Improvement of our engineering critical assessment for dents

The updated PHMSA regulations, effective May 2023, require gas pipeline operators undergoing a dent ECA to perform dent profile comparisons between recent and previous ILIs to identify significant changes in dent depth and shape. Significant changes can indicate unstable conditions due to geohazards or other factors, necessitating immediate investigation.

ROSEN has been offering ECAs for dents for some time now. In line with industry requirements, we are also constantly developing this service to ensure our customers are compliant. As this regulatory change will be mandatory for operators from 2024 , we have developed the Dent Scan Tool, a robust software solution capable of reading and visualizing 3D radial measurement data from up to three repeat ILIs. The tool is optimized for use with data from ROSEN’s high-resolution XT and standard-resolution MD geometry ILI systems. However, it can also process data from third-party vendors after conversion to ROSEN’s format. Customers will then receive the results of the dent ECA in a report.

Functionality and features of Dent Scan

Dent Scan allows for comprehensive dent profile comparisons, examining axial and circumferential profiles as well as 3D contour plots. The tool aligns the upstream and downstream shoulders away from the dent peak area, representing undeformed pipe sections, to detect significant changes in dent shape and depth. For example, the tool can identify the re-rounding of a dent post-repair, as shown in Figure 1, and  conversely, Figure 2 illustrates a dent with no significant change, indicating stability.

Dent Scan Software Examples

Figure 1 depicts the axial (top image) and circumferential (bottom image) profile comparison for a dent that shows significant shape changes; the upstream and downstream shoulders are aligned for comparison purposes, and each profile is taken at the intersection of the deepest point of the dent in the most recent inspection data. This bottom-side dent was reported with a “repaired” comment, and the comparison depicts re-rounding as a result of removing the indenter and being subjected to operational pressure where the dent depth was reduced from 1.7% to 1.0% of pipe outer diameter (%OD) after repair of the dent. The peak dent depth difference between repeat inspections is found to be 0.18 inches, which is 2.25x the reported ILI system depth sizing tolerance.

Figure 2 depicts an example of a dent not showing significant change in depth or shape. A difference in depth of 0.02 inches (0.07% increase) is reported, which is within the specified depth sizing tolerances of the ILI system (0.08 inches or 0.3% OD). Based on the data comparison from both inspections, no significant change in dent depth or shape is observed.