Magnetic Flux Leakage Inspection Research Articles

Magnetisation as a key parameter of magnetic flux leakage pigs for pipeline inspection: Jansen, H.J.M.; van de Camp, P.B.J.; Geerdink, M. Insight, Vol. 36, No. 9, pp. 672–677 (Sep. 1994)

Magnetic flux leakage (MFL) pigs are frequently used for inspecting pipelines for corrosion defects. Experiences with MFL pigs to date indicate that inspection results are sometimes unreliable. Errors in calibration and data analysis can lead to severe under- or over-sizing of defects and subsequent improper conclusions and actions. Experimental and modelling studies have been carried out on the error sources that can influence the reliability of an MFL inspection. It has been found that a number of significant error contributions can be minimised by a proper design of the magnetising system and when the pipe wall is sufficiently magnetised. On the basis of these findings, criteria are being developed for pipe wall magnetisation as a function of pipe wall thickness. This «magnetisation operating window» will depend on the design of the magnetic circuit in the pig, whereby there will be a trade-off between pig flexibility and magnetisation capabilities.

Calculations of the effects of anisotropy on magnetic flux leakage detector signals

Oil and gas pipelines are inspected for corrosion using magnetic flux leakage (MFL) inspection tools. It has been found that varying line pressure, bending or residual stresses cause changes in the MFL signals. Changes in the amplitude are thought to be due to stress-induced changes in the bulk magnetic anisotropy or preferred easy axis of the steel pipe wall. This suggestion is supported by results presented here of finite element calculations of the effects of changes in anisotropy on MFL signal amplitudes.

A comparative study of 3D and axisymmetric magnetizer assemblies used in magnetic flux leakage inspection of pipelines

Axisymmetric numerical codes are often used in modeling non-destructive testing phenomena, to approximate geometries and defects which are not truly axisymmetric in nature. This is especially true in cases where large computational resources are needed to model the exact geometry. However, there has been no study to confirm the nature and extent of errors introduced by an axisymmetric approximation. The gas pipeline industry makes use of bath axisymmetric and non-axisymmetric magnetizers for the magnetic flux leakage inspection of pipelines. The authors utilize this platform to perform a comparative analysis of axisymmetric and non-axisymmetric magnetizers from a design perspective and also study the differences in respective electromagnetic behavior.

A large Hall probe read head sensor for magnetic flux leakage inspection of pipelines

A large Hall probe read head sensor for magnetic flux leakage inspection of pipelines

Use of magnetic flux leakage inspection pigs for hard spot detection and repair

Use of magnetic flux leakage inspection pigs for hard spot detection and repair

Utilization of magnetic flux leakage inspection pigs for hardspot detection and repair

Utilization of magnetic flux leakage inspection pigs for hardspot detection and repair

Magnetic flux leakage inspection of wire rope

Magnetic flux leakage inspection of wire rope

Improved nondestructive testing of 60 mm M720 mortar projectile magnetic flux leakage inspection system of M720 mortar

Abstract : The objective of this project was to provide basic outline drawings (BOD) for the concept design (level 1) and specifications of an automated magnetic flux leakage inspection system (AMFLIS) for detecting anomalies/flaws within the projectile body of the 60 mm mortar. The inspection of the M720 mortar projectile body for anomalies was performed by magnetic particle inspection (MPI) followed by visual inspection before and after painting the projectile using normal light. MPI cannot indicate the depth of a crack (anomaly); therefore, as per the item specification, no cracks in the projectile body shall be accepted and thereby increase the cost of the projectile body due to false rejects. The basic principles of MFL are shown in figure 1. The item tested was rotated in the field of a magnet and was magnetically saturated. In the absence of defects (discontinuities), the magnetic flux lines (saturated) continue to be contained and flow within the interior of the test item. If any defects were present, they forced some of the flux lines to flow external to the surface of the test item producing a leakage field.

Basic principles of magnetic flux leakage inspection systems for the evaluation of oil country tubular goods

Basic principles of magnetic flux leakage inspection systems for the evaluation of oil country tubular goods

Test rigs for magnetic flux leakage inspection tools for pipelines

Test rigs for magnetic flux leakage inspection tools for pipelines

Magnetic flux leakage inspection of wire rope : Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 21–33, Gordon and Breach Science Publishers (1985)

Magnetic flux leakage inspection of wire rope : Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 21–33, Gordon and Breach Science Publishers (1985)

A large Hall probe read head sensor for magnetic flux leakage inspection of pipelines: 38251 Atherton, D.L.; Cheng, C.W. Canadian Society for Nondestructive Testing, Vol. 8, No. 6, pp. 44, 46–50 (Nov./Dec. 1987)

A large Hall probe read head sensor for magnetic flux leakage inspection of pipelines: 38251 Atherton, D.L.; Cheng, C.W. Canadian Society for Nondestructive Testing, Vol. 8, No. 6, pp. 44, 46–50 (Nov./Dec. 1987)

Basic principles of magnetic flux leakage inspection systems for the evaluation of oil country tubular goods: 37157 Stanley, R.K. Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 97–149. Gordon and Breach Science Publishers (1985)

Basic principles of magnetic flux leakage inspection systems for the evaluation of oil country tubular goods: 37157 Stanley, R.K. Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 97–149. Gordon and Breach Science Publishers (1985)

Magnetic flux leakage inspection of wire rope: 37155 Bergander, M.J. Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 21–33. Gordon and Breach Science Publishers (1985)

Magnetic flux leakage inspection of wire rope: 37155 Bergander, M.J. Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 21–33. Gordon and Breach Science Publishers (1985)

Basic principles of magnetic flux leakage inspection systems for the evaluation of oil country tubular goods 37157 Stanley, R.K. Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 97–149. Gordon and Breach Science Publishers (1985)

Basic principles of magnetic flux leakage inspection systems for the evaluation of oil country tubular goods 37157 Stanley, R.K. Electromagnetic Methods of Nondestructive Testing. Edited by William Lord. Nondestructive Testing Monographs and Tracts, Vol. 3, pp. 97–149. Gordon and Breach Science Publishers (1985)