Study on Online Eddy Current Detecting of the Boiler Heating Surface Tube Elbow in Thermal Power Plants

According to the characteristics of the closed ends, the tight tube panel layouts and the narrow detecting space in online eddy current detecting of the boiler heating surface tube elbow in thermal power plants, an external placed saddle-shaped eddy current detecting probe is designed, which can be used to test the small diameter austenitic stainless steel tube elbow. The comparative sample tube is made in accordance with the eddy current detecting technical standards. Through the sample testing and the applications in thermal power plants, the results show that the designed saddle-shaped eddy current detecting device has better sensitivity and reliability to the linear defects more than 0.2 mm deep and the hole-like defects larger than D1.4 mm. It can realize the non-destructive online testing of the austenitic stainless steel tube elbow that has serious oxidation and corrosion as well as more concentrated stress.