Cathodic protection surveys are an integral part of maintaining safe pipeline operation. Such surveys are mandated by law in many countries of the world. One of the standard mearts of testing cathodic protection system operation and pipeline protection levels, is the annual or bi-annual test point survey. These tests normally provide potential data on less than 0.5% of the pipeline. Computerized dataloggers forcatiodic protection system monitoring enabled the development of the close interval survey (C.I.S.) into a viable means of assessing the effectiveness of cathodic protection systems along the full length of both coated and bare pipelines. An accurate C.I.S. will provide an in-depth knowledge of the line and the information required to maintain the pipeline integrity. Project planning, cooperation of the client and contractor, a high level oftechnical expefiise, fieldcrafi anddedicated equipment merequired to benefit from this type of survey. The C.I.S. will generate very large volumes of data, and it is essential that this data be technically correct and its management and reporting efficient.
KEYWORDS: cathodic protection, close interval potential survey, test station survey, rectifier sphere of influence, potential
spiking, current interrupters, stationary datalogger, potential survey graphs.