What Does
Close Interval Survey (CIS) Mean?
A close interval survey is a measurement tool used to examine cathodic protection systems attached to pipelines to ensure adherence to inspection codes and standards. The survey is complete by obtaining voltage measurements at fixed time intervals and pipeline length in reference to an existing grounded electrode.
Corrosionpedia Explains Close Interval Survey (CIS)
Close interval surveys are performed on underground pipelines. There are three types of close interval surveys: on/off, depolarized and on surveys.