Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Metal Magnetic Memory – A non-Intrusive NDT Technique
Submission Author:
Byron Souza Filho , BA
Co-Authors:
Byron Souza Filho, LEONARDO FIORINI, Sergio Nogueira
Presenter: LEONARDO FIORINI
doi://10.26678/ABCM.COBEM2021.COB2021-1163
Abstract
Metal magnetic memory (MMM) is a newly developed non-destructive testing (NDT) technique. It can detect and prevent early failure caused by defects such as corrosion, stress concentration, micro-crack, fatigue damage, Stress Corrosion Cracking (SCC) and weld defects, of ferromagnetic components. MMM technique relies on the measurement of self-magnetic flux leakage (SMFL), due to residual magnetization or irreversible change of the local magnetization state of components in stress concentration zones (SCZ) around damages under working. It was first studied in the 1980s, when researchers in Russia observed the stress-induced magnetic fields on defective areas of boiler pipes in a power station. Further, it was widespread in the world as a way to address structural integrity of ageing ferromagnetic pipelines. And it is being used to inspect unpiggable pipelines worldwide. This Technique can also be applied to avoid exposition of personal to hazards by eliminating internal inspections in some conditions, as non-intrusive inspection. This paper will present a brief discussion on the physical basis and the boundary conditions for application of the MMM Technique, the procedures for processing the inspection results in magnetic components and also in the practical assessment of defective welded joints. In Brazil, the main application has been driven for pipeline inspection. In this case MMM is usually combined with pipe locating and GPS technologies. The pipeline operator usually locates the buried pipeline with a pipe locator device, inspects the pipeline using MMM equipment and records GPS coordinates along the segment in order to locate anomalies for further field correlations (dig verification trenches or even provide maintenance to the pipeline). We are going to present the results of an inspection of a buried pipeline in Brazil, comparing the reported inspection indications with the field correlation from the customers, showing the accuracy of the MMM Technique in terms of anomalies identification, sizing and location.
Keywords
Metal Magnetic Memory, Non-Destructive Testing Techniques (NDT), stress concentration zones, Non-Intrusive Inspection
