Beyond ECDA for evaluating ‘unpiggable’ pipelines: advances in internal and external tools

摘要

This paper was first presented at the Evaluation, Rehabilitation, and Repair of Pipelines Conference held in Houston innNovember 2011, and organised by Tiratsoo Technical and Clarion Technical Conferences.nAs a result of multiple incidents in the pipeline industry that occurred in the last 25 years and the need to addressnpipelines that could not be inspected – unpiggable – using in-line inspection (ILI), or could not be taken out of servicento be hydrotested due to high security concerns, a team was formed of pipeline operators, researchers, and vendors tonstart putting together the first direct assessment process in 1998. This team was formed for the purpose of coming upnwith an integrity process using proven monitoring technologies which consisted primarily of above-ground (external)ntechniques which we all know as close-interval survey (CIS), direct- or alternating-current voltage-gradient (DC ornACVG), and current-attenuation techniques which later became NACE standard SP0502 ‘external corrosion directnassessment’ (ECDA). The key word is ‘process’ using existing or proven above-ground techniques and tools. More thanna decade has gone by and newer technologies have been developed and proven; however, NACE and the United StatesnPipeline and Hazardous Materials Safety Administration have been cautious in giving approval for newer techniquestools for both internal and external threat applications. This article will discuss these new technologies and tools thatnhave been developed in the last ten years. The direct-assessment process is still valid even though the tools change;nhowever, the question should always be asked: “Are these the right tools to adequately address the threat(s)?”