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Finite element calculations and computer measurements of magnetic flux leakage patterns for pits
N DT Abstracts 45241 Lohxhina, N.N.; Finogenov, V.K. Modernization of an electromagnetic flaw detector for the inspection Of stainless steel pipes on a line 51-102 Industrial Laboratory, Vol. 55, No. 10, pp. I 139-l 140 (Apr. 1990) Electromagnetic flaw detector with feedthrough transducers for the inspection of stainless steel pipes with diameters larger than 47 mm not produced in the Soviet Union. When the automatic inspection line for the
applying AC of steadily diminishing amplitude but superimposedon a DC bias field. 40488
A new, reliable inspection technique has come into use, magnetic flux testing. Unlike the eddy current method, it furnishes clearcut information even in the presenceof permeability fluctuationsof the material and in cases of gradual wall thicknesswastage. This makes magnetic flux testing clearly superior to eddy current testing in this raw material as a consequenceof the exact size determination and the distinction it permits among all types of faults, up to internal/external faults, pitting corrosion, and wall attrition.
above-mentionedpipes with 51-102 mm diameter was devised and built we modernizeda flaw detector VD-31Pwith improveddesignof the transducer unit. 44472
Atherton, D.L.
Developments in magnetic inspection techniques for pipelines CSNDT Journal, Vol. 1 I, No. 1, pp. 28-35, (Jan.-Feb. 1990) Magnetic flux leakage inspectiontechniquesare describedin this paper
40356
This report is devoted to the problem of inspection of circumferential butt welds in tubular products. The advantages and limitations of the magnetographicmethod are discussed.It is shown that the magnetographic method possesses sufficient sensitivity to ensure reliable control of circumferential welds in pipes with wall thicknessof up to 20 mm.
Atherton, D.L.
Magnetic inspection is key to ensuring safe pipelines Oil and Gas Journal. Vol. 87, No. 32, pp. 52,53,56,58,61 (7 Aug. 1989)
39759 Harle, J.C. Magnetic-flux pig run successful on TAPS Oil and Gas Journal, Vol. 86, No. 41, pp. 72-75 (10 Oct. 1988)
This paper considers the advantages and limitations of two magnetic techniques for inspecting buried natural gas pipelines. The safety and economic considerationsare also covered. Magnetic flux leakage anomaly detectorsoffer in-service inspectionvia inspectionpigs. These are excellent for detecting corrosion but offer little sensitivity to cracks. Allowance must be made for stressto ensufe accuracy. Remote tield eddy current techniques allow stress-corrosioncracks to be detected. Operation limitations of each technique are noted and some existing solutionsdetailed. 41695
The trials run on the trans.-Alaskapipeline system (TAPS) are described in this paper. A new magnetic flux corrosionpig developed for the trials, has produced acceptable results for indicating probable metal loss due to corrosion. Pits one inch in diameter with 10% wall thinning have been detected.
39504 Shannon, R.W.E.; Braithwaite, J.C.; Morgan, L.L. Flux-leakage vehicles pass tests for pipeline inspection Oil and Gas Journal, Vol. 86, No. 32, pp. 47-59 (8 Aug. 1988)
Goor, B.
In-service inspection of ferritic heat exchanger tubes Nuclear Europe, Vol. 9, No. 3-4, p. 17 (1989)
Magnetic flux leakage equipment has been developed which can accurately locate and describe metal-loss defects and determines pipeline conditionsbefore defects becomecritical. Detection and sizing of a range of stress corrosion cracks has been performed successfully in operating pipelines.
Ferritic Heat Exchanger tubes, widely used in the power generation industry, can be reliably tested with the magnetic flux inspection (MFI) technique. An in-service MFI method has now been developed which improves on eddy current measurementsin a number of ways. Sizing and characterization of defects is more accurate. The system can differentiate between defects and interference signals. MFI is fast, reliable, accurateand offers high levels of sensitivity. The inspection method is described and results discussed.
