Re‐examining the influence of chloride ions on electrochemical CO₂ corrosion of pipeline steels—corrosion of the heat‐affected zones (HAZs) of API‐X100 steel

Abstract

This research investigates the corrosion characteristics of simulated heat‐affected zones (HAZs) of API X‐100 pipeline steels in CO2‐saturated brines of different chloride concentrations. It links the significances of the HAZ microstructure and chloride concentration to the corrosion kinetics and corrosion products. The ferritic HAZs dissolve at almost two times the rate of acicular ferritic and bainitic HAZs. This paper shows that the samples corrode at rates increasing with the chloride concentration to a maximum rate, at a low chloride concentration, beyond which the corrosion rates decrease with increased chloride concentrations. For the base steel, for instance, the corrosion current densities increased from 8.5 μA/cm2 in 0.02 mol/L to the maximum 22 μA/cm2 in 0.07 mol/L before they decreased to 10 μA/cm2 in 0.1 mol/L. The corrosion products showed an increase with the chloride concentration, from almost 1‐3 μm to 25‐35 μm in 0.02 and 0.85 mol/L solutions, respectively.

Failure analysis of an oil pipe wall perforated by pitting corrosion

“…The corrosion process may be dominated by the three reactions, Eqs. – : …”

“…What is more, Fe 2+ can react with CO 3 2− via a one-stage reaction with carbonate, or via a two-stage reaction with bicarbonate. [19][20][21][22] The corrosion process may be dominated by the three reactions, Eqs. (7)-(9) [19,20,22] :…”

Modeling Corrosion Reactions of Steel in a Dilute Carbonate Solution

“…It might not have fully consolidated some of the mechanistic details that are until today being investigated, but it provides a visual guide that helps better understand the corrosion reactions and the significance of the properties and reactivity of the corrosion products. The test samples are made of API-X100, a new-generation pipeline steel, whose electrochemical significance and behavior were explained and examined previously ( Ref 1,8,10,[20][21][22].…”

Effects of chloride concentration on CO2 corrosion of novel 3Cr2Al steel in simulated oil and gas well environments

“…Hausler et al demonstrated that Cl − had no noteworthy effect on CO 2 corrosion. However, Eliyan revealed that corrosion reactions exhibited a special trend with chloride concentration, as they increased and later decreased due to the thickening of corrosion products. Liu found that for carbon steel, Cl − had no effect on the composition of the corrosion product.…”