Executive Summary Literature Review Impact of Gasoline Blended with Ethanol on the Long Term Structural Integrity of Liquid Petroleum Storage Systems and Components JUNE 2002 Copyright American Petrol[.]
INTRODUCTION
This report summarizes the results of a literature review conducted for the American Petroleum
Institute on the impact of gasoline blended with ethanol on the long-term structural integrity of liquid petroleum storage systems and components
The growing use of ethanol in motor fuels raises concerns about its long-term impact on liquid petroleum storage systems, particularly underground storage tanks (USTs), underground piping, and related components.
The literature review aims to assess the current understanding and research regarding the impact of ethanol/gasoline blends on the long-term structural integrity of underground storage tank (UST) systems and components This review is designed to guide decision-makers in identifying further research needs and necessary modifications or additions to existing standards for underground storage systems and components utilized for storing and dispensing ethanol-blended gasoline.
LITERATURE REVIEW
Appendix A includes the synopses and bibliographic details of all articles reviewed for this project, organized by their index numbers The reference numbers mentioned in this report correspond to these article index numbers.
FINDINGS
Overview of Ethanol in Gasoline Fuel
Ethanol is an alcohol derived from the fermentation of biomass, primarily corn, but other sources can also be utilized It exists in two forms: "hydrated" ethanol, which contains some water, and "anhydrous" ethanol, which has had all water removed As a fuel oxygenate, ethanol is commonly blended with gasoline to enhance its oxygen content, resulting in a mixture known as "gasohol," typically consisting of 10% ethanol and 90% gasoline, although various proportions may be used Additionally, ethanol serves as a volume extender and octane enhancer in gasoline fuels, making it a significant component in the production of ethanol fuel.
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This literature review explores various ethanol blends, emphasizing gasohol and the storage systems required for different concentrations of ethanol Additionally, it highlights the significance of studies on higher ethanol concentrations, particularly in relation to the effects observed in the lower layer of phase-separated ethanol/gasoline mixtures.
Methanol, an alcohol produced from natural gas, is also used as an oxygenate or fuel substitute
Research indicates that methanol may serve as a worst-case scenario for assessing ethanol compatibility, although this has not been universally validated across all materials Various studies highlight that methanol is significantly more corrosive to the materials utilized in fuel storage compared to ethanol.
Ethanol has served as an oxygenate in the Midwest for over two decades, with minimal material compatibility issues reported for 10% ethanol blends Notably, there have been no significant leaks or failures directly linked to ethanol usage The primary concerns involve the swelling, hardening, or minor leakage of elastomeric seals and O-rings Despite this track record, there is a growing interest in investigating the long-term effects of ethanol/gasoline blends on storage system materials, particularly regarding potential leaks caused by the shrinkage and cracking of seals and O-rings when switching between ethanol and non-ethanol services.
Phase Separation and Water Bottoms
Water and gasoline do not mix, leading to phase separation when water is present in gasoline, which results in distinct layers of water and gasoline The layer containing water is referred to as the lower water phase.
Water accumulation in fuel tanks can lead to phase separation, particularly in ethanol-blended fuels Unlike gasoline, alcohol is a polar molecule that readily mixes with water, with its solubility influenced by other components in the mixture Ethanol, while also miscible with gasoline, has a stronger affinity for water, causing it to bond with water preferentially When water content reaches around 0.5% in a 10% ethanol and 90% gasoline blend, the ethanol and water can separate from the gasoline, resulting in potential fuel quality issues.
106) The blend separates into an alcohol/water lower phase (water phase) and an upper phase consisting of gasoline with a slightly reduced alcohol concentration (hydrocarbon phase)
(186) No study reports the exact composition of each phase, but one paper states that the
- 3 - lower layer consists of 75% ethanol, cosolvents, and 25% water (124, 135)
Phase separation poses a significant risk due to the formation of alcohol-rich water bottoms, which can heighten the likelihood of localized corrosion on steel tank walls This increased corrosivity is linked to elevated oxygen levels and higher conductivity in the ethanol/water phase Currently, there is a lack of test data to measure the changes in conductivity and the corresponding corrosion rates in these alcohol-rich environments Additionally, alcohol can dissolve corrosion by-products, leaving the metal vulnerable to ongoing corrosive processes, while other fuel components, such as acetic acid, may further accelerate corrosion rates However, some research suggests that alcohol-rich water bottoms may not be more corrosive than their non-alcohol counterparts.
