Corrosion in Systems Storing & Dispensing Ultra Low Sulfur Diesel (ULSD), Hypotheses Investigation Anne Marie Gregg Seth Faith, Barry Hindin, Michael Murphy, Kevin Ralston, Steve Risser, and Doug Turner Battelle Memorial Institute Brad Hoffman, Tanknology October 8, 2012 1
Does this look familiar? 2
From as early as 2007, PEI started receiving reports of unusually severe and accelerated corrosion in ULSD USTs Occurring in as little as 6 months 3
Initial observations • Corrosion appears in both liquid and vapor areas • Metallic wetted and unwetted areas are susceptible • No reported evidence of corrosion – at refineries – within pipelines • No apparent connection between – geographical region – supplier – age of equipment 4
Equipment Issues Reported • Filters clogging/requiring • Tank probes malfunctioning more frequent replacement • Check valves not seating • Seal/gasket/o-ring • Shear valves not deterioration sealing/failing tests • STP replacement/column • Swivels failing/shorter pipe wear/motor problems lifespan • Tanks rusting/leaking • Dispenser leaks/failures/ • Meter failure premature replacement • Line leak detectors damaged • Solenoid valves or broken clogged/failing • Automatic nozzle shutoff • Corrosion on the riser pipe failure/shorter lifespan • Pipe failure 5
Regulatory Regulatory D Drivers rivers • 2005: Energy Policy Act of 2005: – Established Renewable Fuel Standard • 2006: US EPA Clean Air Highway Diesel final rule – Required 97% reduction in sulfur content of highway diesel fuel – Low Sulfur Diesel Fuel (LSD) : 500 parts-per-million (ppm) 15 ppm in ULSD • 2007: Energy Independence and Security Act of 2007 – Set goals for biofuels production • Current status – ULSD: 80% of the change over occurred in 2006 and the remaining 20% occurred by 2010 – Ethanol: Over 90% of all gasoline is being sold with 10% ethanol content 6
Who’s Who Clean Diesel Fuel Alliance • Association of American (CDFA) Taskforce Railroads • www.clean-diesel.org • American Petroleum Institute • Ford Motor Company Contracted with Battelle • National Association of teaming with Tanknology Convenience Stores through competitive RFP • National Association of Truck to provide objective Stop Operators evaluation • Petroleum Equipment Institute • Petroleum Marketers Association of America • Steel Tank Institute 7
Project Design Hypotheses Investigation • Phase 1 – Industry observations, anecdotal information, and Tanknology inspection database - ~12 potential hypotheses - Concluded 3 working hypotheses • Phase 2 – Detailed investigation of 6 sites - Field sampling - Chemical and microbiological components – Interpretation of results – Concluded final hypothesis 8
Project Design Phase 2: Working Hypotheses 1. Aerobic and anaerobic microbes produce byproducts that establish a corrosive environment in ULSD systems 2. Aggressive chemical specie(s) (e.g., acetic acid) present in ULSD systems promote aggressive corrosion 3. Additives in the fuel contribute to the corrosive environment in ULSD systems 9
Selecting the Inspection Sites 12 sites were considered, 2 did not have symptoms Minimize Variety in: Maximize Variety in: • Tank Material • Installation Year • Fuel Throughput • Prior Fuel Service History • Tank Size • Geographic Location thereby adding variety in: – Climate – Fuel Supplies (refinery) 6 Sites Selected – Fuel Routes (pipelines, barge) • 1 site that was believed to not – Carriers (company owned, have symptoms of corrosion third party) • 5 sites with a history of severe, rapidly induced corrosion 10
Data Summary Site Characteristics NY-1 "Clean Site ID NC-1 NY-2 CA-1 CA-2 CA-3 Site" Inspection Date 8-Feb-12 15-Feb-12 16-Feb-12 21-Feb-12 22-Feb-12 23-Feb-12 Year of Tank 1998 2008 1988 1990 1991 1991 Installation Tank Capacity 17,265 12,000 6,000 10,000 12,000 6,000 (gallons) FRP- FRP- FRP- Tank Material FRP- double FRP-double FRP-single double double double Tank Diameter 120 120 92 92 120 92 (inches) Monthly Throughput 29,000 18,000 6,500 26,000 20,000 25,000 (gallons/month) Product Level 27.5 48 35 15 49 28 (inches) Filter Replaced filter not 24-Jan-12 unknown 2-Feb-12 13-Jan-12 9-Jan-12 Date identified Biocide Treatment December 2 times in unknown unknown none unknown History 2011 past year 11
Inspection and Sampling Plan • Data collected on inspection checklist, in laboratory record book, with photos and video • Each site inspected in February 2012 • Samples collected – Fuel – Water bottom – Vapor – Bottom sediment – Scrape samples • Analyses conducted by 5 independent laboratories 12
