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Inspection of zircaloy cladding tubes by eddy currents
U.S. Patent No. 4,742,299 (3 May 1988) A piece of apparatus for raising an eddy current probe is described in this paper. The probe is fixed to a floatable member whereas an air bearing supports the levitation mechanism. 39649
Filist, S.A.
Visualization of defects in eddy-current flaw detection Soviet Journal of Nondestructive Testing, Vol. 23, No. 8, pp. 563-568 (Feb. 1988) The author proposes a classification of matrix eddy-current transducers designed for visualization of defects in eddy-current inspection. The design of these transducers is examined in order to optimize their main parameters, and the methods of compensating differences between their components are discussed. It is shown that the defects can be identified, provided they are classified in advance. A method of visualizing the resulting information, as part of the iteration process, is examined. 39648
Bernardi, J.; Seretti, A.; Samson, R.
Sizing radial cracks in bores holes by eddy current Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 194-202. Nondestructive Testing Information Analysis Center, Texas, USA. Fatigue strain on metallic structure assembled by rivets or fasteners can lead to the development of some fatigue cracks in the bores holes. When rivets or fasteners can be removed cracks detection and orientation is very easy using eddy current methods. Avions Marcel Dassault-Breguet Aviation (AMD-BA) did a preliminary study with commercially available equipment. A dedicated piece of equipment for sizing fatigue has been developed. This equipment scans the bore hole (automatically) and inspects it. Once the crack has been detected, the orientation, localisation, sizing and profiling are done with industrial accuracy eddy current signal and crack identification correlation has been made possible by the use of eddy current mechanic control (4 axis), advanced digital equipment, absolute and differential measurements with the same probe and customized software. For the presentation, many AMD-BA results will be shown especially on laboratory fatigue crack samples and on aircraft inspection. 39647
Chern, E.J.; Djord]evic, B.B.
publicly available leak rate data for steam generator tubes with axial and circumferential SCC and a comparison with an analytical leak rate model is presented. Lastly, nondestructive eddy-current (EC) measurements of defect severity are reported. Laboratory EC measurements to determine accuracy of defect depth sizing using conventional and alternate standards is described. A mini-round robin test utilizing several firms that routinely perform in-service inspections was conducted to supplement the laboratory EC data and estimate EC capability, and detect and size SCC. 39496
Bailey, D.M.
Automatic eddy current signal acquisition system International Advances in Nondestructive Testing, Vol. 13, pp. 295-310 (1987). Edited by W.J. McGonnagle. Gordon and Breach Science Publishers. This paper reports on the development of an Automatic Eddy Current Signal Acquistion System (AECSAS.), which will allow real-time remote (depot) evaluation of field level Nondestructive Inspection (NDI) eddy current test signals. AECSAS was proposed because of a depot requirement to monitor closely field level eddy current inspections of aircraft fastener holes. The object of the AECSAS development was to provide an eddy current inspection system that was capable of monitoring calibration, performing equipment checks, taking scan data, performing signal processing on the data, flagging suspect holes, storing the raw scan data on disk, and MODEMING the data to the depot for review. The system is composed of an automatic eddy current scanner, a portable computer for field data acquisition and a depot computer (and software) for special signal processing. Future developments of the system will include more sophisticated signal processing, real-time field level determinations of fastener hole condition, and a reduction in the bulk of the system. 39495 Halgand, P.; Senevat, J. Inspection of zirealoy cladding tubes by eddy currents Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1460-1467. Pergamon Press, 3173 pp. (1988) An eddy current inspection method of zircaloy cladding tubes was developed as a complementary method to ultrasonic inspection.
Eddy current tube centerline deflection measurements
39494
Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 188-193. Nondestructive Testing Information Analysis Center, Texas, USA. Tubes are a vital component of most structures, especially nuclear power plants. Unintended deflection can induce localized stresses and excessive corrosion and will cause cracking and functional failure of the tube. A mechanical device that measures the tube deflection along a desired rotational plane by using eddy current nondestructive evaluation (NDE) sensing principles has been investigated. The eddy current edge effect was used as the sensing mechanism because it displayed a more linear response than the lift-off effect. Mathematical algorithms for analyzing the acquired eddy current signals and transforming them into physical deflection dimensions were developed. The radius of curvature of a desired section can be calculated based on a given set of the deflection measurements. Laboratory experiments to verify the operating principles are reported and advantages and disadvantages of the devices are discussed.
