Importance of Magnetizing Field on Magnetic Flux Leakage Signal of Defects

The measurement of magnetic flux leakage (MFL) is widely used as a non-destructive technique for inspecting oil and gas pipelines. In this method, many factors can affect the MFL signal, but the magnetization of the pipeline is a fundamental issue that bears consideration. We investigated the depend...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on magnetics 2018-06, Vol.54 (6), p.1-6
Main Authors: Pham, Hong Quang, Trinh, Quang Trung, Doan, Duy Tuan, Tran, Quang Hung
Format: Article
Language:English
Subjects:
Cartography
Defects
Dependence
Gas pipelines
Leakage
Magnetic field measurement
Magnetic flux
Magnetic flux leakage
Magnetic flux leakage (MFL)
Magnetism
Magnetization
Magnetometers
Natural gas
Nondestructive testing
Permanent magnets
Petroleum pipelines
pipeline inspection
Pipelines
Quadratic equations
Saturation magnetization
Steel plates
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The measurement of magnetic flux leakage (MFL) is widely used as a non-destructive technique for inspecting oil and gas pipelines. In this method, many factors can affect the MFL signal, but the magnetization of the pipeline is a fundamental issue that bears consideration. We investigated the dependence of the MFL signal on the magnetizing state of pipeline samples with respect to both near-side and far-side defects by varying the number of permanent magnets in each pole of the U-core system, varying the distance between the two poles, varying the gap between the U-core system and the surface of the steel plates engineered from a gas pipeline, and varying the depth of the rectangular defects. By systematically controlling the magnetization of the samples, we observed novel behaviors of the MFL signals as a function of defect depth. For samples having above-saturated magnetization, the dependence of the MFL signal can be expressed as a quadratic function for all defect depths. However, for samples having below-saturated magnetization, the MFL signal increases linearly at low-defect depths, but exhibits a quadratic response at high-defect depths. These findings have relevance for both fundamental research and practical applications, and they provide a novel and precise cartography method for accurately quantifying the depth of defects in MFL measurement.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2018.2809671