Fatigue and thermal stress analysis of submerged steel pipes using ANSYS software

Submerged pipes are commonly used in the petroleum and oil manufacturing industries. These pipes include three-layered compound pipes, with inner, middle, and outer layers made of API 5L X70 steel, polypropylene, and concrete, respectively. Their different stresses, internal, external and thermal, were assessed individually. Thereafter, a combined analysis was carried out using the finite element method by means of ANSYS software. The results show that the deformations and stresses are in the safe zone, whereas thermal stresses can isolate the inner layer from the outside temperature. Moreover, fatigue resulting from environmental forces was studied to assess the maximum cycle lifetime number, deformation, stresses, and von Mises stress. Despite the most severe conditions chosen for the analysis, the pipeline was observed to withstand both negative environmental and operational conditions.