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General
The documents referenced herein are essential for the application of this document For references with specific dates, only the cited edition is applicable In the case of undated references, the most recent edition of the referenced document, including any amendments, is relevant.
Normative References
API Publication 327, Aboveground Storage Tank Standards: A Tutorial
API Recommended Practice 562, Lining of Aboveground Petroleum Storage Tank Bottoms
API Standard 570, Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-service Piping Systems API Recommended Practice 574, Inspection Practices for Piping System Components
API Recommended Practice 579/ASME FFS-1, Fitness-for-Service
API Recommended Practice 580, Risk-Based Inspection
API Recommended Practice 582, Recommended Practice and Supplementary Welding Guidelines for the Chemical,
API Standard 620, Design and Construction of Large, Welded, Low-pressure Storage Tanks
API Standard 650, Welded Tanks for Oil Storage
API Recommended Practice 651, Cathodic Protection of Aboveground Storage Tanks
API Recommended Practice 652, Lining of Aboveground Petroleum Storage Tank Bottoms
API Standard 653, Tank Inspection, Repair, Alteration and Reconstruction
API Technical Report 939-D, Stress Corrosion Cracking of Carbon Steel in Fuel Grade Ethanol: Review, Experience
Survey, Field Monitoring and Laboratory Testing
API Bulletin 939-E, Identification, Repair, and Mitigation of Cracking of Steel Equipment in Fuel Ethanol Service API Recommended Practice 1615, Installation of Underground Petroleum Storage Systems
API Recommended Practice 1621, Bulk Liquid Stock Control at Retail Outlets
API Recommended Practice 1631, Interior Lining and Periodic Inspection of Underground Storage Tanks
API Recommended Practice 1632, Cathodic Protection of Underground Petroleum Storage Tanks and Piping
API Recommended Practice 1637, Using the API Color-Symbol System to Mark Equipment and Vehicles for Product
Identification at Service Stations and Distribution Terminals
API Publication 1642, Alcohol, Ethers, and Gasoline-Alcohol and Gasoline-Ether Blends
API Standard 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents
API Standard 2015, Requirements for Safe Entry and Cleaning of Petroleum Storage Tanks
API Recommended Practice 2016, Guidelines and Procedures for Entering and Cleaning Petroleum Storage Tanks API Publication 2021, Management of Atmospheric Storage Tank Fires
API Standard 2217A, Guidelines for Safe Work in Inert Confined Spaces in the Petroleum and Petrochemical
API Publication 2219, Safe Operation of Vacuum Trucks in Petroleum Service
API Publication 2300, Evaluation of Fire Fighting Foams As Fire Protection for Alcohol Containing Fuels
API Standard 2610, Design, Construction, Operation, Maintenance & Inspection of Terminal and Tank Facilities BOE-6000 1 , Hazardous Materials Regulations of the Department of Transportation
BOE Circular No.17, Rules and Recommendations Relating to the Location of Loading Racks, Unloading Points, and
Storage Facilities for any Flammable Liquid With Flash Point Below 20°F (Including Gasoline, etc.)
BOE Pamphlet 34, Recommended Methods for the Safe Loading and Unloading of Non-Pressure (General Service) and Pressure Tank Cars
1 Bureau of Explosives, P.O Box 1020, Sewickley, PA 15143, www.boepublications.com.
BOE, United States Hazardous Materials Instructions for Rail
ICC International Fire Code Chapter 22 2 , Motor Fuel-Dispensing Facilities and Repair Garages
ICC International Fire Code Chapter 27 Hazardous Materials – General Provisions
ICC International Fire Code Chapter 34 Flammable and Combustible Liquids
NFPA 11 3 , Standard for Low-, Medium-, and High-Expansion Foam
NFPA 30, Flammable and Combustible Liquids Code
NFPA 30A, Code for Motor Fuel Dispensing and Repair Garages
NFPA 77, Recommend Practice on Static Electricity
NFPA Uniform Fire Code Article 52, Motor Vehicle Fuel-Dispensing Stations
NFPA Uniform Fire Code Article 79, Flammable and Combustible Liquids
NFPA Uniform Fire Code Article 80, Hazardous Materials
NWGLDE 4 , List of Leak Detection Evaluations for Storage Tank Systems
STI 5 , Keeping Water Out of Your Storage System
STI SP001, A Standard for Inspection of In-Service Shop Fabricated Aboveground Tanks for Storage of Combustible and Flammable Liquids
Informative References
APEA/IP 6 , Design, Construction, Modification, Maintenance and Decommissioning of Filling Stations, “The Blue
APEA/IP, Guidance on Storage and Dispensing of High Blend Ethanol Fuels including E85 at Filling Stations
ASTM D323-08 7 , Standard Test Method for Vapor Pressure of Petroleum Products (Reid Method)
ASTM D4806-08a, Standard Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as
Automotive Spark-Ignition Engine Fuel
ASTM D 4814, Standard Specification for Automotive Spark-Ignition Engine Fuel
ASTM D5798-07, Standard Specification for Fuel Ethanol (Ed75-Ed85) for Automotive Spark-Ignition Engines
2 International Code Council, 500 New Jersey Avenue, NW, 6th Floor, Washington, DC 20001-2070, www.iccsafe.org.
3 National Fire Protection Association, Batterymarch Park, Quincy, Massachusetts 02269-9990, www.nfpa.org.
4 National Work Group on Leak Detection Evaluations, www.nwglde.org.
5 Steel Tank Institute, 944 Donata Court, Lake Zurich, Illinois 60047, www.steeltank.com.
6 Association for Petroleum and Explosives Administration, P.O Box 106 Saffron Walden Essex CB11 3XT, England, www.apea.org.uk.
