In this study, we investigated the performance and reliability of commercial corrosion sensors for monitoring the integrity of piping systems in various fluid environments as an alternative to ultrasonic transducers. To this end, we investigated pipes’ wall-thinning using commercial electrical resistance (ER), linear polarization resistance (LPR), and ultrasonic transducer (UT) sensors under various operating environments. A pilot-scale closed-loop test bed was built to simulate a real pipeline flow situation, from which the sensor data were collected and analyzed. Experimental results indicate that, in the case of the LPR sensor, it is challenging to accurately measure the corrosion rate when a specific measure exceeds the threshold in a severe corrosion environment. In contrast, the ER sensor could measure metal loss under all conditions and reflect the corresponding characteristics. The metal loss (about 0.25 mm) of the real pipe after the experiment was confirmed to be equal to the metal loss (0.254 mm) measured by the sensor. Furthermore, the regression analysis revealed a high correlation between the results obtained from the ER and UT sensors. Thus, evaluating the remaining thickness of the piping system using the commercial ER sensor is deemed to be effective and reliable.

In this investigation, potentiodynamic polarization experiments were conducted on UNS S31603 and UNS N08367 in a modified green death solution, which simulates the environment of a desulfurization device (scrubber), using temperature as a variable. A Tafel analysis showed that the corrosion current density of UNS S31603 at the highest temperature (90 °C) was approximately 4.5 times higher than that of UNS N83067. A surface analysis using a scanning electron microscope revealed that pitting and intergranular corrosion occurred simultaneously in UNS S31603, whereas UNS N83067 exhibited a stronger tendency toward intergranular corrosion. After electrochemical experiments, the corrosion rates according to maximum damage depth were compared with the corrosion rates according to corrosion current density; the relationships between the two values were expressed as α values. The α values of UNS N08367 were higher than those of UNS S31603, indicating that the local damage rate of UNS N08367 was higher.

Inorganic electrolytes are commonly used in commercial electropolishing. However, interest in eco-friendly electrolytes is on the rise. This investigation presented how electropolishing with choline chloride, an eco-friendly electrolyte, affects the molar ratio of ethylene glycol and applied potential. Electrochemical experiments were conducted in natural seawater on stainless steel electropolished under ideal conditions. The passive current density increased as the ethylene glycol molar ratio rose (1:1, 1:2, 1:3) in choline chloride. However, the plateau of the passive current density was most clearly observable in a solution composed of choline chloride and ethylene glycol at a 1:2 molar ratio. Electropolishing under optimal conditions reduced the surface roughness and height by 67.3% and 90.5%, respectively, compared to mechanical polishing. The corrosion current density of the mechanically polished and electropolished stainless steel was calculated as 0.35 ㎂/cm2 and 0.01 ㎂/cm2, respectively, and the pitting potential was 286.08 mV and 410.11 mV, respectively.