The Remote-field Eddy-current Test Technique Used In Defect Inspection Of The Service Power Station Boiler Four Tubes

The power station boiler is one of the three important machines of coal-fired power plants. Four tubes of boiler which include waterwall tube, superheater, reheater and economizer are the most important parts of power station. And they are also an important inspection parts of power station boiler regularly inspection.At present, it is limited for detection technology and test conditions, when the power station boiler is inspecting for regularly, Four tubes of boiler generally uses the traditional test method, adopting ultrasonic thickness and surface nondestructive testing for random inspection,so it exists missed detection risk.The traditional test method is not only work efficiency lowing, and long time for testing,so increasing running cost of the enterprise.The remote-field eddy-current test technique is a new kind of eddy current testing technology relativing to the conventional eddy current testing. It is a kind of low-frequency eddy current testing technology of penetrating the metal wall. The advantages of The remote-field eddy-current test technique is non-contact measurement, without coupling agent,without surface cleaning of the material,and will not cause environmental pollution. It is equipped with the spider to the higher position. So it can completely solve problems existing in the four tubes inspection. But the four tubes can not to be damaged in service inspection,So it can not using the inner wear probe, only using outside wear probe.Now,it still not solves the technical problems the remote-field eddy-current outside wear type probe, and the far field eddy current testing for the four tubes was still in the stage of trying, there is not systematic detection method and technology,which can be used.Firstly, the remote-field eddy-current test technique is analyzed by using the finite element simulation, the remote-field eddy-current test equipment were reviewed and understand and contrasted in domestic and foreign, Choosing the testing equipment which be exploited by Canada Russell NDE company. The equipment configurats two kinds of the testing probe,inner wear and outside wear. Secondly, test preparation is proceed in the laboratory, according to four tubes proning to defects, making for the contrast samples,then processing artificial defects which can simulats actual defects on the contrast samples.Combined with the matching detection equipment, to formulating the preliminary detection process.Artificial defects are detected correctly by the process,and making sure that the detection system achieves the required sensitivity. Then, using the detection sensitivity, the pipes,which are processde artificial defects,are tested in the laboratory. To verifing the correctness and feasibility of the detection process. At the same time,adjustmenting the thepreliminary detection process, which get the best test results. After that, on the basis of complete laboratory tests, the detecting process is applied to the detection of the four tube,and the process will be further verified. Finally, making the remote-field eddy-current testing work instruction documents which includes the test process, test records, test report of the four tubes. Expect that the detecting process can is widely used in the four tubes inspection.