PR-469-143708-R02 In-line Inspection and Assessment for Pipeline Girth Weld Defects

Abstract

During 2010 to 2012, the United States reported a total of eight girth weld failures and economic loss amounted to $4,382,000 [Summarized from data provided by PHMSA, http://www.phmsa.dot.gov/pipeline/library/data-stats/flagged-data-files]. PRCI has several projects (current and historic) that investigate various integrity concerns of vintage girth weld defects. Globally, the integrity of girth welds of oil and gas pipelines has increased as a concern due to failures with high consequences. A primary integrity issue to pipelines that has been the motivation of this project, considers defects originating during field construction but over time may also be subject to external loads and stresses due to earth movement. Girth weld defects in newly built pipelines are also assumed to exist but would be much smaller in size, and more difficult to detect, which motivated the investigation into minimum defect detection levels of the inspection technologies. The research objectives of this project were to characterize, and summarize, the applicability of ILI (In-line Inspection) technologies of MFL4 (Magnetic Flux Leakage), USCCD (UltraScan and trade; Circumferential Crack-Like Detection) and EMAT (Electro-Magnetic Acoustic Transducer) for inspection of defects related to pipeline girth welds. Pull-through tests and infield site excavations of operational pipelines, have been collected and used here for detection, defect type classification and sizing quantification. From 2015 to 2016, a comparison of test results of MFL4 and USCCD and EMAT technology for girth weld defects is discussed. Based on the same pull test facility and manufactured defects for MFL4 and USCCD ILI inspection, comparison of the results were carried out for these two operational technologies for their inspection performances. The report also outlines the activities carried out to investigate a feasibility of EMAT technology to detect circumferentially oriented cracks based on current technology.