The goal of this work was to test for the occurrence of the current ϫ resistance ͑IR͒ voltage form of crevice corrosion in a corrosion-resistant alloy. Crevice corrosion occurred immediately ͑prior to a change in the solution composition͒ in alloy T-2205 duplex stainless steel exposed to an acidic-chloride media. This was indicated by the immediate, large ͑mA͒ measured current, large ͑0.5 V͒ measured electrode potential, E(x), profile and polarization curve on the crevice wall, and in situ visual observation of the corrosive attack on the part of the crevice wall that was in the active peak region of its polarization curve. Thus, these results show that the IR voltage and the resulting active peak E(x) values on the crevice wall were entirely responsible for stabilizing the crevice corrosion process in this spontaneously active metal/electrolyte system.

Top-of-the-line corrosion (TLC) is a potential issue for carbon steel pipelines transporting natural gas. This type of corrosion is driven mostly by the gradient of temperature between the warm produced fluids and the outside environment, but also is affected strongly by the presence of corrosive species such as carbon dioxide (CO 2 ), hydrogen sulfide (H 2 S), and organic acids. This paper presents an assessment of the corrosion risk of a specific sour offshore development: the Karan gas field (Arabian Gulf, Saudia Arabia). The study was performed through laboratory experiments in a large-scale flow loop as well as in a specially designed autoclave equipped for corrosion studies under dewing conditions. Corrosion rates were obtained using the weight-loss method and the surface layer was analyzed with x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). The TLC rate was found to be low under all conditions tested, and no indications of localized corrosion were observed. Mackinawite, cubic iron sulfide, and troilite (stoichiometric pyrrhotite) were identified in the corrosion product layer. KEYWORDS: carbon dioxide, hydrogen sulfide, top-of-the-line corrosion, water condensation rate ISSN 0010-9312 (print), 1938-159X (online) 13/000115/$5.00+$0.50/0 © 2013, NACE InternationalFIGURE 17. Influence of the gas temperature on TLC.