National Tank Conference Alternative Fuels - Policy and ...
Transcript of National Tank Conference Alternative Fuels - Policy and ...
National Tank ConferenceNational Tank ConferenceAlternative Fuels Alternative Fuels -- Policy and Policy and
StandardsStandards
Steel Tank InstituteSteel Tank InstituteWayne Geyer & Lorri GrainawiWayne Geyer & Lorri Grainawi
API Study of SCC API Study of SCC ––Stress Corrosion CrackingStress Corrosion Cracking
Stress Corrosion Cracking (SCC) occurring in Stress Corrosion Cracking (SCC) occurring in approximately 20 storage tanks and one pipelineapproximately 20 storage tanks and one pipelineSignificant industry standards, research & Significant industry standards, research & articles to understand storage and handling of articles to understand storage and handling of alternative fuels such as Ethanol being done by:alternative fuels such as Ethanol being done by:–– ASTMASTM–– Renewable Fuels AssociationRenewable Fuels Association–– APIAPI–– Pipeline companiesPipeline companies–– SwRI, NACE & many othersSwRI, NACE & many others
What is SCCWhat is SCCStress corrosion crackingStress corrosion cracking ((SCCSCC) is the ) is the unexpected sudden failure of normally unexpected sudden failure of normally ductile metals or tough thermoplastics ductile metals or tough thermoplastics subjected to a constant tensile stress in a subjected to a constant tensile stress in a corcorrosive environment.rosive environment.
SCC SCC NotNot Occurring in:Occurring in:
Any place where ethanol has been Any place where ethanol has been blended with gasoline blended with gasoline Smaller tanks (shop & small field erect)Smaller tanks (shop & small field erect)Ethanol manufacturing facility (process Ethanol manufacturing facility (process system, tanks or equipment)system, tanks or equipment)Transportation equipment: barges, Transportation equipment: barges, tanker cars or tanker truckstanker cars or tanker trucksAnyAny segment of Brazilian systemsegment of Brazilian system
SCC Occurs WhenSCC Occurs When
SCC SCC occurring in distribution & blending occurring in distribution & blending facilitiesfacilities::–– Field Erected tank bottomsField Erected tank bottoms–– Floating roofs & Seal componentsFloating roofs & Seal components–– Lower shells of field erected tanksLower shells of field erected tanks–– Pipe racks and associated equipmentPipe racks and associated equipment–– Pipelines from terminal to end userPipelines from terminal to end user
SCC Areas
SCC Areas
SCC Relevant FactorsSCC Relevant Factors
Hydrated vs. anhydrous form of EthanolHydrated vs. anhydrous form of EthanolDissolved oxygen contentDissolved oxygen contentLocal areas of stress concentrations Local areas of stress concentrations (even when well below design basis)(even when well below design basis)Cyclic or flexing portions of tank or pipeCyclic or flexing portions of tank or pipeLap vs. butt weld seamsLap vs. butt weld seamsCold worked or localized bending areasCold worked or localized bending areas
Compatibility of Steel with BiodieselCompatibility of Steel with BiodieselObjectiveObjective
This study was cosponsored by National This study was cosponsored by National Biodiesel Board and NORA.Biodiesel Board and NORA.Measure corrosion rate of steel with Measure corrosion rate of steel with biodiesel blends using an accelerated test biodiesel blends using an accelerated test method.method.Corrosion rate measured using Corrosion rate measured using electrochemical impedance, weight loss electrochemical impedance, weight loss and optical examination.and optical examination.
Test SetTest Set--upup
Due to the low conductivity of the solution, Due to the low conductivity of the solution, a twoa two--electrode setup was used, in which electrode setup was used, in which two electrodes made out of carbon steel two electrodes made out of carbon steel were placed in the electrochemical cell at were placed in the electrochemical cell at a very small separation distance. a very small separation distance.
Steel Coupons / Two electrodesSteel Coupons / Two electrodes
Test FuelsTest Fuels
Two types of BiodieselTwo types of Biodiesel–– Soy Soy
–– Animal FatAnimal FatBiodiesel is produced from raw vegetable Biodiesel is produced from raw vegetable oils or animal fats, but the oil or fat must go oils or animal fats, but the oil or fat must go through the chemical reaction (called through the chemical reaction (called transesterificationtransesterification) to make it into biodiesel ) to make it into biodiesel
Test FuelsTest Fuels
Two types of dieselTwo types of diesel–– Ultra Low Sulfur DieselUltra Low Sulfur Diesel–– 3500 3500 ppmppm sulfur diesel sulfur diesel (heating oil)(heating oil)
Test fuelsTest fuels
Biodiesel blendsBiodiesel blends–– 0%0%–– 5%5%–– 20%20%–– 50%50%–– 100%100%Water equal to 1% of fuel volume Water equal to 1% of fuel volume added to 1/2 of the samplesadded to 1/2 of the samples
Biodiesel test setBiodiesel test set--upup
Test setup
Plexi glass to hold wires and keep temperature constant in oven during impedance measurement
Test cells in oven with electrical connections
Oven set at 43 C = 109.4F
Temp controller on top of oven
Test ApproachTest Approach
LongLong--term exposure of steel coupons to term exposure of steel coupons to biodiesel blends, petroleum fuels and biodiesel blends, petroleum fuels and waterwaterTypical low carbon steel usedTypical low carbon steel usedSteel tested as normally used, i.e., not Steel tested as normally used, i.e., not blasted or polishedblasted or polished12 week exposure at 4312 week exposure at 43 C equivalent to C equivalent to 12 months storage12 months storage
Data CollectedData Collected
Impedance spectra collected once a week Impedance spectra collected once a week The cells were disassembled, visually The cells were disassembled, visually inspected, photographed and weighed inspected, photographed and weighed after 1 month, 2 months and 3 months at after 1 month, 2 months and 3 months at conclusion of testconclusion of test
Corrosion expectedCorrosion expected
In the fuel blends, it was expected that as In the fuel blends, it was expected that as the fuel aged, acetic acid would form the fuel aged, acetic acid would form increasing the number of charge carriers, increasing the number of charge carriers, thus increasing the corrosion rate. thus increasing the corrosion rate. But, conductivity of the fuel blends was too But, conductivity of the fuel blends was too low to measure any corrosion, even at end low to measure any corrosion, even at end of 12 week period.of 12 week period.
