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E xternal C orrosion D irect A ssessment

E xternal C orrosion D irect A ssessment. NACE 2005 Northern Area Western Conference by Gord Parker, C.E.T. Radiodetection Ltd. Background. (USA) The Pipeline Safety Improvement Act of 2002 signed into law on December 17, 2002 applies to natural gas transmission (dist. coming)

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E xternal C orrosion D irect A ssessment

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  1. ExternalC orrosionD irectA ssessment NACE 2005 Northern Area Western Conference by Gord Parker, C.E.T. Radiodetection Ltd.

  2. Background (USA) The Pipeline Safety Improvement Act of 2002 • signed into law on December 17, 2002 • applies to natural gas transmission (dist. coming) • must identify "high consequence areas (HCA)" • conduct risk analyses of these areas • perform baseline integrity assessments of each pipeline segment • inspect the entire pipeline system according to a prescribed schedule and using prescribed methods

  3. Other provisions of the law include (US) The Pipeline Safety Improvement Act of 2002 • Participation in one-call notification programs • Increased penalties • “Whistle-blower" protection • Qualification programs for employees O.Q. • Government mapping of the pipeline system • Other Housekeeping Stuff

  4. BUT… • Some pipes have serious limitations to inspection • Not Pigable (small valves/openings, 90° fittings) • No redundant loops – had to stay in service • Hence, no hydro-testing either • Best Quote I’ve heard this year… “Congress is a little leery of engineering because you can’t barter, you can’t negotiate with it.”

  5. Direct Assessment came along • It seems to have been accepted & implemented fast • There are 3 types of DA (for 3 types of threats) • External Corrosion (ECDA) • Internal Corrosion (ICDA) • Stress Corrosion Cracking (SCCDA) • ECDA is the most mature of them. • RPO502 – 2002 is the defining NACE document

  6. ECDA is a 4 Step Process • Pre-assessment • Most important step • Indirect Inspections • Above-ground Tools • Direct Examinations • Verification Digs AND Mitigation • Post-assessment • Define Reassessment Period (US: 7 yr typ. max) • Assess Overall Effectiveness

  7. Important Definitions • ECDA Region– Section(s) of pipeline with similar physical characteristics and history in which the same indirect inspection tools are used • Segment– A portion of pipeline assessed using ECDA. Consists of one or more regions. • HCA– High Consequence Area (higher population density, limited mobility, gathering places, etc.)

  8. General Notes • There is some flexibility to chose suitable processes • Continuous Improvement Process • Compare successive applications to gauge effectiveness • Primary Purpose – Preventing future problems • RP0502 is for onshore, buried, ferrous pipelines • Stand-alone or compliment other tests (ILI, hydro) • Has limitations (like all asses’mts), use appropriately • Use under the direction of ‘competent persons’

  9. Step 1 – Pre-Assessment • Determine if ECDA is feasible and applicable • Collect ‘Soft’ Data (both current & historic) • Construction, Operating, Maintenance, CP survey, Adjacent Land Use (and changes to), and more • This is a big part – spend the time planning • Define Regions • Especially HCA • Select Indirect Tools appropriate for those regions

  10. Include each of these Data Elements • Pipe-Related • mat’l, diam.,thickness, year, seam type, coating • Construction Related • year, route, aerial photos, construction practices, valves, depth of cover, more • Soils/Environmental • soil, drainage, topography, use, frozen, wet • Corrosion Control • CP system, location, stray current, history, evaluation, coating • Operational Data • temperature, stress, fluctuations, excavations, accidents

  11. Decide which tools are applicable • Close-Interval Survey (CIS) • AC Voltage Gradient • DC Voltage Gradient • Pearson • Electromagnetic • AC Current Attenuation Surveys • Stray Current analysis • Different regions may require different tools

  12. Step 2 – Indirect Inspections • Identify and Define the severity of coating faults, other anomalies, and areas where corrosion may be • Requires at least two aboveground tools over the entire length of region • Then align & compare the data • More than 2 may be required

  13. Gathering Indirect Data • Quite expensive • Do it right the first time • Plan for traffic, access, problems, surveying • Conduct & Analyze with accp’d Industry Practices • Reading spacing must be suitably fine • Different tool (passes) done close in time as well • Precise Geographic References (GPS)

  14. Compare Results • If indirect tool results vary greatly, reexamine (directly if need be) • Compare the results with Pre-Assessment

  15. Step 3 – Direct Examinations • Purpose: To determine which indirect indications are most severe and collect data to assess corrosion • Requires pipe surface exposure & testing • At least one dig is always required

  16. Steps Included • Prioritization of Indications • Excavations & Data Collection • Measurements of Coating Damage & Corrosion • Remaining Strength Calculations • Root Cause Analysis • Process Evaluation

  17. Prioritization (3) • Immediate Action Required • Ongoing corrosion likely • Multiple Severe Indications • Unresolved Discrepancies from Indirect Exams • Scheduled Action Required • Severe indications NOT in area of other severe • Suitable for Monitoring • Inactive or little likelihood of ongoing/prior corrosion

  18. Measurements Used in Direct Exams • Pipe-Soil potentials • Soil Resistivity • Water & Soil Samples (ph, etc.) • Under film liquid ph • Photographic Documentation • Other Integrity Data • MIC, SCC, etc..

  19. Coating Measurements • Type • Condition • Thickness • Adhesion • Degradation (blisters, disbondment, etc.) • Corrosion products • Mapping and photographic documentation

  20. Mitigation • Shall identify and undertake remediation • Aim to mitigate and preclude future problems • Assess Classification Criteria • Reclassification & Reprioritization

  21. Indications Encountered – 4 levels • In each segment…. • Immediate – dig all • Scheduled – dig most severe • If first use of ECDA, must dig 2 • Monitored – dig most severe • If first use of ECDA, must dig 2 • No Indication – one excavation is required • To validate Direct tests

  22. Step 4 – Post Assessment • Define re-assessment intervals • Assess overall effectiveness of ECDA program • Remaining life calculations • Feedback & Continuous Improvement

  23. ECDA Success Requires • Expertise, skill, and experience in understanding and implementing the standard • Detailed procedures for all steps • Document all decisions made in process • Assessment and integration and analysis of data during all steps of the DA process • Data Management • Understand what may limit DA effectiveness

  24. Cost • A properly done ECDA process will have very similar costs to ILI. • Don’t expect it to be an order of magnitude cheaper.

  25. Questions • ? • Thank You • Gord Parker, Radiodetection Canada • gord@radiodetection.cawww.radiodetection.ca

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