DIAGNOSIS, NUMERICAL MODELING AND DEVELOPMENT OF THE CATHODIC PROTECTION REFURBISHING OF THE METAL SHEET PILING OF THE DOCKS OF QUETZAL MARINE TERMINAL IN GUATEMALA

摘要

This paper reports the refurbishing of the 1200 A cathodic protection (CP) system on a 2-mile (3200 m) long, 100-foot (30.48 m) deep steel sheet piling wall after 30 years service. Included are the diagnosis of the sheet piling by underwater ultrasonic measurements; the analysis of the performance of the mixed metal oxides (MMO) anode array along the docks; and the effects of cable defects that exposed the copper sheathing to aggressive environments on the anodic side of the circuit and rapid deterioration. The paper also reports the performance of the high current rectifiers; the replacement of the MMO anodes; the redesign of the anode mountings; and, the wiring details of the anode connector cables and rectifier modifications. The paper includes results of the tests of the CP current distribution in the wiring as well as the return current from the protected structure to the rectifier. The status of the CP system performance after the refurbishing is presented. The work included developing a numerical model of the CP system as designed. The limitations of the original design are discussed in view of all the metallic structures involved, other than the steel sheet pilings, serving in environments other than the main dock sea front.