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Method to determine number and size of samples taken from zinc roof to analyze pitting corrosion

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Abstract
Pitting corrosion is one of the most dangerous corrosion types for zinc roofs. The theory of extreme-value statistics is a powerful tool to quantitatively analyze pitting corrosion. For obtaining reliable results, it is very important to know how to collect small samples correctly and effectively. The method proposed by JSCE (1988) is disucsses. This method considers only the influence of the number of small samples on the estimated maximum pit depth over a large area and not the influence of the number of pits per small sample. An improved method, which takes both influences into account, is presented in this paper. Two examples are given to demonstrate the application of the improved method in zinc roofs.
Date
12/2001
Author(s)
Rongjin Zheng; Jan Carmeliet; Hugo Hens; Walter Bogaerts
Page(s)
Keyword(s)
zinc roof; metal roofing; corrosion; pitting; ASHRAE; ORNL


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