Corrosion in Underground Storage Tanks (USTs) Storing Ultra-Low - PowerPoint PPT Presentation

Corrosion in Underground Storage Tanks (USTs) Storing Ultra-Low Sulfur Diesel (ULSD): EPA Research on Risks, Prevalence, Causes, and Next Steps Presented at the National Tanks Conference September 16, 2015 Ryan Haerer EPA Office of Underground Storage Tanks

Outline What is ULSD Corrosion? ◦ The problem ◦ Impacts EPA’s Research Study ◦ Potential causes ◦ Overview ◦ Key Findings What do we do with the ◦ Conclusions results? ◦ Educate ◦ Address issues ◦ Update standards and practices ◦ Further research into prevention and treatment

Corrosion in USTs Storing ULSD Reports began around 2007 Internal metal components – often STP shaft Severe and rapid onset Yet unidentified cause Extent not fully known Appearance different and impacts more severe than corrosion in sump spaces of USTs storing gasoline/ethanol blends

What do we know about the possible cause? Reports of corroded metal equipment in vapor space of USTs storing ULSD – first in 2007 Two changes to fuel supply around same time ◦ Reduced sulfur content in diesel beginning 2006 (500ppm LSD to 15ppm ULSD) ◦ Increased production and use of ethanol and biodiesel* 2012 Hypotheses Investigation by Clean Diesel Fuel Alliance of 6 UST storing ULSD * Energy Independence and Security Act of 2007 expanded Renewable Fuel Standard, setting volumetric blending targets for renewable fuels

Corrosion Risks to the Environment – Exposed Metals in the Vapor Space Release prevention equipment could fail to function ◦ Corrosion on flapper valves could restrict movement and allow an overfill ◦ Product level floats get stuck on corroded shafts and fail to signal a rising product level, fuel release, or water infiltration ◦ Ball float valves – ball or cage may corrode ◦ Line leak detectors failing performance testing at higher rates

Some Observed Corrosion Examples –

Corrosion Risks to the Environment – Bottoms of Tanks Metal components could corrode completely and possibly release fuel to environment ◦ ULSD prone to collect water and sludge in bottom of tanks ◦ Some jurisdictions seeing much higher rates of bottom failures of primary walls of double-wall steel tank bottoms since ULSD ◦ Single-wall tanks possibly leaking undetected

Some Observed Corrosion Examples

Costs of Metal Corrosion for Owners Increased pace of filter changes More frequent servicing of equipment Shorter lifespan before replacement of equipment

Findings from Clean Diesel Fuel Alliance 2012 Hypotheses Investigation ◦ Not conclusive, but suggested microbiologically influenced corrosion (MIC) a possible cause worth further research ◦ Microbes feed on ethanol present in ULSD, creating acetic acid Ethanol can be converted into acetic and butyric acid (and ◦ Ethanol possibly entering ULSD through switch-loading possibly into glycolic acid) of trucks wherein a gasoline-ethanol load is followed by a diesel one, or by diesel and gasoline-ethanol blend UST’s sharing the same vent line.

Could other factors be in play? ◦ Glycerol can also be converted to corrosive acids ◦ Propionic acid presence in 2012 suggests this possibility ◦ Glycerol (possibly) in biodiesel, biodiesel possibly in ULSD* ◦ Allowable concentration from production, or ◦ Out of specification biodiesel ◦ Likely that a combination of factors involved Glycerol into glyceric, lactic, and propionic acids *ASTM D975 allows biodiesel to be blended into ULSD up to 5% without being labeled biodiesel

2014-2015 Study on the Corrosion of Metal Components in USTs Storing ULSD Environmental Protection Agency Office of Underground Storage Tanks (OUST) Battelle Memorial Institute UST owner volunteers and industry partners, esp. CRC Diesel Corrosion Panel – could not have made the study happen without them! Thank you! Provided critical site access for real-world data collection Provided data input on tank history and management practices Critical review of study design and draft reports

What did we set out to accomplish with the 2014-2015 Research Effort? Research designed: This research was NOT intended to: For continuity- ◦ Build on previous research and help figure out how to address the problem ◦ Allow others to build on what we find Definitively pinpoint a specific cause – every UST is unique To better understand the extent of the Identify specific solutions to the problem problem and potential risks identified in the limited reports we’ve heard Identify correlations among UST systems with severe or minimal corrosion

Identify Volunteers for a Diverse UST Sample Population • 10 geographic clusters 42 USTs by Capacity and Material 42 sites • 20 24 fiberglass, 16 steel, 2 steel coated • 8 of 10 have steel and fiberglass in cluster 16 • • 8 owners 12 # of USTs Government, retail, fleet • Single and multiple site 8 • Large range of fuel throughputs and suppliers • 4 • Diverse USTs 0 1 – 29 years in service • 5,000 6,000 7,000 8,000 10,000 12,000 15,000 20,000 5,000 to 20,000 gallons in capacity Tank Capacity (gallons) • Different product storage histories Steel Fiberglass • Various approaches to maintenance •

Collect Data on UST Conditions at Each Site Collect samples: Vapor • Fuel • Water bottom • Inspect with internal tank video Collect information on maintenance, throughput, fuel supply, biocide use, etc.

