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Ph Measurement During Cathodic Protection And DC Interference

Product Number: 51321-16766-SG
Author: Mehdi Attarchi; Andrea Brenna; Marco Ormellese
Publication Date: 2021
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The increase of pH at the cathode-to-electrolyte interface is a recognized chemical effect due to cathodic protection. The alkalinity formed in cathodic protection could also reduce the corrosive effect of DC non-stationary anodic interference. In the present study, pH variations during cathodic protection and DC non-stationary anodic interference are recorded using a new arrangement of the sample-pH probe and a sufficiently fast pH logger. The test was carried out on low carbon steel immersed in simulated soil solution. As expected, the pH increases during the application of cathodic protection. In the DC interference cycle, which is 60 peaks per day with a duration of one minute, the pH at the mentioned distance gradually reduces. If the protection time between two peaks was long enough, around 10 minutes in the studied case, the pH could return to the previous value. If the protection time between two peaks is short, such as one minute, even anodic interference current equal to the protection current could destroy the high pH layer at the surface after 60 one-minute interference peaks.

The increase of pH at the cathode-to-electrolyte interface is a recognized chemical effect due to cathodic protection. The alkalinity formed in cathodic protection could also reduce the corrosive effect of DC non-stationary anodic interference. In the present study, pH variations during cathodic protection and DC non-stationary anodic interference are recorded using a new arrangement of the sample-pH probe and a sufficiently fast pH logger. The test was carried out on low carbon steel immersed in simulated soil solution. As expected, the pH increases during the application of cathodic protection. In the DC interference cycle, which is 60 peaks per day with a duration of one minute, the pH at the mentioned distance gradually reduces. If the protection time between two peaks was long enough, around 10 minutes in the studied case, the pH could return to the previous value. If the protection time between two peaks is short, such as one minute, even anodic interference current equal to the protection current could destroy the high pH layer at the surface after 60 one-minute interference peaks.

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