Carbon steels are susceptible to stress corrosion cracking (SCC) in ethanol. The propensity for SCC strongly depends on the potential of the carbon steel and the oxygen concentration of the ethanol. Thus, a rugged reference electrode to reliably monitor the potential of steel in ethanol and a tool that can measure oxygen concentration in ethanol are desired to provide sufficient knowledge in determining the SCC susceptibility. The gel reference electrode used in this work showed sound performance for use in ethanol to monitor the corrosion potential of carbon steel. Compared to conventional reference electrodes, it has a small leaking rate and thus can reduce the contamination of the tested environment significantly. Furthermore, unlike an electrode with a liquid filling solution, constant maintenance is not needed because a polymer gel was used, which makes the electrode an ideal candidate for use in pipeline and storage tanks for long term potential monitoring. The oxygen concentration was measured with an optical oxygen probe. Oxygen is approximately ten times more soluble in ethanol than in water. The evaluated probe responds to the environment changes quickly and precisely and is a good tool to monitor oxygen concentration in ethanol as a way to determine the SCC propensity of the steel.
Key words: biofuel, ethanol, stress corrosion cracking, SCC, reference electrode, oxygen probe, oxygen sensor