7 ASME International, 345 E 47th Street, New York, New York 10017, www.asme.org.
CONCAWE Report 3/08 8 , Guidelines for Blending and Handling Motor Gasoline Containing up to 10 % v/v Ethanol
UL 58 9 , Steel Underground Tanks for Flammable and Combustible Liquids
UL 79, Power-Operated Pumps for Petroleum Dispensing Products
UL 87, Power-Operated Dispensing Devices for Petroleum Products
UL 87A, Outline of Investigation for Power-Operated Dispensing Devices for Gasoline and Gasoline/Ethanol Blends with Nominal Ethanol Concentrations up to 85 Percent (E0-E85)
UL 142, Steel Aboveground Tanks for Flammable and Combustible Liquids
UL 330, Hose and Hose Assemblies for Dispensing Flammable Liquids
UL 331, Strainers for Flammable Fluids and Anhydrous Ammonia
UL 567, Emergency Breakaway Fittings, Swivel Connectors and Pipe-Connection Fittings for Petroleum Products and LP-Gas
UL 674, Electric Motors and Generators for Use in Division 1 Hazardous (Classified) Locations
UL 842, Valves for Flammable Fluids
UL 971, Metallic Underground Piping For Flammable Liquids
UL 971A, Outline of Investigation for Metallic Underground Fuel Pipe
UL 1238, Control Equipment for Use with Flammable Liquid Dispensing Devices
UL 1316, Glass-Fiber-Reinforced Plastic Underground Storage Tanks for Petroleum Products, Alcohols, and Alcohol-
UL 1356, Outline of Investigation for Pipe Joint Sealing Compounds
UL 1604, Electrical Equipment for Use in Class I and II, Division 2, and Class III Hazardous (Classified) Locations
UL 1746, External Corrosion Protection Systems for Steel Underground Storage Tanks
UL 2080, Fire Resistant Tanks for Flammable Liquids
UL 2085, Fire Protected Tanks for Flammable Liquids
8 Conservation of Clean Air and Water in Europe, www.concawe.be.
9 Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, Illinois 60062, www.ul.com.
Definitions
For the purposes of this document, the following definitions apply.
An organic compound containing one or more hydroxyl groups (-OH) bound to a carbon atom.
Alternative fuels include ethanol, natural gas, propane, hydrogen, biodiesel, methanol, electricity, and P-Series fuels as defined by the Energy Policy Act of 1992 (EPAct) Additionally, synthetic fuels produced through the Fischer-Tropsch process, which converts coal to liquid, are also classified as alternative fuels.
Neat ethanol that contains less than one percent water.
Fuel ethanol Neat ethanol with up to five volume percent hydrocarbons added as a denaturant
A liquid measurement table used to correct the metered volume of a blend component to the volume at a standard temperature of 60 °F Each component or blend of components needs a separate table.
Gasoline without ethanol Base gasoline is sometimes called clear gasoline.
Gasoline refined especially for blending with an oxygenate such as fuel ethanol to produce a gasoline-ethanol blend for commerce.
The 0.1 % to 0.4 % increase in volume that occurs when gasoline and ethanol are mixed
A fire extinguishant utilizes heat absorption and chemical reactions to effectively extinguish fires while reducing smoke and flame effects It is designed to leave no residue or collateral damage, making it an ideal choice for environments where people are present, especially with the latest formulations ensuring safety during use.
A hydrocarbon added to neat ethanol to make it unfit for consumption Suitable denaturants are listed in ASTM D4806.
A facility receives base gasoline and fuel ethanol through various transportation methods, including tank trucks, railroad tank cars, pipelines, barges, or tankers These fuels are stored in stationary tanks until they are blended and subsequently loaded into tank trucks for distribution to bulk plants, filling stations, and end-use consumers.
Ethyl alcohol Neat ethanol A straight-chain alcohol with the molecular formula C 2 H 5 OH
A motor fuel which is a blend of ethanol and gasoline.
The acronym used to describe a blend of XX percent ethanol by volume and gasoline For example, E10 is 10 % ethanol and 90 % gasoline.
E85 is a fuel blend defined by ASTM D5798, consisting of 75 to 85 volume percent ethanol (Ed75 to Ed85) and 25 to 15 volume percent hydrocarbons This specification allows for adjustments based on ambient temperatures and geographic location, particularly during colder months when E85 may contain as little as 65 volume percent ethanol to enhance volatility Commonly known as "nominal E85," the term "E85" in this context refers to the range of blends outlined in ASTM D5798.
An engineered access cover or tank access point that may or may not have spill containment capability
A public or private facility for the storage and dispensing of motor fuels to motor vehicles Also called a service station or fuel dispensing facility.
The lowest temperature at which a flammable liquid can form an ignitable mixture in air when a spark or ignition source is passed over or near it
Denatured ethanol, commonly known as E97, is a type of ethanol that contains 1.96% to 2.5% denaturant, adhering to ASTM D4806 specifications This fuel ethanol is designed for blending with base gasoline to be used as motor fuel and may include up to 1% water by volume.
A motor fuel which is a blend of fuel ethanol and base gasoline
A gasoline-ethanol blend with an ethanol content of greater than 10 % by volume A gasoline-ethanol blend above E10.
Having an affinity for water; readily absorbing or dissolving in water.
Tending to repel or fail to mix with water.
Ratio blending is a precise method that maintains the correct proportions of all components throughout the delivery process This ensures that the delivered blend consistently meets specifications, allowing for the delivery to be halted at any moment without compromising quality.
3.1.28 in-line non-proportional blending
A specific method of ratio blending involves delivering the low proportion components only when the high proportion component is flowing at a high rate Once the low proportion components are delivered, the high proportion component continues to flow until the desired blend is achieved The final fuel blend remains off specification until the entire preset volume is loaded.
A designation for products certified and published in a database by a nationally recognized testing laboratory (NRTL)
The concentration of oxygen below which combustion is not possible, independent of the concentration of fuel It is expressed in terms of volume percent oxygen.
