The influence of ovalization on OTEC cold water pipe subjected to bending moment

This study aims to determine the influence of ovality on cold water pipes (CWP) of a floating Ocean Thermal Energy Conversion (OTEC) platform. The ultimate strength of the cylindrical shell is suspected to depend on the interaction between the specific factors of the basic geometry and the imperfection parameters. The parameter that may affect the reduction in load-carrying capacity is geometric imperfection, namely ovality. This flexible pipe takes advantage of the seawater temperature difference between the sea surface and a depth of 800 meters. In this case study, the CWP is a cylindrical pipe strengthened with a stringer stiffener and has an exterior ring stiffener structure. The behaviour of this CWP under bending load is relatively unexplored. The analysis was carried out on a 10 m diameter aluminum pipe following the results of previous studies with a length between stiffeners of 100 m. The scenario used in the loading is bending loading caused by the effects of ocean currents. The results show that the critical bending moment stress derived from linear and non-linear analysis decreases as the initial ovality amplitude increases. This reduction is almost 50% of the initial bending capacity value if the ovality reaches 10%. In addition, the prediction results from the analysis will be added to the initial study of the OTEC design in further studies.