Finite Element Evaluation of Stress Distribution in the Buried Steel Pipelines in Presence of Polyethylene Coating

Stress analysis of buried pipes is essential for safety, longer life, and prevention of structural failures. The present research work is related to the stress analysis in the gas transmission steel pipeline buried in the soil. The steel pipe has a three-layer polyethylene coating with viscoelastic properties. The stresses are caused by traffic loads, including the passage of vehicles on the surface, soil weight and fluid pressure inside the pipe. The stress analysis on the buried pipe for three different states including (I) static loading- pipe without coating, (II) static loading- pipe with viscoelastic coating, and (III) dynamic loading- pipe with viscoelastic coating have been performed using finite element method. The results of numerical modeling in ANSYS for static loading and uncoated pipe have been compared with the theoretical outcomes and the accuracy of the modeling has been confirmed. Based on the obtained observations, the dynamic loading and viscoelastic coating were able to affect the stress distribution created in the buried pipe, in comparison with the static loading without coating. Also, increasing the friction in the pipe-soil interface kept the tensile stress at the top of the pipe crown constant and had a negligible effect on the stress at the bottom of the crown.