Effects of harsh weather and seawater on glass fiber reinforced epoxy composite

The lack of reliable engineering data on the durability of glass fiber reinforced Epoxy (GFRE) pipes when exposed to harsh Arabian Gulf outdoor environment has limited their wide use for saltwater and crude oil handling and transportation. This article explores the combined effect of natural and accelerated weathering and seawater on tensile properties of GFRE pipe materials. Saltwater filled pipes were exposed to outdoor environment in Dhahran, Saudi Arabia for periods ranging from 6 to 12 months. Ring-shaped tensile test specimens were also immersed in oxygenated saltwater at room temperature for time periods ranging from 300 to 10,000 h. The natural exposures resulted in gradual reduction of tensile strength and fracture strain with exposure time in saltwater filled pipes. The exposure to oxygenated saltwater immersion also showed detrimental effects after 300 h of exposure. Longer immersion periods did not result in further strength degradation. The stiffness of the GFRE pipe specimens remained more or less unaffected by exposure to seawater. Fractographic analysis of unexposed specimens showed a combination of Mode I and Mode II failure characterized by inclined hackles as well as fiber breakage. High outdoor temperature and moisture absorption decreased fiber-matrix interface strength and caused degradation at the fiber level resulting in lower ultimate strength, fracture strain, and stiffness of the GFRE.