbon steel. This gas with water and corrosive agents such as dioxide gas and acetic acid are corrosive to carbon steel. Ethanol is usually injected continuously to prevent "hydrate" formation in the pipelines. This paper aims to analyze the effect of acetic acid in different concentrations and shear stresses on the corrosion of carbon steel, as well as the inhibitor effect of ethanol on corrosion in conditions of non-formation of protective films. It was found that the presence of acetic acid inhibits the anodic reaction and increases the limiting current cathodic in the corrosion process of carbon steel. These effects compete among themselves and affect the corrosion rate. It has been proved that the inhibitor action of ethanol in the corrosion process, is attributed to the increase in solution resistivity and a decrease in the acid strength of the protons. Despite the addition of ethanol had decreased of the rates of uniform corrosion in carbon steel, it was observed localized corrosion in the specimens. The conclusion is that the acetic acid plays a fundamental role in the corrosion process of carbon steel and that ethanol inhibits the uniform corrosion, but further tests are required to investigate the process of localized corrosion in these conditions
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    Avaliação do efeito do fluxo e da concentração de ácido acético na corrosão por CO2 dos aços carbono SAE 1020 e 1045
    (Universidade Federal do Espírito Santo, 2015-03-31) Monfardini, Warlen Alves; Macêdo, Marcelo Camargo Severo de; Martins, Marcio Ferreira; Rodrigues, Cezar Henrique Manzini
    The CO2corrosion is a big concern in many industries, in particular in the oil and gas exploration field. In this industry, the CO2is in gaseous form and it is hydrated forming H2CO3(carbonic acid). This acid is a weak acid and it can decrease the pH value and increase the corrosion rate. Another factor that has been studied is the presence of acetic acid (HAc) which is present in small concentration (a few mM). Considering the relevance of concentration of acetic acid, presence of CO2and mass transport, this work aim evaluate the flow effect and acid acetic concentration on the CO2corrosion of low carbon steels (SAE 1020 and 1045). Were performed the potentiodynamic polarization by a RDE geometry in solution with 3 % NaCl, saturated by CO2(1 atm), andsmall concentration of HAc (0, 300, 1000, 2000 ppm). Through the polarization curves was possible to observe a significant influence of the flow and concentration of HAc on the corrosion parameters like Ecorr, Icorr, Ilim, ba, bcand Ru. This behavior evidence a complex interaction between anodic and cathodic reactions on the corrosion process in presence of HAc. After each testing, the superficial surface wasobserved by optical microscopy and scanning electron microscopy (SEM). Was observed pitting attack in practically all conditions