In this study, a reduced-scale model of a marine pipeline is designed and constructed in an innovative way for model experiment in the water tank. The pipeline model proposed based on similarity criterions consists of a flexible tube, which is initially straight, and stainless steel powders inside the tube. To determine the proper material for the tube of the model, study on the elastic modulus and strength of several kinds of potential materials is carried out through mechanics experiments. Polypropylene, which has never been considered for a marine pipeline model, is finally selected to be the fit-for-purpose material of the tube.
As offshore oil and gas engineering operations usually involve the cooperation of multiple structures such as vessels, platforms, pipelines and cables, their dynamic responses during operation could be complex. Therefore, a model experiment plays an irreplaceable role in the design and preparation of such kinds of operations, either to forecast the dynamic behavior of offshore structures and understand some of the related phenomena, or to provide verification for theoretical models and simulation systems that are being currently developed. In those operations, marine pipelines in deep water are inevitably on a large physical scale that requires great lengths of pipe (Brown and Palmer 2007). On that large scale, marine pipelines are extremely flexible due to large slenderness, even though they are made of steel and sometime covered by concrete. Connected to floating structures like vessels and platforms on the sea surface, during pipeline installation or permanently, a portion of the pipeline (also known as risers) is basically in a free-hanging configuration under water. As a result, mechanical responses including the axial tension and bending moment differ along the length of the whole pipeline (e.g., the free-hang section and the section on the seabed), and vary constantly in time domain. A comprehensive understanding of the dynamic behavior of pipelines is fundamental to the success of the offshore oil and gas production developments. This understanding could reduce costs and ensure the safe operation of pipeline systems in harsh environment (Morooka and Tsukada 2013). For that understanding, a model experiment is necessary. That's why a reduced-scale pipeline model is essential to perform experimental study on pipeline-involved operations in deep water such as pipe-laying, especially when the global response of the pipeline is the main concern.
