Corrosion Control and Monitoring

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Corrosion Control and Monitoring

• ABC Company
• ABC Chemical Complex
• Engineering Specification

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Corrosion Control Monitoring

• SCOPE
• This Engineering Specification includes external
  and internal corrosion control and monitoring for
  DOT regulated pipelines.
• Design, construction, construction inspection,
  construction acceptance, operation, and
  maintenance of DOT regulated pipelines are
  covered by this Engineering Specification.

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Corrosion Control Monitoring

• GENERAL
• All DOT regulated ABC pipelines require
  protection from the environment.
• Corrosive elements in the pipeline stream must be
  neutralized or the pipe material must be
  resistant to the stream.

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Corrosion Control Monitoring

• Minimum requirements for corrosion control
• External Corrosion Control
• Buried DOT regulated pipelines will be coated and
  cathodically protected
• Internal Corrosion Control
• Known corrosion rate based on historical data
• Corrosion rate from a national standard data base
• Data collected from laboratory prototype testing

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Corrosion Control Monitoring

• Minimum requirements for corrosion control
  (Continued)
• Above Ground External Corrosion Control
• Coat with an approved system with resistance to
  the soil and internal fluid temperature

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Corrosion Control Monitoring

• REFERENCES
• NACE RP 0169-92
• Surface Preparation
• NACE No. 1, SSPC-SP 5, White Metal Blast Cleaning
• NACE No. 2, SSPC-SP 10, Near White Metal Blast
• NACE No. 3, SSPC-SP6, Commercial Blast
• NACE No. 4, SSPC-SP 7, Brush-Off Blast

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Corrosion Control Monitoring

• PERSONNEL REQUIREMENTS
• Engineering design will be performed by a
  Corrosion Engineer with training and experience
  in the proposed corrosion control system.
• Coating, lining, and painting inspection will be
  performed by an inspector with appropriate
  training and experience.

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Corrosion Control Monitoring

• PERSONNEL REQUIREMENTS (Cont..)
• Cathodic protection installations will be
  inspected by an inspector with training and
  experience in cathodic protection inspection.
• Internal corrosion monitoring installations will
  be inspected by an inspector with training and
  experience in internal corrosion monitoring
  inspection.

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Corrosion Control Monitoring

• DESIGN REQUIREMENTS, EXTERNAL
• Cathodic Protection Criteria
• Buried Onshore Pipelines Pipe-to-soil potential
  equal to or more negative than -0.85 volts
  referenced to copper-copper sulfate electrode and
  recorded immediately after current interruption
  (Instant-off potential).
• Offshore Pipelines Pipe-to-water potential
  equal to or more negative than -0.80 volts
  referenced to a silver-silver chloride electrode
  with instant off potential reading.

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Corrosion Control Monitoring

• Tank Bottoms Steel-to-soil potential equal to
  or more negative than -0.85 volts with a
  copper-copper sulfate half cell and instant
  off potential.
• Maximum pipeline potential Equal to or less than
  -1.5 volts to a standard copper-copper sulfate
  half cell with the current temporarily
  interrupted.

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Corrosion Control Monitoring

• Coating Requirements
• New buried pipe sections shall be coated with one
  of the following types
• Fusion bonded epoxy
• Coal tar epoxy
• Polyolefin tape
• Prefabricated films
• Other coating systems approved by Central
  Engineering
• Surface preparation shall be in accordance with
  manufacturers recommendation and Appendix B.

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Corrosion Control Monitoring

• Methods Used for Cathodic Protection
• Galvanic Anode Systems
• Provide protection to the structure by the
  potential difference generated by the
  electrochemical reaction between the structure
  and the anode through a soil or water
  electrolyte.
• Typically used in soil or water with resistivity
  less than 5000 ohm-cm.

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Corrosion Control Monitoring

• Methods Used For Cathodic Protection (Cont)
• Impressed Current Systems
• Uses external source of DC power, usually an AC
  trans-former with an AC to DC rectifier, to
  provide the driving voltage to the structure to
  be protected.
• Potential difference between the anode and the
  structure creates current flow from the anode
  into the soil and onto the pipeline.
• Used when the soil resistivity exceeds 5000
  ohm-cm and/or more than 5 amperes of impressed
  current are required.

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Corrosion Control Monitoring

• Equipment
• Galvanic Anode Systems
• Anode Magnesium onshore, Galvalum III offshore.
• Junction box to connect leads from structure and
  anode.
• Impressed Current Systems
• DC transformer/rectifier (supplied as a unit).
• Anode(s) with inert or low reactivity
  characteristics.
• Terminal box with resistors to adjust current
  flow to each anode or anode string.

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Corrosion Control Monitoring

• Miscellaneous
• Install lightning arrestors.
• Provide electrical isolation Insulating flanges
  or spools.
• Minimize interference with bonding stations.
• Install test stations to measure potentials.
• Complete the following documentation
• Bonding and/or anode bed data sheet.
• Bonding station data sheet.
• Test station data sheet.

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Corrosion Control Monitoring

• Impact on Operating Equipment
• Apply NEMA electrical-class safety requirements
  to all equipment associated with impressed
  current installations.
• Install CP equipment in areas not requiring
  intrinsically safe design.
• Locate anode beds to minimize effect on other
  structures and to minimize mechanical damage from
  foreign construction.

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Corrosion Control Monitoring

• Perform interference testing on all equipment
  that may be damaged by the new CP installation.
  Testing shall include, but is not limited to, the
  following situations
• Pipelines crossing within 5 feet.
• Metal Structures within 5 feet of the pipeline.
• Metal Structures within 200 feet of the anode bed.

