| Abstract | Corrosion of galvanized tanks was studied in domestic installations in rental housing projects of Central Mortgage and Housing Corporation at Peterborough, Belleville and Brantford, Ontario where sample tanks of the Ontario Hydro- Electric Power Commission were used and at Windsor, Ontario where regular commercial tanks were used. In the first series it was shown that temperature was an important factor affecting the corrosion. In the series conducted at Windsor it was shown that when 3-kw side-arm heaters were used instead of small immersion heaters the design change was the greatest single factor in reducing corrosion. Copper piping was shown to have an influence upon the corrosion, especially if a copper dip tube was used inside the tank. Results from tests involving corrosion inhibitors were inconclusive, perhaps because the concentration of about 10 ppm was too low. Micrographs of the galvanized coatings show that the corrosion attack was very irregular, starting with fissures and separating the zinc-iron layers from the base. These fissures appear even in the uncorroded edges indicating they are produced in the galvinizing process and that changes in this progress may improve the corrosion resistance. Reversal of potential between the steel and the zinc also is apparent in some micrographs. |
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