This paper will discuss results from studies undertaken by IFREMER and EDF over the last ten years. The aim of these studies has been to examine the aging and long term behaviour of glass fibre reinforced epoxy composite tubes for cooling water system applications. First, aging of resins and composites in water is discussed. Results from tests to establish the kinetics of resin hydrolysis are used in a simple model to predict composite degradation with time, and correlated with results from panels immersed for 8 years at 20, 40 and 60°C. Then results from creep tests on tubes under internal pressure with closed ends, lasting up to 18 months are given. Creep strains are shown to be lower than those measured in similar tubes with free ends reported previously. Damaged and assembled tubes have been tested. Finally current research activities are discussed.