Magnetic flux leakage is one of the most common and robust methods of ILI (In Line
Inspection) used by pipeline operators worldwide to detect and characterize a broad range of
pipeline features and anomalies. Magnetic flux leakage data signals are influenced by the
shape and configuration of metal loss zones; with the feature shapes used as a basis for
algorithm development and interpretation techniques developed to provide estimates of metal
loss lengths, widths and depths. For pipelines, primary lengths and widths of features may be
oriented in any random direction with respect to the pipeline axis and applied magnetic fields.
In addition to field levels, material properties, velocity effects, length, width, and depth, feature
orientation will also influence the magnetic field data acquired for typical pipeline metal loss
anomalies. Difficulties encountered in characterizing specific classes of metal loss features
have led to the development, implementation, and use of tools employing multiple axis sensors
in an effort to improve performance for these categories of metal loss features. To
demonstrate the effects of feature orientation, examples will be presented with the results
providing insights into the signal response for metal loss zones as the angular orientation of
the features are varied within the applied magnetic field.