Improvement in reliability and accuracy of heater tube eddy current testing by integration with an appropriate destructive test
39498
Fisher, J.L.; Cain, S.T.; Beissner, R.E.
Remote-field eddy current model development Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 174-187. Nondestructive Testing Information Analysis Center, Texas, USA. A model has been developed to predict remote-field eddy current behavior of eddy current probes used for internal examination in tubular products. It was designed to detect inner- and outer-diameter flaws in both ferromagnetic and non-ferromagnetic piping. The probe as modeled consists of a coaxial circular excitor coil and circular sensor coils of arbitrary location and orientation inside the pipe. Two separate models are used. The no-flaw model, based on an analytic approach, uses the pipe's cylindrical symmetry to solve the differential equation describing the magnetic vector potential in the pipe's interior and exterior. The second model, describing flaw response, uses unperturbed fields of the no-flaw analytic model, and a boundary element approach to calculate the perturbed field on the flaw surface as well as applies the reciprocity theorem to determine the sensor coil response. Calculations were conducted in cases with and without flaws. Response to the outer wall corrosion was predicted by using a spheroidal model of a corrosion pit.
Kurtz, R.J.; Bickford, R.L.; Clark, R.A.; Morris, C.J.; Simonen, F.A.; Wheeler, K.R.
39497
Steam generator tube integrity program Phase I1 final report U.S. Nuclear Regulatory Commission, Washington, D.C. (United States), NUREG/CR-2336, 100 pp. (Aug. 1988) The Steam Generator Tube Integrity Program (SGTIP) was a three phase program conducted for the U.S. Nuclear Regulatory Commission (NRC) by Pacific Northwest Laboratory (PNL). In the second phase tube specimens were degraded by chemical means rather than machining methods. This report describes the results of Phase II including burst and collapse testing of chemically defected pressurized water reactor (PWR) steam generator tubing to validate empirical equations of remaining tube integrity developed during Phase I. Three types of defect geometries were investigated; stress corrosion cracking (SCC), uniform thinning and elliptical wastage. In addition, a review of the
176
Giovanelli, F.; Gabiccini, S.; Motto, P.; Tarli, R.
Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1410-1420. Pergamon Press, 3173 pp. (1988) An experiment is described using samples of AISI 304L tubes from the low-pressure (LP) preheaters of a BWR 900 MW nuclear plant. Since 1981, periodic eddy current (EC) testing has been carried out on these preheaters in order to identify the damaged tubes and to plug those with more than 40% loss in thickness using an ASME tube and phase analysis. Improved accuracy was achieved by taking samples of tubes that proved to be significant as a result of EC tests and television endoscope inspection. An innovatory technique was specially developed for taking such samples without extracting the tube bundle. The subsequent laboratory tests made it possible to identify the various causes of damage, recognize all the EC signals and, integrating the ASME methodology, improve the accuracy of the assessment of thickness loss. 39493
Bernardi, J.; Seretti, A.; Samson, R.; Hardy, F.; Neron, E.
Sizing radial cracks in bore holes using eddy current Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1348-1356. Pergamon Press, 3173 pp. (1988) Fatigue strain on metallic structures assembled by rivets or fasteners can lead to the development of fatigue cracks in the associated bore holes. Following an AMD-BA preliminary study with available commercial equipment it was found that fair results could be obtained at the price of highly trained technicians to operate the equipment. This study led to the joint development by AMD-BA and Tecrad Inc. of dedicated equipment for sizing fatigue cracks in bore holes. This paper gives an overview of the results that have been obtained using this new equipment on laboratory fatigue crack samples as well as on aircraft cracks. 39492
Bernardo, J.M.; Sainz, B.; Valdecantos, C.; Cortes, V.
Low frequency eddy current detection and evaluation of corrosion in aircraft skins Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1329-1335. Pergamon Press, 3173 pp. (1988) Applicability of low frequency eddy current tests for the detection and evaluation of corrosion on aircraft fuselage skins is evaluated. Experiments carried out on laboratory samples 1.8 mm thick chemically milled to simulate corrosion, show that results are quite good when only one sheet is involved and frequencies between 4 and 10 KHz are applied. But when corrosion is under doubler areas the separation between skin and doubler is a major variable to get quantitative measurements. Experiments were carried out with two different commercially available eddy current instruments, one with needle indicator and the other with flying dot CRT (cathode ray tube) display. 39491
Schur, F.
