A dynamic monitoring system for bearings has been developed. The defects of bearings in motors can be detected and classified into some groups from their vibration signals by an accelerometer screwed on the monitored bearings using the dynamic monitoring system. The abnormality of the bearings is judged from many factors such as the peak value, the root mean square value and the ratio of peak to root mean square value. And then, the grade of its abnormality is diagnosed how heavy the defect is, when t...
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Dynamic Monitoring for Bearings of Rotating Machines in Plant

The purpose of this report is to establish a predictive methodology for estimating rate of wall thinning in a piping system used in ag eing nuclear power plants. First, mechanism of flow accelerated corrosion caused by steam of flowing water is given by KWU-KR model. Se condly, a method for setting geometrical parameter based on pipe wall thickness measurements is considered. Thirdly, estimation method ology for wall thinning rate is formulated within the framework of Kalman filtering. Finally, some simula...
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Prediction of Wall Thinning by Flow Accelerated Corrosion using Kalman Filtering

A guided wave testing is used in non-destructive inspections for pipe wall thinning and detects defects over a wide range of pipe. In this paper, first, hit/miss results are calculated from signal responses of the guided wave testing by using thresholds. The hit/miss results decide POD curves. We confirm the differences of the POD curves affected by the thresholds. Second, an optimal parameter tuning method which is effectively adjusted based on the condition of testing is integrated to the POD. The va...
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Reliability Evaluation for Guided Wave Testing of Elbow Pipe Thinning

The aim of this work presented here is to demonstrate the way to identify the shape of pipe-wall-thinning in straight pipe. First, the database is developed to obtain approximate solution of waves reflected from pipe-wall-thinning with three-dimensional guided wave simulator and proper orthogonal decomposition (POD). In particular, we show that the database can be used to efficiently approximate the solutions to the guided wave propagation problem. Second, the inverse problem procedure is introduced to...
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3-Dimensional Shape Identification of Pipe-Wall-Tinning With Ultrasonic Guided Wave

Motivated by growing demand for quantitative nondestructive evaluation of pipe wall thinning, the aim of this paper is to develop a simulator for gu ided wave analysis. First, an inspection system can be represented by a linear elastic system in cylindrical coordinates. Secondly a dynamical numer ical scheme for wave propagation on a pipe wall is proposed based on Fourier-Galerkin approach. Finally, the effectiveness and validity of the propo sed method are shown in computational experiments. ...
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Development of a Guided Wave Simulator and its Application to Monitoring of Pipe Wall Thinning

This paper deals with an ECT diagnosis system using network communication. This system consists of an inspection module, a computational m odule and a communication interface module which can visualize some inspection results from the inspection module with ECT and some analys is results from the computation module. Here, three modules are connected through network architecture and communicated each other. Moreov er, an operator can control interactively the inspection and computational modules in order to...
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Development of ECT Diagnosis System with Network Communication

The purpose of this study is to develop a hybrid sensor to be able to measure two or more physical values (the pipe surface temperature, the pipe wall thinning and the temperature of an internal fluid) with one sensor with an electromagnetic acoustic transducer. Each result of a measurement can improve the measurement precision by doing working that calibrate each other. The piping surface temperature was measured by converting the direct current resistance at the temperature by using the EMAT coil. A...
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Study on pipe health monitoring method by hybrid measurement using electromagnetic ultrasonic

This paper is concerned with a sizing methodology of crack using Bayesian inference arising in eddy current testing. There is often uncertainty about data through quantitative measurements of non destructive testing and this can yield misleading inference of crack sizing at on-site monitoring. In this paper, we propose optimal strategies of measurements in eddy current testing using Bayes ian prior-to-posteriori analysis. First our likelihood functional is given by Gaussian distribution with the measuremen...
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A Method for Crack Sizing using Bayesian Inference arising in Eddy Current Testing

This paper is concerned with a simulator related to nondestructive test using Electromagnetic Acoustic Transducer (EMAT). The simulator developed here can be applied to pipe wall thinning of stainless steel used in nuclear power plants. First, mathematical models for the inspection are given by a transient e ddy current equation and by a time dependent elastic wave equation in two dimensions. Secondly, shape of pipe wall thinning is modeled by B-spline functio n and is applied to the mathematical models us...
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Development of NDT Simulator with Method of Mapping for Detection of Pipe Wall Thinningusing EMAT

This article is concerned with E-JAM academic papers. The aca demic journal focuses on structural safety evaluation practic es in the nuclear power industries. In this article, we introd uce the scope of the journal as well as the journal policies....
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Scope and Policy of E-JAM Academic Papers