Welds of a thermal power plant boiler, which may be damaged by thermal fatigue cracking,
creep fatigue, etc., are surface-inspected using PT (penetrant testing), MT (magnetic particle
testing), etc. However, PT and MT inspections require the removal of the high-temperature
oxidized scale generated on the tube surface, and this preprocessing work takes time. Furthermore,
because there are parts with complicated shapes and narrow areas depending on the equipment, the
work efficiency of PT and MT may be lowered and that results in long inspection times.
Accordingly, Mitsubishi Heavy Industries, Ltd. and Mitsubishi Hitachi Power Systems, Ltd.
developed surface defect detection technology using Pencil ECT (Eddy Current Testing) as a
technique for efficiently detecting the damage. This paper describes the characteristics of Pencil
ECT and case examples of defect detection implemented on actual boilers.
