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E xternal C orrosion D irect A ssessment NACE 2005 Northern Area Western Conference by Gord Parker, C.E.T. Radiodetection Ltd.

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Presentation on theme: "E xternal C orrosion D irect A ssessment NACE 2005 Northern Area Western Conference by Gord Parker, C.E.T. Radiodetection Ltd."— Presentation transcript:

1 E xternal C orrosion D irect A 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. RP O502 – 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


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