UNS N04400 cladding on steel valves can corrode during marine service. The uniform corrosion rate of an EN coating in artificial seawater was measured by electrochemical impedance spectroscopy and was found to be less than that for N04400. The main conclusion is that an EN coating could be a viable solution to repair N04400-clad valves in-situ.
Electrochemical test methods including open-circuit potential, electrochemical impedance spectroscopy, potentiodynamic polarization, and zero-resistance ammetry were used for corrosion investigation of UNS C69100 in a 3.5 wt.% sodium chloride aqueous solution, with optical and scanning electron microscopy.
This paper compares and contrasts the accelerated laboratory autoclave (NACE TM0185) performance at 300°F (149°C), and 250 psig, of eight polycyclamine cured epoxy linings. The latter were tested for tank, vessel and pipe spool applications in the oil and gas industry. Five of the linings were commercially available and three were experimental. A modified amine cured epoxy was also evaluated in the study, a lining used to transport shale oil in railcars at temperatures up to 200°F (93°C).