How to use salt spray data in real environments?

I want to convert resultant hours of salt spray corrosion test to estimated values in years for real life environments such as marine. In other words, How could I predict the result of real life tests using salt spray data?




I have to agree with Klaus. ASTM B117 is, at best, a QC procedure. In my experience, most corrosion and coatings scientist who use B117 do so because it is very well established, but it does not correlate to a real-world measure of performance. ASTM D5894 is a better cabinet test and there is also an SAE procedure developed for automobiles.


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*Note that I'm not an expert in this field and wikipedia itself is not a scientifically relevant primary source*. The latter might however be different for sources cited there.


**In short, you seemingly better shouldn't.**


It seems that the German wikipedia article on the [salt spray test](http://de.wikipedia.org/wiki/Salzspr%C3%BChtest) has collected a lot of critical remarks from different sources. In summary, standardized (ASTM B117 or DIN EN ISO 9227) salt spray tests may be used in quality control, but **cannot** be transfered to to real world. 


According to the wikipedia article, DIN EN ISO 9227 explicitly states:



> 
> Nur selten besteht ein direkter Zusammenhang zwischen der Beständigkeit gegen die Einwirkung von Salzsprühnebel und der Beständigkeit gegen Korrosion in anderen Medien. Die verschiedenen Faktoren, welche das Fortschreiten der Korrosion beeinflussen, können sich je nach den herrschenden Bedingungen sehr unterschiedlich auswirken. Dazu gehört z. B. auch die Bildung von Schutzschichten. Die Prüfergebnisse sollten deshalb nicht als direkter Hinweis auf die Korrosionsbeständigkeit der geprüften metallischen Werkstoffe in allen Umgebungsbedingungen betrachtet werden, in denen diese Werkstoffe verwendet werden können.
> 
> 
> 


I'd roughly translate this to: *Only rarely, a direct correlation between the resistance towards saline fog and the corrosive influence of other media can be found. Depending on the conditions, different factors promoting corrosion may have a distinctively different impact. This includes, e.g., the buildup of protective layers.
Consequently, testing results should not be taken as a direct hint on the general corrosion stability of metallic materials under all planned conditions.* 


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