STEEL FOR CRUDE OIL TANK CEILING HAVING EXCELLENT CORROSION RESISTANCE, CRUDE OIL TANK AND UPPER DECK OF CRUDE OIL TANKER

摘要

PPROBLEM TO BE SOLVED: To provide a steel for a crude oil tank ceiling having excellent corrosion resistance in which the reduction of the generation amount of corrosion can be reduced, and further, the dropping-off of generated sludge is suppressed as well, to provide a crude oil tank, and to provide the upper deck of a crude oil tanker. PSOLUTION: The steel for a crude oil tank ceiling has a composition including, by mass, 0.01 to 0.30% C, 0.01 to 2.0% Si, 0.01 to 2.0% Mn, 0.005 to 0.10% Al, 0.010% (not including 0%) S, 0.05 to 0.5% Cu, 0.05 to 0.5% Ni, 0.005 to 0.20% Ti, 0.01 to 5.0% Cr and 0.0005 to 0.20% Ca, and the balance Fe with inevitable impurities, which satisfies the requirement of ([Cu]+[Ni])/[S]=100 to 800, and further, a coating layer which has a surface roughness of 20 to 60 m by ten point average roughness Rz, and consists essentially of zinc is formed on the surface. PCOPYRIGHT: (C)2010,JPO&INPIT