Evaluación del efecto del contenido de azufre en la velocidad de corrosión del acero grado A335-P9 en un crudo pesado

Abstract

The effect of sulfur in the formation of a iron sulfide (FeS) layer and its influence on the corrosion rate of grade ASTM A335-P9 steel was investigated, in an environment that simulates the processing conditions of heavy oils. Different electrochemical techniques including: electrochemical impedance spectroscopy and Tafel extrapolation as well as gravimetry were used. The exposure times used in gravimetry were 3, 6, 9, 10, 15 and 20 hours at temperatures of 200, 230, 260, 280, 300 and 320°C. The temperatures used for electrochemical techniques were 25, 200, 230, 240, 250 and 270°C. The sulfur content in the heavy oil and the stirring speed were kept constant at 1.55wt% and 15rpm respectively. The morphology of the surface damage was studied using X-ray diffraction and scanning electron microscopy. The results of impedance curves and potentiodynamic curves confirmed a reduction in the corrosion rate of ASTM A335-P9 steel with the temperature probably due to the formation of a layer of iron sulfide.

Keywords

• heavy crudes
• sulfur
• electrochemical impedance spectroscopy
• Nyquist diagrams
• Tafel extrapolation
• and gravimetric method