Consideration of damages of a floating roof-type oil storage tank due to thermal stress

Several cracks were found on some actual floating roofs of the crude oil tanks in a southern Japan refinery. It was assumed that one of the causes is due to thermal stress during the day. In order to figure out whether the thermal stress could cause damage on the floating roof, strain and temperature were measured on the actual floating roof by using optical fiber gauges. Furthermore, thermal stress analysis and fracture possibility estimation were also carried out as additional analysis. As a result, thermal stress on the floating roof turned to be relatively small and could not cause the initial crack. However, the temperature fluctuation in a day could affect the crack propagation.