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Corrosion Control Monitoring

• Impact on Operating Equipment
• Design CP systems with capacity for current loss
  through interference bonds and future current
  loss due to coating deterioration.
• Minimize casing installations for protection of
  the carrier pipe. Perform interference testing
  as shown in Company Corrosion Control
  Monitoring Specification Appendix E. Provide
  bonding stations for each casing installation.

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Corrosion Control Monitoring

• DESIGN REQUIREMENTS, INTERNAL
• Corrosive chemicals in the pipeline stream
• May reduce stream (liquid or gas) quality or
• Cause general thinning or pitting attack
• Shall be handled by one of the following methods
• Neutralization or removal of the corrosive
  chemicals.
• Select a pipe material which is resistant.
• Coat the internal surfaces of the pipe.

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Corrosion Control Monitoring

• Design package will contain
• Provisions for upset/emergency conditions.
• Recommended corrosion monitoring program.
• Recommended corrosion monitoring equipment.
• Installation of personnel safety devices and
  platforms required for safe performance of
  duties.
• Pigging procedure when pigging facilities are
  included in the design package.
• Compliance with regulations of local, state, and
  federal jurisdiction for pigging procedures.

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Corrosion Control Monitoring

• Documentation Requirements
• Determine thickness measurement locations (TMLs)
  based on the most probable locations for
  corrosion or erosion-corrosion damage. Select
  TMLs with the assistance of the Corrosion
  Engineer.
• Collect baseline thickness readings on all new
  installations.
• Install corrosion monitoring equipment where the
  worst case corrosion attack is expected.
• Provide corrosion monitoring data sheets.

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Corrosion Control Monitoring

• DESIGN REQUIREMENTS, ABOVE GROUND EXTERNAL
• Coat with a coating system that is recom-mended
  for the environment.
• Prepare surface in accordance with
  external-coating-system manufacturers
  recommendations. See Company Corrosion Control
  Monitoring Specification Appendix B.

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Corrosion Control Monitoring

• INSTALLATION
• Quality Control, External Systems
• Coatings
• Qualified Inspector presence - 100.
• Field applied coating systems - 100 inspection.
• Shop applied coating systems - 100 inspection.
• Coating repairs - 100 inspection.
• Protect all stored coating materials at the
  construction site from weather, particularly
  directly sunlight and heat.

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Corrosion Control Monitoring

• Pad in the pipe trench
• Inspect just prior to laying the pipe in the
  trench.
• Remove all trash and construction debris.
• Cables
• Inspect upon receipt at job site to detect nicks
  and damage.
• 100 inspection at the mill with proper mill
  cert..
• Avoid damaging cable insulation during
  installation.
• Splice cables aboveground in terminal boxes.
• Use non-conductive conduits for cable
  installation.
• Make cathode cable connections aboveground, if
  possible.
• Repair buried connection in accordance with the
  original coating manufacturers recommendations.

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Corrosion Control Monitoring

• Transformer/Rectifier Systems
• Install by a qualified electrician.
• Test rectifier at maximum design load to assure
  the DC output meets the manufacturers
  specifications including the maximum AC ripple.
• Calculate rectifier efficiency and record on the
  rectifier data sheet.
• Verify the positive cable is attached to the
  anode bed and the negative cable is attached to
  the protected structure or pipe.

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Corrosion Control Monitoring

• Miscellaneous Considerations
• Inspect cables in terminal boxes to assure
  correct labels.
• Verify test stations, bonding stations, and
  associated hardware for cathodic protection
  service.
• Contact owners/operators of foreign pipelines to
  enable testing before and after new cathodic
  protection project commissioning.
• Record base readings on the new pipeline or
  structure prior to cathodic protection system
  energizing. Record potentials at all interference
  bonds and test stations.
• Energize system in small current increments and
  record potentials with each increase until
  protection is achieved.
• Check bonding stations for interference problems.
• File all commissioning data in the original
  equipment file.

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Corrosion Control Monitoring

• Quality Control Requirements, Internal Surface
• Inspect corrosion monitoring installations with
  the services of a qualified Corrosion Technician.
• Take baseline data prior to pipeline
  commissioning.
• Install lined pipelines per design.
• Repair lining of field joints as recommended.
• Install corrosion monitoring devices per design.
• Complete electrical installations with qualified
  electricians.
• Document commissioning information as a part of
  the original equipment file.

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Corrosion Control Monitoring

• Quality Control Requirements, Internal Surface
• Delay work initiation pending review of design
  package by coating inspector.
• Protect coating material from weather.
• Prepare surface for coating per manufacturers
  recommendation immediately before coating
  installation.
• Follow manufacturers recommendation for dew
  point and humidity.

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Corrosion Control Monitoring

• OPERATIONS
• Perform cathodic protection surveys annually in
  accordance with Company CP procedure.
• Monitor bonding and test stations annually.
• Read and record rectifier output monthly with
  changes reported to the SR. Inspector for
  evaluation and action.
• Correct deficiencies in a timely manner.

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Corrosion Control Monitoring

• MAINTENANCE
• Test rectifier stacks for proper performance
  annually.
• Check anode bed resistance annually.
• Check insulating flanges and spools annually.
• Document all maintenance tests and add to the
  equipment file.

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Corrosion Control MonitoringAppendices

• A - Coating Reference Index
• B - Surface Preparation
• C - Sample Data Sheets
• Rectifier Data Sheet
• Anode Bed Data Sheet
• Galvanic Anode Data Sheet
• Potential Survey Data Sheet
• Predesign Testing