The study overlooked the impact of impurities in the solution Elevated alcohol levels in water bottoms could potentially harm FRP tank walls designed for low alcohol blends, yet there have been no documented issues or evaluations in existing literature.
To minimize the risk of phase separation in ethanol/gasoline blends, it is crucial to prevent water infiltration into the systems Ensuring that tanks are completely free of water before the initial filling is essential, and all necessary precautions should be implemented to reduce the chances of water infiltration and condensation within the tank It is advisable to remove any water layer present.
API (132) Manual and automatic methods are available to detect the presence of a water phase in buried tanks (177)
Ethanol helps prevent water bottoms by keeping water dissolved in fuel, which is then removed from the system during fuel consumption This process depends on minimal water entry, adhering to current specifications to ensure that the water content remains below the threshold for phase separation.
Microbial growth in storage tanks is often promoted by the presence of water bottoms, which can lead to contamination of both metallic and non-metallic materials Bacterial and fungal microbes can infiltrate storage systems during fuel transfers, through vents, and via equipment, thriving in areas where water accumulates, such as at the fuel/water interface in water bottoms and on tank walls and ceilings where condensation occurs.
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Controlling microbial growth can be effectively achieved through thorough cleaning and the application of biocides While existing literature indicates that ethanol may enhance the likelihood of microbial attacks, it lacks detailed information regarding the magnitude of this increase.
Fiberglass Reinforced Plastic (FRP) Tanks
FRP tank laminates are composites of thermosetting resins and glass fibers Some thermosetting resins (e.g orthophthalics) do not perform well in alcohols and alcohol fuels (20,
Resins commonly used in FRP tanks, such as isophthalics, terephthalics, and vinyl esters, can swell and soften when exposed to alcohols like ethanol and methanol, with methanol causing more significant effects Ethanol/gasoline mixtures may be more aggressive than pure ethanol The softening of these materials can be quantified through mechanical tests measuring Barcol surface hardness and modulus of elasticity These physical changes result from permeation, which can be assessed via absorption and swelling tests, and are generally reversible if the laminate dries properly However, after the desorption of alcohol, some permanent loss of mechanical properties may occur, although the underlying mechanism remains unclear The reduction in stiffness and increased creep can lead to decreased resistance to buckling, which is crucial for the design of FRP tanks, potentially impacting the safety factors for buckling design when exposed to ethanol/gasoline blends.
The U.S standard for manufacturing fiberglass-reinforced plastic (FRP) underground storage tanks (UST) is outlined in Underwriters Laboratories (UL) 1316, which was first published in 1983 This standard mandates long-term immersion tests in ethanol and ethanol/gasoline blends for tanks designed for such services, a requirement established in the 1987 edition Prior to this, there were no testing requirements for alcohol exposure While tanks meant solely for petroleum products are exempt from alcohol immersion testing, those intended for ethanol/fuel mixtures must demonstrate that, after high-temperature exposure, the material retains at least 50% of its short-term flexural strength, stiffness, and impact resistance when results are projected to 270 days.
UL 1316 does not assess creep, creep buckling, or creep rupture in FRP underground tanks Creep buckling refers to the gradual increase in buckle amplitude over time, influenced by the stiffness of the FRP laminate and the soil envelope's resistance to deformation Currently, there is a lack of published data on the creep buckling of FRP underground tanks, with only limited information available on the creep rupture of FRP laminates.
Leading FRP UST manufacturers offer warranties for single-wall tanks designed for gasohol storage, specifically blends containing 10% ethanol and 90% gasoline Additionally, certain manufacturers extend warranties to double-wall tanks that can accommodate higher ethanol concentrations.
Since at least 1981, some tank manufacturers have offered warranties for gasohol, asserting that tanks made before 1981 should perform comparably to newer models when storing 10% ethanol blends One manufacturer noted that the resin types used in their tanks have remained unchanged since 1980, with early models already qualified for gasohol storage However, prior to 1987, UL 1316 did not mandate ethanol immersion testing, leaving a gap in documentation regarding how earlier tank laminates were certified for ethanol exposure A recent advisory from a state government indicates that testing for ethanol compatibility began in 1984, recommending that users verify the performance of tanks made before this date before converting them for ethanol storage Concerns about the vulnerability of fiberglass reinforced plastic (FRP) tanks to ethanol have prompted the US Department of Energy to suggest installing a chemical-grade rubber lining in these tanks before ethanol use, although this recommendation lacks specificity regarding different resin types, making it overly broad for all FRP tanks.
