Magnetic Pipeline Screening Technology Helps Operators Make More Informed Integrity Decisions


In recent years, pipelines that transport critical energy resources have come under increased scrutiny from governments, interest groups and even private citizens that are concerned about the environmental risks of a pipeline rupture.

The increase in publicity surrounding pipelines has led to more pressure on companies that own existing pipelines to ensure they are operated as safely as possible. It has also led to strong opposition to the building of any new pipelines to increase energy output and capacity.

While investment into renewables research and alternative energy sources are important long-term initiatives, the transportation of energy through pipelines to meet current demand is crucial to the economy and communities.

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Despite the conventional belief that pipelines are dangerous, they are the safest and most efficient way of transporting the energy resources that modern society needs. To put this in perspective: It would take thousands of tanker trucks operating 24 hours a day to replicate the output of a single major transmission pipeline. Not only would this pose a risk of a spill and be near impossible logistically, it would leave a significant environmental footprint from the vehicles required to transport the products.

Leveraging Technology to Keep Pipelines Safe

There are more than 1 million miles of energy pipelines in North America owned and operated by hundreds of different companies. To keep their pipelines operating safely, these operators spend huge amounts of money every year on pipeline integrity programs that reduce the risk of transporting energy products. These programs use a variety of above-ground and inline tools that can identify damage on the pipeline before it leads to a spill.

The energy industry is also innovative. Not only are large amounts of money spent every year on established pipeline integrity tools, but millions of dollars are invested annually by pipeline owners and technology companies to develop new solutions that help reduce the risk of operating a pipeline. This investment has led to the development of advanced solutions to prevent pipelines from failing.

Most current pipelines are ferromagnetic, which makes corrosion the most common problem operators are trying to address. Because of this, the industry has developed tools like impressed current cathodic protection that can proactively prevent corrosion of a pipeline. Additionally, there are inline inspection (ILI) tools that can reactively identify corrosion on a pipeline that has occurred along with many other defects such as dents, buckles and deformation.

Pure HM Technology

Because the technology is identifying changing magnetic fields and not necessarily a specific defect, operators are quickly learning that it can be used for a variety of applications related to keeping pipelines safe.

Despite the wide array of tools available to make pipelines safer, they can still fail due to factors that are undetectable using mainstream technology. In the past year, there have been several high-profile failures due to geotechnical factors that weren’t detected using the suite of integrity solutions that operators regularly use.

Geotechnical problems — such as slope movement and soil support issues — are threats that are difficult to detect using traditional tools.  The main reason is that these problems do not necessarily result in a measurable geometric defect in the pipe wall before they cause the pipeline to fail. Detection of these types of geometric defects can be done with current ILI methods, but at this point the damage has already occurred. These problems are also not necessarily preceded by corrosion, meaning Magnetic Flux Leakage — which identifies corrosion on the pipe wall — and preventative corrosion tools — which identify factors that cause corrosion — cannot detect a geotechnically-induced stress concentration that doesn’t have a corresponding geometric defect.

Due to recent failures caused by geotechnical issues and other problems undetectable using traditional methods, the oil and gas technology industry has poured resources into the research and development of new tools that can proactively identify these issues. Recently, technologies that measure magnetic field changes in pipelines have been piloted as a solution for identifying geotechnical defects.

New Pipeline Integrity Technology Identifies Stress in Pipelines

These technologies are passive screening tools that identify magnetic field anomalies corresponding stress concentrations in steel pipelines. They work by using sensitive magnetometers to characterize the magnetic field surrounding a buried pipeline. Where steel is under stress, there is a corresponding natural magnetic field generated. This phenomenon is called the inverse-magnetostrictive effect, or the Villari effect, and it has been well studied for decades; however, it has only recently become possible to detect and record the necessary data to find stress concentrators on buried pipelines from above ground due to improved electronic technology.

PureHM is one such company that has developed a screening tool capable of measuring these magnetic field changes on its Spectrum XLI Pipe Wall Assessment (PWA) platform. The system is used to find dents, buckles and even metal loss or cracks in the pipe wall that were under stress. The technology can also find stress resulting from ground subsidence or other geotechnical sources before the pipe is physically damaged.

The limitation to this technology is that is difficult to quantify the source of stress, making it a complimentary screening tool, and not an inspection alternative to the high-resolution ILI tools available.

Spectrum XLI PWA inspections are completed using the same process as other above-ground surveys. A field team prepares the equipment, and walks over the pipeline to map its exact location and determine the depth of cover. The technician team then walks the PWA sensors along the pipeline to collect the magnetic data.

Major Pipeline Operator Pilots Spectrum XLI PWA to Identify Geotechnical Hazards

Identifying potential geotechnical hazards is a priority for all operators, and in the case of one major Canadian pipeline operator, a critical priority after one of its pipelines failed due to slope movement that induced sufficient strain on the pipeline to cause it to fail.

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The supply pipeline that failed transports crude oil into a facility and runs through a remote area.  A major consideration for this operator is that the line runs within a multi-pipeline corridor with several other lines. Thus, the operator was concerned that if the first line failed due to slope movement, the other lines in the corridor were at risk of the same issue.

In 2016, the operator piloted Spectrum XLI PWA on the pipeline immediately beside the failed line to see if the technology could identify a stress concentrator at the location where the pipeline failed. Identifying stress at the failure site would provide the operator with some screening information about the condition of pipeline, as previous ILI’s did not identify issues that would indicate the pipeline was at risk of failing. This would also act as a validation for the PWA technology on an area with a known problem.

The pilot inspection was completed, and the Spectrum XLI PWA data showed a stress concentrator on the neighboring pipeline at the same location as the pipeline that previously failed. This was a major proof-point for the operator, as it validated that there are technologies that can effectively identify geotechnical hazards on pipelines, even if the stress concentrator itself cannot yet be quantified.

Despite identifying the presence of stress, Spectrum XLI PWA is an emerging screening tool that is best used in coordination with other data, such as ILI or above-ground survey data. The ability to survey a specific area that previously experience a failure allowed PureHM to test the PWA technology against a known point. This helps in the development and commercialization of new technologies.

As technologies such as Spectrum XLI PWA continue to evolve, many major pipeline operators are applying the inverse-magnetostrictive effect or Villari effect to various pipeline integrity projects. Because the technology is identifying changing magnetic fields and not necessarily a specific defect, operators are quickly learning that it can be used for a variety of applications related to keeping pipelines safe.

Tim Ross, P.Eng, is business development manager for PureHM based in Calgary, Alberta.



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