How can stray currents on a pipeline be detected and mitigated?

• A. Rely solely on visual inspection of the pipeline.
• B. Use DC current and voltage measurements, install insulating joints, and ensure proper CP adjustment.
• C. Create a higher external magnetic field to divert currents.
• D. Install all-metal coatings to block currents.

Answer: (B)

Stray currents are DC currents from external sources that can travel onto buried pipelines and cause corrosion where the current exits into the soil. Detecting them relies on measuring the actual DC current flowing in the pipe and surveying the pipe-to-soil potentials with reference electrodes along the line. Abnormal or shifting potentials and measurable current indicate stray-current activity that needs attention.

Mitigation focuses on interrupting the current path and stabilizing the pipeline’s potential. Installing insulating joints between sections of the pipeline stops current from moving from one metal section to another, breaking the pathways stray currents use. At the same time, properly adjusting the cathodic protection system ensures the pipe is sufficiently protected and that the voltage turns the metal surface into a cathode rather than a site for anodic corrosion. Together, detection and these two mitigation steps effectively control stray currents. Other approaches, like altering magnetic fields or using generic all-metal coatings, don’t address the actual current flow or provide reliable reduction of stray-current corrosion.