Tests conducted in 1992 on certain resin types found that isophthalic resins tested did not meet
A 1986 study indicated that older tank laminates maintain adequate short-term strength and stiffness in 10% ethanol blends but struggle with 20% blends In contrast, newer tanks perform well across all ethanol concentrations Most fiberglass reinforced plastic (FRP) tanks are expected to be suitable for gasohol storage (10% ethanol), and field experience has shown no negative effects from such storage However, there is a lack of analytical and experimental data linking the reduced properties from ethanol exposure, such as softening and stiffness reduction, to long-term performance.
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Sustained loads, such as those from soil and hydrostatic pressure on underground tanks, can lead to stress corrosion cracking, which affects the strength of glass fiber reinforced composites under continuous stress While research has been conducted on this phenomenon in acidic aqueous environments, there is a lack of studies addressing its impact on ethanol blended fuels.
Creep rupture tests on E-glass fiber-reinforced polymer (FRP) exposed to water revealed a rupture strength of approximately 30 to 50% of the short-term strength after 10,000 hours of sustained stress Research indicates that ethanol exposure is less detrimental than water in causing creep rupture failure in FRP piping It is important to note that FRP tanks containing ethanol or fuel mixtures are often subjected to water or brine on their exterior, depending on whether they are single or double-walled The properties of FRP laminates are affected by permeation and swelling, along with a gradual resin relaxation process Careful analysis and interpretation of creep test results are essential, as creep properties under full absorption conditions must be differentiated from time-dependent deformation related to initial absorption, swelling, and softening to avoid inaccurate creep response estimates This subject is not thoroughly addressed in existing literature, and the impact of soil-structure interaction should be considered when analyzing creep buckling, particularly for single-walled tanks.
Recent studies have examined absorption tests to evaluate the impact of liquid immersion on fiber-reinforced polymers (FRP) However, the connection between absorption and structural performance remains insufficiently explored.
FRP tanks can be vulnerable to microbial bacteria that thrive at the fuel/water interface, particularly at the bottoms of water However, research indicates that there have been no reported negative impacts of microbial degradation on FRP tanks when ethanol is present.
Steel Tanks
Alcohols do not chemically react with carbon steel, but research indicates that they can enhance steel corrosion Among various alcohols, ethanol is found to be less corrosive than methanol.
Pure ethanol does not significantly increase the corrosion rate of steel (158, 167, 239), but
- 7 - water, which can be dissolved in the ethanol, can increase the corrosion rate (151, 154, 158,
Ethanol's capacity to dissolve water enhances fluid conductivity, potentially increasing the risk of galvanic and electrolytic corrosion; however, this does not significantly affect steel tanks Corrosion rates in steel are most pronounced in single-phase blends containing 20% ethanol and in the water-alcohol mixture found in the water phase of separated blends.
Corrosion occurs in phase-separated blends within the water-alcohol layer, leading to an initial increase in corrosion rates that eventually decline to zero over time In stationary and refilling immersion tests, the corrosion of steel in this layer diminished, indicating the formation of a protective passivating film Interestingly, corrosion in phase-separated ethanol blends may be less severe than in water layers found at the bottom of gasoline tanks without ethanol The presence of water in gasoline fuels can dissolve contaminants, such as salts and acid residues, which increases the corrosivity of the water-bottom Additionally, detergents and corrosion inhibitors may preferentially adhere to one phase, rendering them ineffective in the other.
Chloride ions, along with water, acids, bases, and other contaminants, can greatly enhance the corrosion of metals in contact with ethanol and its blends Among these, chloride ions are the most corrosive; however, the presence of multiple contaminants leads to a notably higher corrosion rate compared to any single contaminant To mitigate this issue, the use of corrosion inhibitors is advised and commonly implemented to protect steel exposed to ethanol blends.
Increasing concentrations of acetic acid, which forms from acetaldehyde by oxidation of ethanol, increases the corrosion rate of steel (154) Other studies report the acid-corrosion link (152,158)
Stress corrosion cracking (SCC) and environmental stress cracking (ESC) can be influenced by alcohol; however, there is a lack of studies linking these phenomena to the damage of carbon or other steels in ethanol environments at normal temperatures Additionally, the literature review did not reveal any instances of SCC or ESC affecting underground storage tanks (UST).
