Numerical study of encased RTP behavior under internal pressure

Abstract

Reinforced Thermoplastic Pipe (RTP) rehabilitation for internally corroded pipes is unquestionably a determination to extend the pipe's lifetime and reduce maintenance costs. The host pipe effectively increases the geometric stiffness of the RTP, but the pressure capacity of the encased RTP remains unknown. A study was conducted in this paper to investigate the encased RTP behaviour under internal pressure. To carry out the study, a non-linear finite element (FE) model was created using FE software. The FE model of standalone RTP was validated against the actual burst test to ensure that the model is very close to the actual response. The validated model was then extended as an encased RTP and tested under internal pressure. The non-linear finite element analysis shows that as the internal pressure rises, the encased RTP expands. The expansion of RTP is dramatically reduced once it interacts with the host pipe wall, which governs the hoop strength and, as a result, increases the pressure capacity of the encased RTP. The established internal pressure-strain curve can be a useful engineering tool for determining the actual strain of RTP under internal pressure while avoiding the costly and time-consuming full-scale experimental setup. For future work on encased RTP against host pipe wall imperfections under internal pressure, a numerical study should be performed.