A Research on Composite Nondestructive Testing Sensor of Boiler Water Wall Tubes

In this paper, a new composite NDT testing sensor for boiler water wall tubes defect detection is designed which using a combination of the electromagnetic acoustic transducer (EMAT) method, the magnetic flux leakage (MFL) method and the pulse eddy current testing (PECT) method. The purpose of the research is to make up for the limitation of the traditional single NDT method in terms of defect detection capability. Firstly, through analyzing the detection mechanism, establish the equivalent finite element of the composite detection sensor. Secondly, based on the numerical simulation, the working point for three different NDT methods and the structural parameters of composite detection sensor is determined. Thirdly, the experiment of the composite detection sensor is conducted cooperating with mechanical devices and testing equipment, and four types of defects on the water wall tubes are successfully identified. The experimental results proved the new hybrid NDT testing sensor can meet requirement of full-scale defects inspection for boiler water wall tubes.