Estimating corrosion growth rates to determine pipeline integrity assessment inspection intervals
GTI researchers have developed a simple method to determine the external corrosion growth rate of pipe segments using a combination of field readings and historical data. The project has provided operators with a web-based corrosion growth rate tool that can be used to calculate reassessment intervals based on site-specific data rather than industry standard corrosion growth rates that may be over- or under-conservative. The use of this tool could lead to reducing life-cycle integrity management costs while simultaneously improving assessment internal selections.
Some operators fill the annular space between the carrier pipe and the casing with wax to mitigate the threat of external corrosion. While PHMSA has accepted that this procedure may eliminate the need for reassessments, there is still a requirement to ensure that the threat of corrosion has been mitigated through periodic monitoring. Researchers have developed a technique that will use commercially available tools to monitor the corrosion growth rate and the integrity of the wax fill without requiring an excavation. This technique allows operators to evaluate the collected data and determine if the threat of external corrosion can be removed.