<p>This study presents an analytical method for predicting elastic stress in complex piping systems with interconnected elbows and straight pipes under internal pressure. While existing research provides stress solutions for individual pipe components, their applicability to complex configurations remains limited. Finite element analysis (FEA) of various pipe geometric parameters and junction type reveal that the elastic stress at elbow-to-elbow junctions closely corresponds to the average stress at the centers of the connected elbows. Based on this observation, a set of analytical equations was derived to predict stress distributions across different junction geometries. The proposed solution was validated through detailed comparisons with FEA results across multiple evaluation sections, demonstrating excellent agreement in both simple and complex configurations. The effect of straight pipe length in elbow–straight–elbow systems was also examined, revealing a critical length beyond which stress distributions converge to those predicted by the elbow–straight junction formula. The proposed methodology enables accurate and efficient stress estimation without relying on complex numerical simulations, offering practical applicability for structural design in nuclear power plants, thermal power facilities, and offshore platforms.</p> Graphical Abstract <p></p>