Pipeline Cathodic Protection (CIPS) and Coating Defect (DCVG) Surveys
Corrosion Control Engineering has skilled technicians at all our office locations that specialise in Direct Current Voltage Gradient (DCVG) and Close Interval Potential Surveys (CIPS).
As an essential part of corrosion control, the DCVG survey is the most accurate method available to size and locate pipe coating defects. If a coating is compromised then the pipeline can be at risk of corrosion. The technique is based on measuring the voltage gradients in the soil above a cathodically protected pipeline. Once the technician has recorded the DCVG measurements and GPS locations, the %IR values are calculated. Depending on the degree of magnitude of the %IR, a determination can be made if physical examination direct assessment and repair are necessary.
The Close Interval Potential Survey (CIPS) technique assesses the cathodic protection effectiveness over the entire length of the pipeline, not solely at the test points. Cathodically protected pipelines are equipped with permanent test points where cables are attached to the pipeline to measure the pipe-to-soil potential. This potential should be sufficiently cathodic to ensure adequate corrosion protection.
During the CIPS survey, the technician will obtain the direct current pipe-to-soil potentials at regular and consistent intervals to evaluate the CP potentials of the pipeline. To achieve accurate potentials, the technician establishes an electrical connection to the pipeline by means of a trailing copper wire connected to CP test point. The wire unwinds from a spool as the operator walks the length of the pipeline, and the pipeline potential is measured with a set of reference electrodes at ground level, positioned directly over the pipeline at frequent intervals. GPS and CP potential data is collected while traversing the pipeline to create accurate reference points to find true pipe-to-soil potential along the entire length.
Ask the Corrosion Specialists
Talk to Corrosion Control Engineering to find out more about pipeline CP surveys.