Current Magnetometry Inspection (CMI) vs. In-Line Inspection (ILI)

As the pipeline industry seeks innovative solutions to enhance the integrity and safety of its infrastructure, the advent of Current Magnetometry Inspection (CMI) technology has marked a significant shift in the approach to pipeline assessments. This section delves into the methodologies of CMI and traditional In-Line Inspection (ILI), contrasting their applications, advantages, and limitations to offer a comprehensive understanding of their roles in modern pipeline management.

Understanding CMI

CMI stands as a pioneering technology designed to inspect and map underground buried pipelines from above ground. It eliminates the need for direct physical access to pipelines, allowing for in-service inspections without the necessity of soil removal. This method is particularly beneficial for assessing pipelines deemed unpiggable due to their inaccessible locations, complex geometries, or operational constraints.

Key Features of CMI:

  • Non-invasive Inspection: CMI's above-ground operation negates the need for excavation or pipeline modifications, ensuring minimal environmental impact and operational disruption.
  • Wide Applicability: Capable of inspecting all pipeline geometries and types made of ferromagnetic material, CMI overcomes many challenges faced by traditional ILI tools.
  • Operational Efficiency: With the capacity to cover up to ten kilometers daily, CMI offers rapid assessment, reducing the time and resources typically required for pipeline inspections.

The Realm of ILI

Conversely, ILI tools, including smart pigs, crawlers, or free-floating devices, necessitate direct access to the pipeline, often requiring operational pauses and specific pipeline conditions for effective use. ILI methods are renowned for their ability to provide detailed internal inspections, identifying issues like corrosion, cracks, and wall thickness variations.

Challenges with ILI:

  • Operational Disruptions: ILI inspections often require pipeline shutdowns or modifications, leading to potential operational losses and increased costs.
  • Limited Accessibility: ILI tools cannot be used in unpiggable pipelines, which are restricted by their design, location, or operational parameters.
  • Preparation and Planning: Extensive pre-inspection preparations, including pipeline cleaning and modifications, are necessary to accommodate ILI tools, adding layers of complexity and potential delays to the inspection process.

CMI vs. ILI: A Comparative Outlook

While ILI remains a valuable tool for detailed internal pipeline assessments, CMI's non-invasive, flexible, and efficient methodology presents a compelling alternative, especially for challenging environments and unpiggable pipelines. CMI's ability to operate without halting pipeline operations or engaging in extensive preparatory work offers a distinct advantage in terms of cost, time, and environmental impact. Moreover, CMI's adaptability to various pipeline types and conditions underscores its versatility and potential to serve as a complementary or alternative solution to ILI in the broader spectrum of pipeline integrity management.

In summary, the selection between CMI and ILI hinges on specific pipeline conditions, operational requirements, and the nature of the anomalies being investigated. While CMI offers a revolutionary approach to pipeline inspections, especially for scenarios where traditional ILI tools face limitations, a comprehensive integrity management program may benefit from the strategic integration of both technologies, leveraging their respective strengths to ensure the safety and reliability of pipeline operations.

Applicable on pipelines    
     With bend radius <3D no yes
     With different internal diameters no yes
     Without guide bars in T-branches no yes
     Without pig launcher no yes
     Which are not cleaned before inspection no yes
Interruption or change of product flow necessary not necessary
Pipelines that are of out of service no yes
Types of detected features    
     Internal features yes no
     External features yes yes
     General corrosion yes yes
     Cracks special tools needed no
     Pitting corrosion yes yes
     Lamination special tools needed no
     Deformation yes yes
Anomaly classification absolute size active vs. passive corrosion
Anomaly type classification yes no
Girth weld identification yes yes
Metal part identification yes yes
Pipeline localization relative absolute
Bend characterization yes yes
Right of Way (RoW) control no yes
Depth of cover (DoC) mapping no yes
     Response threshold level for features > 1 mm > 1 mm³
     Maximum DoC independent up to 8 m
     Outer Diameter (OD) of pipelines > 6“ > 1“
     Electrical connection to the pipeline not necessary necessary
     RoW preparation not necessary free of heavy vegetation


Mapping – Case study

CMI is used for the 3D-mapping and digitalization of pipelines in a high consequence area


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It’s for a reason that we are amongst Germany’s Top 100 innovators. Because our mission is to overcome these inspection challenges and, together with our clients, continuously improve the safety and reliability of all pipelines.