Data Quality (Identifying Anomalies)

The CML measurements to be used for the Corrosion Rates (CR) calculation are shown on the CML Measurement History tab of the Circuit. IMS will identify "bad" readings (anomalies). For example, IMS will always identify when the current thickness reading is greater than the previous reading, since normally an Equipment's wall thickness does not get thicker. The next sections explain how IMS flags unusual readings.

Growth Warning “W”

A thickness reading that is thicker than the previous reading, but not more than 10% thicker than the previous reading will be flagged with a "W" (Warning). This reading will still be used in the calculations. The user should always review growth warnings!

The "W" will be removed if the current thickness reading is marked as “Verified” (a Quality Indicator) and the thickness reading will still be used in the IMS calculations. (Quality Indicator = Ignored, Verify, or Good.)

A Growth Warning occurs when both:

Growth Error “E”

A reading that is 10% thicker than the previous or base reading, or 15% thicker than any other “Good” reading will not be used in the IMS calculations. IMS will mark this thicker reading with an "E" (Error). You should always review/verify “erred” readings!

The "E" will be removed if the thickness reading is marked as “Verified”. IMS can now use this reading in the calculations since it is no longer considered a “growth” error reading. Usually when verifying an “erred” reading, you should also “ignore” the ones that are really causing the problem.

A Growth Error occurs when:

Time Error “T”

Short time spans between thickness readings usually create unreal CRs. When corrosion calculations result in short time intervals, the user must review and understand what caused the short inspection interval. When thickness readings are taken at an interval less than 6 months, the previous reading will never be used in the IMS calculations. IMS will mark the previous reading with a "T" (Time Error).

Note: The "T" will not be removed when the current thickness reading is marked as Verified.

Duplicate Warning “D”

When the same value is inputted twice it will be marked with a “D”.

Historical Warning “H”

A reading will be marked as historical when a new Baseline reading is entered.

Reviewing/Verifying Error Readings

When an Error has occurred, you will need to verify the Error. Ideally you should then first verify the reading in the field. After verifying the reading in the field, you can fix the calculation in IMS.

To do this in IMS:

• Open the Circuit Details Page (see IMS Details Page).

• Go to the CML | CML Measurement History section.

• Click the CML Measurement History tab (for more information on the tab see PEI Circuits - Details Page).

• Search for the CML with the error (E tag).

Verify the error:

• Right click on the Quality indicator (“I” \ “G” \ “V”, etc.).

• Select “Verified” or “Ignore” from the dropdown.

• Click the Save button to save the CML Measurement History.

Take Note

After verifying an Error, you will need to re-calculate and Approve the calc summary (see Calculating and Approving the Calc Summary).

Mitigating CMLs with a CAIR

It is possible to (risk) mitigate a CML with a CAIR. To do so:

• Go to the CML Measurement History section of the Circuit. (This can also be done directly from Circuit TrendPLot or the S-IDAP TrendPlot.)

• Right-click on a CML measurement’s quality indication (“I” \ “G” \ “V”, etc.).

• Click Mitigation.

• A pop-up will open. Approved CAIRs associated with the Circuit’s linked Equipment will show in the list. Select one of the Approved CAIRs and click OK. (Or create a new CAIR from here - in this case you will first need to Approve the CAIR before you can assign the CML to it).

• Click the Save button to save the CML Measurement History.

• After the CML Measurement History is saved, the whole CML, i.e., all the CML’s readings, will be mitigated. This will be indicated in the Measurement History tab with orange CAIR flags. You can click on the flag to navigate to the associated CAIR Details Page.

• The associated CAIR Details Page will also show that the CML has been mitigated in the Mitigated CMLs section. From this section you can remove the CML if needed or add another CML.

  

The PERF penalty will not be applied when a CML is mitigated. Also, with the next inspection, when a new reading is taken for the previously mitigated CML, then the new reading will be marked as a Base (B) reading.

Take Note

CML mitigation is intended to be used when the CML or area inspected has its risk of leak mitigated by temporary repair, e.g., engineered enclosures, isolation/blinded, or other methods. In cases where there is a CAIR to replace but the risk of leak has not been mitigated, the CML mitigation functionality in IMS should NOT be used.