Session: 03-03-04 Feature Assessment Case Studies - Corrosion II

Paper Number: 133557

133557 - Verification of Internal Corrosion Through ILI and Non-Destructive Testing: Lessons Learned 

Abstract: 

Verification of In line Inspection results can and often is challenging for pipelines with internal corrosion,especially in areas of extensive corrosion and/or areas with challenging corrosion morphologies such as pinhole corrosion. The most reliable method which many operators choose is to rely on cut-outs for the purpose of both mitigation and ILI-verification. However depending on the diameter and the critically of the pipeline, verification of internal corrosion features from in line inspection  is based exclusively on ultrasonic (UT) non-destructive examination (NDE). These ultrasonic inspection techniques can range from hand held pencil probes to automatic scanning systems. The output from these methods does vary both in quanity and quality which can and does impact the potential tool validation as per API 1163.

 

This paper outlines the results from these radically different ultrasonic inspection techniques and then compares it to laserscan and pit gauge measurements once the inner surface of the pipe wall is available. This work was done across multiple pipeline diameters and various internal corrosion mechanisms. It reviews the strengths and weakness of the individual NDT measurements and compares them to the original Magnetic Flux Leakage inspections from the prespective of validating the in line inspection. An output from this study is a series of  guidelines that should be used when verifying internal corrosion that both operators and tool providers can use to determine tool performance. These guidelines help to verify both the ILI tool performance as well as the relevant non destructive method.

An additional output from this study is a determination of how the grid size of the NDT method affects the tool validation on a internal corrosion for the various Pipeline Operator forum guidelines for defect dimensions. This was achieved by downsampling of the AUT data to replicate an increasingly coarser grid of data point.

Presenting Author: Stephen Westwood OnStream Pipeline Inspection

Presenting Author Biography: Stephen brings over twenty years of design experience in In Line Inspection tools. Stephen holds a PhD in Experimental Magnetism and BSc in Experimental Physics. Stephen's expansive knowledge of pipeline inspection tool development includes algorithm development and magnetic design of In Line Inspection tools. Previous roles have seen Stephen building and leading multi-disciplinary groups in new product development throughout his career. Stephen's industry knowledge, experience and unparalleled reputation will be a driving factor in Onstream's continued development and growth within the In Line Inspection industry.

Authors:

Stephen Westwood OnStream Pipeline Inspection
Bala Ganapathy Gibsons
Paul Spoering Onstream
Michael Zhou Gibsons Energy
Taras Bolgachenko Onstream