Corrosion monitoring techniques and benefits of newer methods
By leveraging the power of AIoT, industry can overcome the hidden challenges of permanent ultrasonic sensor solutions and achieve superior operational performance
Venkat Eswara and Sascha Schieke mPACT2WO, a Molex Business
T he oil and gas production industry is facing sub- stantial financial challenges attributed to corrosion, incurring annual costs estimated at $1.372 billion. 1 These costs, along with environmental risks, are expected to rise as operations move into more demanding environ - ments. Corrosion poses a major threat in process industries, especially in asset-intensive sectors like oil and gas and petrochemicals. It can cause leaks, reduce asset perfor - mance, and lead to unplanned shutdowns and potentially catastrophic incidents. Additionally, corrosion introduces operational risks, safety concerns, and liabilities. As a result, corrosion monitoring has become a critical aspect of plant operations and maintenance, with detection methods and procedures continuously evolving. Evolution of corrosion monitoring techniques Traditionally, ultrasonic thickness monitoring has been performed manually using portable ultrasonic equipment. However, manual inspections are time-consuming and costly, and they require extensive data cleaning to address the method’s limitations. To mitigate these shortcomings, permanently installed ultrasonic solutions were introduced. Table 1 highlights the main differences between manual inspections and those using permanently installed auto- mated sensors.² Permanently installed ultrasonic solutions have been in use for more than three decades across various industries, but they present challenges regarding the accuracy and reliability of thickness measurements. These challenges can be addressed by adopting Artificial Intelligence of Things (AIoT) technology. By leveraging AIoT, industries can sig - nificantly enhance the accuracy, precision, and reliability of ultrasonic corrosion monitoring, thereby improving asset integrity and operational efficiency.
Measurements with permanently installed systems
Manual measurements
Accuracy
Precision
True thickness
Average measured thickness
Thickness
Ultrasonic measurement: accuracy and precision The quality of ultrasonic thickness data is determined by its accuracy, which refers to how close the measurements are to the true thickness, and its precision, which refers to how consistent the measurements are around an average thickness value. This relationship is illustrated in Figure 1 . However, the accuracy of ultrasonic thickness meas - urements may not necessarily improve with permanently installed sensors. This is because the accuracy depends on a different set of factors. This becomes evident when examining the principle of ultrasonic thickness measure - ments and the essential equation used to calculate thick - ness. Both portable and permanently installed ultrasonic instruments measure the time-of-flight (ToF) of ultrasonic waves in a part. The precision of ultrasonic thickness measurements is enhanced by using permanently installed ultrasonic sen- sors, as they eliminate factors contributing to the variability of manual measurements. These factors include the exact Figure 1 Accuracy and precision of ultrasonic thickness measurements²
Corrosion monitoring methods: Manual inspection vs automated inspections
Aspects
Manual inspection Predominant method
Automated inspections
Method prevalence Instrument reliability Accuracy and precision
Minor method
Reliable portable instruments Limited accuracy and precision
Reliable temporarily/permanently installed systems
High accuracy and precision
Subsequent analysis accuracy
Limited accuracy of subsequent analysis
Highly accurate subsequent analysis
Table 1
99
PTQ Q4 2024
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