Heat exchanger tubes in the main equipment of thermal power plant boilers, such as
economizers and reheaters, have concerns about the occurrence of local thinning caused by wear
of the external surface and widespread corrosion thinning. As a technology for the accurate
detection of such damage, Mitsubishi Heavy Industries, Ltd. (MHI) and Mitsubishi Hitachi Power
Systems, Ltd. developed the cable-less inner UT system, which is an ultrasonic water immersion
method that can measure tube thickness from inside the tube. This paper describes a summary of
the cable-less inner UT system and an example case of heat exchanger tube thickness measurement
performed on an actual boiler.