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`,,``,`-`-`,,`,,`,`,,` - systems as a result of ethanol use
Oxygenates like ethanol may promote microbial growth and corrosion in steel tanks, but definitive research linking ethanol to increased corrosion is lacking Microbial induced corrosion occurs due to the depassivation of the steel surface, and microbes can form biofilms that exacerbate electrolytic corrosion Additionally, microbes can produce acids that contribute to hydrogen embrittlement of steel The extent of these effects remains uncertain To reduce microbial growth, it is advisable to periodically remove accumulated water from tanks, and the API recommends the immediate removal of any water bottoms in ethanol blends Inspections for slime films can indicate microbial presence, and biocide additives may help control microbial growth.
Coatings/Linings
Protective coatings and linings are applicable to both FRP and steel tanks, as well as piping systems Thermoset resins, such as isophthalic polyesters and vinyl esters, are qualified for use in FRP tanks that store ethanol/gasoline blends, making them ideal for coatings and linings.
When using FRP tanks, it is crucial to test compatibility with the specific concentration of ethanol, as some resins may not withstand levels above 10% The structural performance of coatings must account for resin softening and mechanical property reduction Additionally, polymer coatings can be vulnerable to microbial attack Electrochemical studies indicate that certain vinyl ester coatings provide superior resistance to water bottom conditions in steel tanks Urethane and ethylene acrylic acid polymers have proven effective as coating materials, and many newer internal coating formulations are compatible with ethanol blends Furthermore, polyester resin and Polyvinylidene Fluoride (PVDF) barrier layers effectively reduce the permeability of ethanol-blended fuels in automotive fuel lines.
Gasohol is incompatible with specific epoxy coatings, and older steel tanks that are lined with general-purpose materials may not be appropriate for storing ethanol blends.
Various metal coatings for automotive fuel tanks were tested and exhibited variable compatibility
- 9 - with water and ethanol mixtures (230).
Piping
Piping materials in petroleum storage and distribution systems consist of FRP, steel, and thermoplastics, with pipe failures causing more petroleum releases than underground tanks The research findings for FRP tanks, steel tanks, and their coatings and linings are applicable to similar materials used in fuel piping Additionally, other materials such as elastomers and thermoplastics are examined in later sections of this report.
In the U.S., the use of FRP and other plastic piping is regulated by UL 971 Nonmetallic Underground Piping for Flammable Liquids, first issued in 1997 and based on a 1995 bulletin This standard mandates tests involving immersion in various fuels, including alcohol and alcohol/fuel blends, for up to 270 days, requiring materials to retain at least 50% of their mechanical properties after this duration Additionally, UL 971 stipulates permeability testing, with specific limits for both primary and secondary pipes, although no research data has been found to substantiate these limits.
The "Secondary Containment of Underground Piping for Flammable and Combustible Liquids" standard mandates immersion testing in liquids that reflect actual service conditions, including alcohols, but excludes specific blends The ULC stipulates that materials must retain 70% of their properties after 180 days of immersion However, the qualification process for non-metallic piping regarding ethanol and ethanol/gasoline blends before these standards was unclear A governmental advisory recommends that users seek ethanol compatibility performance data for single wall piping produced before 1984.
Automotive fuel line piping is a critical area of research, particularly concerning permeation and new EPA regulations Nylon 12 typically fails to comply with these updated standards due to high permeation rates However, effective solutions have been identified, such as incorporating barrier layers made of polyester, Polyvinylidene Fluoride (PVDF), or Ethylene Tetrafluoroethylene (ETFE).
Warranties for secondary containment piping (FRP, high density polyethylene, and urethane)
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`,,``,`-`-`,,`,,`,`,,` - cover only limited (less than 72 hours) exposure to fuel (239)
Piping, flexible or otherwise, requires joints, which are typically secured with adhesive This adhesive may be incompatible with ethanol if the adhesive was not properly mixed and cured
Corrosion in metal storage systems can be exacerbated in vapor recovery and secondary containment systems due to oxygen exposure and the challenge of ensuring effective corrosion inhibitors are present.
Other Components
Liquid storage systems include various materials that can be impacted by ethanol exposure Studies and practical data on ethanol compatibility have been documented for many of these materials, resulting in a transition to more compatible materials in storage systems adapted for ethanol use.
