Achieving a North American record for longest intelligent inspection of a natural gas pipeline

摘要

TransCanada was faced with a significant challenge to inspect a 941 km NPS 48 pipeline.The options for the inline inspection(ILI)were multiple segments which would cause an increased cost with new pigging facilities required and a delay to the ILI schedule, or attempt to pig the longest natural gas pipeline section in North America.The extraordinary proposal would require a Smart Approach to preparing the pipeline for ILI, and assessing its readiness.The program required long distance, high speed Smart Tools and a massive 48”combination Magnetic Flux Leakage(MFL)tool capable of negotiating the 941km line from Burstall, Saskatchewan to He des Chenes, Manitoba, Canada.Given the alternative of the installation of 3 additional launcher and receiver stations and the risk to overall project schedule from extended inspection operations, TransCanada took the bold decision to clean and inspect the pipeline in a single pass.This option created a new set of challenges to guarantee’first run success’in one of the harshest pigging environments and in a line where the cleanliness condition was unknown.In any ILI program an understanding of the pipelines internal condition, geometry and cleanliness is critical to success, more so for a 941km pipeline In particular unknown debris deposits existing in the pipeline could be collected with the highly aggressive MFL tool brushes, could easily and very quickly have led to very significant debris build up during inspection that at best would likely cause degraded data leading to an unwanted re-run and at worst, the possibility of a stuck pig and subsequent retrieval program.Assessing readiness and assuring success, the project utilized a Debris Mapping Tool to measure and quantify debris levels in the pipeline.The insight gathered by the tool provided a baseline upon which the likelihood of success could be measured.In July 2017, a successful Debris Mapping and MFL inspection was completed.This paper discusses the main program risks, mitigation steps taken over and above a standard ILI run.Key considerations and actions taken relating to additional engineering and tool modifications to various components of the inspection vehicle itself will be discussed.Lastly, insight will be given into an extensive smart cleaning program using a combination of mechanical cleaning associated and debris level assessment, specifically designed and tailored for the project to ensure that the pipeline was both ready for ILI and that cleaning had reached optimum for ILI so that full, high quality MFL data would be collected in a single run.