Aboveground facilities often have steel-tube posts underground to provide improved earthquake resistance. These posts, buried in the earth, are prone to corrosion on the external surface, potentially reducing tube wall thickness and thus post strength as well.rnThe wall thickness of the tubes can be measured by the ultrasonic technique (UT); however, this method is influenced by unevenness on the internal surface of the tubes, leaving some wall areas unmeasurable. With this method it is difficult to measure tube wall thickness continuously or to obtain the wall thickness of specifically defined tube areas. In addition, such subterranean measurement is subject to many restrictions. To solve these problems, we have developed a method that uses the remote field eddy current technique (RFECT).
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