Computerized evaluation of eddy-current signals Proceedings of the 4th European Conference on Non-Destructive
NDT International June 1989
Filist, S.A.
Visualization of defects in eddy-current flaw detection Soviet Journal of Nondestructive Testing, Vol. 23, No. 8, pp. 563-568 (Feb. 1988) The author proposes a classification of matrix eddy-current transducers designed for visualization of defects in eddy-current inspection. The design of these transducers is examined in order to optimize their main parameters, and the methods of compensating differences between their components are discussed. It is shown that the defects can be identified, provided they are classified in advance. A method of visualizing the resulting information, as part of the iteration process, is examined. 39648
Bernardi, J.; Seretti, A.; Samson, R.
Sizing radial cracks in bores holes by eddy current Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 194-202. Nondestructive Testing Information Analysis Center, Texas, USA. Fatigue strain on metallic structure assembled by rivets or fasteners can lead to the development of some fatigue cracks in the bores holes. When rivets or fasteners can be removed cracks detection and orientation is very easy using eddy current methods. Avions Marcel Dassault-Breguet Aviation (AMD-BA) did a preliminary study with commercially available equipment. A dedicated piece of equipment for sizing fatigue has been developed. This equipment scans the bore hole (automatically) and inspects it. Once the crack has been detected, the orientation, localisation, sizing and profiling are done with industrial accuracy eddy current signal and crack identification correlation has been made possible by the use of eddy current mechanic control (4 axis), advanced digital equipment, absolute and differential measurements with the same probe and customized software. For the presentation, many AMD-BA results will be shown especially on laboratory fatigue crack samples and on aircraft inspection. 39647
Chern, E.J.; Djord]evic, B.B.
publicly available leak rate data for steam generator tubes with axial and circumferential SCC and a comparison with an analytical leak rate model is presented. Lastly, nondestructive eddy-current (EC) measurements of defect severity are reported. Laboratory EC measurements to determine accuracy of defect depth sizing using conventional and alternate standards is described. A mini-round robin test utilizing several firms that routinely perform in-service inspections was conducted to supplement the laboratory EC data and estimate EC capability, and detect and size SCC. 39496
Bailey, D.M.
Automatic eddy current signal acquisition system International Advances in Nondestructive Testing, Vol. 13, pp. 295-310 (1987). Edited by W.J. McGonnagle. Gordon and Breach Science Publishers. This paper reports on the development of an Automatic Eddy Current Signal Acquistion System (AECSAS.), which will allow real-time remote (depot) evaluation of field level Nondestructive Inspection (NDI) eddy current test signals. AECSAS was proposed because of a depot requirement to monitor closely field level eddy current inspections of aircraft fastener holes. The object of the AECSAS development was to provide an eddy current inspection system that was capable of monitoring calibration, performing equipment checks, taking scan data, performing signal processing on the data, flagging suspect holes, storing the raw scan data on disk, and MODEMING the data to the depot for review. The system is composed of an automatic eddy current scanner, a portable computer for field data acquisition and a depot computer (and software) for special signal processing. Future developments of the system will include more sophisticated signal processing, real-time field level determinations of fastener hole condition, and a reduction in the bulk of the system. 39495 Halgand, P.; Senevat, J. Inspection of zirealoy cladding tubes by eddy currents Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1460-1467. Pergamon Press, 3173 pp. (1988) An eddy current inspection method of zircaloy cladding tubes was developed as a complementary method to ultrasonic inspection.
Eddy current tube centerline deflection measurements
39494
Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 188-193. Nondestructive Testing Information Analysis Center, Texas, USA. Tubes are a vital component of most structures, especially nuclear power plants. Unintended deflection can induce localized stresses and excessive corrosion and will cause cracking and functional failure of the tube. A mechanical device that measures the tube deflection along a desired rotational plane by using eddy current nondestructive evaluation (NDE) sensing principles has been investigated. The eddy current edge effect was used as the sensing mechanism because it displayed a more linear response than the lift-off effect. Mathematical algorithms for analyzing the acquired eddy current signals and transforming them into physical deflection dimensions were developed. The radius of curvature of a desired section can be calculated based on a given set of the deflection measurements. Laboratory experiments to verify the operating principles are reported and advantages and disadvantages of the devices are discussed.
Improvement in reliability and accuracy of heater tube eddy current testing by integration with an appropriate destructive test
39498
Fisher, J.L.; Cain, S.T.; Beissner, R.E.
