Application of the Coercimetric Method to Diagnosing Corrosive Damage in Metallic Structures
Abstract
Application of the Coercimetric Method to Diagnosing Corrosive Damage in Metallic Structures
Incoming article date: 27.03.2021The paper studies the applicability ofthe coercive force (Нс) as a parameter for measuringthe wall thickness ofpipelines,vessels,andother metallic structuresthroughnonmagnetic insulationduring material degradation undercorrosion conditions. A procedure is developedfor remote inspectionof metallic structures atsites of maximum corrosion rateby the coercimetricmethod,withoutbreaking the insulationandstopping the operation ofthe object being tested.The effects of metal thickness, the size ofthe poles of the magnetizer, andthe thickness of non-ferromagneticinsulationon the absoluteand relativevalues of the coercive force are comparatively analyzed. The application of theproposed relative value methodis shown to be able to decrease significantlythe effectof steel composition and structureonthe metal thickness dependence of Нс. The results of measuring the coercive force of differently thick 09G2S steel specimens through non magnetic insulation are presented, as well as the behavior of the relative values of the coercive forceas dependent onmetal and insulation thickness.Foridentical metal thicknesses, the absolute values of the coercive force of different steels may differby a factor of 10 ormore, whereasthe difference in the relative values of Нс with equally decreasing metal thickness does not exceed 15%. The developedtechnique isinsensitivetothe misalignment of the outer and innermetal surfaces,and itenablesthe thickness oflow-alloysteels like 09G2Sto be measured witha relative error of 10%.
Keywords: metallic structure, diagnostics, degradation, corrosion, coercive force, thickness measurement, nonmagnetic insulation