This paper proposes a reliability assessment method for thickness measurements of pipe wall using probability of detection (POD). Thicknesses of pipes are measured by qualified inspectors with ultrasonic thickness gauges. The inspection results are affected by human factors of the inspectors and include some errors, because the inspectors have different experiences and frequency of inspections. In order to ensure reliability for inspection results, first, POD evaluates experimental results of pipe-wal...
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Reliability assessment for thickness measurements of pipe wall using probability of detection

This study discusses a practical application of diagnostic signature analysis to testing machine plant. The specific　features　of　acoustic signal from rotating machines are caught by diagnostic signal analysis.　As a result, the automated inspection and diagnosis of the rotating states of motors have become possible. For the diagnostic technique composed of signal averaging and normalization method is used. The statistical classifications using a characteristic function and an estimated function have p...
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Practical Application on Diagnostic Analysis to Testing Machines By Observing Noise Signals in Plants

This paper is concerned with quantitative evaluation of pipe wall thickness Electro Magnetic Acoustic Transducer (EMAT). This pipe wall thinning occurs on a piping internal wide range at an orifice, an elbow, and a reducer downstream. A shape of a pipe wall thinning like Flow-Accelerated Corrosion (FAC) is near arc. And a pipe wall thinning has the s urface like scales. Test samples were fabricated to simulate FAC in the series of experiments. A shape of corrosion of the test samples is arc. Other test sam...
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Measurement of Pipe Wall Thickness using EMAT in Flow-Accelerated Corrosion

This study deals with a crack detection method with a mobile robot for preventive maintenance of power plant. Eddy current testing (ECT) is a major technique for detection of c racks found out in structures of the power plant. In this paper, we develop a mobile robot with ECT sensor composed of a transmitter-receiver coil probe. The robot detects a cr ack by ECT sensor signals and localizes the crack by the position of the robot. Then, the robot traces the crack and reconstructs the shape of the crack. By ...
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Development of Mobile Inspection Robot in Eddy Current Testing

This paper is concerned with a method for identification of crack shape in material. Natural crack is described by a layered conducting model with respect to each finite element of a sample material. Two dimensional image is obtained by eddy current testing simulator with the layered conducting model. The inverse analysis is discussed with the background knowledge of nonlinear output least square method....
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A Method of Crack Profiles Identification in Eddy Current Testingusing a Layered Model of Natural Crack

This paper is concerned with a method for identification of crack shape in conduc ting materials. ulti-directional scanning strategies using Eddy Current Testing i s performed for sizing complex natural akings. Two dimensional measurements by m eans of multi-directional scan are used in a output least uare identifications. ,...
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A Method for Crack Profiles Identification in Eddy Current Testing by the Multi-directional Scan

The aim of this work presented here is to analyze the mechanism of ultrasonic test signals in magnetic materials using electromagnetic acoustic transducer (EMAT). The coupling mechanism for EMAT between the electromagnetic fields and the applied excitation of ultrasonic wave are investigated. First, a nonlinear magnetic model in two dimensions is presented for the coupling mechanism. Secondly, the coupling mechanisms in ferromagnetic materials are studied analytically and numerically. Finally, the nume...
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Analysis of Ultrasonic Source in Magnetic Materials Using Electromagnetic Acoustic Transducer

This paper is concerned with quantitative evaluation of pipe wall thickness using Electro-Magnetic Acoustic Transducer. Various test specimens are fabricated to simulate Flow-Accelerated Corrosion (FAC). First, measurements by Electro-Magnetic Resonance (EMAR) technique are examined. It is found that the resolution of thickness measurements is superior to the Pulse-Echo method. On the other hand, the measurement by EMAR is time-consuming because it requires long range of sweeping frequencies. Secondl...
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Measurement of Pipe Wall Thickness using Electro Magnetic Acoustic Transducer

computational method for recovering adjacent defect shape is considered using a model based approach elated to an elec trical potential method. An inspection model for the electrical potential method is ormulated by a Poisson's equation in three dimensions. The defect shape is then described by the intensities f source functions. The output least square method is applied to our inverse algorithm. The effectiveness of ur approach is shown in the laboratory experiments....
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hape Identification of Coating Defect in Underground-Pipeline using Electrical Potential Method

This paper is concerned with signal processing arising in pipe wall thinning measurements using electromagnetic acoustic transducer (EMAT). First, electromagnetic acoustic resonance method (EMAR) is applied to pipe wall thickness measurement. Secondly, a heuristic method for extracting features of resonance spectrum obtained by testing data is proposed. Finally , the validity and the feasibility of our proposed method are demonstrated through the practical test at the real plant....
英字タイトル:
Signal Processing for Pipe Wall Thickness Measurements using Electromagnetic Acoustic Resonance Method