API 2024 Inspection and Mechanical Integrity Summit

Magnetic Memory Method

The Metal Magnetic Memory (MMM) technique is a highly reliable and innovative inspection method that detects and analyzes self-magnetic leakage fields (SMLF) on the surface of pipelines with immense accuracy and efficiency.

By identifying stress concentration zones, defects, and structural inhomogeneities in pipelines and welded joints without causing any damage to the product, the MMM technique has become the preferred choice for pipeline operators seeking comprehensive inspection solutions.

The MMM technique utilizes sensitive magnetic sensors to measure the resulting magnetic field distribution on the surface of pipelines, allowing specialists to identify areas of concern and diagnose potential problems such as corrosion, cracks, or other structural abnormalities. Additionally, the MMM technique is cost-effective and time-efficient, enabling on-site inspections without excavation, disassembly, or operations shutdowns.

One of the most significant advantages of the MMM technique is its ability to perform inspections regardless of the covered soil conditions. Whether the pipeline is buried under asphalt, rock, or even concrete, MMM technology can accurately detect anomalies without being affected by the surrounding environment, making it a versatile inspection solution for pipeline operators.

As a general concept, the MMM operator walks or flies with the magnetometer along the path of the pipeline and the instrument records the fluctuations (changes) of the magnetic field, recording the anomalies of the metal in Magnetograms. The data are then interpreted and converted into a generalhazard indicator of the anomalies detected.

The results are inserted in a spreadsheet with references of remarkable points and identification of each anomaly. The anomalies are detected by means of comparison of magnetic flux change in the pipeline, load jumps and polarity change in three geomagnetic field vertices.

The method detects magnetic anomalies, caused by loads such as:

- Cracks / micro-cracks

- Weld defects

- Marks due to mechanical shocks, dents, and other damages.

- Corrosion.

- Delamination of the material.

- Segments with high stresses caused by soil settling, bending, repositioning of lands, water currents and

crossings of roads and paths, etc.

The exceptional depth detection capability of the MMM technique enables it to detect buried anomalies in pipelines as deep as 15 times the diameter of the pipe, ensuring the thorough inspection of buried pipelines.

Additionally, MMM is a safe and environmentally friendly inspection and maintenance method that eliminates the need for hazardous chemicals and reduces the risk of injury during the inspection process.

Using MMM to monitor the structural health of pipeline components over time can ensure their continued safe and operational performance, which helps to reduce the risk of costly repairs and dangerous situations.

Results From Actual Trials in Canada

In August 2022, EMB successfully conducted a comprehensive MMM inspection of an 8-inch pipeline located in  British Columbia. Over the course of the inspection, a total of 19 kilometers of pipeline were meticulously examined, resulting in the identification of 30 severe anomalies, 188 mild anomalies, and 821 light anomalies.

The EMB team promptly communicated our findings to the client, emphasizing the utmost importance of addressing the 30 severe anomalies as a top priority. The client subsequently acknowledged that 14 of these anomalies corresponded with their existing In-line Inspection (ILI) data. As a result, they have committed to carrying out the necessary excavation work to further investigate and resolve the remaining 16 severe anomalies.

In March 2023, the client diligently conducted five excavation operations to validate the 16 unidentified anomalies highlighted in our MMM inspection report. These five sites were specifically chosen as they were separate from the 14 locations that had already been corroborated with pre-existing In-line Inspection (ILI) data.

Upon further examination, four out of the five investigated locations were confirmed to exhibit potential threats, with one site displaying a minor crack on the periphery of the specified area. As for the fifth location, which seemingly posed no immediate risk, we clarified that it could potentially represent a steel microstructure variation. Such variations can only be accurately identified through Destructive Testing procedures.

We have requested the client to provide us with detailed information regarding this particular anomaly to enable us to reassess the associated graphs and data thoroughly.

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