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Issue link: https://read.dmtmag.com/i/94351
MARKETING & SUPPLY BY KEITHREID Presented at the PEI/NACS Show, the initial study on claimed ULSD corrosion finds a link to ethanol INITIAL ULSD CORROSION STUDY severe, but sporadic and inconsistent and there was no obvious "smoking gun" such as a specific supplier to provide an easy explanation. The cor- rosion occurred in both liquid and vapor areas and metallic wetted and unwetted areas. Further, similar corrosion could not be traced to refineries or pipelines or tied down to specific geographical regions. When found, the impact was noticed on virtually any metallic component in the fuel dis- pensing infrastructure from the tank to the nozzle. To pursue the matter further, the Clean Diesel A Fuel Alliance, which includes the Association of American Railroads; American Petroleum Institute; Ford Motor Company; National Association of Convenience Stores; National Association of Truck Stop Operators; Petroleum Equipment Institute; Petroleum Marketers Association of America; and the Steel Tank Institute commissioned the Columbus, Ohio-based research firm Battelle in conjunction with the underground storage tank test- ing and compliance services provider Tanknology, based in Austin, Texas, to study the matter. The results of this initial completed study were presented at the 2012 PEI/NACS show on Oct. 8 in Las Vegas, Nev., and raised some controversy. In general, the corrosion was tied to microbial action relative to the presence of ethanol in the tanks from cross contamination. As the conclusion states: "…the project final hypothesis is that corrosion in systems storing and dispensing ULSD is likely due to the dispersal of acetic acid throughout USTs. It is likely produced by Acetobacter bacteria feeding on low levels of ethanol contamination. Dispersed into the humid vapor space by the higher vapor pressure and by disturbances during fuel deliveries, acetic acid 14 NOVEMBER/DECEMBER 2012 S EARLY AS 2007 SOME DISTRIBUTORS began noticing corrosion issues that they believed were connected to the newly mandated ultra low sulfur die- sel. The corrosion was in many cases is deposited throughout the system. This results in a cycle of wetting and drying of the equipment concen- trating the acetic acid on the metallic equipment and corroding it quite severely and rapidly." The investigation was broken down into stages. The first phase focused on some of the more subjec- tive observations and Tanknology's inspection data- base. That generated 12 potential hypotheses that were narrowed down to three working hypotheses: Aerobic and/or anaerobic microbes are produc- ing by-products that are establishing a corrosive environment in ULSD systems. To test this hypothesis, genetic sequencing was used to defin- itively determine whether microbes are present, which microbes are in the samples from inspect- ed sites, and whether the microbes have metabo- lites that could contribute to the corrosion. Aggressive chemical specie(s) (e.g., acetic acid) present in ULSD systems is(are) facilitating aggres- sive corrosion. Testing this hypothesis involved analysis of the chemical constituents present in the fuel, water, and headspace vapor within the USTs. These chemical constituents may be corrosive in nature or may contribute to the production of cor- rosive species, more specifically, acetic acid. Additives in the fuel are contributing to the corrosive environment in ULSD systems. The approach for testing this hypothesis focused on gathering information from additives manufac- turers, refineries, terminals, stations, and pub- lished literature to understand the potential effect of additives on the overall chemical characteris- tics of the fuel and headspace vapor within USTs. The second phase involved a detailed investiga- 1. 2. 3. tion of six sites (culled from 12) that included field sampling. The site inspections entailed document- ing the extent of corrosion in the UST systems and the fuel circumstances (inventory volume, water bottom height, temperature, etc.). One site was from North Carolina; two sites were from New NPN Magazine n www.npnweb.com