39501 Koch, F.O.; Wahl, H.-J.: Feil, Fr. Development and testing of an automatic magnetic particle test with computerized video system Proceedings of the 4th European Conference on Non-Destructive Testing. London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp.
41107 Bubeck, E.; Geweke, W.; Pawelletz, R. Transversal flaw testing of seamless tubes - a new test system Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam
(Netherlands)
23-28
Apr.
115 l-l 156. Pergamon Press, 3 173 pp. ( 1988) The application of automatic magnetic particle test equipment to HFIpipes showed that the test results are clearly improved if the software is adaptedto the defect indication. The probability of detectingdefects reached a value of 95% with I false indication per pipe. Moreover a sum of 1% indications was registered which was not detected by the visual inspection but should have been.
1989, Vol. 2, pp.
1331-I 333. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. The new leakage flux test system for ferromagnetic tubesof diameter 1” - 7” shows an excellent flaw detectability due to the optimized construction of the transmitter systemwith its magnetic circle, probesand test heads.The modem test electronics is controlled manually and/or via computer interface. This and further features like function control, signal storageand automatic sensitivity balance makes the whole system reliable and cost-efftcient for those tube manufacturerswho sell high quality products. 40703
Scherbinin, V.E.; Shur, M.L.
Experience gained in the use of the magnetographic method of NDT of butt welds in oil and gas pipelines Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. lllO-1116.PergamonPress,3173pp.(l988).
as a means of nondestructively testing the vast lengths buried gas transmissionpipelines in environmental and safety, reasons but also as a means of determining maximum operating pressure and throughput and stabilizing economic considerations. A circumferential array of magnetic flux leakage anomaly detectors is fitted in a pipeline device called a “pig” for in-service inspections,which respondsto defects, such as corrosion, in the pipe wall. Stress is highlighted as a dominant parameter governing magnetic behaviour in the steel pipe walls. 42492
Von Goor, B.
Inspecting ferritic heat exchanger tubes (In German) Atomwirtschaft Atomtechnik, Vol. 34, No. 2, pp. 80-81 (Feb. 1989)
38533
Atherton, D.L.
Finite element calculations and computer measurements of magnetic flux leakage patterns for pits British Journal of Nondestructive Testing, Vol. 30, No. 3, pp. 159-162 (May 1988) Two dimensional finite element calculations for anomalous leakage fluxes, generated by far side grooves in pipes inspected, using magnetic leakage flux anomaly detectors, are compared with precision, computer controlled, experimental measurements of three dimensional synthetic corrosion pits. The experimental measurements are presented as contour maps and surface plots. There is a strong linear correlation between peak anomalous radial flux densities calculated using two dimensional finite element techniques and those measured experimentally for the correspondingthree dimensional anomalies.
Atherton, D.L.; Szpunar, J.A.; Szpunar, B.
Magnetization and stress effects in steel Nondestructive Characterisation of Materials 2, Montreal (Canada), 21- 23 Jul. 1986, pp. 585-594. Edited by J.F. Bussiere, J.P. Monchalin, C.O. Ruud. R.E. Green Jr. Plenum Press, 1987 Stress has long been known to be one of the major factors affecting the
magnetic inspection techniques for steel. Stress effects are studied by two complementary approaches,experimental studies of magnetic flux leakage signals using experimental studies of magnetic flux leakage signals using laboratory test rigs to reproduce the behaviour of magnetic inspectiontools used for pipelines and studies of the magnetic behaviour of representative steel specimens under tensile and compressive strains. It has been shown that the first magnetomechanicaleffect is that the initial application of stress to a magnetized ferromagnet causes a shift in magnetization towards the anhysteretic or equilibrium magnetization. Points on the anhysteretic magnetization curve are obtained, rather similarly to demagnetization, by
38252 Atherton, D.L.; Welbourn, C. A rotating-drum rig for testing pipeline anomaly detectors under simulated line pressure Materials Evaluation, Vol. 46, No. I, pp. 10 l-I07 (Jan. 1988) A rig for testingmagnetic flux leakage detectorsfor pipeline monitoring applications is described. It uses short sections of line pipe supported and driven by two pairs of truck wheels. Test detectors are pressedagainst the
40
applying AC of steadily diminishing amplitude but superimposedon a DC bias field. 40488
A new, reliable inspection technique has come into use, magnetic flux testing. Unlike the eddy current method, it furnishes clearcut information even in the presenceof permeability fluctuationsof the material and in cases of gradual wall thicknesswastage. This makes magnetic flux testing clearly superior to eddy current testing in this raw material as a consequenceof the exact size determination and the distinction it permits among all types of faults, up to internal/external faults, pitting corrosion, and wall attrition.
