Validation of Latest Generation MFL In-Line Inspection Technology Leads to Improved Detection and Sizing Specification for Pinholes, Pitting, Axial Grooving and Axial Slotting
Proceedings Publication Date
Jürgen Ehrhardt
Eric Quick, Martin Bluck, Justin Pearce, Jeff Sutherland, Andrew Bain
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In 1996, the Pipeline Operators Forum (POF) published its first version of an In Line Inspection Specification to standardize how an operator and vendor would undertake a pipeline inspection.  Within the POF document, anomalies have been classified into categories as a function of their length and width in order to allow vendors to state their Probability of Detection and sizing tolerances for each classification. 

Previously, when utilizing axial MFL tools, ILI vendors were not capable of supplying probability of detection and sizing specifications for several categories such as Pinholes and Axial Slotting.  Recent advancements with MFL technologies has allowed for improvements to be stated for both probability of detection and sizing tolerances for Pinholes, Pitting, Axial Grooving and Axial Slotting. 

This paper will summarize experience gained from both pull through and field results of the latest generation MFL Technology leveraging data from a high density array of axial, radial, & transverse sensors.  The data will show there is a distinguishable improvement in the Probability of Detection and Sizing tolerances for many of the POF categories which will allow pipeline operators make more informed pipeline integrity decisions.

The paper will start with a review the Pipeline Operators Forum’ Specifications and Requirements for Intelligent Pig inspection, looking into more details at some selected definitions such as: Anomaly, Detection Threshold, Probability of Detection, Probability of Identification, Measurement Threshold and Sizing Accuracy.

It will then focus on the next generation MFL technology in more details, looking at how Intelligent Design, Data Quality and Service Flexibility are key components to push the MFL entitlement.  Time will be spent on illustrating some of the novel hardware features from a performance and operating standpoint, as well as a review of the data analysis software developed for flexible processing, analysis, & reporting. 

The final section of the paper will review the detailed work carried out in pull-through tests, to develop the new & differentiated specification for metal loss, and will also relate to case studies of inspections and dig verifications which have enabled further validation of the published specification, in line with the POF. The paper will close with the next steps to be followed to improve the performance of the next generation MFL technology even further and take the system to entitlement.