Cathodic Protection of Process Vessels

Abstract Gas & Oil Separation Plants (GOSPs) have oil trains designed to process wet crude oil and associated gas for separation into dry and stabilized crude oil, high-pressure gas, low-pressure gas & disposal water. GOSPs employ several process vessels in each train for this separation. Each train consists of high-pressure production trap (HPPT), low-pressure production trap (LPPT), Water Oil Separator (WOSEP), a dehydrator, desalter vessels, and a crude stabilizer. Corrosion control and management is essential for these vessel internals to support operation. Cathodic protection (CP) by galvanic anodes plays a crucial role in ensuring that these vessels remain protected from corrosion during their life. Aluminum anodes, zinc anodes and high temperature zinc anodes are used for CP. Specially designed Anode Monitoring Systems (AMS) are used for monitoring of the CP system performance including the anode consumption. Accelerated anode consumption, failure of electrical isolation between stainless steel (SS) & carbon steel (CS), SS vessel internals draining CP current, corrosion of the carbon steel, are some of the challenges in managing corrosion of these vessel internals. This paper presents approaches followed, including design practices, monitoring, field issues and associated remedial actions. In addition, it will show how the data from the field is used to estimate the CP system status and life of anodes to manage corrosion of Saudi Aramco’s process vessel internals.