This work involves a close-interval potential (CIP) data survey on approximately 154Km of Crude Oil/Gas pipeline networks. The CIP was carried out at 5-meter intervals along pipeline right of way (ROW) with a microprocessor controlled data collector (data logger) and a Cu/CuSO4 reference half-cell.
The survey runs from Makaraba, Utonana, Abiteye, Dibi, Olero Creek, Opuekeba, and terminating at the Escravos Tank Farm of the western swamp facilities. This study therefore seeks to generate corrosion data with a view to determining weak sections of the pipelines/flowlines. The CIP survey is also aimed at ascertaining the effectiveness of the CP system and integrity of the Crude Oil/Gas pipeline networks. The CIP values obtained were used to evaluate changes in structure potentials with respect to the environment, location/severity/population of "hot spots" (corroding areas), and potential areas of coating disbondment, holidays, blistering, seam tenting, cracking and wrinkling and location of areas that are subject to stray current electrolysis. Using all the CIP accumulated data; a risk assessment is presented to determine the present integrity of the pipeline networks. The assessment reveals that the pipeline networks were safe for continued operation under its present condition. Further, it recommends a repair/replacement program for some segments of the pipeline in order to bring the system to an acceptable level of operational safety and product availability.
Key words: cathodic protection, close-interval potential, hot spots, risk assessment matrix