Empirical Formula for Predicting Burst Pressure of Thermoplastic Composite Pipes

Thermoplastic composite pipes (TCPs) offer superior corrosion resistance, fatigue performance, low weight, and spoolability compared to steel alternatives. A typical TCP wall comprises an inner thermoplastic liner, a continuous fiber-reinforced unidirectional (UD) thermoplastic tape reinforcement layer, and an outer thermoplastic jacket, thermally fused into a fully bonded structure. A theoretical model based on three-dimensional anisotropic elasticity, complemented by finite element analysis, is developed to quantify through-thickness stress distributions under internal pressure. Burst pressure – defined as the maximum sustainable internal pressure – is predicted by applying the Hashin fiber tensile failure criterion to the computed stress state. Parametric sensitivity analysis reveals that inner diameter, reinforcement layer thickness, and UD tape longitudinal tensile strength are the dominant factors. Focusing on the optimal ±55° winding architecture, a burst pressure database is generated to derive a compact empirical predictive formula. Validation against experimental results for glass fiber-reinforced pipes demonstrate the formula's accuracy. The resulting formulation provides a rapid and practical tool for the preliminary design and screening of TCPs.