Abstract
Corrosion coupons are one of the most frequently used methods to measure the severity of corrosion in oil and gas pipelines. Typically, operators use weight loss coupons to determine rates of general corrosion and occasionally pitting. Extended analysis (EA) coupons are less frequently used but can provide additional information such as rate of pitting and the corrosion mechanism which are critical when evaluating the need for additional information or considering the most effective course for mitigation. Improper mitigation can result in wasted time, resources, or worsened corrosion rates in some instances; therefore, proper understanding of corrosion rates and mechanisms is a critical step in the corrosion management process. Examples of analysis methods that are frequently applied to EA coupons include optical profilometry, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (XRD), and biological characterization methods such as quantitative polymerase chain reaction (qPCR) and adenosine triphosphate (ATP). This paper discusses these different analysis methods and the significance of the data obtained and presents a case study where a mitigation plan was developed based in part on the active corrosion mechanism identified using EA coupons.
