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Thickly coated hot-dip tin sheet was evaluated in fuel immersion, exterior corrosion, and weldability tests to determine its viability for methanol fuel tank applications. Performance in solutions of pure gasoline and low percentage methanol blends at ambient temperature and 60°C was excellent for hot-dip tin coated steels. However, in high-temperature testing in high methanol fuel blends, hot-dip tin sheet experienced some coating etching that was likely related to the added contaminants of formic acid and chlorides. Regarding exterior atmospheric corrosion protection, tin coatings are not sacrificial to exposed sheet steel, and therefore, tin coated sheet could be expected to provide exterior corrosion protection similar to terne coated sheet at similar coating weights. Tin coatings may require a primer coating for added exterior corrosion protection in fuel tank applications.

Methanol represents one of the most attractive alternative fuels intended to replace gasoline, but it is corrosive to the terne-coated steel sheet traditionally used for automobile fuel components. Application of a methanol-resistant polymer coating on a steel substrate was found to be a viable solution for methanol-resistant fuel tanks. One-sided electrogalvanized sheet was coated on the bare side with a nonconductive and adhesive thermoplastic. The present work studied the weldability of this sheet with the thermoplastic at the faying interface. A systematic parametric study was performed. Welds were evaluated using a set of criteria based on the joint integrity and corrosion resistance. It was found that the coating melted and resolidified in a continuous film adjacent to the welds. The resistance seam-welding operational envelopes were shifted toward lower welding travel speeds and welding currents.