An Integrated Approach to Integrity for the Un-Piggable Pipe: New Inline and External Techniques
New techniques and technologies in the industry are markedly improving a pipeline owner’s ability to establish fitness for service for un-piggable pipe. By combining new, innovative techniques for non-intrusive external line inspection with free-swimming, inline tools, owners can now better understand the condition of these critical assets. New external techniques include an indirect inspection platform that combines all the standard indirect inspection technologies into a single platform, and all performed on a single inspection. Inspection techniques include depth of cover, GPS centreline, ROW inventory, Coating Survey (ACVG/DCVG/ACCA), and close interval potential surveys for evaluating cathodic protection. Inherent in the term “un-piggable” is the idea that traditional ILI inspection tools are not able to inspect such pipe due to limiting factors like tight-radius bends, lack of pigging facilities and internal coatings. A containment verification tool with the ability to inspect such un-piggable for the presence of pinhole leaks has been used extensively over the last three years, and case studies will be presented. Sized smaller than the ID of the pipeline, the tool rolls through the pipeline while being pushed by the fluid flow in the pipe, so tight radius bends are not a concern and the tool does not require the presence of pig launch and receive facilities. New capabilities just added to the platform allow for a pipe wall assessment inspection capability to be performed concurrently with the containment survey. This new capability is designed to detect stress on a metallic pipe. While not providing the defect resolution of MFL or UT tools, the assessment data provides an effective means of screening a pipeline for issues of concern. In concert, the containment verification and the new external assessment capabilities allow pipeline owners and operators to establish a reasonably comprehensive baseline condition assessment of their un-piggable pipeline inventory.
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