An Engineer’s Guide to Eddy Current Testing

2013 ◽  
Author(s):  
Robert J. Bell ◽  
Albert S. Birks
Keyword(s):  
Heat Exchanger ◽  
Eddy Current ◽  
Heat Exchangers ◽  
Signal Analysis ◽  
Test Methods ◽  
Eddy Current Testing ◽  
High Rate ◽  
Thin Wall ◽  
Electrical Currents ◽  
Current Testing

This paper applies to individuals charged with maintaining the reliability of shell and tube heat exchangers. These persons typically specify and/or retain the services of others to examine heat exchangers with nondestructive test methods, such as eddy current and are responsible for submitting run-repair-replace recommendations to management. Electromagnetic Testing (ET) uses the electromagnetic characteristics of components made of conductive materials to determine their condition. Eddy Current Testing (ECT), an electromagnetic method that utilizes induced electrical currents, is usually used to examine non-ferromagnetic materials. ECT’s high rate of examination, relatively good accuracy with thin wall components, repeatability and volumetric measurement make it an ideal method for examining nonmagnetic heat exchanger tubes. This paper will provide a brief description of the method, concentrating on ECT because most power generation industry heat exchanger tubing is non-ferromagnetic in nature. This paper will also address the following: • Training and Certification of Technicians. • ET signal analysis, an exacting science? • ASME Section V, Appendix II vs. Appendix VIII for in-situ ECT of all heat exchanger tubing. • Signal analysis variables and limitations. • A need to know the potential degradation mechanisms. • Condition assessment vs. eddy current testing.

Remote Field Eddy Current Testing Technology for Ferromagnetic Heat Exchanger Tubes

2012 ◽  
Author(s):  
Yubao Chen ◽  
Jiong Zheng ◽  
Weijian Luo
Keyword(s):  
Heat Exchanger ◽  
Eddy Current ◽  
Eddy Current Testing ◽  
Testing System ◽  
Current Testing ◽  
Testing Technology

As a conventional NDT method, eddy Current testing (ET) has been greatly developed both in instrumentation and technique in recent years. Remote Field Eddy Current Testing (RFET) is a representation of this advancement. The principle of RFET and the composition of the testing system are detailedly discussed in this paper. And then, its application in the ferromagnetic heat exchanger tubes is described simply.

Development of a four-wheeled robotic platform for autonomous inspection

2020 ◽  
Author(s):  
◽  
Wenxin Gao
Keyword(s):  
Machine Learning ◽  
Heat Exchanger ◽  
Machine Vision ◽  
Eddy Current ◽  
Control Algorithm ◽  
Eddy Current Testing ◽  
Machine Learning Algorithms ◽  
Robotic Platform ◽  
Current Testing ◽  
Autonomous Inspection

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] There is a significant need of developing advanced robots to mitigate the time-consuming and labor-intensive maintenance and examination of the heat exchanger tubes in power plants. Heat exchanger tubes are very critical to energy conversion efficiency of a power plant. Eddy current testing is a mainstream methodology to evaluate working conditions of these tubes. However, the current testing apparatus requires human to manually insert the probes into and extract out of individual tubes, and monitor measurement results in the meantime. This process can be very tedious and requires a large amount of operation time because there are usually a bundle of tubes arranged in a closely packed way. In addition, the eddy current testing equipment requires sophisticated technicians to operate. If the tube inspection can be performed by a robot, significant economic benefit can be obtained. To realize such goal, the proposed robot show possess functions of machine vision enabled by as high-resolution camera image recognition, adaptive motion and actuation enabled by a control-looped control algorithm, autonomous eddy current probe signal analysis, and real-time decision making by machine learning algorithms. This thesis focuses on development of an omni-direction four-wheeled robotic platform for autonomous inspection of exchange heat tubes. Chapter 2 introduces the robotic platform design and analysis. It includes the mechanical components design for the robot, the detailed drawings, finite element analysis (FEA) for critical components, the motion analysis for part movement detection and the overall balance analysis of the robotic platform. Chapter 3 describes the manufacturing and assembly of the robot. Discussion on the part cutting and drilling accuracy, the strategy of choosing the materials, and problem shooting during the assembly such as solving the mismatch between two metal parts due to machining is provided. Chapter 4 shows the control methodology for the wheels and actuation of the wheels according the requirement of omni-direction movement, rotation, and the probe station operation. A circuit schematic diagram and the detailed control algorithm are also included in the content. This chapter also discusses integration of the robot platform and the machine vision. As concluded in the future work, functions of machine vision by the high resolution camera to capture image data, operating the eddy current testing to capture signal data, training machine learning algorithms for autonomous detection of defects inside the tubes are discussed.

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