ABSTRACT

The large reinforced concrete seawater intake structures, which are part of a cooling system in several petrochemical plants located in the Arabian Gulf, have been catholically protected to arrest chloride-induced corrosion of the steel reinforcement. The cathodic protection systems have an operating history of 1-5 years. The design and operating features of the cathodic protection systems are described and discussed. Monitoring data of each system collected over the years since commissioning of the systems are described and discussed to evaluate performance of each system.

INTRODUCTION

Saudi Basic Industries Corporations (SABIC) is one of Saudi Arabia?s leading industrial conglomerates. It produces more than 20 million metric tons of chemicals, steel products, etc. and operates 15 world scale plants in the industrial cities of Jubail and Yanbu. The infrastructure in the city of Jubail has been designed and constructed by the Royal Commission to meet the needs of the industries. Special attention was paid in providing utilities to the industries. Cooling water is provided by a network of open canals carrying seawater to and from the Gulf. Fifteen complexes draw cooling water from this system. Large and massive reinforced concrete intake structures and reservoirs are constructed in each of the complexes. Majority of the plants came on-stream in the early 1980s. Several of the sea water structures started showing signs of distress due to chloride induced corrosion, which manifested as cracking and spalling of concrete. Since the structures are critical for the operation of the plants it was decided to rehabilitate some of the structures in distress and install cathodic protection (CP) systems to control chloride-induced corrosion of the steel reinforcement. This paper describes the design and operating features of the CP systems of three seawater intake concrete structures and evaluates their performance. A typical plan and elevations of the structures are shown in Figure 1.

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