Cathodic protection of UNS S31600 with Al A96061 alloy sacrificial anodes for molten quaternary amine transportation

This paper examines the occurrence of lacy pitting corrosion and the implementation of cathodic protection during the transportation of a quaternary ammonium salt on the surface of stainless steel UNS S31600 at a temperature of 60 °C. The formation of lacy pitting corrosion is attributed to the neutralization and subsequent hydrolysis of residual by-products within the molten product, leading to the creation of a porous dome that triggers the development of deep hemispherical pits. To address the issue effectively, the water content of the product is investigated within the minimum and maximum limits (2.5% and 8.0%). To study this specific system, a combination of techniques including stereoscopic microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) are employed. Additionally, potentiodynamic curves and electrochemical impedance spectroscopy (EIS) are utilized. The experimental results obtained from these techniques are used to evaluate the current and potential distribution within the transportation tank of a truck, assisting in the identification of the optimal location for a sacrificial anode.