PurposeThis paper aims to estimate the corrosion rate of the carbon steel in crude oil using the electrochemical noise (EN) analysis technique.Design/methodology/approachEN measurements and electrochemical impedance (EIS) spectroscopy were employed to study the corrosion behaviour of carbon steel in crude oil and the optimum conditions of the noise analysis for estimating corrosion rate of the carbon steel are discussed. The time series noise patterns were transformed into frequency domains by fast Fourier transformation, and then their power spectrum densities (PSDs) at a frequency were determined to be compared with the corrosion rate.FindingsThe PSDs of the potential and of the current varied with changing of rotation rate of electrode and immersion time. Square roots of the PSDs for the potential difference and for the currents were in positive and almost linear correlation with the corrosion rate obtained from EIS plots. In addition, the spectral noise was negatively and linearly correlated with the corrosion rate. The relationship between the corrosion rate and the spectral noise resistance was better at lower frequencies.Research limitations/implicationsIt is suggested that this research is carried out for crude oils with other physical and chemical characteristics.Practical implicationsThe PSD value at 3 mHz from the noise of the current and the spectral noise resistance at the same frequency are the optimum conditions for estimating corrosion rate in this research.Originality/valueThis paper arguably fills a gap in the current understanding of the interactions between corrosive species commonly found in crude feedstocks and process streams.