In order to detect the inner wall defects of utility boiler tubes

based on the analysis of eddy current detection principle

this paper establishes the three-dimensional simulation model of pipes and detection coils

and analyzes the single-channel and multi-channel eddy current detection of pipe inner wall defects. The results show that

the highest detection sensitivity is located at 1/2 of the coil radius within the coil diameter range

and the lowest sensitivity is located at the outer diameter boundary of the coil. On this basis

a multi-channel eddy current detection device is designed and manufactured

which can effectively distinguish the detect of 5.0 mm×0.2 mm×0.2 mm(long×wide×depth) in the inner wall of the sample pipe

and the actual measurement result is accurate and reliable.It provides a new method for high-sensitivity automatic detection of inner wall defects of utility boiler tubes.