On thermoplastic piping stress analysis

Thermoplastic piping is becoming increasingly important in the general industry applications. Owing mainly to their corrosion resistance, light weight and low maintenance requirements, plastic pipes can be found in many industry branches with their use becoming ever more widespread. Despite this fact, up to date there are no piping codes or other sound references which would clearly and univocally define the procedure and parameters for thermoplastic pipe stress analysis. Paper discusses stress analysis and design of thermoplastic piping systems and proposes a dedicated procedure for their calculation. Presuming isotropic and perfectly plastic material properties, stress intensification factors, which do not exist in open literature, have been determined using finite element and regression analysis. Results presented in the paper show that the new equations result in a much better fit and much lower mean deviation than existing equations for metallic piping. Although stress intensification factors determined based on the finite element analysis can be found even in some of the most advanced piping codes in use today, it could be recommended that in future dedicated tests on physical specimens be made in order to confirm the presented findings or suggest better equations.