ULTRASONIC ANOMALY DETECTION IN HDPE MINE TAILING LINES

Erosion and Gouging in High-Density Polyethylene (HDPE) Mine Tailing Lines

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What are Mine Tailing Lines?

Mining operations use tailing lines to transport remaining rock “tailing” leftover after mineral extraction. A mixture of tailing and water is pumped through the pipeline (usually made from high-density polyethylene (HDPE)) into the ocean or lakes for disposal.?There are no dangerous chemicals in the product and there is no danger posed to the environment or the public. HDPE tailing lines are susceptible to accelerated erosion and gouging over oil and gas lines and other physical deformations due to the transportation of large amounts of hard rough material.

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Tailing Line Launchers and Receivers

While tailing lines are usually fitted with launchers, receivers are not typically present.?The reason for this is that tailing lines are used to transport mining byproducts for disposal and end on the seabed.?Dacon has specifically designed ultrasonic inline inspection PIGs with floatation capabilities for tailing line inspection.?Allowing PIGs to be expelled from the end of the pipeline and then be collected at the surface by boat.

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Ultrasonic Erosion and Gouging ILI Data

The below image shows high-resolution ultrasonic A-scan, B-scan, and C-Scan data from a 44” mine tailing line inline inspection.?The data shows two anomalies in the pipe wall. Internal (I.D.) erosion along the bottom of the pipe at the 6 o’clock position and an external (O.D.) gouge on the top of the pipeline. A highly accurate visual representation of each anomaly can be seen below with remaining wall thickness measurements.?Each identified corrosion feature detected within the pipeline is pressure sentenced using the formulae provided in ASME B.31G to produce an Estimated Repair Factor (ERF).

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Erosion Data

The erosion has been caused by tailing flowing down along the bottom of the pipeline and can be seen in the A-Scan Data running the entire length of the pipeline. The B-Scan data shows a cross-section of the pipeline with remaining wall thickness from nominal wall thickness.

Gouging Data

External (O.D.) gouging is caused by external factors such as excavators, ship anchors and environmental factors like landslides or falling debris. The B-Scan data below shows the remaining wall thickness while the C-Scan data shows the width and the position of the defect on the circumference of the pipeline.

Odometers installed on the PIG also record detailed information of pipeline length and allow for accurate location reporting allowing for maintenance or future follow-up depending on the

Contact a Dacon Inline Inspection expert for more information on Dacon’s HDPE inline inspection capabilities.