Evaluation of Ammonia Hydroxide for Mitigating Stress Corrosion Cracking of Carbon Steel in Fuel Grade Ethanol

Carbon steel is susceptible to stress corrosion cracking (SCC) in fuel grade ethanol (FGE). It has been found SCC in FGE can be inhibited by adding inhibitors. This paper reports the work conducted to evaluate several different commercially available inhibitors and a generic chemical, NH₄OH. The efficacy of the inhibitors was tested using slow strain rate (SSR) testing and crack growth rate (CGR) tests in simulated FGE (SFGE). The performance of these inhibitors in reducing the corrosion rate of carbon steel in SFGE was also evaluated using electrochemical method. The electrochemical results were compared to the SSR and CGR results in an effort to develop a rapid screening method for selecting inhibitor to prevent SCC in FGE.