FUEL Sample Analyses Fuel Analysis Methods Method Identifier Determination of Water in Petroleum Products, Lubricating Oils, and Water Content Additives by Coulometric Karl Fischer Titration ASTM D6304 8 (Procedure B) Determination of Density, Relative Density, and API ASTM D4052 10 Density Gravity of Liquids by Digital Density Meter Acid Number of Petroleum Products by ASTM D664 11 Total Acid Number Potentiometric Titration WATER Determining Corrosive Properties of NACE TM-172 12 Corrosion Rating Cargoes in Petroleum Product Pipelines Particulates Particulate Contamination in Middle Distillate Fuels ASTM D6217 13 by Laboratory Filtration FUEL Determination of Biodiesel (FAME) Content in Diesel Water Bottom Analysis Methods Method Identifier Determination of ASTM D7371 14 Fuel Oil Using Mid Infrared Spectroscopy (FITR-ATR- Biodiesel Content Acetic, Formic, Propionic, PLS Method) Ion Chromatography (IC) for short chain fatty Modified EPA 300 acids ASTM D93 15 Flash Point by Pensky-Martens Closed Cup Tester Flashpoint Lactic Acids Determination of Free and Total Glycerin in Biodiesel Blends by Anion Exchange ASTM D7591 16 Free and Total Glycerin IC Test for Free Glycerin Lab In-House Method Glycerin Chromatography GC-MS Full Scan Lab In-House Method Unknowns of Interest Determination of Dissolved Alkali and Determination of Total Sulfur in Light Hydrocarbons, Alkaline Earth Cations and Ammonium in Cations (Sodium, Calcium, Magnesium, Potassium, Ammonium) and ASTM D6919 19 Spark Ignition Engine Fuel, Diesel Engine Fuel, and ASTM D5453 17 Sulfur Content Water and Wastewater by Ion Anions (Chloride, Sulfate, Nitrate and Fluoride) Engine Oil by Ultraviolet Fluorescence Chromatography Electrical Conductivity of Aviation and Distillate ASTM D2624 18 Conductivity Fuels pH EPA 150.1 20 pH (Electric) Determination of Short Chain Fatty Acids by Gas Lab In-House Method Acetate, Formate, Propionate, Lactate, Glycerate Chromatography-Mass Spectrometry (GC-MS) Conductance (Specific Conductance, umhos Conductivity EPA 120.1 21 at 25°C) Nonhalogenated Organics Using GC/FID SW846 8015B 22 Ethanol and Methanol VAPOR Vapor Analysis Methods Method Identifier Determination of Hygrometer used per Ullage % Relative Humidity manufacturer % relative humidity instructions Carboxylic Acids in Ambient Air Using ALS Method 102 Acetic, Formic, Propionic, and Butyric Acids GC-MS Determination of Modified Lactic Acid in Ambient Lactic Acid NIOSH 7903 Air

Assess and Categorize Corrosion Coverage Based on protocol developed by CRC Diesel Performance Group – Corrosion Panel 3 assessments of coverage on STP shaft ◦ Minimal as < 5% ◦ Moderate from > 5% to < 50% ◦ Severe as > 50% If in unanimous agreement, UST was categorized If not in agreement, discussed and considered overall condition of UST equipment and categorized by panel vote

Observed Corrosion Examples – Example Of An UST System with a Fiberglass Example Of An UST System with a Fiberglass Tank With Severe Corrosion Coverage Tank With Minimal Corrosion Coverage (Installed 1986) (Installed 2003 And Age Of Filter < 1 Month).

Observed Corrosion Examples – Example Of An UST System with a Steel Tank Example Of An UST System with a Steel Tank With Minimal Corrosion Coverage Example With Severe Corrosion Coverage (Installed (Installed 1994) 1992).

More Corrosion Examples – STP Shafts Drop Tubes Tank Walls Ball float cages ATG floats/shafts

42 USTs by Corrosion Category and Material 20 Looking at the Data 16 9 11 12 8 4 8 4 7 3 0 Minimal Moderate Severe Steel Fiberglass Analyzed data according to corrosion category Identify potential predictive characteristics Identify any trends with respect to corrosion development

A note about findings: Please do not cite. This is preliminary data from the report which has not yet completed peer-review. This is presented only to share what we initially observed. Only the final peer-reviewed paper should be cited as an official source of information from the study.