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The Interdependent Deposit-Steel Interaction during Underdeposit Corrosion (UDC)

Wednesday, 3 October 2018: 16:10
Universal 2 (Expo Center)
A. N. Shamso (Qatar University, Imperial College London), A. M. Abdullah (Center for Advanced Materials, Qatar University, Qatar), N. Laycock (Qatar Shell), and M. P. Ryan (Imperial College London)
Underdeposit Corrosion (UDC) is a major problem that faces the integrity of pipelines in the oil and gas industry, especially in sour environments (H2S- rich). Among the deposits, typically, present in sour environments, iron sulfides (FexSy) require particular attention due to their complex nature as well as their physical and chemical interaction with the bare steel, which affects the corrosion rate significantly. In this study, we investigate the changes in the surface morphology, chemical composition and electrochemical behavior of iron that is underneath sand and iron sulfides deposits. These changes are monitored after (i) potentiostatic growth of artificial pits (pencil electrode configuration), (ii) potentiostatic corrosion of an iron sheet, and (iii) a ZRA coupling of a steel-deposit pair. A scanning electron microscope coupled with an energy dispersive X-ray spectrometer (SEM/EDX), and Raman spectrometer are used to reveal the changes in the physical and chemical properties of the metal and deposits. Data are presented in terms of the deposit-metal interdependent physical and chemical changes as a function of the used deposit and the electrochemical tests.