CIS is used to designate a potential survey performed on a buried or submerged metallic pipeline, in order to obtain valid DC structure-to-electrolyte potential measurements at a regular interval sufficiently small to permit a detailed assessment.

Types of CIS include data collection prior to application of cathodic protection (CP) (nativestate survey), as well as data collection with the CP systems in operation ("on" survey), with the CP current sources synchronously interrupted (interrupted or "on/off" survey), with asynchronous interruption of CP current (waveform analyzer survey), and with CP currents turned off for some time to allow the structure to depolarize (depolarized survey).

A hybrid survey is a CIS combined with other types of measurements such as side drains, lateral potentials, or cell-to-cell surface potential gradients along the pipeline.

This standard addresses hybrid survey techniques such as trailing-wire DCVG or intensive measurement surveys (CIS with side drains).

Surface potential gradient surveys are a series of surface potential gradients measured along or normal (perpendicular) to a pipeline.

This standard addresses DC cell-to-cell surface potential gradient surveys (e.g., hot-spot surveys, side-drain surveys) used to evaluate the direction of current in the earth and to identify possible anodic areas on a pipeline. AC-voltage gradient surveys (such as ACVG) and cell-to-cell surveys (such as traditional DCVG) used to evaluate the effectiveness of the coating are described in other NACE publications.

This standard includes procedures to perform these types of surveys along a buried or submerged pipeline. The standard acknowledges that all potential measurements contain error, and includes some guidance to minimize the error in each measurement. The standard does not address interpretation of survey data. A qualified person must determine whether the data contain an acceptable amount of error and can be used to evaluate the level of cathodic protection.

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