What Does
Close Interval Potential Surveys Mean?
Close Interval Potential Surveys (CIPS) is an above ground inspection method and is a part of a structured External Corrosion Direct Assessment (ECDA) process. CIPS is used to inspect metallic pipelines in order to determine the efficacy of their cathodic protection (CP) system. As per National Association of Corrosion Engineers (NACE) the specified standard for CP system operation is SP0169.
CIPS is performed in order to comply to state or federal regulations and also as a tool to carry out risk assessment.
Trenchlesspedia Explains Close Interval Potential Surveys
CIPS method of pipeline inspection can be used for both offshore and onshore buried pipelines. The method is called close interval because the pipe to soil potential is measured at close intervals. For onshore pipelines, the interval is 2 meters between measurements.
The actual CP current influences the CP current flowing when the pipe to soil potentials are being measured leading to an error in measurement known as IR error. To overcome this error during measurement, the impressed CP current to the pipeline is interrupted synchronously and the measurement is taken just after the current stops flowing but before the pipe depolarizes.
There are two types of CIPS namely, native potential and depolarized surveys which determine the level of CP required for a metallic structure, and on potential and interrupted potential survey, which determines whether corrosion is taking place, and if corrosion is observed, it determines the level of corrosion.