Análise quantitativa de danos por corrosão sob tensão em arames de armadura de tração de risers flexíveis submetidos a corrosão por frestas em meio doce

• Autor(a) principal: Trindade, Matheus Porto
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/jspui/handle/riufs/14746
• topic: Engenharia; Ciência dos materiais; Oleodutos submarinos; Tubulações - Corrosão; Aço - Corrosão; Anticorrosivos; Risers; Crevice corrosion; Stress corrosion; Tensile armor wires; ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

The failure of components of flexible risers can occur, among several factors, due to the collapse of their tensile armor, which are manufactured from drawn carbon steel wires. These wires have a high susceptibility to corrosion to ocean water which, when associated with high tension, high pressure and temperature, CO2 saturation and occurrence of crevices, increases the propensity to pitting corrosion. This corrosion mechanism, called stress corrosion associated with sweet crevice corrosion, causes premature failure of the armor components, which arouses great interest in the offshore petrochemical industry. In this study, the influence of the crevices between the polymeric and metallic layer, typical of the annular region of the riser ducts, was quantified in the severity of pitting corrosion in two distinctly cold-formed carbon steel wire profiles. Immersion corrosion tests were carried out, subjecting the wires to three points bending and exposing them to a saline solution under atmospheric pressure (1 bar) at room temperature (25 ºC) and 20 bar at 60 ºC. The effects of pitting corrosion were subsequently evaluated by optical microscopy and Raman spectroscopy. The electrochemical polarization and immersion tests at 1 bar and 25 ºC showed no significant differences. The occurrence of crevices and internal energy presented itself as a significant enhancer of pitting corrosion, while the carbon content was not distinctive, demonstrated by the greater frequency and depth of the pits and the arrangement of corrosion deposits in samples with crevices.