Magnetic-flux-leakage (MFL) measurements are used for corrosion inspection of buried oil and gas pipelines. MFL signals are sensitive to the depth of defects, such as corrosion pits, in the pipe wall and to external stresses generated mainly by the line pressure. MFL signal variations have been studied from the inside wall in the presence of various circumferential bending stresses and magnetic flux densities for three outside wall pits of depths 30 %, 50 % and 80 % of the wall thickness. Magnetic Barkhausen noise (MBN) measurements have been used to study the stress-induced changes in the direction of the bulk magnetic easy axis and directional anisotropies of the pipe wall. These help one to understand the stress-dependent MFL results.
The effects of defect depth and bending stress on magnetic Barhausen noise and flux-leakage
Auswirkungen der Fehlertiefe und der Biegespannung auf das magnetische Barkhausen-Rauschen und die Fluß-Lecksignale
Journal of Physics D: Applied Physics ; 30 , 14 ; 1976-1983
1997
8 Seiten, 9 Bilder, 20 Quellen
Aufsatz (Zeitschrift)
Englisch
zerstörungsfreie Prüfung , Barkhausen-Effekt , Rauscheigenschaft , magnetische Induktion , Pipeline , Lochfraßkorrosion , mechanische Spannung , Biegen , Messdatenverarbeitung , Hall-Generator , magnetischer Fluss , magnetische Anisotropie , Schadenfrüherkennung , Fehlererkennung , Fehlerortung , Erdöl , Erdgas , Risstiefe , unlegierter Stahl
Defect separation considerations in magnetic flux leakage inspection
Tema Archiv | 2005
|Effects of line pressure stress on magnetic flux leakage patterns
Tema Archiv | 1992
|Magnetic flux leakage device for offshore oil pipeline defect inspection
Tema Archiv | 2005
|Barkhausen noise and magnetic flux leakage signals from interacting defects
Tema Archiv | 2003
|