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

E xternalC orrosionD irectA ssessment

NACE 2005 Northern Area Western Conferenceby

Gord Parker, C.E.T.Radiodetection Ltd.

Background

(USA) The Pipeline Safety Improvement Act of 2002signed into law on December 17, 2002applies to natural gas transmission (dist. coming)must identify "high consequence areas (HCA)"

conduct risk analyses of these areasperform baseline integrity assessments of each pipeline segmentinspect the entire pipeline system according to a prescribed schedule and using prescribed methods

Other provisions of the law include

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

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.”

Direct Assessment came alongIt 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

ECDA is a 4 Step ProcessPre-assessment

Most important stepIndirect Inspections

Above-ground ToolsDirect Examinations

Verification Digs AND MitigationPost-assessment

Define Reassessment Period (US: 7 yr typ. max)Assess Overall Effectiveness

Important DefinitionsECDA 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.)

General NotesThere is some flexibility to chose suitable processesContinuous Improvement Process

Compare successive applications to gauge effectiveness

Primary Purpose – Preventing future problemsRP0502 is for onshore, buried, ferrous pipelinesStand-alone or compliment other tests (ILI, hydro)Has limitations (like all asses’mts), use appropriatelyUse under the direction of ‘competent persons’

Step 1 – Pre-AssessmentDetermine 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

Include each of these Data ElementsPipe-Related

mat’l, diam.,thickness, year, seam type, coatingConstruction Related

year, route, aerial photos, construction practices, valves, depth of cover, more

Soils/Environmentalsoil, drainage, topography, use, frozen, wet

Corrosion ControlCP system, location, stray current, history, evaluation, coating

Operational Datatemperature, stress, fluctuations, excavations, accidents

Decide which tools are applicableClose-Interval Survey (CIS)AC Voltage GradientDC Voltage GradientPearsonElectromagneticAC Current Attenuation Surveys

Stray Current analysisDifferent regions may require different tools

Step 2 – Indirect InspectionsIdentify and Define the severity of coating faults, other anomalies, and areas where corrosion may beRequires at least two aboveground tools over the entire length of region

Then align & compare the data

More than 2 may be required

Gathering Indirect DataQuite expensiveDo it right the first timePlan for traffic, access, problems, surveyingConduct & Analyze with accp’d Industry PracticesReading spacing must be suitably fineDifferent tool (passes) done close in time as wellPrecise Geographic References (GPS)

Compare ResultsIf indirect tool results vary greatly, reexamine (directly if need be)Compare the results with Pre-Assessment

Step 3 – Direct ExaminationsPurpose: To determine which indirect indications are most severe and collect data to assess corrosionRequires pipe surface exposure & testingAt least one dig is always required

Steps IncludedPrioritization of IndicationsExcavations & Data CollectionMeasurements of Coating Damage & CorrosionRemaining Strength CalculationsRoot Cause AnalysisProcess Evaluation

Prioritization (3)Immediate Action Required

Ongoing corrosion likelyMultiple Severe IndicationsUnresolved Discrepancies from Indirect Exams

Scheduled Action RequiredSevere indications NOT in area of other severe

Suitable for MonitoringInactive or little likelihood of ongoing/prior corrosion

Measurements Used in Direct ExamsPipe-Soil potentialsSoil ResistivityWater & Soil Samples (ph, etc.)Under film liquid phPhotographic DocumentationOther Integrity Data

MIC, SCC, etc..

Coating MeasurementsTypeConditionThicknessAdhesionDegradation (blisters, disbondment, etc.)Corrosion productsMapping and photographic documentation

Mitigation Shall identify and undertake remediation

Aim to mitigate and preclude future problems

Assess Classification CriteriaReclassification & Reprioritization

Indications Encountered – 4 levelsIn each segment….

Immediate – dig allScheduled – 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

Step 4 – Post AssessmentDefine re-assessment intervalsAssess overall effectiveness of ECDA programRemaining life calculationsFeedback & Continuous Improvement

ECDA Success RequiresExpertise, skill, and experience in understanding and implementing the standardDetailed procedures for all stepsDocument all decisions made in processAssessment and integration and analysis of data during all steps of the DA processData ManagementUnderstand what may limit DA effectiveness

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

Questions

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Thank YouGord Parker, Radiodetection [email protected] www.radiodetection.ca