A gasoline-ethanol blend with an ethanol content of 10 % or less by volume A gasoline-ethanol blend of E10 or below.
The ratio between the measured volume and the actual volume flowing through a liquid flow meter The factor for a meter can vary with flow rate.
A third-party public safety evaluation organization, like Underwriters Laboratories (UL), is responsible for publishing equipment standards and performing tests and product evaluations Nationally Recognized Testing Laboratories (NRTLs) carry out regular inspections of manufacturing processes to ensure compliance with these established standards.
Anhydrous ethanol that has not been made unfit for consumption by denaturing
Ratio blending, also known as in-line blending, involves the simultaneous loading of two or more product components through dedicated meters and control valves to a common blend point on a single header This process can be categorized into proportional and non-proportional blending methods.
A measure of the volatility of gasoline as determined by test method ASTM 323.
Sequential blending is a blending method where each component is measured and controlled individually before merging into a common line, similar to ratio blending Unlike ratio blending, the components flow one after the other rather than simultaneously An alternative approach involves using a single meter and control valve positioned downstream of the blending point; however, this setup limits calibration to only one component at a time, ensuring the blend fuel is accurate only after all components have been fully loaded.
Sidestream blending is a technique akin to sequential blending, where a smaller proportion of the blend stock is precisely metered and introduced into the flow of a larger blend stock component After mixing, the total flow stream is then metered This method can be implemented in either a proportional or non-proportional manner.
Blending is achieved by separately metering each component into a tank truck using distinct loading arms, which are manually switched by the truck driver or operator In certain instances, components may be loaded into compartments at various locations However, there is no automated verification of the final product blend's validity.
Collection and routing of vapors generated from filling a stationary storage tank into a delivery truck tank.
Collection and routing of vapors generated during vehicle refueling into a stationary storage tank.
A flat metal plate is installed permanently at the bottom of an underground storage tank, specifically beneath the gauging point, to safeguard against impact damage when measuring the liquid level with a gauge stick.
The practice of loading a low vapor pressure product into a tank which previously contained a high or intermediate vapor pressure product, which can create a flammable atmosphere in the tank vapor space
Wild-stream blending involves the off-rack mixing of two products to create a blended product for loading One product is measured using a meter and control valve, while the second flows based on demand, known as wild flow The completed blend is then transferred through a custody transfer meter and control valve at the loading rack.
Acronyms
For the purposes of this document, the following acronyms apply.
APEA/IP Association for Petroleum and Explosives Administration/Institute of Petroleum
AFFF aqueous film forming foam
ASTM American Society for Testing and Materials
BOB blend stock for oxygenate blending
BTEX benzene, toluene, ethylbenzene and xylene
CARB California Air Resource Board
CFR Code of Federal Regulations
DEQ Department of Environmental Quality
EPAct Energy Policy Act of 1992
ICC International Code Council kPa kilopascals
MSDS material safety data sheet
MTBE methyl tertiary butyl ether
NFPA National Fire Protection Association
NRTL nationally recognized testing laboratory
NTEP National Type Evaluation Program
NWGLDE National Work Group on Leak Detection Evaluations
ORVR onboard refueling vapor recovery
OSHA Occupational Safety and Health Administration
POTW publicly owned treatment works psi pounds per square inch
PWHT post weld heat treatment
SPCC Spill Prevention Control and Countermeasures
4 Ethanol and Ethanol Blend Characteristics
General
Blending fuel ethanol with base gasoline results in products that possess distinct properties compared to their original components It is crucial to assess the design and compatibility of all materials that will interact with gasoline-ethanol blends, including their vapors Key properties to consider include the potential for stress corrosion cracking in steel structures, vapor flammability, vapor pressure, ethanol's hydrophilic characteristics, and its differential solvency effects on polymeric materials, which can lead to issues like swelling, extraction, permeation, and embrittlement Additionally, the water tolerance of ethanol blends must be evaluated When introducing a new blend, it is essential to analyze these properties throughout the supply chain to ensure product quality and safe handling and storage.
See Annex A for gasoline and gasoline-ethanol blend properties.
Vapor Pressure
At 20 °C (68 °F), the vapor pressure of pure ethanol is 59.3 mm Hg When mixed with gasoline, low concentrations of ethanol increase the vapor pressure of the blend compared to gasoline alone Specifically, creating an E10 blend by adding ethanol to gasoline raises the vapor pressure by about 6.89 kPa (1 psi) However, as more ethanol is added, the vapor pressure of the blend decreases until it matches the vapor pressure of pure ethanol at 100% concentration.
Base gasolines are refined to meet Reid vapor pressure (RVP) standards that account for seasonal temperature changes, typically remaining just below regulatory limits However, the addition of ethanol raises the RVP of the blend above these limits, affecting gasoline-ethanol mixtures.
Blended stocks for oxygenate blending (BOB) contain 10% or less and have a lower Reid Vapor Pressure (RVP) than gasoline intended for sale This low RVP BOB enables the sale of ethanol blends while adhering to maximum RVP regulations Under the Clean Air Act Amendments, the federal EPA grants a 1.0 psi RVP waiver for ethanol blends in air quality attainment areas, provided state implementation plan limitations do not prohibit it.
A higher vapor pressure blend can be marketed if it includes base gasoline that complies with the RVP standard and contains between nine and ten percent ethanol by volume.
The vapor pressure of E85, like gasoline, is regulated based on seasonal and regional factors, with limits set by ASTM D5798 To adjust vapor pressure, blenders may alter the gasoline proportion in the blend, especially during warmer months when lower RVP gasoline is used In such cases, a higher RVP blendstock may be necessary to comply with ASTM specifications Some terminals can enhance volatility by adding pressurizing agents like butane or pentane, but this may require registration as a refiner and adherence to OSHA safety management regulations, which are not covered in this practice.
