Effectiveness of impressed current cathodic protection system on underground steel Engen refinery transfer lines system

Abstract

This study investigated to determine the effectiveness of impressed current cathodic protection (ICCP) on protecting Engen underground steel transfer lines from corrosion. These lines have a history of leaks aggravated by stray currents from a direct current (DC) traction system. The main challenge facing the organisation under study is to find a solution to this situation. Different types of field surveys and simulations were performed, such as pipe-to-electrolyte or soil “ON” spot potential, DC stray current, close interval potential (CIPS), direct current voltage gradient (DCVG), transformer rectifier unit (TRU) performance, soil resistivity, alternating current (AC) interference, anode ground bed (AGB) performance, instant OFF pipe-to-soil potential. Surveys were categorised into two groups. These were baseline and post-surveys. The main objective was to check the difference or deviation from previous results. Baseline surveys were done before upgrading the anode ground beds at Swamp, Checkers, and Travancore TRU locations. Post-surveys were performed after the upgrade of anode ground beds (AGB’s) on the above-mentioned locations to validate the reliability of the anode upgrades. Some of the cathodic protection (CP) polarisation criteria standards such as NACE 0169, TM0497, TM0102, RP0285, PDO-65-12, 0SAES-X-400, ADNOC, ISO 15589-1, API were used as a reference during the field survey and simulation data collection, data analysis, conclusions and recommendations. The underground pipelines that have aging coating will show and will demand a high cathodic protection current to comply with CP underground structure polarisation criteria. By performing CIPS, DCVG, DC stray current, anode ground bed performance and instant “OFF” pipe-to-soil polarisation surveys, it was possible to gauge the transfer lines’ coating status, anode ground bed status, defect locations and entry points of stray current. These surveys also contributed to making effective conclusions and recommendations for the organisation to have a safe, reliable Engen steel underground transfer lines system.