Alcohol blends serve as effective solvents, capable of dissolving rust, scale, gums, and other deposits, which can result in accelerated filter fouling and increased wear from suspended particles Therefore, it is essential to thoroughly clean the system before transitioning to ethanol blend service Additionally, the system must be completely dried to prevent water contamination in the fuel Frequent checks and timely changes of filters are recommended during the initial usage phase.
Elastomers play a crucial role in seals and gaskets within petroleum storage systems, but those not designed for ethanol blends can experience issues such as swelling, shrinkage, and increased permeability The extraction of plasticizers can lead to shrinkage, often hidden by swelling, while embrittlement and cracking can cause leakage when the elastomeric components are no longer exposed to ethanol Fortunately, there are elastomers specifically engineered to resist ethanol blends, along with barrier technologies that minimize contact with ethanol, thereby reducing permeability and enhancing material compatibility.
- 11 - materials is available from several sources (50, 81, 86, 102, 132)
Buna-N seals in U.S submersible pumps have experienced failures when exposed to higher oxygenate fuels; however, newer Buna-N products are less likely to encounter this issue Elastomers in vehicles manufactured before 1975 are prone to incompatibilities, while those produced after that date generally perform well The introduction of gasohol in 1992 across 39 metro areas occurred without any reported problems.
When using pipe dope, it's important to note that alcohol-based varieties may wash out if not adequately dried, but they are generally acceptable when installed correctly Additionally, cork and natural rubber do not work well with ethanol blends, while materials such as Teflon, fluorocarbons, and fluorosilicones are compatible.
Pumps and other moving parts may be subject to increased corrosive wear (150) and loss of lubrication (135)
Cast iron pump rotors can rust within just a week of service when exposed to ethanol containing 7% water and air Although these rotors were engineered for continuous immersion in such ethanol blends, the presence of air accelerated corrosion Testing conducted in Brazil with high water content ethanol may not accurately reflect the conditions of ethanol fuels available in the U.S.
Research indicates that lead, zinc, and brass exhibit heightened corrosion rates when exposed to high alcohol concentration fuels In contrast, stainless steel and bronze are deemed compatible with ethanol and its blends While most carbon steels can tolerate ethanol, their corrosion susceptibility escalates in the presence of elevated oxygen levels and contaminants Additionally, some studies suggest that aluminum is compatible with ethanol blends.
(132) while others suggest increased corrosion rates (73)
The American Automobiles Manufacturers Association advises conducting "soak testing" along with electrical conductivity, chemical stability, and filter tests to assess metal compatibility with ethanol fuels Additionally, field conductivity tests are recommended, as elevated conductivity levels may signal metal contaminants in the fuel due to corrosion, potentially leading to increased rates of galvanic corrosion.
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The addition of ethanol to gasoline increases permeation through certain non-metallic materials, with permeation rates for ethanol being lower than those for methanol For untreated high-density polyethylene (HDPE), the highest permeation rates occur at alcohol concentrations of 10 to 30%, and pure gasoline exhibits a higher permeation rate than ethanol alone While barrier technologies have proven effective in reducing the permeation rate of HDPE for gasoline, their effectiveness diminishes with ethanol blends Additionally, interior linings and asymmetric barriers may help resist swelling and structural degradation from ethanol exposure, although further asymmetric testing is required to validate this.
CONCLUSIONS AND RECOMMENDATIONS
Summary of Findings
Following summarizes the significant findings of this literature review:
Gasohol has served as a motor vehicle fuel for more than two decades, with minimal reported compatibility issues in fuel storage systems The main concerns have been the swelling and minor leakage of incompatible elastomer seals and o-rings However, comprehensive studies on compatibility issues remain limited, and there is a lack of published data regarding the long-term performance of materials in contact with ethanol/gasoline fuels.
Water bottoms are a common issue in gasoline storage tanks, where water contamination settles at the bottom, increasing the risk of localized corrosion in steel tanks In ethanol/gasoline blends, ethanol can mix with any water that enters, leading to phase separation at specific water concentrations, such as a 0.5% water to gasohol ratio, resulting in an alcohol-rich water layer To manage water bottoms caused by this phase separation, it is essential to implement current recommendations to prevent water ingress and to regularly monitor and remove any accumulated water.