Genomics Biological Analysis • Extracted DNA from 16 samples • Analyzed 4 samples from 3 sites using genomics techniques – Compared data to library of DNA to identify organisms – Bacteria, fungi, viruses, and metabolic pathways • Confirmatory test for the presence of bacteria on samples with DNA yield too low for genomics analysis – PCR amplification of 16s rRNA gene 13
Dominant Organisms by Site Genera NY-1 NY-2 CA-2 CA-2 Gluconacetobacter sp. 35% 44% 53% 55% Acetobacter pastuerianus 33% 23% 24% 19% Gluconobacter oxydans 4.0% 3.0% 20% 19% Lactobacillus sp. 1.0% 34% 0.1% 4.0% Fungi (e.g. 9.0% 0.3% 0.1% 0.2% Zygosaccharomyces sp) Bacteriophage (virus) 7.0% 2.0% 0.8% 0.7% Gammaproteobacteria 5% 4% 0.3% 0.3% (hydrocarbon-degrading) Bacteria of the acetic acid producing family ( Acetobacteraceae ) were prevalent at three inspection sites. The hydrocarbons contained within the diesel fuel may not be the primary carbon source for the consortium of bacteria present. 14
Diversity Assessment • All sites inspected displayed presence of bacterial DNA, although in different abundances. • The conditions of the ULSD tanks are conducive to growth of limited, specialized organisms. • Less unique organisms present in the community (H) • Limited species that dominate the community (E) Historical sediment NY-1 NY-2 CA-2 CA-2 samples c Shannon’s 2.6 2.7 1.5 1.7 4.8 - 5.3 diversity (H) Shannon’s 0.23 0.22 0.13 0.14 0.74 - 0.80 equitability (E H ) As H approaches zero, an ecosystem (microbial) is dominated by very few species. E H assumes a value between 0 and 1, with 1 being complete evenness/diversity. c Previous data from marine sediments (natural environmental samples) from research studies at Battelle using the same genomics methods. 15
Chemical Analyses Summary • Fuel – Acetate and trace amounts of ethanol – 3 failing NACE ratings – Sulfur 5.9 - 7.7 ppmv • Water – Acetate, ethanol and glycolate – High conductivity, chlorides, and low pH at all sites • Vapor – High humidity, acetic acid, formic acid, and propionic acid at all sites 16
Corrosion Inducing Factors Conditions exist to lead to observed attack 1. Corrosion of metallic components – observed during inspections 2. Ingredients for a corrosive aqueous electrolyte exist – Water, oxygen, acid content, aggressive species (Chlorides) at all 6 sites 3. Microbiological activity determined at all 6 sites 4. Mechanism for electrolyte and aggressive species dispersion exists during fuel deliveries – With higher vapor pressure than ULSD, acetic acid is dispersed into vapor space 17
Corrosive Electrolyte Acetic Acid/Acetate Content Data indicate that acetic acid is the dominant acid species throughout the UST systems inspected. NC-1 NY-1 NY-2 CA-1 CA-2 CA-3 Vapor -Acetic Acid (ppmv) 0.57 1.8 3.6 7.8 9.5 16 Fuel -Acetate (ppm) ND 7.7 2.8 2.7 ND 5.9 Water -Average Acetate (ppm) a 16,500 9,000 21,000 22,500 17,500 20,000 Relative Humidity (%) a 90.9 83.3 95.5 73.7 71.8 95.2 In-tank Temp ( ° F) a 57.1 46.8 44.7 61.8 66.4 58.2 a average of two or more results ND = Not detected • Acetic acid was measured in all vapor samples. • Acetate was measured in all water samples and 4 of 6 fuel samples. • Acetic acid was identified in 75% of the scrape samples and from all sites. • Other acids were determined and should be investigated (formic, glycolic, propionic) 18
Estimated Ethanol Contamination from Unknown Source(s) Ethanol was unexpectedly identified and measured in liquid samples, suggesting ethanol is contaminating or forming in the fuel. NC-1 NY-1 NY-2 CA-1 CA-2 CA-3 Fuel-Ethanol (vol%) 0.04 0.01 0.17 0.06 ND ND Water-Ethanol (vol%) 3.17 0.66 0.45 0.40 ND 0.04 • If entering system with fuel, ethanol will separate into the water bottom (fuel-ethanol < water-ethanol) • Ethanol was used for decontamination of sampling equipment – unlikely contamination source – At all sites, fuel was sampled first, then the water bottom. Liquid sampling equipment was decontaminated once sampling was complete at each site. 19
Possible Ethanol Sources • Switch Loading – Diesel fuel is often delivered in the same trucks as ethanol-blended gasoline. • Ventilation Systems – ULSD USTs that have been converted from a gasoline tank could have manifolded ventilation systems with gasoline tanks. • Symbiotic Biological Activity – Microbes or fungi using or producing ethanol 20
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