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Can sheet steel rust away in only 4 years?

2003

How fast can sheet steel rust? I am trying to determine the rate of oxidation on 10 gauge sheet steel. The sheet of steel in question is mounted vertically on a pitched shingle roof in a climate that receives about 12 inches of rain per year. I am working to ascertain the evaporation rate of water at the site of this particular sheet of metal (under my evaporative cooler). The big question is, how much of the sheet's surface area could I expect to rust over a 4 year period.

I'm looking to answer this question because a failure of this sheet of metal resulted in a major leak costing more than $1000 to repair. The roofers that are doing the repair state that there is no way that much damage could have occurred in just four years and the sheet should have been replaced when the roof was installed (4 years ago). If I can prove that the sheet was bad when the roof was replaced, I could recoup the cost of repairing the leak from the roofers that did the original work.

Thanks for your help,

Scott Willson
Homeowner - Tucson, Arizona, USA

Nobody can give a really good answer to such a question from a distance since it involves weather, wind, exposure angles, coating materials on the original sheet metal, quality of water in the evaporator, maintenance, etc., etc. I don't think you'll get to the answer that way.

However, you might be able to approach the problem as follows: How long has this evaporative cooler and the pan underneath it been there? The reason I would ask that is, say the answer is 40 years--then you might expect a roofer to recognize sheet metal that had reached 90 percent of its useful life, and suggest replacement. If the evaporative cooler has been there for only 8 years though, I don't know if I'd expect even a trained and commissioned metallurgist to be able to predict that the metal was at its half-life four years ago.

Although 10-gauge is quite thick, one generally doesn't rely on the steel itself to resist corrosion, but rather the coatings upon that steel. But again, I may not be correctly picturing what you are describing.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

Even if you are near salt water it is unlikely that 10 gauge steel would rust out as in completely through in 4 years. But as the previous gentleman said there are a lot of unknowns, like has there been anything rubbing against the sheet or is there vibration on the sheet. These things could shorten the lifespan, But as to an exact date you would probably have to send it away and have it tested. Big Bucks, thanks for the QUESTION.

Robert P KAINZ
METAL RESTORATION - ONTARIO, CANADA
2003