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The objective of verification is to confirm that the defect sizes match the data extrapolated from the software.
DIG-UP VERIFICATION PROCEDURES
An ILI project is not complete until the reported features have been verified in the field. The process which is followed in the field to achieve this is important as inappropriate inspection techniques in the field can invalidate an otherwise valid report.
Field verification of reported features has two important aspects as this helps confirm:
The reported features confirming the condition of the line to operator and helps support any actions that may be taken.
The tool performance for use on other lines where dig verification is not possible.
It is necessary to determine the performance of the inspection, in order to conduct the required preventative maintenance plans with the certainty of risk required by the Operator. Factors of Safety (FOS) can only be used effectively if the tolerances being used to calculate the FOS actually match those provided in the inspection report, or are more conservative in nature. It is not acceptable to use sizing tolerances that are not conservative, which means the actual measured dimensions are greater than those predicted even with the tool vendors tolerance added.
Most ILI suppliers will provide support for field verification activities. The ILI Suppliers are not just interested in when the ILI tool has not performed to specification. They need good quality field data to help verify the tool performance specifications for a range of feature types.
To achieve consistency with data collection it is necessary to set standards and protocols that must be followed.
This requires trained field personnel to gather the data with the required accuracy and competency so that the results can be relied upon. The techniques and equipment used must be tested and certified in calibration. The calibration and device tolerances must be taken into account when evaluating the results.
Significant problems have occurred where reported feature sizes are incorrectly measured in the field. This has an impact not only on the verification of the reported features but also on determining the tool performance.
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