Transcript Joe Mataich, Southern Region CATS Manager, PHMSA

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.
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U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
Basic Corrosion Cell
Metallic Path
Fe
Fe
Fe
Ionic Path
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U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
Pipeline Corrosion
Metallic Path
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U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
Cathodic Protection
Anode
Cathode
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Galvanic Anode CP System
Relies on potential difference between steel and anode
(Mg, Zn, Al)
Impressed Current Cathodic Protection
Has DC power source (rectifier)
Pipe-to-Soil Potential Measurement
Used to evaluate adequacy of Cathodic Protection
Voltmeter
-975
Reference electrode
(Cu/CuSO4)
U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
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
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U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
Cathodic Protection Criteria
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•
•
•
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- 850 mV
100 mV Polarization
Negative 300 mV Shift
Net Protective Current
E log I
* Gas and Liquid * Gas Only
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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
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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
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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
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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?
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