An Advanced Approach to Fitness-For-Service (FFS) and Corrosion ...

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DOT 49CFR195 High Consequence Area Requirements Immediate Repair • Calculation of the remaining strength of the pipe (using ASME/ANSI B31G; RSTRENG) shows a predicted burst pressure less than the established maximum operating pressure at the location of the anomaly. • In addition any metal loss greater than 80% wt is also considered to be an immediate repair regardless of the feature dimensions. 180 – Day Conditions • Calculation of the remaining strength of the pipe shows an operating pressure that is less than the current established maximum operating pressure at the location of the anomaly. For this pipeline this has been calculated by assuming that the pipeline is operating at 72% SMYS resulting in a safety factor of 1.39. • An area of general corrosion with a predicted metal loss greater than 50% wt. • Predicted metal loss greater than 50% of nominal wall that is located at a crossing of another pipeline, is in an area with widespread circumferential corrosion, or is in an area than could affect a girth weld. • Corrosion of, or along a longitudinal seam weld. To maintain safety prior to any immediate repairs an operator must temporarily reduce the operating pressure or shut down the pipeline until the operator completes these repairs. On the basis of the above, 1 external feature requires immediate repair and 12 external features require remediation within 180 days of the date of discovery.
Corrosion Growth Assessment • CGA conducted in two stages: – Feature matching between 2006 and 2009 inspections – Align inspection data to common distance – Comparison of reported feature lists to identify features reported in both inspections – Estimation of growth rates based on reported dimensions – Signal-based comparison to validate the growth rates – Review of 2006 and 2009 inspection signals for selected features
Page 1 and 2: An Advanced Approach to Fitness-For
Page 3 and 4: � Purpose of Presentation � To
Page 5 and 6: Pipeline Summary • 12” x 30 mil
Page 7 and 8: Internal Corrosion • The pipeline
Page 9 and 10: External Corrosion • Location 1:
Page 11 and 12: Manufacturing Anomalies Orientation
Page 13 and 14: Dent / Deformation Anomalies Orient
Page 15 and 16: Extra Metal Anomalies Orientation -
Page 17 and 18: Peak Depth (%wt) Immediate Integrit
Page 19: Immediate Integrity - Manufacturing
Page 23 and 24: Feature Matching Process • Distan
Page 25 and 26: Feature Matching Process 65% 55% 37
Page 27 and 28: Corrosion Growth Signal Comparison
Page 29 and 30: Corrosion Growth Signal Normalizati
Page 31 and 32: Example Signal Comparison • Featu
Page 33 and 34: Further Investigations • 1 featur
Page 35 and 36: Future Integrity Number of Single R
Page 37 and 38: Repair Methods Type of Defect Grind
Page 39 and 40: Recommendations - External Corrosio
Page 41 and 42: Recommendations - Re-Inspection Int
Page 43: Iain K. Richardson MACAW Engineerin

An Advanced Approach to Fitness-For-Service (FFS) and Corrosion ...

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