PL ILI Comparison - Match Defects and Corrosion Rates - Tables

Take Note

This overview will explain how to read the data in the right lower pane of the ILI Comparison Module.

The right lower pane of the ILI Comparison module focuses on matching Defects and calculating Corrosion Rates. This section utilizes the matched Girth Weld list as reference points to adjust Defect locations from previous In-Line Inspections (ILIs) to align with the most recent data.

Automated Defect Match

Using the Matched Girth Weld list as the reference points, the Defect locations from the previous ILI Run are adjusted to align with the recent ILI Run. The following criteria are applied for matching metal loss:

1. Same wall loss side (i.e. either both internal or external)

2. Total offset in axial direction < Distance Matching Threshold (default: 0.3m)
   Note: There is currently no check on circumferential direction.

3. If multiple flaws are matched within the Distance Matching Threshold, the algorithm selects the one with the closest distance between the centers of the defect boxes.

You can also select a subset of reported defects for comparison by specifying the parameter Depth Matching Threshold (default: “5%”). This parameter ensures that only Defects in the recent ILI with a Depth greater than the threshold are included in the Defect matching process. It must be set to at least the ILI Defect Depth Reporting threshold or higher.

The Pipeline Operator Forum (POF) established guidelines titled “Specifications and Requirements for Intelligent Pig Inspection of Pipelines” which outline the recommended operational and reporting requirements for ILI Inspections. According to these guidelines, all Defects should report their position and orientation at point S as shown in the figure below. However, some ILI vendors may instead deviate from this requirement and report the metal loss defect location at point S1 (indicated in the image below by the red solid dot). Therefore, you should verify with your ILI vendor how the defect start location is reported. If the defect start location is at point S1 instead of S, ensure that the checkbox labeled Defect Starts at its Circumferential Center in the Scenario tab is checked.

The lower right pane of the ILI Comparison module contains the following four tabs:

• Results

• ILI Run1

• ILI Run2

• Interventions

Results

The Results tab provides a comprehensive overview of the defect-matching outcomes between Run 1 and Run 2.

The columns displayed in the tab are explained in the table below.

Filtering Data

You have three options for filtering data: All, Distance, and Chart. Each option allows you to view data in different ways.

To display all available data in both the grid and the graphs in the lower left pane.

• Select the All option.

This will display the data from all the matched Defects.

To view data for unmatched Defects in Run 1:

• Tick the Unmatched old checkbox.

To view data for unmatched Defects in Run 2:

• Tick the Unmatched new checkbox.

To filter data by Distance:

• Select the Distance option.

• In the Start field, enter the starting point.

• In the End field, enter the endpoint along the Pipeline.

Example:

Entering 5300 m for Start and 5350 m for End will filter data based on Abs Distance 2 within this range. This filter applies to both the grid and the graphs in the lower left pane of the ILI Comparison module.

Selecting Chart will filter the data based on the selection in the chart in the lower left pane.

To filter the data using the Chart in the left lower pane:

• Select Chart.

• In the Chart in the lower-left pane, click and drag a point to the right.

This will zoom in on the selected range in the chart and display the corresponding data in the table.  

ILI Run 1

The tab ILI Run 1 shows the data for the defects found during the first ILI Run.

For details on the columns displayed in the ILI Run 1 tab, refer to the table below.

ILI Run 2

This tab contains the same information as Tab ILI Run1 except for the Distance adjusted column.

Interventions

The Interventions tab shows an overview of manually matched and unmatched Defects.

Overruling Defcts Match

In the Interventions tab, you can manually adjust the matched and unmatched Defects.

Example:

In the image below, Defect “717” from Run 1 matches both Defect “250” and “252” from Run 2.

To manually override existing Defect matches or create new ones:

• Click on the Plus button at the top left of the table.

• In the Run 1 Defect field, enter the ID of the Defect from Run 1.

• In the Run 2 Defect field, enter the ID of the Defect from Run 2.

• From the Action drop-down menu, select:

  • “Match” to link two unmatched Defects.

  • “Unmatch” to unlink two matched Defects.

• Click Save.