In 2004 Sumitomo Metal Industries Ltd (Sumitomo Metals) developed SMICORE (SMI Crude Oil Corrosion Resistant Steel), a steel plate with enhanced corrosion resistance for the upper decks and bottoms of crude oil tanks in oil tankers, which are exposed to severe corrosive conditions. SMICORE was applied on a trial basis in “Sanko Blossom”, a crude oil tanker that went into commission in August 2005. At the time of the ship’s first dry dock inspection, after a period of two years and nine months from when the trial ship went into commission, Sumitomo Metals conducted corrosion research on the parts to which SMICORE had been applied, based on the cooperation of Sumitomo Heavy Industries Marine & Engineering and The Sanko Steamship Co. As a result, it was confirmed that the amount of reduction in the thickness of the upper deck plates was up to around 60% less than in the case of conventional steel. Whereas pitting corrosion with a depth exceeding 2mm occurred in conventional steel plates, there was no pitting corrosion with a depth of more than 2mm in the case of SMICORE. The depth of pitting corrosion in SMICORE steel plates decreased by around one-fourth compared to conventional steel in the no. 2 tank and up to around 60% compared to conventional steel in the no. 3 tank. Moreover, based on the pitting corrosion thickness of the parts studied on this occasion, when Sumitomo Metals estimated the maximum pitting corrosion depth for all tanks by means of statistical processing, it was found that the maximum pitting corrosion depth for SMICORE would be about 40% that of conventional steel.
