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The following discussion that occurred on the NACE corrosion network indicates how localized an atmospheric condition can be.
Does anyone have evidence or even an opinion that airports are more corrosive than nearby areas? If so, could it relate simply to sulfur dioxide emissions from (car and truck) traffic that prevail? Does aviation fuel have any significant sulfur content?
John Leitch
We conducted surveys of automobile corrosion at parking lots near the airport in Montreal for many years. One of the lots was a new car dealership which was at the end of a runway right under the approach for takeoff and landing. We found that the metallic trim (type 434 SS, chrome plated steel, etc.) on these new vehicles were undergoing localized corrosion such as pitting and crevice corrosion after a short time on the lot. This corrosion was much more severe than that observed on other city driven vehicles. I concluded that other factors, in addition to road deicing salts and acid rain and snow, were involved.
I attributed the excess corrosion to exhaust emissions from the aircraft jet engines. The appearance of the localized corrosion on the trim was similar to that observed down-wind and close to volcanic activity. Both of these environments have sulfur containing compounds which can cause this type of corrosion.
Robert Baboian
Thank you, Robert, for that information. It rather agrees with some personal observations of many years ago. Anyone who has ever worked in or near a foundry that melted iron in a cupola before the days of strict air pollution control regulations should remember that. Unless captured and scrubbed, the emissions from a cupola (smoke, if you will) contain sulfur compounds and various oxides that become airborne. On a dry, windy day, there was no problem - the ash would simply blow somewhere else. On a dry, calm day, there was no real problem. The ash would settle on parked cars, but would blow off as you drove away. On a very rainy day, there was no problem. The ash would be washed off cars.
But on a damp, misty day, there was trouble. The dampness would not only allow the ash to settle and cling to parked cars, but would also supply water that would allow the sulfur-rich compounds to form acid. I had a 1960 white Ford Falcon that began to form tiny rust dots all over it, with horizontal surfaces being the worst. The soup that formed would eat right through the paint, and just about anything else. Fortunately, those days are gone. I still kind of miss the car, though.
GACraft
