The polypropylene copolymer (PPR) is a thermoplastic material widely used to transport hot and cold water under pressure. In operation, PPR pipes are sometimes subjected to accidental damages that may cause a reduction in residual resistance or even a complete fracture of the structure. Hence the need to characterize the behavior of virgin and defective PPR pipes under pressure to develop carefully a maintenance strategy to ensure a minimum cost with the maximum reliability. In this article and according to ASTM D1599, we conducted a set of real tests of bursting on virgin and notched pipes to assess the level of damage reaches mechanically and characterize the behavior pipes in PPR pipes. The experimental results allowed and identification of the three stages of development of damage namely: initiation, progression and sudden acceleration. The estimation of the damage degree by the model of static damage led to identify theoretically the three stages of the evolution of damage. Subsequently, a theoretical reassessment of the damage level was done through a judicious adaptation of the theoretical model proposed in unified theory of damage. Theoretical and experimental results showed a good agreement.