Smart pigs are used as part of an integrity management plan for oil and gas pipelines to detect metal loss defects. The pigs do not measure the defects: they collect signals from on board equipment and these signals are later analysed. Signal analysis is complex; consequently, defect sizing tolerances and confidence levels can be difficult to determine and apply in practice. They have a major effect when assessing the significance of the defect, and when calculating corrosion growth rates from the results of multiple inspections over time. This paper describes how defect sizing tolerances and confidence levels are obtained by pigging companies, and compares standard and high resolution pigs. Probability theory is used by the authors to estimate the likelihood that a defect is smaller or deeper than the reported (by the pig) value for both standard and high resolution tools. The paper also shows how these tolerances can be included in defect failure assessment and the results of multiple pig runs.
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2004 International Pipeline Conference
October 4–8, 2004
Calgary, Alberta, Canada
Conference Sponsors:
- International Petroleum Technology Institute
ISBN:
0-7918-4176-6
PROCEEDINGS PAPER
Smart Pig Defect Tolerances: Quantifying the Benefits of Standard and High Resolution Pigs Available to Purchase
Stephen Westwood,
Stephen Westwood
BJ Pipeline Inspection Services, AB, Canada
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Phil Hopkins
Phil Hopkins
Penspen, Newcastle upon Tyne, UK
Search for other works by this author on:
Stephen Westwood
BJ Pipeline Inspection Services, AB, Canada
Phil Hopkins
Penspen, Newcastle upon Tyne, UK
Paper No:
IPC2004-0514, pp. 1181-1194; 14 pages
Published Online:
December 4, 2008
Citation
Westwood, S, & Hopkins, P. "Smart Pig Defect Tolerances: Quantifying the Benefits of Standard and High Resolution Pigs." Proceedings of the 2004 International Pipeline Conference. 2004 International Pipeline Conference, Volumes 1, 2, and 3. Calgary, Alberta, Canada. October 4–8, 2004. pp. 1181-1194. ASME. https://doi.org/10.1115/IPC2004-0514
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