The predefined spatial distribution and strength characteristics (absolute value and gradient) of a magnetic field are shown to be reproducible with the use of local sources of the magnetic field (permanent magnets). Consideration of the problem symmetry allows derivation of some characteristics of the field in an analytic form without conducting numerical calculations. A relation has been derived for the distribution of attractive forces in the area between the blocks of a cleaning pig magnets and a pipe. The maximum of the distribution corresponds to the centers of magnetic blocks, while the minimum corresponds to the centers of the gaps between the blocks. If the dimensions of the magnetic blocks in the direction of the pipe axis diminish, the field and the attractive force diminish and the nonuniformity of the angular distribution of these quantities increases. For each ratio of the cleaned pipe radius to the field source radius, the source axial symmetry has an optimum order, which ensures its largest force effect. An expression for such an estimate has been derived. The effects of the cleaned pipe ferromagnetic material and the presence of higher harmonics in the field enhance the angular dependence of the magnetic system field.
Calculation of the magnetic systems of diagnostic and cleaning pigs for oil and gas pipelines
Berechnung des magnetischen Systems für Diagnose- und Reinigungsmolche in Öl- und Gasfernleitungen
Russian Journal of Nondestructive Testing ; 42 , 1 ; 19-27
2006
9 Seiten, 6 Bilder, 3 Quellen
Article (Journal)
English
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