Corrosion of copper and steel alloys in a simulated underground storage-tank sump environment containing acid-producing bacteria

• A protocol was developed to simulate microbiological corrosion during fuel storage.
• Acid-producing bacteria induce vapor phase corrosion of copper and steel.
• Extensive localized corrosion was observed on copper and carbon steel coupons.
• Corrosion product analysis revealed similarity to abiotic acetic acid corrosion.
• Acetobacter sp. may inhibit aqueous corrosion of steel during immersion.

We simulate corrosion observed in underground fuel storage tank systems by headspace and aqueous exposure to biotic organic acid. Carbon steel and copper were exposed to Acetobacter sp. inoculated into aqueous-ethanol solutions over a period of approximately 30 days. The steel alloy exhibited pitting corrosion and the copper alloy exhibited pitting and intergranular corrosion due to acetic acid produced by the microbes. Corrosion rates were dependent on formation of corrosion products and are ranked as follows in order of increasing magnitude: Copper-aqueous < Steel-aqueous < Copper-headspace < Steel-headspace. The laboratory test method developed here reproduces corrosion observed in practice.

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