In cold areas during winter, the amount of gasoline in gasoline-ethanol blends sold as E85 may increase from 15 % up to 35 % by volume to maintain vapor pressure.
Vapor Density
Ethanol vapor is denser than air, but not as dense as gasoline vapor If released in air, vapors can collect in low places.
Liquid Density
Neat ethanol and gasoline-ethanol blends are slightly heavier than gasoline.
Flash Point
The flash point of neat ethanol is approximately 13 °C (55 °F) The flashpoints of gasoline-ethanol blends vary greatly depending on ethanol level, denaturant and water content.
Flammability
The lower explosive limit (LEL) of neat ethanol is 3.3%, while the upper explosive limit (UEL) is 19% Notably, the flammability range of neat ethanol and high-blend ethanols is broader compared to that of gasoline.
The flammability of ethanol blends up to 10 % by volume (E10 and below) is similar to that of base gasoline, and is normally too rich to burn in a tank headspace.
The headspace in tanks containing E70 to E100 is flammable for all ambient storage temperatures.
Flammability data is lacking for E11 through E69.
Flame Visibility
Neat ethanol burns cleanly with a slight blue flame and no visible smoke, while denatured ethanol also produces minimal smoke and may show a faint orange flame In contrast, a gasoline-ethanol blend has a less bright flame compared to pure gasoline, yet it remains visible even in daylight.
The low luminosity of ethanol flames results in lower radiant heat transfer compared to gasoline flames which provides some fire-safety advantages relative to gasoline.
Electrical Conductivity
Ethanol and gasoline-ethanol blends exhibit higher electrical conductivity than gasoline, which may increase the risk of galvanic corrosion between dissimilar metals in contact with these fuels In contrast, gasoline acts as a relative electrical insulator due to its low conductivity.
Water and Gasoline Solubility
Neat ethanol is fully miscible or infinitely soluble in water and in gasoline Neat ethanol will form a homogeneous mixture with either water or gasoline.
Phase separation in gasoline-ethanol blends happens when water content surpasses the saturation level, leading to the creation of distinct water/ethanol and gasoline layers The denser water-ethanol layer, known as aqueous ethanol, settles at the bottom of the tank This separation can occur rapidly, especially in blends close to saturation, with even a slight increase in water or a drop in temperature triggering the process.
A typical water saturation level for an E10 blend is 0.5 volume percent at 60 °F.
A typical water saturation level for an E85 blend is 13 to 15 volume percent at 60 °F.
Phase separation is unlikely to occur in fuel ethanol during handling or storage.
See 5.5.2 and 7.8.3 for further information
General
The implementation of fuel ethanol storage and the blending of gasoline with fuel ethanol at distribution terminals will require new equipment and adjustments to operating conditions Consequently, it is essential to review existing equipment and procedures to ensure safe operations and the production of on-specification blended products.
Product Receipts
Distribution terminals receive neat and fuel ethanol via tank trucks, tank cars, ships, and barges, as pipelines are typically not used for this purpose Each delivery method requires careful precautions to ensure safe handling and to maintain the quality of the product.
Multi-product motor fuel pipelines currently prohibit the transport of neat or gasoline-ethanol blends due to concerns over elastomer deterioration in critical equipment and ethanol's tendency to absorb water during transit Ethanol can also compromise the integrity of other products in the pipeline by loosening rust and sediment, which can clog filters and contaminate storage tanks Additionally, water mixed with ethanol poses a risk of contaminating blended products, and contact with jet fuel can degrade filter coalescer performance, leading to further contamination These issues are significant barriers to the pipeline transport of ethanol and its blends, although investigations are ongoing to assess the feasibility of such transportation.
Tank trucks are essential for transporting ethanol from production facilities to terminals It is crucial that trucks designated for neat ethanol and fuel ethanol transport are exclusively used for this purpose If a dedicated truck is unavailable, a truck previously used for gasoline or gasoline-ethanol blends may be utilized, but trucks that have carried other materials should be avoided Before loading ethanol, it is important to ensure that the tank truck compartments are thoroughly cleaned and free of water and any residual products from prior loads.
Before unloading an ethanol shipment, it is crucial to examine the delivery truck for any damage that may have occurred during transit, as this could lead to water contamination Any compartments that show signs of product contamination must be rejected and not unloaded.
The ethanol delivery zone at a terminal must be designed for the safe access, unloading, and departure of tank trucks High-blend ethanol fuels necessitate a greater number of ethanol tank truck deliveries compared to E10, potentially leading to heightened traffic congestion at terminals.
Before unloading, it is essential to ensure that delivery tank trucks are properly bonded and grounded This can be achieved through the use of electrically continuous unloading hoses or by establishing a direct bonding connection to the truck For detailed guidance on safe unloading procedures, refer to API 2003.
Pumps and hoses for unloading neat or fuel ethanol from tank trucks must be compatible with both ethanol and gasoline It is essential that the unloading pumps and lines at the terminal are specifically designated for ethanol service Additionally, if the unloading pump is situated on the delivery tank truck, it should also be compatible with both ethanol and gasoline.
To ensure effective spill control in the ethanol transfer area, it must have the capacity to contain the largest truck compartment This can be achieved by designing the unloading area with a volume greater than the largest anticipated truck compartment, allowing any spilled liquid to be captured Alternatively, if the area lacks sufficient impound capacity, a high flow rate drainage system should be installed to quickly direct any spills to a dedicated underground storage tank or isolated impoundment It is essential that spill impoundment areas comply with NFPA 30 requirements and are included in the site's Spill Prevention, Control, and Countermeasure (SPCC) plan.
Paving materials in containment areas must be compatible with ethanol and gasoline while also supporting heavy traffic loads, with concrete being the preferred choice It is essential to fill joints and cracks with sealing materials that are compatible with these fuels Regular inspections of containment areas are necessary to ensure they remain leak-tight For further details, refer to API 2610 regarding truck unloading procedures.
