Pipeline inspection apparatus and method

摘要

A apparatus for pipeline integrity monitoring comprising a magnetically permeable backing bar and at least three magnets comprising a relatively medium-strength magnet positioned at one end of the backing bar, a relatively low-strength magnet positioned at the other end of the backing bar, and a relative high-strength magnet positioned between the medium-strength and the low-strength magnet. The at least three magnets are adapted and positioned to induce a plurality of resultant fields within the pipeline wall comprising a first resultant field suitable for detecting a reduced metal-related anomaly and a second resultant field suitable for detecting a mechanically worked-related anomaly. Preferably, the first resultant field has a strength greater than 120 Oersted and the second resultant field has a strength between 40 and 80 Oersted.