Corrosion Behavior of SA508 Coupled with and without Magnetite in EDTA-Based Solutions

Abstract

The effects of magnetite on the corrosion behavior of SA508 were studied in 10% and 20% EDTA-based chemical cleaning solutions at 93 °C and 121 °C using electrochemical and immersion tests. SA508 was the anode of the galvanic pair between SA508 and magnetite. The galvanic coupling shifted the mixed corrosion potential of SA508 in the positive direction and thus increased its corrosion rate. The increase of the EDTA concentration and solution temperature led to an increase in the extent of the galvanic effect.

Galvanic Corrosion of SA106 Gr.B Coupled with Magnetite in Alkaline Solution at Various Temperatures

“…Thus, several studies on the galvanic effect of magnetite on the corrosion behavior of various secondary materials and water chemistry conditions were recently reported [16,17,18,19,20,21,22]. With respect to SG tube materials, such as Alloy 600 and Alloy 690, the corrosion rate of SG tube materials significantly increased due to a shift in their corrosion potentials in the positive direction in alkaline aqueous solutions [16,17,18,19].…”

“…Additionally, magnetite exerts a synergistic effect on increase in the corrosion rate of SG tube materials with chemical impurities, such as chloride ions [18] and lead ions [19]. The effect of magnetite contact on the galvanic corrosion of SA508 SG tubesheet material was also investigated in ethylenediaminetetraacetic acid (EDTA)-based chemical cleaning solutions through electrochemical and immersion tests [20]. SA106 Gr.B carbon-manganese steel corresponded to the anode when this steel and magnetite were electrically connected in an alkaline solution at room temperature [21].…”

From initial treatment design to final disposal of chelating agents: a review of corrosion and degradation mechanisms

“… 101 Thermal degradation of EDTA was found to decrease the amount of free EDTA rapidly at higher temperatures. 102 Final degradation products of EDTA have also been shown to be dependent on the temperature of the system 92,103 ( Fig. 6 ).…”