IBEX1 Alcohol in Gasoline: Some Implications in Aluminum Fuel Tanks Kenneth M. Smith, Jr., P.E. Michael J. Danko, E.I.T. Engineering Systems Inc Exchange Avenue Aurora, IL V: x287 F: Cell:

IBEX2 Engineering Systems Inc. Engineering consulting firm specializing in Research and consulting Forensics, Accident investigation Many engineering disciplines Materials, Mechanical, Electrical, Biomechanical Commercial Marine, Civil, Structural, Marine –Marine Research focus at Ft. Myers, FL

IBEX3 Gasoline Gasoline is not uniformly formulated product –Formulation varies brand to brand –Season to season –State to state –Sometimes day to day E-10 (10% ethanol) is mandated in many mid- west states Results not uniform for all products!

IBEX4 Aluminum Fuel Tanks USCG, ABYS, NMMA approved and commonly used especially in larger yachts Good history in service Good value and many good properties wrt gasoline tankage. Does E-10 affect tank performance? (Lab tests, sea salt water and AL5052)

IBEX5 Corrosion Surface protection is “automatic” –Aluminum oxide formation Galvanic corrosion potential when: –Electrolyte (conductive medium) –Dissimilar metals present Most vulnerable areas –If metals contaminate tanks –Near welds

IBEX6 Mechanism Dissimilar metals form a “battery” Local anodes and cathodes –Current flows through metal –Cathodes sacrifice metal into liquid as ions –Local metal loss, pitting potential Must have a conductive liquid electrolyte

IBEX7 Corrosion Sites Where water phase pools under gasoline At the water-gasoline interface Near dissimilar metal or contamination site Accelerated with Cu for these tests of Al 5052

IBEX8 E-10 Holds Water How much --Depends on: Temperature Hydrocarbons in the gasoline blend (aromatics and others) Alcohol blend Co-solvents in the gasoline. Often blended with TBA More alcohol in blend holds more water

IBEX9 Affects of E-10 on Corrosion Carries more water (including salt water) into solution or suspension Apparently concentrates salt in water phase when second phase forms

IBEX10 Specific conditions Dissolves seawater Promotes general corrosion Observed in laboratory

IBEX11 Conclusions E-10 introduces slight increase in corrosion potential in aluminum tanks Requires a combination of unusual factors –Salt water contamination (long term) –Contamination of tank with solids May be possible to passivate surfaces to reduce corrosion potential further –Requires focused research

IBEX12 Brand ABrand B Coupon #% Salt Water Corrosion rate: 0.1 mils/yrPit Depth (mils)

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