above-mentionedpipes with 51-102 mm diameter was devised and built we modernizeda flaw detector VD-31Pwith improveddesignof the transducer unit. 44472
Atherton, D.L.
Developments in magnetic inspection techniques for pipelines CSNDT Journal, Vol. 1 I, No. 1, pp. 28-35, (Jan.-Feb. 1990) Magnetic flux leakage inspectiontechniquesare describedin this paper
40356
This report is devoted to the problem of inspection of circumferential butt welds in tubular products. The advantages and limitations of the magnetographicmethod are discussed.It is shown that the magnetographic method possesses sufficient sensitivity to ensure reliable control of circumferential welds in pipes with wall thicknessof up to 20 mm.
Atherton, D.L.
Magnetic inspection is key to ensuring safe pipelines Oil and Gas Journal. Vol. 87, No. 32, pp. 52,53,56,58,61 (7 Aug. 1989)
39759 Harle, J.C. Magnetic-flux pig run successful on TAPS Oil and Gas Journal, Vol. 86, No. 41, pp. 72-75 (10 Oct. 1988)
This paper considers the advantages and limitations of two magnetic techniques for inspecting buried natural gas pipelines. The safety and economic considerationsare also covered. Magnetic flux leakage anomaly detectorsoffer in-service inspectionvia inspectionpigs. These are excellent for detecting corrosion but offer little sensitivity to cracks. Allowance must be made for stressto ensufe accuracy. Remote tield eddy current techniques allow stress-corrosioncracks to be detected. Operation limitations of each technique are noted and some existing solutionsdetailed. 41695
The trials run on the trans.-Alaskapipeline system (TAPS) are described in this paper. A new magnetic flux corrosionpig developed for the trials, has produced acceptable results for indicating probable metal loss due to corrosion. Pits one inch in diameter with 10% wall thinning have been detected.
39504 Shannon, R.W.E.; Braithwaite, J.C.; Morgan, L.L. Flux-leakage vehicles pass tests for pipeline inspection Oil and Gas Journal, Vol. 86, No. 32, pp. 47-59 (8 Aug. 1988)
Goor, B.
In-service inspection of ferritic heat exchanger tubes Nuclear Europe, Vol. 9, No. 3-4, p. 17 (1989)
Magnetic flux leakage equipment has been developed which can accurately locate and describe metal-loss defects and determines pipeline conditionsbefore defects becomecritical. Detection and sizing of a range of stress corrosion cracks has been performed successfully in operating pipelines.
Ferritic Heat Exchanger tubes, widely used in the power generation industry, can be reliably tested with the magnetic flux inspection (MFI) technique. An in-service MFI method has now been developed which improves on eddy current measurementsin a number of ways. Sizing and characterization of defects is more accurate. The system can differentiate between defects and interference signals. MFI is fast, reliable, accurateand offers high levels of sensitivity. The inspection method is described and results discussed.
39501 Koch, F.O.; Wahl, H.-J.: Feil, Fr. Development and testing of an automatic magnetic particle test with computerized video system Proceedings of the 4th European Conference on Non-Destructive Testing. London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp.
