PL FFS Details Page - FFS Volumetric - Burst Limit State

In the FFS Volumetric - Burst Limit State section of the FFS Details Page will show the FFS results. 

• Click on the applicable Inspection in the Inspection details and Defects 
  

The FFS Volumetric - Burst limit state section contains the following Tabs:

Assessment Table

The data/column titles shown in this tab depend on the Assessment code. For Original ASME B31G, Modified ASME B31.G, and DNV OSF the following columns are displayed:

Planned/Repair

In this tab, the Defects that will be repaired (planned) and Defects that have been repaired will be shown.

In the example below one defect (396) is in the plan to repair and one defect (406) was repaired on 1-Aug-2022. The planned and repaired defects have been specified in the Remedial action module.

Assessment and scatter chart

This section is used to select and visualize the FFS results as graphs.

Assessment Ranking

This section acts as a kind of filter for the Charts on the right and the Summary grid below.

To filter the Defects:

• Enter the number of Ranked defects (100 is entered by default).
• Select parameters for which you want to see the Defects from the applicable drop-down menus: 
  • Pipe section.
  • Diameter.
  • Wall thickness.
  • Design factor.
• Select the Defect type (Internal, External, and/or Non-corrosion metal-loss).
• Select the Failure type (Leak and/or Rupture)
• Select the specific property under Ranked by (CT, ERF, and/or Depth).
• Enter the Start and EndDistance if applicable.
•  A change in the parameters will update the number of defects in the Charts on the right side and the data in the Summary grid.

Assessment Chart

This tab shows the FFS results as a graph. For the RP-F101 2015 methodology, the following graph appears:

This graph shows:

• The title Corrosion tolerance assessment plus the assessment methodology. If the results are from a sensitivity run, then the string Sensitivity is also in the title.
• The x-axis title is the Defect depth + sizing accuracy.
• If sizing accuracy for length has been specified then the y-axis title is the Defect length + sizing accuracy otherwise the y-axis title is the Defect length.
• The black curves are the design assessment curves.
• The reporting threshold of the inspection tool is represented by the two vertical red-dotted lines.
• Clustered defects (open circles, applicable for RP-F101 only), For Shell, see information on DNV RP-F101 defect interaction SR.14.13139.
• Unacceptable clusters or defects have a corrosion tolerance of less than 0.
• Legend above the chart.
• The number of defects in the graph has been set in the tab Ranking (see above).
• Graphs for the other two assessment methods, Original ASME B31.G will look as follows:

and Modified ASME B31.G

Furthermore, the graph shows the corrosion tolerance line for each defect. This is the line from the origin, through the defect point to the assessment curve. The intersection of each line piece with the assessment curve is depicted with a small black dot.

When you click or hover over a Defect, the following information is displayed: the ID, X and Y coordinates, and a gray line connecting the selected Defect to an associated one.

The corrosion tolerance line is not applicable for RP-F101 because of the clustering. When clicking on a clustered defect the Cluster Number is shown.

The graph shows the Non-corrosion metal loss Defects but without Corrosion tolerance lines.

Scatter chart

In the Scatter graph, the different categories for the Y-axis are plotted against the distance of the pipeline (X-axis).

The different Y-axis options are:

• Orientation [degrees] (default)
• Length [mm]
• Width [mm]
• Depth + Accuracy [mm]
• Depth [mm]
• Actual wall thickness [mm]
• ERF
• CT [mm]
• Defect Morphology (L/D ratio)
• The ERF (Estimated Repair Factor) and CT (Corrosion Tolerance) are based on calculated values, the other items are based on input values. The option Depth is based on the measured values. For Shell, the details about the ‘ERF’ and ‘CT’ calculations are described in the theoretical FFS document, SR.14.13139.

The Defect Morphology (L/D ratio) graph:

The graph shows the different corrosion morphology categories. The measured depth is used to obtain the length/depth ratio, that is: without the addition of depth sizing accuracy.

Assessment Code DNV OSF

To use this code the Pipeline Design Code on the Equipment Details page should be set to "DNV OSF", for example:

Then in the FFS module, the Assessment code should be set to 'DNV OSF':

If the data has been imported and analysed in the Assessment chart a vertical line will be displayed at Nominal WT – Min. WT.

In the example below the Nominal WT = 5.6mm, so the vertical line is at 5.6 – 3 = 2.6 mm.

The defect + inaccuracy added is 2 mm, which gives a Corrosion tolerance of 0.6 mm for this Defect.