Steel material for crude oil tank with excellent corrosion resistance, and crude oil tank

Abstract

This steel material has a component composition comprising, in mass%, C: 0.03-0.18%, Si: 0.03-1.50%, Mn: 0.1-2.0%, P: 0.025% or less, S: 0.010% or less, Al: 0.015-0.049%, N: 0.008% or less, W: 0.005-0.5%, and Nd: 0.0001-0.010%, with the remainder being Fe and unavoidable impurities, wherein the dislocation density alpha of the steel material is set to within a range that satisfies formula (1), thereby obtaining a steel material for a crude oil tank that has excellent general corrosion resistance in the upper plate of a crude oil tank such as a tanker oil tank unit and that also has excellent local corrosion resistance in the bottom plate of the crude oil tank. Formula (1): alpha(/m2)<={1020*[%W]*[%Nd]}/{5*([%Al]-0.01)}, where [%M] is the content (mass%) of an element M in the steel material.

Description

technical field [0001] The present invention relates to an oil tank of a crude oil tanker formed by welding steel materials, and a tank for transporting or storing crude oil (hereinafter collectively referred to as "crude tank"). Steel materials for crude oil tanks that can prevent full surface corrosion at the bottom of the crude oil tank and localized corrosion at the bottom of the crude oil tank, and crude oil tanks made of the steel. [0002] It should be noted that the steel material for crude oil tanks of the present invention includes thick steel plates, thin steel plates and section steels. Background technique [0003] It is known that steel materials used on the inner surface of crude oil tanks of oil tankers, especially the back of the upper deck and the upper part of the side walls, are corroded over the entire surface. The following reasons etc. are mentioned as a cause which causes this whole surface corrosion. [0004] (1) Repeated occurrences of dew condens...

AI Technical Summary

Problems solved by technology

However, the coating work of crude oil tanks not only requires a large coating area, but also requires recoating every 10 years due to the deterioration of the coating film. Therefore, huge costs are incurred in inspection and coating.

Furthermore, it is pointed out that the damaged part of the repainted coating film will actually promote corrosion in the corrosive environment of crude oil tanks

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