STI/SPFA
Visual InspectionVisual InspectionUpon visual inspection of the test Upon visual inspection of the test coupons, a small amount of surface coupons, a small amount of surface rusting was observedrusting was observed
Figure 4. Photographs of carbon steel specimens exposed to ULSD and soy-based biodiesel blends with and without the presence of water: (a) 100 % biodiesel, no wadded; (b) 50 % biodiesel + 50 %ULSD, no water added; (c) 100 % petrodiesel, no water added; (d) 100 % biodiesel, 1 vol% water added; (e) 50% biodiesel + 50 %ULSD, 1 vol% water added and (f) 100 % ULSD, 1 vol% water added. Exposure time: 2 months.
Surface RustSurface Rust
In most cases, the amount of surface In most cases, the amount of surface rusting was slightly higher in 100 % ULSD rusting was slightly higher in 100 % ULSD than in biodiesel or biodiesel + ULSD than in biodiesel or biodiesel + ULSD blends. blends. This surface rusting was caused by a This surface rusting was caused by a reaction between the surface oxide layer reaction between the surface oxide layer of the metal and the fuel blend. of the metal and the fuel blend.
Low magnification optical Low magnification optical micrographs micrographs
100% Biodiesel
50% ULSD/ 50% Biodiesel
100% ULSDNo water added to any fuel
Typical Microscope ImagesTypical Microscope Images100 % animal-based biodiesel, no water added
toolmark
1 mm
Sample 25Sample 25
Greatest weight loss occurred with 5% Greatest weight loss occurred with 5% animal based biodiesel/ ULSD/ 1% wateranimal based biodiesel/ ULSD/ 1% waterOptical examination indicated no Optical examination indicated no measurable pits on this samplemeasurable pits on this sampleCorrosion rate calculated at 0.09 mm/yrCorrosion rate calculated at 0.09 mm/yr(.00354 in/yr)(.00354 in/yr)Equates to Excellent Corrosion Resistance Equates to Excellent Corrosion Resistance ratingrating
#25 #25 -- Microscope ImagesMicroscope Images5 % animal-based biodiesel + 95 % 3500 ppm S petrodiesel, 1 vol% water added
1 mm
Sample 30 Sample 30 ––20% bio/ 80% 3500 / 1% water20% bio/ 80% 3500 / 1% water
Optical examination revealed small pitOptical examination revealed small pit
Before After
Depth profile of surface damaged found on specimen exposed to 20 % animal-based biodiesel + 80 % 3500 ppm S petrodiesel, 1 vol% water added
Greatest Pit depth = 4.57 um = 0.000179 inches
Conclusions Conclusions
Corrosion rated as Corrosion rated as ““outstandingoutstanding”” or or ““excellentexcellent””Corrosion rate so low using Corrosion rate so low using electrochemical impedance that it could electrochemical impedance that it could not be measured.not be measured.Any pits that occurred < 5 Any pits that occurred < 5 µµmm
AcknowledgementsAcknowledgements
Many thanks to both National Biodiesel Many thanks to both National Biodiesel Board (NBB) and National Oil Heat Board (NBB) and National Oil Heat Research Alliance for helping to fund this Research Alliance for helping to fund this project.project.Also a special thanks to Steve Westbrook Also a special thanks to Steve Westbrook at Southwest Research Institute for his at Southwest Research Institute for his many contributions.many contributions.
Other organizations & committeesOther organizations & committees
NACE committee on BiofuelsNACE committee on Biofuels–– Develop a standard on corrosion and Develop a standard on corrosion and
degradation issues for transportation and degradation issues for transportation and storage of biofuels. storage of biofuels.
Ethanol Ethanol RoadmappingRoadmapping meetingmeeting–– GovGov’’tt and Industry are pursuing major and Industry are pursuing major
initiatives to assess the opportunities and initiatives to assess the opportunities and challenges related to ethanol challenges related to ethanol
ASTM D02.14 ASTM D02.14 -- Corrosivity of Fuels Corrosivity of Fuels
Questions?Questions?
For more information, contact:For more information, contact:Lorri GrainawiLorri GrainawiDirector of Technical ServicesDirector of Technical ServicesSteel Tank InstituteSteel Tank [email protected]@steeltank.com847.438.8265 x244847.438.8265 x244