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Corrosion Control A PHMSA Perspective

Corrosion Control A PHMSA Perspective . Pipeline Safety Trust Conference New Orleans, LA November 17, 2011. Joe Mataich CATS Program Manager PHMSA, Southern Region. Definition of Corrosion.

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Corrosion Control A PHMSA Perspective

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  1. Corrosion ControlA PHMSA Perspective Pipeline Safety Trust Conference New Orleans, LA November 17, 2011 Joe Mataich CATS Program Manager PHMSA, Southern Region

  2. Definition of Corrosion The Deterioration of a Material, Usually a Metal, that Results from a Reaction with its Environment. Galvanic Corrosion of a Metal Occurs because of an Electrical Contact with a More Noble (Positive) Metal or Non-metallic Conductor in a Corrosive Electrolyte.

  3. Fe Fe Fe Basic Corrosion Cell Metallic Path Ionic Path

  4. Anodic Area PipelineCorrosion Metallic Path Cathodic Area

  5. Anode Cathodic Protection Cathode

  6. Galvanic Anode CP SystemRelies on potential difference between steel and anode (Mg, Zn, Al)

  7. Impressed Current Cathodic ProtectionHas DC power source (rectifier)

  8. Pipe-to-Soil Potential Measurement Used to evaluate adequacy of Cathodic Protection Voltmeter underground pipeline -975 Reference electrode (Cu/CuSO4)

  9. Cathodic Protection Criteria • §192.463 Requires Cathodic Protection to a Level that Complies with Appendix D of Part 192 • §195.571 Requires Cathodic Protection to a Level that Complies with section 6.2 and 6.3 of NACE SP0169-2007

  10. Cathodic Protection Criteria • - 850 mV • 100 mV Polarization • Negative 300 mV Shift • Net Protective Current • E log I * Gas and Liquid* Gas Only

  11. Regulatory Inspections • All PHMSA and State Inspectors are trained • PHMSA T&Q Corrosion Course in OKC • Corrosion Control Requirements are checked during inspections • Records • Field Inspections

  12. Cathodic Protection Monitoring Regulatory Requirements • Pipe-to-Soil Potentials measured once per calendar year, not to exceed 15 months • Rectifiers checked six times per calendar year, not to exceed 2.5 months

  13. What can go Wrong? • Pipe-to-Soil Potentials/Rectifier tests • Measurement error • Improperly calibrated measurement equipment • Broken or defective test leads • How PHMSA addresses these • Both are OQ Covered Tasks • PHMSA/State Inspectors trained to identify deficiencies • Potentials and Rectifiers are checked during PHMSA/State field inspections

  14. Shielding of CP CurrentCurrent is blocked by disbonded coating, rocks etc.Addressed in HCA’s through Integrity Management

  15. Interference CurrentsDC currents from foreign rectifier, transit systems etc.Addressed by regulatory requirements for interference mitigation program

  16. Questions?

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