Magnetic Tomography Method Non-Contact Inspection of Pipeline Condition

Magnetic Tomography Method Non-Contact Inspection of Pipeline Condition

MTM BASICS

MTM is based on Villari effect (magneto-elasticity, of inverse magnetostriction).

When subject to mechanical deformation (or stress), metal changes its magnetization.

The basis of MTM integrity concept is the fact that it is not defects themselves that are dangerous for metal snd constructions, but local combination of defects and high stress is. MTM is capable of remote detection of stress concentration spots in pipe metal by analyzing its magnetic field.

It detects areas with stress concentrators (defects and locally applies forces) and determines the danger degree of these areas.

SCANNING AND CALIBRATION

    1. Determining the pipeline axis position under the ground surface.
    2. Pipeline scanning using a portable magnetometer that automatically records magnetic data and GPS tracks.
    3. Preliminary processing and choosing 1-2 points for calibration.
    4. Additional non-destructive testing is performed in the digs, involving contact methods, after that the calibration of the data is done.
    5. Preparation of the final report, that includes a list of dangerous (anomalous) areas of the pipeline, matched with the map and having their respective danger degree reported.


INFORMATION FOR PIPELINE INTEGRITY MANAGEMENT:

    1. The locations of all detected stress-deformed state anomalies.
    2. Parameters for analyzing safety of all detected defect areas:
    • safe operation term Tsafe
    • safe operation pressure Psafe
    • estimated repair factor ERF
    • local internal stress values S