Creep crack growth has been investigated in a polyvinyl chloride (PVC) on circumferentially cracked round bars, on both virgin and aged pipes after 22 and 35 years service. The aim is to predict the resistance to creep failure of pipes under internal pressure by using the fracture mechanics for creeping solids (FMCS) tools. The approach consists of carrying out creep tests on both smooth and cracked specimens. This experimental database is utilised in order to demonstrate the effect of aging on the creep response of the material. A master curve is then plotted, allowing the creep lifetime assessment of laboratory specimens. On the basis of the master curve and under FMCS concept, a methodology for predicting creep failure of cracked pipes is suggested.