Corrosion Rate and Severity Results from In-Line-Inspection Data

摘要

Pipeline operators are increasingly using in-line inspections to maintain the integrity of their pipelines. Inspection tool vendors, in turn, have been steadily improving the technology to give in-line inspections greater accuracy and resolution. In-line inspections enable the pipeline operator to address the most severe defects on the pipeline. Over the last several years, Morrison Scientific has developed methods of adding another dimension to inspection data. That dimension is corrosion rate. Two methods exist: The first method estimates bulk corrosion rates from a single inspection based on a coating-disbondment, pit-initiation, and corrosion-growth model. The second method calculates corrosion rates from multiple in-line inspections. This second method yields the site-specific corrosion rate for the entire pipeline. This is accomplished by sophisticated pattern-matching soft- ware that matches defects from one inspection to the next. This method automatically adjusts for odometer slippage and orientation differences between inspections. From the differences in defect size between inspections, the method calculates the corrosion rate. Using this corrosion-rate analysis, the pipeline operator can address the specific locations at which active corrosion is occurring. In this way, corrosion-mitigation issues can be corrected early to avoid more expensive repairs and before the integrity of the pipeline is compromised. From the corrosion rates, Morrison Scientific, has also developed a method of predicting future defect severity. These predictions aid the operator to prioritize excavation and repair programs and to determine when a subsequent inspection of the pipeline is warranted.