Theoretical analysis of reinforcement layers in bonded flexible marine hose under internal pressure

Offshore field engineering and technology have advanced immensely over the past few decades. The sector involves numerous activities including oil and gas exploration and extraction, offshore mining as well as sea transportation of minerals. For instance, the bonded flexible marine hose has been widely used in connecting platforms to oil tankers to enable oil transfer. Generally, a housing assembly comprises of vulcanized rubber, reinforced fiber and steel fitting at the end. Unfortunately, marine hoses are susceptible to failures due to induced internal pressures and bending moments. To this note, feasible offshore systems with large flexibility are needed for efficient operations. This calls for the use of multi-layered marine hoses capable of withstanding the moments and pressure challenges.

Among the available marine hose layers, steel helical wire and reinforcement layers are very important. Reinforced layers are generally made of synthetic fibers comprising of winding angles in each of the layers. Thus, the composite layers have presented numerous advantages over the conventional structures. However, the problems associated with the bonded flexible marine hoses have not been fully explored regardless of the development of several guidelines for structural design. Consequently, less emphasis has also been given to the theoretical investigation of the marine hoses. According to the researcher, however, theoretical studies will overcome the mechanical complexity of the structures by focusing on the basic layers thus providing a reference base.

Recently Fudan University researchers: Dr. Young Zhou, Professor Menglan Duan and Dr. Jianmin Ma in collaboration with Dr. Guomin Sun at the Offshore Oil Engineering Company investigated the analysis of reinforced layers in bonded flexible marine hoses under internal pressure. They aimed at developing a theoretical solution to clarify the mechanical behaviors of the reinforcement layers and further presenting a mathematical approach for multi-layer composites of synthetic fibers in structures. Eventually, the feasibility and accuracy of the method were verified by comparing the results to those available in the literature. Their work is published in the research journal, Engineering Structures.

The authors observed that the method allowed for the determination of reinforcement fiber layers that could be used to provide the desired information for guidance during the design, optimization and verification of the marine hoses’ behaviors. Consequently, it was necessary to investigate parameter and failure analysis which produced distinctly new results due to the combination of the winding angles, internal pressure and the number of layers. For instance, an optimal winding angle of ± 55 was noted. Furthermore, the computational time was significantly reduced due to the use of the programming while the post-processed results could be easily and efficiently exported as compared to other techniques.

The study successfully developed a theoretical solution to clarify the mechanical behaviors of the reinforcement layers. Therefore, the obtained findings will form the fundamentals for future research work thus leading to more advancement of the offshore engineering filed and the related operations. Also, it will ensure the efficient design of marine hoses with increased lifespan.