Railroad tank cars must be specifically designated for ethanol service; otherwise, they need to be thoroughly cleaned and dried before loading It is essential to visually inspect tank cars for any damage prior to unloading, and those that exhibit signs of product contamination should not be unloaded.
Before unloading, it is essential to ensure that tank cars are properly bonded and grounded This can be achieved through the use of electrically continuous unloading hoses or by establishing a direct bonding connection to the tank car.
Pumps and hoses utilized for unloading neat or fuel ethanol must be compatible with both ethanol and gasoline It is essential that the unloading pumps and lines at the terminal are specifically designated for ethanol service.
The tank car unloading area must be capable of holding the full contents of a tank car at a minimum This can be achieved by designing the area with a volume greater than the largest expected tank car capacity to ensure any spilled liquid is contained If the unloading area lacks sufficient capacity, implementing a high flow rate drainage system is essential to manage the liquid flow effectively.
To ensure safety and compliance, it is essential to install a system that can efficiently manage the volume from the largest expected tank car, directing it by gravity to a dedicated underground storage tank or isolated remote impoundment Additionally, spill impoundment areas must be designed in accordance with NFPA 30 requirements and included in the site's Spill Prevention, Control, and Countermeasure (SPCC) plan.
Materials in the unloading area must be compatible with ethanol and gasoline, such as concrete, and any joints or cracks should be sealed with appropriate materials Regular inspections of containment areas are essential to ensure they remain leak-tight, and if feasible, tank cars should be unloaded within these contained areas Additionally, loaded tank cars entering the terminal should be directed to the containment area and secured, avoiding parking or storage outside this area before unloading SPCC plans must account for the risks associated with handling multiple tank cars, and necessary engineering controls should be implemented accordingly.
Blending
Gasoline blends up to E10 consist of fuel ethanol, base gasoline, and a deposit control additive, while E85, an alternative fuel, includes fuel ethanol, base gasoline, and a pressurizing agent to enhance volatility The formulations for these blended products are regulated based on seasonal and geographic factors.
When selecting a blending system for a terminal, prioritize safety and product quality to ensure adherence to blend specifications Additionally, consider factors such as initial installation costs, ongoing maintenance expenses, flow rates, and the variety of blend ratios or recipes available To reduce the risk of co-mingling, it is advisable for facilities to implement separate systems for the storage and handling of base gasolines and fuel ethanol.
Ethanol mixed fuels should be blended at terminal loading racks using in-line or sequential blending methods, as these techniques ensure enhanced safety and yield superior fuel quality compared to other blending methods.
Splash blending on trucks can serve as a temporary measure until a permanent blending system is established However, its use should be restricted due to safety risks associated with heightened tank compartment flammability and the potential for human error in the blending process.
Wild-stream blending is not recommended It provides less control over finished fuel quality because both blending streams are not metered.
Batch blending of fuel ethanol and gasoline in aboveground storage tanks (ASTs) is not advisable, especially at larger terminals This method poses significant risks, including challenges in achieving the correct blend, the risk of component stratification due to insufficient receipt velocity, and an increased likelihood of water contamination in the final product Additionally, correcting blend errors becomes difficult once an off-specification blend is present in the tank.
Batch blending neat ethanol in aboveground storage tanks is the standard method for denaturing ethanol, commonly practiced at water and marine supplier terminals.
Rack blending techniques are divided into three basic groups: splash, sequential, and ratio (in-line) blending
Splash blending involves the sequential loading of gasoline and fuel ethanol into a tank truck using different loading arms, which the truck driver or operator manually switches Each loading arm is equipped with its own meter and control valve, and the quantity of each blend component is calculated manually, lacking automatic validation of the final product blend Additionally, components may be loaded into compartments at various locations.
Splash blending has several drawbacks, primarily because the blend recipe is directly determined by personnel at the loading rack Additionally, this method necessitates that the driver or operator manually switch between blend stocks, which involves disconnecting and reconnecting equipment.
After loading the first blend component, the loading hose must be connected to another loading arm for the second component, necessitating the adjustment of two complementary blend stock volumes to accurately meter the load into the truck These operations heighten the risk of blending errors, overfills, or accidents due to the increased time and manpower involved In high-volume terminals, dependence on splash blending can negatively affect the terminal's daily throughput.
In certain situations, component loading can take place at two separate facilities When the second blending component is loaded into a truck compartment that already has a partial load, the risk of an incorrect blend or overfill due to human error significantly increases.
The blend ratio with splash loading is accurate only once all components have been fully loaded, as there is no automatic validation of the blend's correctness Effective blending in the truck depends on the volume and turbulence created by adding the second and, if necessary, third components.
Initial mixing during loading can be incomplete due to the loading rate and volume While incidental mixing may happen in the truck during transport and when loading into the delivery tank, the blend components may not achieve a homogeneous mixture Consequently, splash loading raises the risk of incomplete mixing, potentially resulting in an off-specification blend.
Splash blending is a cost-effective blending method, as it requires minimal equipment investment and does not necessitate automation While independent meters can be calibrated for accuracy, this technique is often avoided due to safety and precision concerns.
Splash blending should be used only as a temporary measure until a permanent blending system can be installed, or at small terminals where only a few loads a day are blended
E10 can be blended using the techniques outlined in section 5.3.3, although in-truck splash blending is not advisable If splash blending is required, it is crucial to load gasoline into the tank truck prior to adding ethanol to maintain vapor concentration above the upper flammable limit Adhering to the accepted industry practices as specified in API 2003 is essential.
E10 blends should conform to the most recent version of ASTM D4814.
E85 can be blended using the techniques outlined in section 5.3.3, although in-truck splash blending is not advisable If splash blending is required, it is essential to load gasoline into the tank truck prior to adding ethanol to maintain vapor levels in the compartment headspace above the upper flammable limit Adhering to the accepted industry practices as specified in API 2003 is crucial.
