Identifying Locations Susceptible to Accelerated Corrosion Finding a Needle in a Haystack

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Identifying Locations Susceptible to Accelerated
CorrosionFinding a Needle in a Haystack

• Oliver Moghissi
• omoghissi_at_cctlabs.com
• CC Technologies

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Concept

• Pipeline corrosion well-managed but isolated
  problems plague the industry
• Without further action, exceptions expected to
  increase with further aging
• Most effective approach includes basic
  understanding of reason for local accelerated
  corrosion

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Concept Cont.

• Existing technology
• Generally effective
• Not sufficiently directed at the exceptions
• Find it and fix it approach short-sighted
• Broad and blind assessment
• Inefficient
• Ineffective (defects are missed)

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The Pipeline Corrosion Problem

• Corrosivity is low mitigation mostly effective
• Corrosion damage is not widespread
• Infrastructure asset is old but generally
  preserved
• Pipelines traverse great distances
• Environmental inhomogeneity
• Stochastic component
• Few isolated extreme value corrosion rates exist
• Threaten public safety
• Reduce reliability

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Corrosion Research for Exceptions

• Focus on the mechanism
• Need basic understanding of reason for local
  accelerated corrosion
• Emphasize pipeline focus
• Involve operators
• Minimize implementability risk
• Mine historical pipeline research
• Level of complexity irrelevant

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A Few Examples

• Cathodic Protection (CP)
• Internal Corrosion
• Coatings
• Stress Corrosion Cracking (SCC)
• Corrosion Growth Rates

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Cathodic Protection (CP)

• Factors with broad application are known (i.e.,
  mature technology)
• CP criteria in common environments
• CP System performance characteristics
• Maintenance impact more than safety/reliability
• Macroscopic current distribution

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CP Related Problems

• Factors affecting CP related failures
• Isolated current interference (AC or DC)
• Environmental inhomogeneity
• Coating Disbondment

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CP Related Needs

• Predicting locations of isolated corrosion
• ECDA
• Local physicochemical soil properties
• Behavior under disbonded coating
• Detection of shielding
• Interaction with external environment
• Environmental evolution and SCC
• Effect of shielding (electrical and chemical)
• AC effects and identification of interference

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Internal Corrosion

• Hydrocarbon product w/out water non-corrosive
• Corrosion mitigation applied to corrosive
  location 100 effective
• Internal corrosion technology borrowed from
  upstream
• High corrosivity
• Relatively uniform
• Intrusive corrosion monitoring tools

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Internal Corrosion Problem

• Local failures in non-corrosive systems (wet or
  dry)
• Adherence to product specifications
• Mitigation not delivered to location
• Monitoring tools at improper location

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Internal Corrosion Needs

• Predicting locations of isolated corrosion
• ICDA
• Factors for accelerated corrosion
• Isolated water accumulation
• Local chemistry
• Including under deposits or biofilm
• Non-intrusive monitoring

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Stress Corrosion Cracking

• Documented U.S. SCC failures are rare
• Crack ILI tools emerging
• Combination of factors
• Stress Defined but difficult to assess residual
  component
• Environment Poorly defined (except maybe high
  pH)
• Affected by coating
• Susceptible metallurgy Poorly defined
• Where are the susceptible locations?

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Protective Coatings

• Coatings are effective over most of the area
• Includes old coal tar
• Modern coatings do not fail in realistic
  simulated environments
• Testing performed on panels
• Accelerated tests use inappropriate parameters
• Local failures typically result from non-ideal
  coating application
• Improve application methods
• Improve tolerance of application errors
• Consider field repair coatings

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Corrosion Growth Rates

• Re-inspection intervals set by the exceptions
• Laboratory studies
• Field experience
• Inspections
• Failures (hydrotest and operating)
• Environment specific
• Non-normal distribution
• Accelerated testing distribution differs from
  practice
• Need prediction of extreme value growth rates in
  specific environment

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Summary

• Pipeline corrosion failures defined by relative
  rates over absolute rates
• Low corrosivity over long distances
• Wide corrosion distribution
• A needle in a haystack
• Focus research on exceptions
• Determine root cause
• Focus identification and mitigation on source of
  problem

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Conclusion The Haystack

• Broad, blind inspection is like picking up and
  examining each piece of hay to see if its a
  needle
• Focusing on characteristics of local accelerated
  corrosion mechanism is like
• Looking where you dropped it
• Following the thread