Metal Loss Musings

Written by Ben Bergius, Commercial Account Executive - Europe

When it comes to pipeline integrity management, metal loss is a leading cause of pipeline failure which can propagate through several mechanisms during the asset's life. Additionally, metal loss can occur during pipeline manufacture and installation, necessitating the need for baseline inspections.

On a day-to-day basis, I have conversations regarding metal loss with operators, and I have noticed a pattern – regardless of the operator, there are significant similarities in the challenges faced. Metal loss is not something that operators can avoid, but by aligning with the right partner, can successfully blend talent, experience, and technological capabilities to manage it effectively and efficiently.

How can metal loss propagate in a pipeline?

When a pipeline enters service, corrosion can become an issue for both the internal and external surfaces of the pipe wall. Internal corrosion can occur when corrosive substances transported by the pipeline react with the internal pipe wall to cause corrosion/metal loss. This can be exacerbated by changes to the medium properties of the substances being transported or by failures of internal and external coatings, as well as cathodic protection deficiencies.

Zero in on the Right Technology

Choosing inline inspection technology is about more than meeting immediate inspection needs; it is about finding a solution that offers accuracy, longevity, flexibility, and compatibility. Selecting the right technology is a critical decision that impacts a pipeline operator's viability, environmental safety, and people's lives.

Traditionally there have been two primary technologies utilized for metal loss inspection in pipelines: magnetic flux leakage (MFL) and ultrasonic (UT) methodologies. In recent years other technologies such as acoustic resonance technology (ART) have emerged to overcome specific threats and pipeline configurations.

MFL utilizes magnets to measure changes in magnetic flux to detect metal loss in pipelines. This technology is suitable for a wide variety of pipeline mediums – namely gas and liquids. MFL technology has been operating for decades and is available from a variety of different suppliers and in a wide range of sizes and resolutions.

Ultrasonics on the other hand require a liquid medium but offers the benefit of direct measurement which allows for the measurement of complex corrosion features with axial resolutions of up to every 0.75 mm (approx. 0.03 in) and circumferential resolutions up to 2.5mm (approx. 0.1 in) – see Figure 1. By utilizing direct measurement technology, UT can detect and measure laminations, and CRA defects and accurately measure corrosion including under pipeline supports. Unlike MFL, UT is not affected by pipeline wall thickness, making it ideal for heavy wall pipelines such as those seen offshore.

Figure 1: The primary ultrasonic resolutions offered by NDT Global

NDT Global's ART is a unique ultra-wideband acoustic measurement technology that delivers highly accurate pipeline wall thickness data. Like other ultrasonic technologies, the direct nature of the measurement provides a significant improvement over magnetic MFL inline inspection (ILI) technologies, when compared in some aspects of defect detection, classification, and sizing.

NDT Global specializes in ultrasonic measurement and acoustic resonance for ILI, being the market leader in these technologies. This focused approach allows NDT Global to push the envelope of direct measurement inspection capabilities, to provide the best insights, and ultimately The Power of Clarity™.

Other than metal loss, are there any other pipeline features that a UT inspection would detect?

NDT Global offers a range of additional modalities that can be incorporated into our Ultrasonic metal loss fleet, including:

  • EVO geometry - detects and measures geometric anomalies i.e., dents, buckles, and roof topping. Combining a metal loss or crack assessment with ultrasonic-based geometry measurement enables a comprehensive inspection in a single run. This capability is a standard feature of ART and optional with UT.

  • EVO Mapping - for detection of pipeline movement. By leveraging high-end exploration technology and leading-edge software, EVO Mapping can pinpoint installations, welds, and anomalies in gas and liquid pipelines even at the preliminary reporting stage. This capability is a standard feature of ART and optional with UT.

  • High-resolution Crack inspections - crack detection technology provides high-resolution feature depth sizing and measurement of complex crack morphologies. Crack inspection is currently performed by our ultrasonic platform and can also be combined with the above-mentioned modalities.

What are some of the key operational aspects that need to be considered as part of an ultrasonic inspection?

First-run success is one of the primary key performance indicators within NDT Global. The safe and reliable operations of our inspection tools are of critical importance.

The first step in the NDT Global quality journey begins during the tendering phase, where a feasibility review of the pipeline characteristics is performed as a standard step in our quotation processes. Accurate and clear pipeline data is critical at this step to ensure first-run success.

Therefore, considering the operating parameters of the pipelines is important to evaluate when considering a UT metal loss inspection. NDT Global operates a vast array of UT metal loss tools adaptable to thousands of different configurations including just some of the following capabilities:

  • Diameter ranges from 6” to 56”

  • Combination tools (metal loss/crack/mapping/geometry)

  • Multi-diameter

  • High-pressure (up to 300 bar)

  • Bi-directional (in select diameters)

Figure 2: Single Module BiDi ART Scan & Ultra High-Resolution UMp+ UT Tool

In addition, our fleet of ART tools provides an even greater range of flexibility with market-leading battery life in a smaller footprint; extensive multi-diameter capabilities and all while being capable of operating in both gas and liquid environments.

What does the future of UT metal loss look like at NDT Global?

NDT Global has been leading the market in ultrasonic metal loss tools for the past two decades and strives to continue that into the future. By leveraging machine learning and artificial intelligence NDT Global looks to improve the data insights of inspection modalities, while simultaneously increasing efficiency. We are also developing innovative technologies, such as UMx & phased array, to further push the metal loss ILI envelope.

Figure 3: PROTON™ Phased Array Tool

As ever, choosing the right inspection technology is pivotal to exceeding industry standards, ensuring safety, and driving economic value. Different scenarios necessitate distinct technologies and demand-specific capabilities, from land-based pipelines that cross vastly different terrains, both above and underground, to undersea pipelines.

Partnering with industry specialists to get the results you need

Contact us, leave a comment, or message me directly to discuss how NDT Global can partner with your company to address the challenges of pipeline integrity and work alongside you to take advantage of cutting-edge technology — and leverage The Power of Clarity™.

Discover the Power of Clarity.

Whether you’re ready to schedule an inspection or have questions about our process, our team can help get you started.

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