E85 should be handled using the same procedures as those for distillates with regard to switch loading
E85 blends should conform to the most recent version of ASTM D5798.
Terminal Material Compatibility
Terminal components that interact with blend stocks and blended products in fuel and vapor pathways must be compatible with the ethanol blends they encounter This compatibility is essential for safety, adherence to fire codes, and compliance with regulatory requirements.
New fuel blends that require a new Material Safety Data Sheet (MSDS) must be considered significantly different from prior products It is essential to assess systems designed for these new fuels for material compatibility and compliance with fire safety and regulatory standards before their implementation To utilize a new component or to continue using an existing one, it is necessary to obtain confirmation of compatibility from the manufacturer or a third-party certification, ensuring adherence to relevant fire codes and OSHA regulations.
Incompatible materials should not be used because of the potential to degrade fuel quality and the possibility of component failure.
Material compatibility for components or systems can be demonstrated through various methods The most widely accepted approach is first-party confirmation from the manufacturer, which verifies compatibility in terminals This confirmation can be further supported by independent third-party assessments and, if necessary, by a Nationally Recognized Testing Laboratory (NRTL) for listed equipment.
Engineering judgment is crucial in designing and constructing terminals due to the unique characteristics and requirements of each facility As a result, many terminal equipment systems, including tanks, piping, and loading racks, are not mandated by codes or regulations to be certified by a Nationally Recognized Testing Laboratory (NRTL).
For components at terminals, equipment manufacturers have two choices to show compatibility:
1) hire a qualified third party or NRTL to determine compatibility, or
Qualified third-party testing laboratories, engaged by component manufacturers, assess material compatibility They evaluate compatibility for specific service types by considering component design, conducting appropriate tests, and leveraging prior experience.
Manufacturers can verify component compatibility through their specific testing methods, which may differ and are not always directly comparable While these determinations are significant in the absence of other compatibility indicators, they may not be recognized by all Authorities Having Jurisdiction (AHJs) and cannot substitute for a Nationally Recognized Testing Laboratory (NRTL) listing when legally required.
Certain components or systems that demonstrate acceptable material compatibility may require additional testing for approval by Authorities Having Jurisdiction (AHJs) if the test fuel differs from the ethanol blend intended for use It is essential for owners and operators to keep comprehensive records of compatibility findings for all system components.
Material compatibility alone does not ensure operational compatibility Terminal operators must confirm the accuracy of systems and components in fuel service with the equipment manufacturer.
5.4.3 Terminal Accelerated Corrosion and Conductivity
Ethanol exhibits higher electrical conductivity and oxygen content compared to gasoline and other hydrocarbon fuels Its chemical properties enable it to absorb water effectively, which, when mixed with gasoline, creates a suspension that promotes galvanic corrosion and rusting This oxygen-rich environment, combined with its conductivity, can lead to corrosion and metal loss in components that typically remain unaffected by gasoline.
Ethanol can corrode certain soft metals, including zinc, brass, copper, lead, and aluminum, leading to potential component failures and compromised fuel quality Additionally, seals, gaskets, and elastomers not designed for ethanol blends may lose integrity, resulting in leaks It is essential to confirm the compatibility of any components with ethanol before use.
Terminal Fuel Quality
Ethanol is a hydrophilic substance that easily absorbs water, creating a uniform solution throughout its dilution range When water enters ethanol and gasoline-ethanol storage tanks, it is quickly absorbed, leading to potential fuel contamination In contrast, gasoline is hydrophobic and has low solubility with water As a result, the inclusion of ethanol enhances the overall solubility of water in ethanol-gasoline blends compared to standard gasoline Understanding the impact of water on gasoline-ethanol blends and methods for detection is essential for ensuring fuel quality.
Phase separation is rare in fuel ethanol or E85 due to their high ethanol concentration Any significant water accumulation in these tanks is likely to be detected early, often due to visible tank defects or inconsistencies in inventory control Regular testing for water content and the reliable performance of tank water draws serve as the most effective indicators of potential water issues, as the ethanol extracted will exhibit high water saturation.
The ability of a gasoline-ethanol blend to absorb water is influenced by the ethanol content In low-ethanol blends like E10, only limited water absorption occurs, but once a certain threshold is reached, saturation happens Any extra water or a decrease in temperature can lead to the separation of ethanol from gasoline, creating a distinct solution with the water This occurrence is referred to as phase separation in ethanol blend storage tanks.
A water/ethanol solution settles at the bottom of the tank, creating a distinct layer, while off-spec gasoline remains above with a lower ethanol content, leading to a decrease in octane levels.
The discovery of phase separation in a storage tank can signal potential defects in the tank or its system It is crucial to take the tank out of service immediately, treating the water phase as a hazardous flammable liquid and disposing of it according to federal, state, and local regulations Additionally, the ethanol-depleted gasoline in the upper phase must be handled as an off-specification product.
Ethanol's solubility in water is influenced by temperature, rising with higher temperatures and greater ethanol concentrations in the blend To prevent irreversible phase separation, it is crucial that fuel ethanol used for gasoline blending remains free from water contamination.
To prevent contamination in gasoline-ethanol blends, it is essential to ensure that the tank and piping system are clean and dry before introducing ethanol Maintaining good housekeeping practices during operations is crucial to prevent water from entering the system Additionally, identifying and eliminating all sources of water is necessary to avoid future contamination.
Water can enter storage tanks through unintended openings in the tank shell or roof, especially during rain or snow External floating roofs are particularly vulnerable to water ingress during bad weather Additionally, temperature fluctuations and high humidity can lead to condensation forming on the inner surfaces of tanks above the internal floating roof If enough condensation accumulates, it can drain past the floating roof seals and contaminate the liquid product.
