Biaxial Failure Envelope and Creep Testing of Fibre Reinforced Plastic Pipes in High Temperature Aqueous Environments

Abstract

Results are presented for a series of tests on filament wound glass fibre reinforced pipes which have been subject to prolonged exposure to high temperature water. Two materials systems in common use in offshore piping applications are tested: continuous fibre e-glass in a phenolic and an epoxy resin matrix, respectively. This is the first work on this type on water saturated GRP at very high temperatures up to 160 C. The results of water absorption tests on the two material systems at 95 C are presented. It is shown that saturated conditions can be achieved within seven days at this temperature. Creep modulus test results for the two material systems as a function of temperature up to 160 C are presented. The reduction in TG for the epoxy material in the saturated state is quantified and it is shown that the phenolic material is largely unaffected by water absorption. The results of biaxial tensile loading tests for the two material systems are presented in the form of failure envelopes at temperatures from 20to 160 C. The considerable weakening of the epoxy system, particularly under the matrix dominated loading conditions, is quantified and it is shown that the failure envelope for the phenolic system is largely unaffected by temperature. Finally, a comparison is made between the two materials as a function of loading condition and temperature as a design guide.