Erosion-corrosion characterisation for pipeline materials using combined acoustic emission and electrochemical monitoring

The prediction and monitoring of erosion and erosion-corrosion attack on oil and gas pipeline materials in service is useful for facilities design, material selection and maintenance planning so as to predict material performance accurately, operate safely, and prevent unplanned production outages. Conventional methods such as failure records, visual inspection, weight-loss coupon analysis, can be time-consuming and can only determine erosion or erosion-corrosion rates when the damage has already occurred. To improve on this, the acoustic emission (AE) technique combined with electrochemical monitoring was chosen and implemented in this study to investigate and characterise erosion and erosion-corrosion degradation rates of oil and gas pipeline materials (X65) under Submerged Impinging Jet (SIJ) systems in a saturated CO2 environment. Measured acoustic emission energy was correlated with the mass loss from gravimetric measurement for different flow velocities and sand loadings. Sand particle impacts were quantified and compared with theoretical predictions, and the associated impact energies predicted from Computational Fluid Dynamics (CFD) were correlated with measured acoustic emission energy and mass loss. The combined acoustic emission and electrochemical monitoring (involving Linear Polarisation Resistance (LPR) and Electrochemical Impedance spectroscopy (EIS)) helped to simultaneously investigate the surface reactivity of the corroding materials as well as capture the sand impacts contribution during the erosion-corrosion degradation processes. Results reveal that the effect of the mechanical damage which is not sensed by in-situ electrochemical measurement is adequately captured by the AE method, thus making the combined technique a novel approach for in-situ monitoring of both the electrochemical and mechanical damage contributions of erosion-corrosion degradation processes