Water can inadvertently enter the ethanol tank due to its presence in the supplied ethanol, which may occur if the product was not kept dry during transit or if moisture was not fully removed during manufacturing It is essential to conduct periodic tests to verify that the ethanol received meets the specified water content standards If water contamination is detected, it is crucial to identify and eliminate the source to prevent further contamination of the fuel.
Microbes can thrive in tanks with gasoline-ethanol blends, potentially causing microbial-induced corrosion (MIC) in both aerobic and anaerobic environments Aerobic microorganisms feed on hydrocarbons at the interface of the water and gasoline layers, while other microbes can establish colonies in tank bottom sludge, directly contacting steel surfaces.
Microbial metabolic wastes generate water, sludge, and acidic byproducts that lead to material degradation The acidic residues from sulfate-reducing bacteria can result in metal corrosion, potentially leading to tank failures if not properly managed The presence of sulfur odor in fuel is a clear indicator of microbial activity Additionally, microbes can damage rubber gaskets and various seal, hose, and coating materials due to their mineral content Recent evidence has also highlighted the occurrence of Microbiologically Influenced Corrosion (MIC) in un-phase-separated ethanol blends.
The main factor driving microbial growth is water presence To prevent this growth, it is essential to minimize water intrusion in tank systems and regularly monitor for early signs of phase separation Additionally, using biocides specifically designed for tank use can effectively manage persistent microbial populations in fuel.
Terminal Spill/runoff Management at Terminals
Ethanol is fully miscible with both gasoline and water, making it impossible to separate from spills or wastewater through gravity separation If a gasoline-ethanol blend spill is not addressed promptly, it will inevitably interact with water at the spill site or within the oil/water separator This interaction leads to phase separation, causing the ethanol to separate from the gasoline-ethanol blend.
`,````,,,,,`,`,`,``,`,````,`-`-`,,`,,`,`,,` - partially dissolve into the water Ethanol that is dissolved in water will pass through a gravity separator and will not be captured
The following are techniques that can be used to manage ethanol-containing waste streams.
— Ethanol transfer areas should be kept separate from traditional gasoline transfer areas The spill and runoff streams from the two sources should be kept segregated
— Discharge to the Sewer—Some jurisdictions allow the discharge of ethanol-water mixtures into the sanitary sewer system Check with the local AHJ regarding discharge requirements and limitations.
— Collection Tanks—Ethanol-containing mixtures can be collected and stored in segregated tanks for off-site treatment or disposal
Constructing wetlands can effectively manage waste streams that consist primarily of ethanol and water, along with minimal hydrocarbons These waste streams can be directed to designated unpaved areas, allowing for natural percolation and biodegradation processes It is essential to consult a qualified environmental consultant and the Authority Having Jurisdiction (AHJ) to evaluate the feasibility of this approach.
Other options employing advanced treatment technologies such as enhanced oxidation may provide alternative management techniques Consult a qualified environmental consultant for further information.
Terminal Source Segregation
To ensure safety in E85 and fuel ethanol loading areas, it is crucial to keep ethanol-containing waste streams separate from clean stormwater runoff Ethanol unloading areas and loading racks must be equipped with impoundments and dedicated drainage systems to effectively capture and contain any spilled ethanol and incidental stormwater runoff Additionally, neat ethanol and fuel ethanol storage tanks should have diked areas that are distinct from petroleum hydrocarbon storage tanks to prevent mingling of stormwater runoff Proper management of collected materials must comply with the requirements set by the Authority Having Jurisdiction (AHJ).
Terminal Aboveground Storage Tanks
Ethanol, whether in its neat form, as fuel ethanol, or in gasoline-ethanol blends, can be stored in terminals using fixed roof tanks or tanks with internal floating roofs A critical factor in the storage of ethanol is preventing its contact with water.
External floating roof tanks are exposed to environmental conditions, which allows precipitation to seep through the roof seals and contaminate the stored product Additionally, rainwater can enter the stored product through faulty roof drains Consequently, the use of external floating roof tanks is not advisable for the storage of ethanol or ethanol blends.
For tanks with diameters less than 12 to 15 feet, floating roofs are not practical due to the risk of the roof becoming stuck or sinking if the tank shell is not perfectly round Instead, fixed roof tanks without an internal floating roof should manage vapor venting using a pressure/vacuum (P/V) valve It's important to note that the true vapor pressure of ethanol at typical storage temperatures is often at or above the threshold that necessitates control measures for storage tanks in certain jurisdictions Therefore, it is advisable to consult with the Authority Having Jurisdiction (AHJ) regarding specific emission control requirements for ethanol or gasoline-ethanol blends.
Ethanol tank headspace vapors are flammable in all storage conditions, making the installation of a flame arrestor on the vent a crucial safety measure For more information, refer to section 4.10, which discusses flame arrestors in detail.
Tanks containing ethanol for blending should be clearly identified Refer to API 1637 for specific color-symbol system information.
The design, construction, maintenance, inspection, testing, and repair of aboveground storage tanks are governed by several standards, including API 620, API 650, API 651, API 652, API 653, API 2610, API 12F, STI SP001, and UL-142 It is essential to adhere to the mandatory provisions outlined in these standards In cases where local codes or regulations impose stricter requirements, those provisions take precedence.
5.8.1 Terminal Stress Corrosion Cracking in Tanks
Stress corrosion cracking is environmental cracking in a susceptible metal or tough thermoplastic material that is produced by the simultaneous application of a tensile stress and exposure to a corrosive environment
To date, there have been no reported cases of stress corrosion cracking (SCC) at ethanol manufacturing facilities, tanker trucks, tank cars, or barges Additionally, blending and transportation facilities handling fully blended fuel ethanol and gasoline have not reported any SCC incidents All documented cases of SCC have occurred at fuel ethanol distribution terminals or gasoline blending and distribution terminals, with the reasons for this discrepancy remaining unclear This may be due to reduced susceptibility to SCC in certain supply chain facilities or a lack of reporting As a result, the causes of SCC continue to be under investigation.
