Behavior of Reinforced Thermoplastic Pipe (RTP) under Tension

Abstract

Recently, reinforced thermoplastic pipe (RTP) is increasingly applied in the oil and gas industry. Since tensile behavior is a fundamental property of RTP, the theoretical method and numerical simulation are both used within this paper to study the behavior of RTP under tension. Using the theoretical method, the model proposed by Knapp is modified and further applied to RTP, considering the interaction between pipe and wires as well as material nonlinearity. Equilibrium equations are derived based on the principle of stationary potential energy. Using the Newton-Raphson method, the problem is solved by an iterative procedure. As for the finite element model, solid and truss elements are used to simulate the HDPE layer and wire, respectively. Results from both methods are compared and an agreement between the theoretical method and numerical simulation is obtained. Both methods can offer valuable advice for RTP design and application.