U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Corrosion Control A PHMSA Perspective Pipeline Safety Trust Conference New Orleans, LA November 17, 2011 Joe Mataich CATS Program Manager PHMSA, Southern Region

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 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

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Basic Corrosion Cell Fe Metallic Path Ionic Path - 3 -

4

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Pipeline Corrosion Anodic Area Cathodic Area Metallic Path - 5 -

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Cathodic Protection Anode Cathode - 6 -

Galvanic Anode CP System Relies on potential difference between steel and anode (Mg, Zn, Al) - 7 -

8 Impressed Current Cathodic Protection Has DC power source (rectifier)

-975 Reference electrode (Cu/CuSO 4 ) Voltmeter Pipe-to-Soil Potential Measurement Used to evaluate adequacy of Cathodic Protection - 9 -

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Cathodic Protection Criteria § Requires Cathodic Protection to a Level that Complies with Appendix D of Part 192 § Requires Cathodic Protection to a Level that Complies with section 6.2 and 6.3 of NACE SP

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Cathodic Protection Criteria mV 100 mV Polarization Negative 300 mV Shift Net Protective Current E log I * Gas and Liquid* Gas Only

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 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

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 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

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 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

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

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

U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Questions?