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 CIS Case HistoryNACE Eastern Area Conference

• Jeffrey L. DidasColonial Pipeline Company2607
  Willard RoadRichmond, VA 23294-3639804-672-2718

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INTRODUCTION

• Close - Interval Potential Surveys (CIS or CIPS)
  are performed for many reasons. The primary
  purpose of a CIS is to ensure that a pipeline is
  cathodically protected in its entirety.
• CIS is also used as a method to verify pipeline
  integrity, evaluate coating condition and follow
  up on areas after pipeline rehabilitation.

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CIS GENERAL DISCUSSION

• Close - Interval Potential Surveys have been
  utilized for decades. In the early years it
  involved hand reels or multiple hand reels of
  wire stretched out between test points and bulky
  analog meters which remained stationary at the
  test points, with a moving reference electrode(s)
  traveling along and over the pipeline.

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CIS GENERAL DISCUSSION

• Todays data loggers and wire dispensers provide
  a light weight, accurate and fairly simple
  method of recording, analyzing and displaying CIS
  data.

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CIS GENERAL DISCUSSION

• Motorized or power reels with several miles of
  survey wire supplemented the hand reels and
  improved the process, which still used a
  stationary analog meter and moving the
  electrodes. During the 1970s digital meters,
  data logging hardware, small diameter survey wire
  and wire dispensers evolved into an over the line
  surveyor having all the survey equipment with the
  surveyor.

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CIS GENERAL DISCUSSION

• Todays data loggers and wire dispensers provide
  a light weight, accurate and fairly simple
  method of recording, analyzing and displaying CIS
  data.
• With todays computer technology and what is
  known about the technology, the survey interval
  has become fairly standard at 1 m (2.5 feet).

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CIS ISSUES GENERAL DISCUSSION

• CIS specification one is required whether for
  internal or external use.
• CIS contractor or in house personnel proper
  training, experience and OQs are required.
• CIS data quality and availability data must be
  per the specification, be usable and repeatable
  and available in a timely manner upon completion
  of the CIS.

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CIS ISSUES - GENERAL DISCUSSION

• Pipeline operators have implemented Integrity
  Management Plans (IMPs) which gives them a
  long term plan to use for evaluating the
  pipelines integrity and implementing a
  rehabilitation plan
• These evaluations use a combination of internal
  inspections using ILI, external inspections using
  CIS and DCVG, then wrapping all these programs
  together using External Corrosion Direct
  Assessment (ECDA), Internal Corrosion Direct
  Assessment (ICDA) and Stress Corrosion Direct
  Assessment (SCCDA).

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CIS ISSUES and ANSWERS - GENERAL DISCUSSION

• When ILI is not practical for the IMP, CIS
  becomes extremely valuable as the primary
  component for performing the evaluations.
• The CIS will determine the areas not meeting a
  cathodic protection (CP) criterion.
• The areas not meeting these criteria will be
  further evaluated using an above ground coating
  evaluation survey and normally a depolarized
  potential survey.

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CIS GPS Survey In Progress

• Typical Cross Country Pipeline ROW

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CIS GPS Survey In Progress

• Wheres the pipe? They appear to be lost in the
  field.

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CIS Technical Issues

• Locating Pipeline
• Interrupter Accuracy and Quality
• Interruption Cycle
• Reference Electrode Calibration
• Crew Quality
• ROW Conditions
• Level of CP and Coating Quality

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Typical CIS Data Plot
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Data Issues

• Repeatability of Data
• Ability to locate Deficiencies GPS Accuracy
• Data integration into database

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CIS DATA ANALYSIS

• The results of the coating evaluation testing
  will drive the rehabilitation program and allow
  selection of the rehabilitation method
• Which method or combination of methods is
  determined by the corrosion engineer analyzing
  all the data, performing current require testing,
  performing coating conductance and / or quality
  surveys, running design calculations for CP
  systems and determining the most cost effective
  methods.

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CIS Case History

• 32 Products Pipeline
• Installed 1961
• Asphalt Enamel Coating
• Recently had a CP Upgrade Performed
• ILI has had Multiple Runs no corrosion issues
• ON/OFF survey with GPS and depth of cover survey
  was run
• Areas not meeting -850 ON were addressed

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Results

• 30 anomaly locations were selected for recoat
• 45 anomaly locations were selected for new CP or
  upgrading existing CP
• 100 compliance was achieved after rehabilitation
  was completed and follow up survey run

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Location Selected for Recoating
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Area Being Excavated
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Problem Area Identified and Coating Being Removed
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Entire Area That was Examined
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Area Kept Growing
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Some Coating was Actually Sticking to the Pipe
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Found a Problem at the Area of Investigation
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Problem Remediated
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Abrasive Blasting in Progress
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Recoating in Progress
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Coating Inspection
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Coating Inspection
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Recoating Complete
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Follow Up Survey in Progress
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Summary and Conclusions

• Close Interval Potential Survey is a proven tool
  to use to evaluate pipelines to ensure it is
  cathodically protected or to locate areas that
  are not protected.
• Using CIS to determine areas of your pipeline
  that require coating rehabilitation does work and
  works very well.

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Summary and Conclusions

• CIS data alone should not be used in locating
  areas that require coating rehabilitation, but a
  combination of CIS data, ILI data (when
  available), above ground coating surveys and
  competent corrosion engineering analysis of the
  entire rehabilitation project is required.