FORMULASI INHIBITOR KOROSI BERBASIS ZINK–FOSFAT DAN MIKO–DEA PADA PIPA PENDINGIN SEKUNDER REAKTOR SERBA GUNA GERRIT AUGUSTINUS SIWABESSY

Abstract

The material for the secondary cooling pipes of RSG-GAS is low carbon steel. The pipes carry fluids that have the potential to cause corrosion. To reduce the corrosion rate, both inorganic and organic inhibitors are added. The inhibitors used are a mixture of zinc-phosphate as an inorganic inhibitor and miko-DEA as an organic inhibitor in a 0.1% NaCl medium. Zinc-phosphate inhibitors are tested at concentrations of 25, 35, and 50 ppm, and miko-DEA inhibitors at concentrations of 50, 75, and 100 ppm. To study the effects on corrosion rate and the corrosion behavior of carbon steel, electrochemical methods were employed, including Open Circuit Potential (OCP) for 600 seconds, Electrochemical Impedance Spectroscopy (EIS) over a frequency range from 10⁵ Hz to 0.01 Hz, and Potentiodynamic Plot (PDP) over a voltage range from -1 Volt to 1 Volt using a potentiostat. To support the corrosion test results, surface morphology of the samples with and without inhibitors was observed using SEM, and compounds in the zinc-phosphate and Miko-DEA solutions were identified using FTIR. The optimal formulation that resulted in the lowest corrosion rate was a mixture of 50 ppm zinc-phosphate and 75 ppm miko-DEA in a 0.1% NaCl medium. The achieved corrosion rate was 10.57 mpy.