Corrosion protection of tank product side bottoms

Corrosion of storage tank product side bottoms and tanks of tankers is one of the most critical problems worldwide in oil and gas industry. The protection methods currently in use include cathodic protection systems (CPS) and soluble corrosion inhibitors (SCI). Crude oils contain water and various soluble inorganic and organic compounds. During the storage and transportation of crude oil, the sediment aqueous solutions (SAS) contains high concentrations of H2S, Cl-, SO42-, etc. The corrosion rates of storage tanks and tanks of tanker bottoms can vary from 0.05 to 3.0 mm per year. The service life of tank bottoms is unpredictable and can range from 2 to 20 years. In many cases, traditional corrosion protection systems (cathodic protection, coatings, and inhibitors) are not efficient enough, have short service life, or cannot be applied. This paper describes a new multistage corrosion protection system that combines different types of soluble corrosion inhibitors and cathodic protection systems. Together they achieve synergistic effects that can decrease the inhibitor protection concentration 3- to 6-fold and the current density 2-to 5-fold. This results in an increased service life of the corrosion protection method.