Electrochemical Corrosion Behavior of Spirally-welded API X-70 Line-pipe Steel in Acidic and Salt Media

Abstract

The electrochemical behavior of spirally-welded API steel was investigated at ambient temperature in 3.5% NaCl and 1M H 2 SO 4 solution using linear polarization and electrochemical impedance spectroscopy (EIS) techniques. In order to reveal the corrosion resistance of different regions within the welded joint some significant characterization parameters in linear polarization and EIS curves were analyzed and compared. The surface morphology of corrosion products was also analyzed by scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The results showed that the corrosion resistance of the steel in both solutions at ambient temperature follows the order Weld Metal-Base Metal and HAZ. The corrosion of welded steel in sulfuric acid solution is more than that in NaCl solution.

Effect of sulfur content in the crude oil to the corrosion behavior of internal surface of API 5L X65 petroleum pipeline steel

“…Fe peaks are considerably suppressed because of Fe's dissolution in the acid solution. The electrons consumed at the cathode because of the reduction of the hydrogen ion are produced during the dissolution of the Fe alloy in the corrosive acid medium by anodic reaction [36]. Also, ferrous ion is a corrosion inhibitor, and changing liquid rates in these tanks and vessels can affect the corrosion rate in the plant or pipeline system [37].…”