• Some studies suggest that hydrated ethanol may increase corrosion potential of steel by increasing conductivity or dissolving protective layers on the steel surface Also,
Dissolved products, including acids, can enhance corrosion activity in steel tanks While there is currently no conclusive research indicating that ethanol significantly impacts the long-term performance of these tanks, further studies are necessary to analyze the composition and corrosivity of both the fuel and water phases within steel tanks.
Water accumulation in fuel tanks can promote microbial growth, which may lead to increased corrosion in steel tanks and degradation of FRP materials While ethanol is known to potentially enhance microbial activity, there is a lack of conclusive evidence or documented cases regarding its effects.
Ethanol can soften fiber-reinforced plastic (FRP) and diminish its mechanical stiffness According to immersion tests following the UL 1316 tank standard, FRP tank laminates are qualified for ethanol storage by evaluating their retained strength, stiffness, and impact resistance.
Most tanks comply with UL 1316 standards for gasohol storage, which contains 10% ethanol There are concerns regarding the ethanol compatibility of older tanks manufactured before the early 1980s However, leading tank manufacturers assert that these older tanks are made from similar resins and should function effectively.
The existing literature lacks sufficient information on how reduced material stiffness from ethanol storage impacts the creep buckling strength of FRP tanks This gap highlights the need for additional research and a thorough evaluation of manufacturer test data, analyses, and relevant research findings.
The compatibility issues of gasohol with FRP and steel tanks extend to FRP and steel piping as well While specific studies on the compatibility of steel piping have not been conducted, non-metallic piping has undergone testing for immersion in ethanol blends, following the standards set by UL 971, which have been in place since 1995.
Compatibility of earlier non-metallic piping materials may have been determined by manufacturers Manufacturers should be consulted on this issue prior to conversion to ethanol/fuel mixtures
• Experiential and research data on ethanol compatibility of other components used in fuel storage systems have been developed and published Some elastomers and
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Sealants have proven inadequate and should be replaced with more compatible materials for ethanol storage systems Steel and cast iron pump components show heightened corrosion and wear when used with hydrated ethanol in the presence of air Additionally, metals such as aluminum, zinc, and magnesium are not suitable for this application It is essential to consult manufacturers regarding the material compatibility of their products, highlighting the necessity for the establishment of uniform testing standards.
Published information concerning compatibility and long-term durability of fuel storage materials in ethanol/gasoline blends may not be complete Further research may be appropriate in several key areas:
Phase Separation and Water Bottoms
• Characterization of the composition of ethanol-rich water bottoms, including ethanol/water content and the presence of contaminants, fuel constituents and by- products
• Studies on the effects of ethanol-rich water bottoms on the growth of microbial bacteria and the local environments created by such microbes in storage systems
Standard procedures for compatibility testing of FRP tank laminates are essential for those that have not been previously qualified for ethanol storage This includes tanks that lack certification from third-party tests like UL 1316 or documented in-house tests by manufacturers.
This article explores the performance of FRP tanks under sustained loading, focusing on the permeation of ethanol and fuel mixtures through FRP laminates It examines the impacts of fuel exposure on one side of the laminates while simultaneously considering exposure to water or brine solutions on the opposite side, simulating real storage conditions Key issues addressed include creep, softening, creep buckling, and creep rupture, providing valuable insights into the durability and reliability of FRP tanks in various environments.
- 15 - investigated Studies should account for the high ethanol content present in water bottoms Analytical models should include the effects of initial swelling
• Tests to quantify the change in conductivity and thus the increase potential for corrosion of steel exposed to ethanol/gasoline blends
The corrosivity of water bottoms in steel tanks is influenced by various mechanisms of corrosion, which are exacerbated by the presence of other fuel constituents and byproducts in the ethanol/water phase Understanding these factors is crucial for mitigating corrosion and ensuring the integrity of storage systems.
• Compatibility testing of non-metallic piping not previously qualified by third party testing such as UL 971
• Development of improved barrier layer technology for certain thermoplastic piping materials, to reduce permeability rates and associated effects on long-term structural properties
• Corrosive wear studies on steel piping subject to ethanol/gasoline blends
• Continue research in the qualification of existing materials and development of new materials for long-term performance in ethanol/gasoline blends, including HDPE in secondary containment applications
• Study the mechanisms of corrosive wear of steel parts exposed to ethanol/gasoline fuels and methods to mitigate premature material failure
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