Abstract
In oil storage tanks, corrosion rate of the steel plate in the bottom part gives important information to the safety management. The rate of corrosion is defined to be an amount of decrease of thickness divided by the service year. However most of the tanks rarely have the data on thickness of initial state to estimate the thickness decrease and usually nominal thickness of plate is used instead of it. The discrepancy between the nominal thickness and the actual thickness is often found to be significant.
In this report, a method is proposed to estimate the mean value and the standard deviation of a normal distribution to which the initial thickness is subjected using the data measured at the time of periodic inspection.
