Typical FRP composites have a high chemical resistance and ease of construction, they have been widely used in chemical plants for applications such as chemical storage tanks. Accidental failures of a chemical tank roof were reported after the tank had been in service less than its expected lifetime. Therefore, comprehensive study of a composite material’s durability over a wide range of temperatures is proposed in this research. By using cyclic temperature of a solution condition, specimen is exposed into a chemical and the temperature is changed, a specimen in a liquid phase may change temperature along with the liquid; however, when a specimen is immersed in a vapor phase, the specimen may not change temperature with the vapor causing temperature difference and dew condensation inside of the material. After conducting bending tests of specimens at various immersion times under cyclic temperature of H2SO4 solution (nonvolatile acid), the strength of specimen in the vapor phase of H2SO4 showed a little bit lower than the specimen in the liquid phase, which contrasts with the results of specimen under isothermal condition that material strength in the liquid showed more damaged than in the vapor. Moreover, the H2SO4 concentration in the vapor is relatively low and the strength is in good agreement with the previous study using pure water under cyclic temperature of solution condition. This evident indicate the impact of the dew condensation on the strength which take place during temperature change. The cross-section of the specimen immersed in the vapor phase under cyclic solution temperature was chosen at the location, where microvoids are found. In general, cracks can easily initiate from microvoids that significantly affect the strength of the specimen. This experimental study is aimed to explain the mechanism of the roof failure and make a recommendation for the new design of FRP chemical tank.
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