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PRCI PR-3-165
- Criteria to Stop Active Pit Growth
- Report / Survey by Pipeline Research Council International, 01/19/1987
- Publisher: PRCI
$125.00$249.00
L51544e
Battelle Memorial Institute
Need: The purpose of this research program was to determine the requirement to stop active pitting and compare that to the requirement to stop general corrosion and prevent pit initiation.
Benefit: This report examines the cathodic protection requirement to stop active pitting in buried natural gas transmission lines and compare it to the cathodic protection requirement to stop general corrosion and further prevent pit initiation. During the two-year period of this research program, two different pit geometries were examined: (1) a small diameter pit of 10 mils in diameter and approximately 10 mils deep which had less than five mils of active pit growth prior to cathodic polarization, and (2) large diameter pits of 1/2-inch in diameter which had approximately 50 mils of pit growth prior to cathodic polarization. Statistical analyses were used to determine whether pit growth continued during the cathodic polarization portion of the experiment or whether the active pit growth was stopped.
Result: This study showed that in some instances the potential requirement to prevent pit initiation is not sufficient to stop active pitting. There appear to be several important factors which influence the potential required to stop active pitting including pH, chloride content and rate of active pitting prior to cathodic polarization.
Battelle Memorial Institute
Need: The purpose of this research program was to determine the requirement to stop active pitting and compare that to the requirement to stop general corrosion and prevent pit initiation.
Benefit: This report examines the cathodic protection requirement to stop active pitting in buried natural gas transmission lines and compare it to the cathodic protection requirement to stop general corrosion and further prevent pit initiation. During the two-year period of this research program, two different pit geometries were examined: (1) a small diameter pit of 10 mils in diameter and approximately 10 mils deep which had less than five mils of active pit growth prior to cathodic polarization, and (2) large diameter pits of 1/2-inch in diameter which had approximately 50 mils of pit growth prior to cathodic polarization. Statistical analyses were used to determine whether pit growth continued during the cathodic polarization portion of the experiment or whether the active pit growth was stopped.
Result: This study showed that in some instances the potential requirement to prevent pit initiation is not sufficient to stop active pitting. There appear to be several important factors which influence the potential required to stop active pitting including pH, chloride content and rate of active pitting prior to cathodic polarization.
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