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Benefits of Anodic Protection and Remote Monitoring on Sulphuric Acid Tanks Contaminated by NOx

Published: 20061022
Author(s): Winston Shim

The corrosion mitigation benefit of Anotection@ anodic protection (AP) systems in sulphuric acid tanks is well established. AP prevents tank wall wastage, iron contamination of acid and hydrogen grooving of tank walls. Yet, the efficacy of AP at the wet/dry (tidal) zone of tank walls has been in some doubt; and no published information is available on its effectiveness in concentrated sulphuric acid contaminated by NOX (nitrogen oxides). Laboratory tests reported that the corrosion rate of carbon steel increases by ten (10) times when exposed to NOX contaminated acid (at approx. 900 ppm) as compared to NOX-free acid. This paper presents wall thickness readings of a sulphuric acid tank contaminated by NOX at levels that would accelerate corrosion. Corrosion rates before and after the installation of an AP system are presented. The results indicate that AP is effective in mitigating corrosion of NOX contaminated sulphuric acid in both the submerged and tidal zones of the tank. Some recent advances made in the area of remote monitoring, including Internet based systems, are also discussed.

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