Vessel/Stinger/Pipeline Fully Coupled Analysis for Pipelaying Operation

During pipelaying operations, dynamic performance of the stinger due to vessel motion has a strong impact on the stinger capacity estimation. However, the conventional stinger structural design is based on the maximum load on the roller boxes corresponding to a target top tension value. In addition, the installation analysis uses the uncoupled vessel motion Response Amplitude Operators (RAOs) to calculate the motion induced loads on the stinger and the pipeline. Since the maximum loads on the stinger are conservatively estimated by linearly superimposing maximum forces from different loading conditions, the conventional design and analysis approach leads to either over-design of the stinger structure or underestimation of the stinger capacity. To improve conventional pipelaying design and analysis methodologies, a time domain vessel/stinger/pipeline Fully Coupled Analysis (FCA) is presented in this study. The new analysis procedure significantly improved the stinger operation limit compared to the conventional design and analysis procedure.