Corrosion Protection of Oil Storage Tank Roofs

摘要

Corrosion of crude oil storage tank roofs is a worldwide problem. The environmentaland application conditions of roof vapor spaces are unpredictable: high concentrationof acidic gases, relative humidity (RH) up to 100%, pH as low as 2 and largevariations in temperature. Pitting and crevice corrosion rates (CR) can be as high as5-10 mm/year. As a result, tanks could be taken out of operation for maintenance toreplace tank roofs as often as every 7-10 years. Stainless steel and aluminum roofsin most cases cannot be recommended for replacing carbon steel roofs as they willstill have problems with pitting and crevice corrosion. This paper will present theresults from eight years of field experience with a corrosion protection systemutilizing volatile corrosion inhibitors (VCI). The new system greatly reduced pitting,crevice and general corrosion rates. As such, this corrosion protection system cangreatly increase the service life of tank roofs more than threefold.