Evaluation of the Tafel Piontelli Model Under Flowing Weak-Acid Conditions: Toward Improved CO2 Corrosion Prediction

This study evaluates the extension of the Tafel-Piontelli framework to predict carbon steel corrosion across a spectrum of acid strengths. While the model effectively describes corrosion in strong acids under static conditions, its reliability for weak acids, particularly under the influence of flow velocity, remains unverified. This study addresses that gap by systematically investigating the role of fluid velocity in acetic acid environments. Using a rotating cylinder electrode to generate controlled flow, this research quantifies how mass transfer enhancement modifies underlying electrochemical mechanisms. Corrosion kinetics were characterized through potentiodynamic polarization (PDP), linear polarization resistance (LPR), and mass loss techniques (ML). Results indicate that corrosion behavior is governed by the synergistic effects of temperature, pH, and flow velocity. A clear transition to mass transfer-controlled corrosion occurs in weak organic acid environments. Flow influence becomes increasingly significant at elevated temperatures, where hydrodynamics markedly accelerates anodic dissolution, while at lower temperatures its effect is minimal. These findings provide the essential experimental basis to adjust the Tafel-Piontelli model for field-relevant conditions, enabling a more robust, physics-based prediction tool for carbon steel where weak acid chemistry and flow jointly govern degradation rates.