Structural design of composite reinforced line pipe

Due to modulus difference between steel layer and composite material layer of composite reinforced line pipe, the load is mostly applied on the steel layer, so the reinforcement effect of composite materials cannot be exerted sufficiently. To ensure the integrity of pipeline, redistribute the load proportion in structural layers and enhance the utilization ratio of composite material, the method for calculating the failure pressure and design pressure of composite reinforced line pipe was developed by analyzing the hydraulic bursting test results and the finite element model. Then, the design requirements on prestress and structural layer thickness were proposed. When prestress treatment is performed on the composite reinforced line pipe, the stress on the reinforcement layer shall not exceed 40% of fracture strength of composite material, and the stress on the steel layer shall be less than the minimum tensile strength of the steel. The thickness of the composite layer shall ensure that its stress is lower than 30% of the fracture strength and the thickness of steel layer shall ensure that its stress is less than its yield strength under the design pressure. The research results provide the basis for the design of composite reinforced line pipe.