Remote-field eddy current model development Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 174-187. Nondestructive Testing Information Analysis Center, Texas, USA. A model has been developed to predict remote-field eddy current behavior of eddy current probes used for internal examination in tubular products. It was designed to detect inner- and outer-diameter flaws in both ferromagnetic and non-ferromagnetic piping. The probe as modeled consists of a coaxial circular excitor coil and circular sensor coils of arbitrary location and orientation inside the pipe. Two separate models are used. The no-flaw model, based on an analytic approach, uses the pipe's cylindrical symmetry to solve the differential equation describing the magnetic vector potential in the pipe's interior and exterior. The second model, describing flaw response, uses unperturbed fields of the no-flaw analytic model, and a boundary element approach to calculate the perturbed field on the flaw surface as well as applies the reciprocity theorem to determine the sensor coil response. Calculations were conducted in cases with and without flaws. Response to the outer wall corrosion was predicted by using a spheroidal model of a corrosion pit.
Kurtz, R.J.; Bickford, R.L.; Clark, R.A.; Morris, C.J.; Simonen, F.A.; Wheeler, K.R.
39497
Steam generator tube integrity program Phase I1 final report U.S. Nuclear Regulatory Commission, Washington, D.C. (United States), NUREG/CR-2336, 100 pp. (Aug. 1988) The Steam Generator Tube Integrity Program (SGTIP) was a three phase program conducted for the U.S. Nuclear Regulatory Commission (NRC) by Pacific Northwest Laboratory (PNL). In the second phase tube specimens were degraded by chemical means rather than machining methods. This report describes the results of Phase II including burst and collapse testing of chemically defected pressurized water reactor (PWR) steam generator tubing to validate empirical equations of remaining tube integrity developed during Phase I. Three types of defect geometries were investigated; stress corrosion cracking (SCC), uniform thinning and elliptical wastage. In addition, a review of the
176
Giovanelli, F.; Gabiccini, S.; Motto, P.; Tarli, R.
Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1410-1420. Pergamon Press, 3173 pp. (1988) An experiment is described using samples of AISI 304L tubes from the low-pressure (LP) preheaters of a BWR 900 MW nuclear plant. Since 1981, periodic eddy current (EC) testing has been carried out on these preheaters in order to identify the damaged tubes and to plug those with more than 40% loss in thickness using an ASME tube and phase analysis. Improved accuracy was achieved by taking samples of tubes that proved to be significant as a result of EC tests and television endoscope inspection. An innovatory technique was specially developed for taking such samples without extracting the tube bundle. The subsequent laboratory tests made it possible to identify the various causes of damage, recognize all the EC signals and, integrating the ASME methodology, improve the accuracy of the assessment of thickness loss. 39493
Bernardi, J.; Seretti, A.; Samson, R.; Hardy, F.; Neron, E.
Sizing radial cracks in bore holes using eddy current Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1348-1356. Pergamon Press, 3173 pp. (1988) Fatigue strain on metallic structures assembled by rivets or fasteners can lead to the development of fatigue cracks in the associated bore holes. Following an AMD-BA preliminary study with available commercial equipment it was found that fair results could be obtained at the price of highly trained technicians to operate the equipment. This study led to the joint development by AMD-BA and Tecrad Inc. of dedicated equipment for sizing fatigue cracks in bore holes. This paper gives an overview of the results that have been obtained using this new equipment on laboratory fatigue crack samples as well as on aircraft cracks. 39492
Bernardo, J.M.; Sainz, B.; Valdecantos, C.; Cortes, V.
Low frequency eddy current detection and evaluation of corrosion in aircraft skins Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 1329-1335. Pergamon Press, 3173 pp. (1988) Applicability of low frequency eddy current tests for the detection and evaluation of corrosion on aircraft fuselage skins is evaluated. Experiments carried out on laboratory samples 1.8 mm thick chemically milled to simulate corrosion, show that results are quite good when only one sheet is involved and frequencies between 4 and 10 KHz are applied. But when corrosion is under doubler areas the separation between skin and doubler is a major variable to get quantitative measurements. Experiments were carried out with two different commercially available eddy current instruments, one with needle indicator and the other with flying dot CRT (cathode ray tube) display. 39491
Schur, F.
Computerized evaluation of eddy-current signals Proceedings of the 4th European Conference on Non-Destructive
NDT International June 1989