AIRBORNE CMI INSPECTION IDENTIFIED SEVERAL CRUCIAL EXTERNAL AND INTERNAL DEFECTS IN A BURIED, UNPIGGABLE PIPELINE

One of our customers operates a steel sewer line that recently developed a leak caused by internal corrosion. The leak was most likely caused by the use of ferric chloride which is known to promote internal corrosion and metal degradation. Due to the pipelines unpiggable nature and lack of technical documentation it has been impossible to assess its integrity since the pipeline’s commissioning in 1972. Our customer urgently needed an integrity assessment solution after the occurrence of first leak. EMPIT‘s airborne inspection technique, Current Magnetometry Inspection (CMI), made it possible for the first time to remotely inspect the buried pipeline and therewith assess overall integrity.

The result of the inspection showed areas with a significantly higher Probability of Failure (PoF), while no significant increase in PoF was found at other sections. Our client decided to take immediate action and verify results through feedback digs. The outcome where several crucial internal anomalies that had a peak depth ranging from 75% to 92% metal loss and an external dent that exceeded a depth of more than 15% of the nominal pipeline diameter.

Since the overall integrity assessment performed with CMI showed that only certain sections had elevated PoF, the operator decided to keep the pipeline in service and developed an asset management plan take further action based on EMPIT’s provided data.