41107 Bubeck, E.; Geweke, W.; Pawelletz, R. Transversal flaw testing of seamless tubes - a new test system Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam
(Netherlands)
23-28
Apr.
115 l-l 156. Pergamon Press, 3 173 pp. ( 1988) The application of automatic magnetic particle test equipment to HFIpipes showed that the test results are clearly improved if the software is adaptedto the defect indication. The probability of detectingdefects reached a value of 95% with I false indication per pipe. Moreover a sum of 1% indications was registered which was not detected by the visual inspection but should have been.
1989, Vol. 2, pp.
1331-I 333. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. The new leakage flux test system for ferromagnetic tubesof diameter 1” - 7” shows an excellent flaw detectability due to the optimized construction of the transmitter systemwith its magnetic circle, probesand test heads.The modem test electronics is controlled manually and/or via computer interface. This and further features like function control, signal storageand automatic sensitivity balance makes the whole system reliable and cost-efftcient for those tube manufacturerswho sell high quality products. 40703
Scherbinin, V.E.; Shur, M.L.
Experience gained in the use of the magnetographic method of NDT of butt welds in oil and gas pipelines Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. lllO-1116.PergamonPress,3173pp.(l988).
as a means of nondestructively testing the vast lengths buried gas transmissionpipelines in environmental and safety, reasons but also as a means of determining maximum operating pressure and throughput and stabilizing economic considerations. A circumferential array of magnetic flux leakage anomaly detectors is fitted in a pipeline device called a “pig” for in-service inspections,which respondsto defects, such as corrosion, in the pipe wall. Stress is highlighted as a dominant parameter governing magnetic behaviour in the steel pipe walls. 42492
Von Goor, B.
Inspecting ferritic heat exchanger tubes (In German) Atomwirtschaft Atomtechnik, Vol. 34, No. 2, pp. 80-81 (Feb. 1989)
38533
Atherton, D.L.
Finite element calculations and computer measurements of magnetic flux leakage patterns for pits British Journal of Nondestructive Testing, Vol. 30, No. 3, pp. 159-162 (May 1988) Two dimensional finite element calculations for anomalous leakage fluxes, generated by far side grooves in pipes inspected, using magnetic leakage flux anomaly detectors, are compared with precision, computer controlled, experimental measurements of three dimensional synthetic corrosion pits. The experimental measurements are presented as contour maps and surface plots. There is a strong linear correlation between peak anomalous radial flux densities calculated using two dimensional finite element techniques and those measured experimentally for the correspondingthree dimensional anomalies.
Atherton, D.L.; Szpunar, J.A.; Szpunar, B.
Magnetization and stress effects in steel Nondestructive Characterisation of Materials 2, Montreal (Canada), 21- 23 Jul. 1986, pp. 585-594. Edited by J.F. Bussiere, J.P. Monchalin, C.O. Ruud. R.E. Green Jr. Plenum Press, 1987 Stress has long been known to be one of the major factors affecting the
magnetic inspection techniques for steel. Stress effects are studied by two complementary approaches,experimental studies of magnetic flux leakage signals using experimental studies of magnetic flux leakage signals using laboratory test rigs to reproduce the behaviour of magnetic inspectiontools used for pipelines and studies of the magnetic behaviour of representative steel specimens under tensile and compressive strains. It has been shown that the first magnetomechanicaleffect is that the initial application of stress to a magnetized ferromagnet causes a shift in magnetization towards the anhysteretic or equilibrium magnetization. Points on the anhysteretic magnetization curve are obtained, rather similarly to demagnetization, by
38252 Atherton, D.L.; Welbourn, C. A rotating-drum rig for testing pipeline anomaly detectors under simulated line pressure Materials Evaluation, Vol. 46, No. I, pp. 10 l-I07 (Jan. 1988) A rig for testingmagnetic flux leakage detectorsfor pipeline monitoring applications is described. It uses short sections of line pipe supported and driven by two pairs of truck wheels. Test detectors are pressedagainst the
40