Complex Corrosion / Pits-in-pits

Here’s How Inspection with True UHR Exposes Pits-in-pits

Pits-in-pits consistently rank as a top pipeline integrity threat, due to their complexity.

Of the many anomalies you need to monitor on your pipeline, pits-in-pits can be one of the most problematic. Pipeline operators consistently rate pits-in-pits as a top integrity threat, but because they are so small and potentially masked by the larger area of metal loss in which they’re embedded, the true nature of pits-in-pits can be hard to decode.

The term pits-in-pits describes pinholes in larger areas of lighter metal loss. Since pinholes are, by definition, 10 mm in size or less (geometric parameter A equals the greater of wall thickness or 10mm), it’s easy to understand how pits-in-pits can be missed or mischaracterized in a typical ILI analysis. Ultra-High Resolution (UHR) MFL ILI tools deploy a denser array of sensors and higher sampling rate which are particularly useful in sizing and characterizing pits-in-pits. This more robust data, coupled with experienced and multi-tier data analysis, makes it possible to understand these often-elusive anomalies reliably and efficiently. 

Characterizing depth to drive decisions

With any type of pits-in-pits, proper characterization of depth is vital in identifying the need for — and urgency of — repair. Yet this is the very thing that can be so difficult to “tease out” within pits-in-pits. UHR MFL ILI makes it possible to understand the size and shape of pits-in-pits, in order to assign them a proper depth. Other leading MFL systems struggle to see the detail required to accurately profile these features, often leading to a mischaracterization of the anomalies actual depth. Only true UHR technology backed by an experienced data analysis team can decipher the nuance of these potentially injurious features.

UHR ILI Systems data in blue, green, yellow and red, paired with an image of pipe corrosion and 3D diagram of pits-in-pits.


Pictured above: Other leading MFL systems struggle to see the detail required to accurately profile these features, often leading to a mischaracterization of the anomalies actual depth. Only true UHR technology backed by an experienced data analyst team can decipher the nuance of these potentially injurious features. Additional real-world examples comparing UHR MFL ILI capabilities in detecting pits-in-pits versus standard ILI tools can be viewed here.

UHR MFL ILI: The right tool for characterizing pits-in-pits

UHR MFL ILI tools from ENTEGRA® represent the latest in ILI capabilities. With a high sampling rate and high density of all tool sensor types including primary corrosion sensors, ID/OD discriminators, and caliper sensors, UHR MFL ILI tools capture the level of detail necessary to properly size and characterize pits-in-pits. Able to distinguish pits stacked on top of each other and pinhole anomalies as small as 3 mm x 3 mm embedded in larger areas of lighter metal loss, UHR MFL ILI tools provide an unprecedented view of pits-in-pits. When this comprehensive data set is then interpreted under the experienced eyes of trained data analysts, the information gathered by UHR MFL ILI tools becomes even more insightful. With pits-in-pits properly characterized and contextualized, you can make more informed decisions about your pipeline.

Learn more about how ENTEGRA UHR MFL ILI technology and human-powered data interpretation help reveal a more complete picture of pits-in-pits to help protect your pipeline’s integrity. Fill out the form below to download our paper presented at PPIM 2023: Applying Ultra-High-Resolution MFL to Achieve a Better Integrity Assessment of Pits-in-Pits.