API has issued two reports identifying probable root causes of SCC See API 939-D and API 939-E for further information.
Until there is a more definitive understanding of how to mitigate significant risks from SCC for carbon steel components in fuel ethanol systems, the following recommendations should be considered.
5.8.1.1 Terminal Post Weld Heat Treatment (PWHT)
Post-weld heat treatment (PWHT) effectively minimizes stress corrosion cracking (SCC) susceptibility in welded steel components by alleviating residual tensile stresses and hardness in heat-affected zones However, PWHT may not be feasible for tank floor seams or floor-to-shell welds, where significant opportunities for SCC reduction are present.
Applying phenolic epoxy coatings with proven chemical resistance to ethanol is essential for minimizing crack initiation and propagation on the internal surfaces of ethanol tanks These coatings should be used on the tank bottoms and extend up to the first three to six feet of the tank shell to ensure optimal protection.
To effectively prevent SCC, it is advisable to apply bottom coating to as much of the shell as possible, extending up to the floating roof seal area, typically around 5 to 7 feet above the bottom when the floating roof is resting on "high legs."
To achieve optimal protection against Stress Corrosion Cracking (SCC), it is essential to coat all wetted surfaces, including the underside panels of the floating roof The lap welding of these panels makes it challenging to prevent ethanol from reaching the heat-affected areas on the bare steel between the laps A viable solution is to seal weld the exposed edges of the lap welded panels, thereby safeguarding the heat-affected areas from ethanol exposure By coating the underside, both the seal welds and the heat-affected areas from the original lap welds on the top side receive protection It is important to note that Post-Weld Heat Treatment (PWHT) or stress relief is not advisable.
The cost to take extraordinary measures to prevent SCC in a floating roof should be weighed against the site and business risks associated with having an unexpected failure in service.
Table 1 offers a qualitative comparison of three levels of tank coating, highlighting the extent of internal coating and its associated benefits Each subsequent level encompasses all the provisions and advantages of the previous levels, illustrating a comprehensive progression in coating quality.
See API 2610 and API 939-E for discussions on coating.
While many steel tanks and pipes have successfully operated in fuel ethanol service for years without experiencing stress corrosion cracking (SCC), there have been instances of SCC occurring within just 12 months of initial use Current experience does not provide a definitive SCC inspection interval, so users must assess various factors when determining inspection frequency These factors include the risk of leakage, potential consequences of a leak, release containment methods, operating conditions, equipment criticality, and the inspection and repair history of similar equipment at the facility.
The general methodology for a risk-based approach to inspection is explained in API 580 along with specific applications where SCC is a factor.
Regardless of approach used to determine the inspection frequency for tanks in ethanol service, inspection intervals should still be consistent with the inspection requirements in API 653 and STI SP001.
Terminal Tank Vents and Air Dryers
To reduce the risk of water vapor entering a fuel ethanol tank and condensing, it is essential to vent the vapor space using a desiccant drier system This system effectively removes moisture from the air that enters the tank, ensuring that the dew point in the vapor space remains significantly lower than the surrounding ambient temperature.
Review local conditions such as humidity and diurnal temperature variations to assess the need for a drier.
Terminal Flame and Detonation Arrestors
A flame arrestor is installed in the vapor return line between the loading rack and the vapor processing unit to stop the spread of a flame front in the presence of flammable mixtures As loading volumes of high-blend ethanols increase, the vapors in the line become more susceptible to reaching flammable levels.
Flame arrestors can also be used on the outlet of vent lines of neat ethanol and fuel ethanol tanks that have flammable vapor/air mixtures in their headspace.
Table 1—Internal Tank Coating Comparisons Coated Area Level of Difficulty Advantage/Disadvantage Degree of Protection
Routine Reduces risk of most common
Protects entire shell against SCC
Adds fall risk to personnel during coating application Increased cost
Seal welding underside of roof
Extensive overhead welding Significantly increased cost Maximum
Ensure that detonation and flame arrestors are approved for ethanol service, and verify that all materials and seals are compatible with ethanol and its vapor Using incompatible materials in the arrestor element may lead to flow restrictions.
Loose scale and rust in vapor return piping can accumulate on detonation/flame arrestor elements, potentially exacerbated by ethanol vapors This buildup of obstructing materials can become saturated with fuel vapor, increasing combustibility and diminishing the arrestor's effectiveness in preventing deflagration propagation It is essential to monitor flame arrestors for foreign material accumulation, as this can impede flow and be assessed by checking the pressure drop across the matrix element.
Ethanol vapor can dissolve in glycol-water solutions utilized in liquid-seal flame arrestors, reducing their effectiveness It is essential to regularly monitor the ethanol concentration by measuring the specific gravity of the liquid bath, as a high enough ethanol concentration may render the solution flammable When disposing of used liquid seal solutions, ensure compliance with relevant waste handling and disposal regulations.
As an option, a detonation arrestor may be considered as an alternative to the liquid seal flame arrestor.
Terminal Pipe, Valves, Pumps, and Piping Systems
For pipes, valves, pumps, and piping systems, follow the recommendations of API 2610 All materials including seals, gaskets and other elastomers should be compatible with the ethanol concentration in service.
It is advisable to steer clear of cold-formed steel components, like dished ends for tanks and filters If avoiding them is not feasible, ensure that the fabrications undergo shot-peening, crack inspection, and internal coating for enhanced durability.
To effectively reduce the occurrence of Stress Corrosion Cracking (SCC) in piping, it is essential to minimize stress levels This can be achieved by decreasing the spacing between pipe supports and designing systems that mitigate stresses caused by thermal movement It is advisable to avoid welding pipe supports directly to the parent pipe and to utilize clamp-type pipe supports whenever feasible For further guidance, refer to API 939-E, which offers recommendations for minimizing SCC in piping systems.