Evaluation of metal-based structures has relied on atmospheric exposure test sites to determine corrosion resistance in marine environments. This work uses surface chemistry and electrochemical techniques to interpret the chemical changes occurring on low carbon and stainless steel during atmospheric and accelerated corrosion conditions to find a correlation between its accelerated and long-term corrosion performance.
Encapsulation of Linseed Oil & Tung Oil in urea-formaldehyde shells was performed using in-situ polymerization technique. Thin film self-healing coatings with uniform and quick self-healing ability were achieved with microcapsules at concentration of 3 wt%. Anti-corrosive performance was evaluated using immersion test & electrochemical impedance spectroscopy (EIS).
The effects of cyclic stress and strain on corrosion-fatigue in sweet and sour corrosion were studied with an electrochemical approach. Cold-drawn and cold rolled carbon steel samples were mechanically cycled in a confined and CO2-saturated synthetic seawater solution, and their electrochemical response was acquired with a classic 3-electrode apparatus.
A technology to detect corrosion damage and estimate extent and location within an enclosed volume. This coating condition monitoring (CCM) system is a network of sensors that measure conditions and electrochemical parameters to evaluate the health of coating and substrate for steel plates and tanks.
The pitting corrosion and crevice corrosion of oilfield production alloys (e.g., 13Cr/UNS S41000, 17-4PH/UNS S17400, 25Cr/UNS S32750, A286/UNS S66286, 718/UNS N07718) and proprietary austenitic stainless steels for directional drilling (PREN between ~20 to ~45) has been investigated. Specifically, series of electrochemical tests have been conducted to rank the alloys, establish simple correlations between electrochemical parameters, PRENmod, and 3-to-60-day immersion tests in 3.5% NaCl at ambient temperature. For all but one alloy, pitting was absent in stark contrast to crevices. Upon tracking populations and dimensional characteristics of crevices over time, trendlines comparing the susceptibility of the alloys towards crevice corrosion were established. Practical conclusions were reached, including the following: (1) 13Cr consistently developed crevices within days, (2) 17-4PH as well as all traditional directional drilling stainless steels developed crevices within one to five weeks, and, (3) neither 718, 25Cr, nor newer directional drilling alloys with both high nickel and high PRENmod showed any sign of crevices upon being tested up to 60 days. Through a variety of comparisons, this investigation also reveals useful technical directions for the development of new, economical, and fit-for-service Oil & Gas alloys for both production and drilling.